Garn hydronic design

Antman Posted By Antman, Dec 31, 2015 at 7:18 AM

  1. Antman

    Antman
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    Sep 27, 2015
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    I'd like to get feedback on my proposed Garn hydronic design from all the experts out there! I tried to simplify the design by keeping it unpressurized. I plan to heat 2 houses, a 25,000 gal salt pool, and a 500 gal hot tub. My focus at this time is on the larger of the 2 houses. The smaller home can be delayed until next year. We are completing the construction of a carriage house which houses a Garn 2000 and its location was strategically chosen because it is between the 2 houses and on one of the highest locations on the farm which is 3' above the bottom floor of both houses.

    While I want to make it simple, I am open to suggestions about how to make it better even if I have to scrap the entire design. Fortunately, I have my wife's support and I'd like to keep it that way by getting it right on the first attempt ;). I was hoping to draw from all the wisdom from those who post on this site so I can hopefully provide insight for others who might make the plunge and become more self-sufficient.

    I guess the biggest unknown for me at this time is whether a solenoid would be sufficient to keep water elevated at the highest point in the system which happens to be where a 17x20 and 20x20 supply plenum need water coils for the updraft propane furnaces. The bottom floor has 10' ceilings and the second floor has 9' ceilings. All 3 DHW tanks and a 14x20 propane furnace are in the attic at the level of the 2nd floor which is the level where any pumps and manifolds would be installed. However, the 17x20 and 20x20 propane furnaces are above the ceiling of the 2nd floor which is 16' above the level of the Garn's slab.

    So, this means that there is an additional 5' to raise water to those 2 supply plenums. This puts me 5' above the maximum 16' rise mentioned in the Garn design manual. I was hoping that zoning with circulators might offset this additional 5'. Could this work or should I just incorporate a FPHX and pressurize?
     

    Attached Files:

  2. TCaldwell

    TCaldwell
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    Oct 26, 2007
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    Is the pool heated all year?
     
  3. jebatty

    jebatty
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    Jan 1, 2008
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    Some red flags pop up for me. The relate to the pump head in your system resulting from the 300' of 1" pex underground (is that one way or round trip?), the 230' of 1-1/4" pex underground (is that one way or round trip?), the 1-1/2" pipe main lines to/from the Garn, plus the distribution plumbing for each heat emitter, plus all the fittings, etc.

    For a partial explanation of my concern I will start with P1 0013 circulator. The "sweet spot" for the 0013 as shown by its pump curve is at 18-20 gpm which occurs at a pump head of 16-18 feet (about 5.6-7.8 psi). A flow rate of 18-20 gpm at a delta-T=20 would move 180,000-200,000 btus. But my pex pressure drop table shows that at 18 gpm the pressure drop is 0.069 psi/foot, or 15.87 psi at 230', or pump head of 36.5 feet. It is clear that the 0013 will not be able to flow 18 gpm or supply btus in the range of 180,000-200,000. Actual results will be even worse because fittings, valves, etc. add additional pressure drop and pump head.

    To get closer to what actually may happen based on your design, and if I don't consider pressure drop from fittings, etc., and I assume a flow rate of 14 gpm, then my pex pressure drop table shows that at 14 gpm the pressure drop is 0.044 psi/ft, or 10.12 psi at 230', or about 23 feet of pump head. The pump chart for the 0013 shows that it will move somewhat less than 14 gpm at 23 feet of pump head, which will move 140,000 btus at delta-T of 20.

    Obviously, if the 230' is only one-way, the problem is much worse.

    Unless about 140,000 btus is all you need at this location, based on what I see from your design chart, your underground pex may be seriously under-sized for the distances involved and there may be other design issues as well. A similar analysis can be made concerning your 300' pex run, and I would be very surprised if serious issues do not exist with that design as well.

    The Garn WHS200 is a beast of a boiler, rated at 325,000 btus maximum. For it to perform according to its capacity, you need an appropriately designed system.
     
  4. Antman

    Antman
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    Sep 27, 2015
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    I haven't heated it in the past, but I plan to keep it at 85-90F with the use of a solar blanket.
     
  5. Antman

    Antman
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    Sep 27, 2015
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    Thank you for your feedback! I was hoping to hear from you as I have picked up many good things from you in other threads. To clarify:

    1. Yes, the distance is one way and my runs will be long. House 1 has a 230' distance underground to the Garn and house 2 has 300' underground.

    2. I estimated heat losses using the slant fin app and verified them using Taco's design software. Using 72F inside temp (where my wife is comfortable) and 18F outside temp (my region of the country is relatively mild and the coldest day is 18F or higher 97% of the time), the heat loss estimate for house 1 is 150MBU. House 2 estimate is 35MBU by the same method. Per the universal hydronic formula, a 20F dT in a non-glycol system requires 15 and 3.5 GPM, respectively.

    3. I made an error by a factor of 2 estimating head loss. I used the longest distance to a load which happens to be at the highest point in the system where the 17x20 and 20x20 plenums are 21' above the Garn slab. I need an additional 50' to get to these loads. So, 230' + 50' = 280'

    wrong estimate: 280' * 1.5 * 0.04 = 16.8 feet of head
    better estimate: 560' * 1.5 * 0.04 = 33.6 feet of head

    I will redraw the plan using 1-1/2" to house 1 and 1-1/4" to house 2.

    My design comes directly from Page 25 of the Garn design manual and I am under the impression that zoning with circulators will handle some of the head in house 1. So the Garn pump for house 1 will effectively face (230' + 10' up into the attic)x2 = 480' of 1-1/2" to the closely space tees on the return side of the distribution system.

    I am still left with the question of whether to pressurize, but I suspect more needs to be revealed taking into consideration the flow dynamics of 1-1/2" buried pipe. Thanks again for your help.

     
  6. jebatty

    jebatty
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    Looks like you have a handle on the issue I raised. I remain skeptical of the design, and I also am aware of plumbing with parallel and series circulators to handle either increase flow and/or high head situations, so it is likely there is a solution. I wish you well on your project.
     
  7. TCaldwell

    TCaldwell
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    Oct 26, 2007
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    Loc:
    860-868-9014 h 203 948 0864 c nw corner ct.
    Still not sure if you plan on year round or seasonal pool heating, the reason i ask is that in our last house I heated a 22,000gal gunite pool seasonly and a 750gal gunite hot tub all year and a 3500sqft house in a 6500 degree day climate with a garn 1900. The bypassed propane pool heater was 250kbtu/hr, the hot tub had a 75kbtu shell/tube hx. The hot tub draw was intermittent once at temp and not all that noticeable, the pool was a one burn a day habit from memorial day to labor day. Even if the pool had been inside, with a hot tub and house to heat during the winter, It would have needed all of 2 burns if not 3 per day, the house has ci baseboard that would do well to 130degf. Not sure how well it would have worked with hot water coil that likes 160deg plus.
     
  8. Antman

    Antman
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    Sep 27, 2015
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    how long did it take to ride 1496 miles? I try to do a MS Ride 150 each year and it takes 2 days! Must be quite a logistical feat to make 1496 miles. Anyway, I'm curious what part of a redesign with 1-1/2" buried as opposed the original 1-1/4" plan for house 1 raises the most concern?
     
  9. Antman

    Antman
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    Sep 27, 2015
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    The kids get about 3 or 4 months to swim in 85+ water with no additional heating, just plain old sun. I'd like to extend it to 8 months if not the entire season. We rarely get temps down to 20F and for no more than a few days. Normally, we have 30-40F days mixed with warmer temps all winter. I'm not too familiar with heating degree days, but from what I briefly googled it appears HDD here is 3000. I have unlimited amount of wood and I enjoy working on the farm so multiple burns/day won't be a problem, especially as the kids get older and hopefully they will enjoy it, too!
     
  10. leon

    leon
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    Feb 3, 2013
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    Loc:
    Southern Finger Lakes Region of New York






    =====================================================================

    Hello antman,

    Am I correct in assuming you have invested in Garn 2000 already or are you are just putting pencil to paper????????

    Do you have a large source of firewood and the time and equipment to process the firewood?? Or will you be buying fuelwood?

    Before you shoot yourself in the foot and make mistakes I would like you to invest in a pair of books by Dan Holohan.
    They can be purchased from AMAZON or Dan Holohan books,

    The Paperbacks are "Pumping Away" and Classic Hydronics. Please do not start anything until you read and reread these books several times. You have to remember that these specs. given to you are written by engineers for engineers and arechitects.

    Dan writes all his books for the layman from all the experience he has gained from working in the plumbing and heating business as a plumbers helper, factory representative, wholesale plumbing house representative, and plumbing problem troubleshooter for commercial steam and hydronic heating working with huge heating loads and small ones.

    Dan writes from the point of experience and makes plumbing for hot water heat and steam heating to understand for the home owner and commercial business owner easy to understand with no difficulty and he makes reading about plumbing fun along the way.

    ---------------------------------------------------------------------------------------------

    I would like you to send your sketch to Dan Holohan and tell him I sent you by putting "LeonZ sent me to you" in the subject line.

    Dans email is dan@heatinghelp.com

    Have you considered a simple anthracite coal stoker boiler in anyway for the heating load you are planning?
    You do not need 2,000 gallons to do this as designed by you if you use an anthracite coal stoker.

    The thing is your not taking advantage of gravity and your simply trying to slap it around.

    Are you going to invest in the Oxygen Barrier Pex and the $15 per foot insulated Pex tubing for the hot water delivery and return loop?? If not wad up your drawing and burn it.

    You need guidance.

    You don't need 2,000 gallons of water to do this as coal stoker boilers are used in huge green houses, make hot water for commercial laundromats and heat many large homes and multiple residences using one coal stoker boiler for hot water hydronic heat and domestic hot water.


    I am getting away from burning wood after 33 years and I am having a coal stoker installed on the 4th of January and I wish I had it done 33 years ago.


    Just remember you have a plumbing problem you want to solve and look at it that way and that way only.

    Several things to look at:

    Will your zoning and local plumbing code permit this to even be done?

    It may not as each residence is not connected physically even though it is rural and assuming it is an active agricultural enterprise.

    Heating more than one home with a common heating plant is considered a Regulated Utility in some states-
    In North Dakota you cannot heat more than three homes using a common heating plant and unless
    the state law has changed it is still in force.

    Are you looking 30 years down the line to where these houses may be sold? It may be a huge problem with one main heating source connected to all of them for heating and the eventual sale of the properties.

    In the State of New York in Tompkins County they have a screwed up zoning area(one of two in the nation apparently) where the Town of Lansing has two separate and distinct zones, Wherein one set of zoning laws is for the Village of Lansing and another set of zoning laws for the Town of Lansing exist.

    If you have no access to anthacite coal for heating locally I think that you are going to find that a trenched geothermal system(four to six feet deep) for each place will cost you much less money to invest in if you have lots of land to to install it on and the heating and Domestic hot water loads will be much much easier take care of.
     
  11. Antman

    Antman
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    Sep 27, 2015
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    The main thing I heard you say is that I need guidance which is why I'm reaching out to the community for feedback before committing to the overall Garn pump/buried pex/distribution system design. I already have the Garn 2000 on a slab in a new barn we are finishing. My neighbor and I are processing a pile of trees the loggers left last year. It looks to be at least 50 full cords of mostly hickory, red oak, white oak, as well as other decent mixed wood like ash. The only thing we are throwing to the side seems to be sweet gum. I've estimated burning 7 and 3 full cords per year for house 1 and 2, respectively. My neighbor says he burns 3 full cords per year and his house is very similar to house 2. Code enforcement has already given me approval for the project.

    I did order the books you suggested and look forward to reading them. And, I emailed Dan the new design with larger lines and told him you referred me to him.

    As far as I know, no one in West Tennessee burns coal. Perhaps they do in East Tennessee closer to West Virginia. It seems to be either NG in the cities or LP in the rural areas for West Tennessee. LP went up to $3.70/gal down here last year when the cattle needed warming up north. Needless to say, cordwood is beginning to catch on around here. I am curious why you switched from wood to coal? For me, I enjoy the workout and the otherwise quiet outdoors. We have an endless supply of large trees on our farm. Not ever going to sell it, would love my kids to take it over when my time is up.

    BTW, the reason I chose the Garn is I wanted a simple, unpressurized system with integrated storage and I wanted to maximize the time between burns. Also, house 2 will be able to take advantage of radiant floor heating which seems to be the best way to heat. We spent $7,000 on LP last year between the 2 houses so I justified being able to pay off this install over 5 years. Of course, that clock doesn't start until the system is up and working. It would be nice to heat this season, but the clock might have to start with heating the pool in the spring:cool:

    I'm glad you mentioned geothermal. I have a 5 acre pasture by the Garn Barn and was curious if anyone knows how I should stub out the garn manifold in the event I ever want to cool in the summer?
     

    Attached Files:

  12. maple1

    maple1
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    Sep 15, 2011
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    I think cooling with Geo in the summer would need ductwork and be a completely separate system. Don't see how that can be tied to the Garn system. Everyone I know who has done Geo has ended up with higher electric bills than they were expecting.

    Have you costed out underground piping yet? That is going to be huge here. The right stuff is in the area of $15/ft, I think - and you don't want to use the wrong stuff.

    I was looking for someone to jump in about your elevation differences - I am kind of suspect about that, but don't really know.
     
  13. jebatty

    jebatty
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    Jan 1, 2008
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    Loc:
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    Thanks for the interest -- 23 days of riding, 25 days total. Shortest mileage day was 23 and longest was 97. Average/day was 65 miles. Temperatures ranged between a low of 28F (two mornings) and a high of 94F. The trip was solo, self-supported. Bicycle plus packs, gear, food, water was about 105 pounds. An amazing adventure for a 66 year old guy. This link covers a quick summary of most of the trip: Rolling

    I am narrowing down on a destination for another trip in 2016.
     
  14. leon

    leon
    Feeling the Heat 2.
    NULL
    

    Feb 3, 2013
    426
    17
    Loc:
    Southern Finger Lakes Region of New York



    ============================================================================

    Hey Maple One, Happy New Year to you and all on the forum.

    It was a tad late when I posted and handfiring the coal boiler.
    I barely touched the Pex issue. and did not do the formulae for
    the head loss issues and the points of pressure change in his
    system as it was 2 in the morning when I waddled to bed after
    loading the boiler.

    I will do the number crunching for that when I waddle back from
    my fathers place if no one jumps in before that as it can go two ways
    with circulators in each residence pumping up hill with a steel expansion
    tank in both homes in the highest location being the attic and a third
    for the ceiling above the Garn boiler for a heat exchanger used to transfer heat
    to the two homes heating loops.


    He is going to have three points of pressure change not including
    domestic hot water loops(if used) being home number one,
    home number two and the circulator used at the GARN if used
    there BUT having the circulators in the homes is easier to deal with
    as no pumping down will will occur and he will have little if any
    water hammer pressures to worry about.

    Bladder tanks lose one PSI annually as a rule and steel expansions
    have zero issues period as they have only water in them with the
    airtrol valve that controls the air bubbles by slowly allowing them
    to enter the path into the expansion tank. after the hot water
    enters the steel expansion tank it cools and allows the air bubbles
    to be absorbed into the cooler water.

    The steel expansion tanks do not have any moving parts they simply take advantage of gravity to the fullest extent and you can have very large expansion tanks or a number of small ones plumbed in parallel with a common header pipe to do wonders for heating and cooling/chilling duties with small circulators.

    As I said a steel expansion tank has to be above the boiler and you
    dont have to worry about them ever unless you drain the system
    wherein they have to have the airtrol vent opened up to allow
    them to drain before the water is drained out of the system.

    He will need at least two steel expansion tanks to allow the
    circulators to operate. preferably he will have a circulator in each
    residence as the steel expansion tank will have to be higher than the
    Garn.

    Folks are going to disagree with me about that but if you use the simplicity
    of a steel expansion tank combined with A LARGE ENOUGH heat exchanger you
    will not need monster size pex for this as the smaller 3/4" insulated $15.00 per foot pex
    only loses 1 degree per one hundred feet.

    The more water the better the flow control in his case and there will be no little to no issues with water hammer as he will be able to keep the water pressure at atmosperic or a little more. you are not creating a great deal of pressure with the water you are just circulating it from the homes to the garn barn if you use a heat exchanger from the garn to the two house heating loops.


    Just an FYI; the larger the steel expansion the greater amount of water you have to to create the water weight in the system and reduce problems with air bubbles and you will have them unless you install Power Purge valves/boiler drain valves that will allow you to push the air out of your systems at each residence at filling and also using the boiler drains on each feed and return for each circuit which eliminates chasing air bubbles
    as the air bubbles would be forced downhill to the hose you are using to vent the specific heating loop/home with very little effort.

    The main benefit is that you are not pumping against the water weight of the GARN as the water weight of the GARN stops at the heat exchanger with a separate circulator to move hot water through the heat exchanger used for the two heating loops.

    As far a circulators go you don't need large diameter pex as long you do it the right way with check valves in the circulators to push the water up hill to the Garn Boiler. Besides that the larger pex is going the strip more heat from the thermal mass of the water in the Garn 2000 and you have to think about that as you will have to fire the garn more often or keep a fire going with it.

    You can only push so many BTU through a given pipe diameter so 3/4 baseboard releases 540 BTU of 170 degree water per foot.


    SO if you take my circulators for example the B+G NRF25's being simple numb dumb three speed pumps at speed three setting each one will circulate 20 GPM at 18 feet of head.

    If you tie in a second B+G NRF25 that's another 20 gallons per minute for a total of 40 gallons per minute NOW understand that 60 minutes times forty gallons per minute is 2,400 gallons in one hour of circulation.

    In forty five minutes you will have moved 2,000 gallons of water and returned the same amount of cooler water back to the Garn and you have cooler water to heat up again and your already behind
    the proverbial 8 ball.

    If you use 3/4 pex and four gallons per minute from each home you will only be moving 480 gallons of cooler water back to the heat exchanger per hour to be reheated to 170 degrees if and only if you use a pair of 3/4 pex loops to the heat exchanger that be connected to a circulator that moves hot water from the boiler to the heat exchanger that is being used to heat the two 3/4 pex loops.
    (your entire mass of hot water (2000 Gallons) will be exchanged every 4 hours rather than every 45 minutes using larger circulators and pex tubing.

    Using a lower water temperature shed heat at lower rate but there is less heat loss
    per linear foot. 140 degree water releases 340 BTU per hour per linear foot of 3/4 baseboard.

    I need you to understand that water to air coils in your duct work are huge energy hogs and can strip the BTU's from the water like a vacuum as all it is is a RADIATOR so keep that in mind please and they same applies to large PEX and dont let anyone say otherwise because the coils will strip the heat from the water and return very cold water back to the Garn if you go that route without a heat exchanger in the Garn barn.

    The other thing is that if a system bypass loop is used you can keep the Garn boiler water hotter at all times

    ============================================================================

    Your going to run out of hot water sooner if you use larger diameter Pex and then you will be burning around the clock loading may more times per day.

    NOW rounding off the Pex you have 1,100 feet in total pex footage to and from both residences.

    If 3/4 pex is used you have 1.84 gallons per hundred feet times 11 gives you 20.24 gallons in the pipe loops in total with 3/4 pex per hundred feet.

    I hope you see where I am going with this as you can use lower temperature water to heat the homes and keep the boiler hotter to provide a faster recovery rate for the two 3/4 inch loops. The circulators will run longer but they dont care.

    If you intend to use the 1 1/4" Pex your going to need much more hot water and a used surplus insulated 8,000 gallon railroad tank car body will be the only solution as long as a system bypass loop is used to heat the 8,000 gallons in the surplus insulated tank car body by using the 2,000 gallons in the Garn boiler constantly circulating between the tank car shell and the Garn for the insulated surplus tank car body to act as a buffer tank for the garn boiler and the heat exchanger if used.

    AS long as a LOW WATER CUTOFF is used in the 2 lower boilers the system will be better protected with the water volume limited to the volume in the pex loop from the heat exchanger loop+ the boiler+and the water in the steel expansion tank if used.

    By drawing the hot water off the top of the boiler you are pulling the air bubbles out and they are easier to purge with a module that has a standpipe with a boiler drain in the top of it( if your current boilers do not have an internal baffle and an air vent in the steam chest.

    Your going to be chasing air bubbles if you cannot purge each loop individually.

    Unless you use the good 3/4" pex at $15.00 a foot FOR ALL underground lines your going to have to keep the lawn mower heated and ready to work.

    Cooling gets little more involved only because you have 5 acres to use and if each home has a straight shot to it in a 1,000 foot loop with the lines 50 feet apart a smaller geo unit would work as the ground temperature would be as low as 52 degrees at 4 feet deep.

    BUT that is not saying you could not run a longer loop if you have the room if you can clear the land.

    Alternatively a deep and narrow in width pond long in length could be dug and lined with a one piece liner to use as a heat exchanger for chilling spiral loops of black PVC that is held down with cinderblocks.
     
  15. leon

    leon
    Feeling the Heat 2.
    NULL
    

    Feb 3, 2013
    426
    17
    Loc:
    Southern Finger Lakes Region of New York
    ============================================================================

    I decided to switch to coal stoker for a lot of reasons.

    100+ year old former one room house, poorly insulated and huge indbreaks/shelterbelts
    over 70 feet high.

    Very little space with no basement and pellet boilers are more expensive than a coal stoker boiler


    The former owner lived in home seasonally and hid all the problems-the home was purchased in 1978 before the laws changed to protect the purchasers rights when buying a home.


    Lousy draft even though I live 1,140 feet above mean sea level
    Age of 61.
    My wifes age of 61.
    The wood supply.
    Always tired of tending the boiler until 2 or 3 in the morning.
    Looking forward to saving $110 a month or more and having more time.
    I have a 3-5 year coal supply on hand.
    Rice coal provides more usable heat per ton than cord wood or kerosene.
    Eliminating the rats nest of plumbing used as system.
    Temperature balancer between the two boilers.
    Eliminating the second circulator for temperature balance between boilers.
    Eliminating the separate kerosene boiler by investing in a Keystoker KAA-4-1 dual fuel unit
    Having more hot water in the boiler 51 gallons including the steel expansion tank, heating loop and boiler.
    Saving money on electricity by eliminating the second circulator

    Cost of heating Oil-Here between 110.00 to 303.00 a month depeding on market conditions and the cost of oil will go back up.

    Poor service from my heating oil company:
    I have been left high and dry several times with having,
    run out of kerosene while on their budget plan for oil deliveries,
    Late night burner failures and being told that my burner cannot be serviced
    because they no longer make parts for the specific RIELLO burner
    and having replaced two of them when It was NEVER NEEDED EVER!!!!
    My desire to eliminate the as my supplier PERIOD.



    No access to natural gas nor do I need it.
    Low propane cost for hot water less than 25.00 per month

    The locals around here buy logs at $33.00 a ton and charge over $200.00 a cord delivered in some bad years and the processed wood is poor and many of the rounds/splits have to be resplit.

    I had enough when I fell on the ice made from the commercial firewood splitters heat
    from the exhaust and hydraulic tank I owned had a habit of creating pools of water from all the heat it created and when I used the salamander to preheat it and then froze up.

    One late night I was done splitting wood and slipped on the ice that was created and I thought I had a facial fracture I was bleeding so much and creating snot rockets and I spent five hours in the local ER and I decided I had enough after 31 years.

    The anthracite coal fields are only 3-4 hours south of me on Route 81 and I can buy bagged coal at a very reasonable price.


    I would have installed a Van Wert Anthratherm coal stoker at the time 33 years ago if I could have afforded the installed price but the coal and wood boiler install was 2K less.



    Live and learn.

    Be sure to install a system bypass loop to keep the boiler water hot and reduce cycling.

    Dan Holohan covers this extensively in his books for fossil fuel boilers and it also works for coal and wood boilers and dont let anyone tell you differently.
     
  16. jebatty

    jebatty
    Minister of Fire 2.
    NULL
    

    Jan 1, 2008
    5,459
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    Loc:
    Northern MN
    My focus as you probably can tell is mostly about the math plus efficiency. Know the heatload, determine an acceptable pump head, size pipe and fittings accordingly, pick an efficient circulator to deliver the gpm at needed delta- T.

    Also place unions and valves to isolate all components that may need future service/replacement. Install sensors to monitor all important points. This will allow you to fully understand how your system actually operates/performs.

    Lots more about all of this. Asking specific questions is better than generalized questions.
     
  17. leon

    leon
    Feeling the Heat 2.
    NULL
    

    Feb 3, 2013
    426
    17
    Loc:
    Southern Finger Lakes Region of New York
    Hello Antman,


    Please understand I only want to help you.

    With regard to hot water for heating
    you have to have a complete grasp of basic terms.

    You are using Circulators not Pumps.
    The terms are exchanged too often and too freely.

    A circulator with a check valve cartridge is better for
    moving chilled water for cooling or hot water for hydronic
    heating long distances or uphill.

    There are five terms I want you to understand fully that you need to understand fully as they are never dealt with completely by many sellers of heating systems.

    1. Total Head Without Flow/Shut off Head

    2. Total Head Without Flow

    3. Suction Static Head

    4. Friction Head

    5. Discharge Static Head


    Using a single heat exchanger for both loops "in the carriage house"
    with a small circulator will reduce the possibility of leaks on the
    down hill side as the amount of water will be limited to the total water
    volume in the two homes and only the two homes as the all heating
    water stays in the carriage house.

    If you have a buffer tank in the carriage house you have more hot water
    at all times, the more hot water the better.
    You can use the buffer tank as a sealed tank that can feed the heat exchanger
    that is shedding heat to the two heating loops.

    ----------------------------------------------------------------------------------------------

    Using steel expansion tanks in the attic in both homes provides you with the
    back pressure in the system that will aid the small circulators with check valves
    in pushing the water uphill with very little effort.

    You cannot use a steel expansion tank and a bladder tank in the same system as the circulator will be confused and have no point of pressure change. AND the automatic air vent will suck all the water out of the steel expansion tank.

    You need to have valves to separate the fossil fuel boilers from the garn wood boiler loops and shut them off when you use the fossil fuel boilers.

    Be completely comfortable with the above terms
    before you make any rational decisions for the
    heating load you have and understand fully that you
    will have more hot water to use if you use 3/4 inch Inside Diameter
    Pex Tubing.

    Your going to waste money and heat if you do not use the
    insulated oxygen barrier pex tubing that costs $15.00 per foot
    as it only loses one degree per 100 foot of length from the boiler
    to the heating load and retains more heat returning to the heating
    appliance-meaning the Garn Boiler. And your going to need to use
    the lawn mower or the rotary cutter over both PEX pipe runs to the
    carriage house. THE less expensive wrapped insulated PEX loves water.
     
  18. Antman

    Antman
    New Member 2.
    NULL
    

    Sep 27, 2015
    51
    0
    Loc:
    Memphis, TN
    Just wanted to say thanks to everyone for the responses and Happy New Year! As I expected, I have some new things to think about. I've heard it before, "There's more than one way to skin a cat." And, I am taking things slow because I want to give myself the best chance of success even if I don't heat at all this season. I'm going to call Garn and let them know my progress and see who they think I should hire for the design based on my personal situation. Fortunately, I have a father-in-law and grand-father-in-law who have been general contractors their entire lives and want to be involved with other installs if this one goes well. My job, other than being the fetcher and finder-of-the-board-stretcher, is to get the design right. It is clear to me that that requires more experience than I have.

    Until then, I guess I'd like to say that I feel Logstor could be the best preinsulated offering. I did get a quote on 1-1/4 and 1-1/2 dualpex and I think it's overpriced. For my long runs it won't be the best option now. I have been back and forth on the pros and cons of preinsulated vs. trench-and-foam. For my setup, I think a modified trench-and-foam: Spray 2-component PUF in a form made of XPS board glued together with 1-component PUF, screws added for additional rigidity including spacers to hold lines in place. Coat of bluemax. Lay down fiber. Additional bluemax layers. 6mil plastic glued back onto itself with as much bluemax and a single layer of fiber as you can get between the overlap making the 6mil joint water tight. We did a materials test and the results look promising. I was surprised how much of a difference the fiber makes. If you are willing to give up on fighting the PUF aging process, I do not see how preinsulated offers any advantage in terms of water resistance. In fact, the logstor jacket may not have the ability to reseal punctures as well as the blueMax with fiber seems to offer. If anyone has a scrap of logstor I'd love to perform that experiment.
     
  19. leon

    leon
    Feeling the Heat 2.
    NULL
    

    Feb 3, 2013
    426
    17
    Loc:
    Southern Finger Lakes Region of New York
    Spray foaming trench lines gets very expensive and the insulated tubing is more forgiving with ground shifting and settling over time

    Thats the major reason for replacing the trench dirt with mason sand or concrete gravel sand and installing pipeline danger tape a foot above it BTW.

    Placing the tubing below the frost line pays you it does not cost more as a gravel sand filled trench is safer on all piping.

    Even burying the tubing on one side of a shallow trench with a foot of sand above it will pay you big dividends in longevity and cost less per foot of excavation expense as you can rent a trencher and fill the trench with sand below the tubing and then to the ground surface.
     
  20. Antman

    Antman
    New Member 2.
    NULL
    

    Sep 27, 2015
    51
    0
    Loc:
    Memphis, TN
    OK. I just realized that both Logstor and the Garn Design Manual are using ID for underground pipe whereas the ASTM sizing for other pex such as uponor which I plan to use is sized closer to OD. This changes things a bit.

    So, for me to get 15 GPM when all 3 of my WTAHX call for heat (20F dT), the smallest logstor I should use is 1-1/4" dualpex (1.28" ID) for my underground run of 230'. I would need to use 1-1/2" uponor for the distribution pipe which has an ID of 1.24". This should be able to provide 15GPM to supply my 150MBH load when all WTAHX call for heat at the same time. However, I likely would not be able to consistently get enough BTUs for DHW. I also would not be able to heat the pool and spa all winter. While the house would likely be able to get nice and toasty, I would be limiting my Garn from delivering the 325MBH that it is capable of putting out.

    On the other hand, if I get 1-1/2" logstor dualpex (ID1.6") for the underground pipe and 2" uponor for the distribution pipe (ID1.6") I could get 270MBH if all loads have similar 20F dT. In this scenario, not only could I get the 15GPM for all 3 WTAHX calling at the same time, I could get an additional 12GPM for DHW/pool/spa heating in the coldest of weather. The cost of going this route with the larger underground/distribution combination is a lot, but, as I've heard before, it's a one-time cost and will make use of the Garn 2000's full potential.

    Now that this is clear to me, I think it makes more sense to put a FPHX by the Garn and pressurize the system on the underground/distribution side of house 1. Another option is to perform the modified trench-and-foam I described earlier with 2" underground pex (1.6" ID) and 1-1/2" distribution pex (1.6" ID). Either way, the circulators will work more efficiently because there will be less of a pressure drop, not to mention avoiding corrosion of cast iron pumps, dezincification of brass, etc.

    I will redraw accordingly and post later tonight.
     
  21. maple1

    maple1
    Minister of Fire 2.
    NULL
    

    Sep 15, 2011
    7,490
    1,307
    Loc:
    Nova Scotia
    That was some of my feeling also on the pressurized topic - but I didn't really know so was waiting to see if you'd get more input on it.

    And, to put it in 'For Dummies' talk on another thought on it - I was also thinking your water wouldn't stay in your boiler (& system) with the rest of the system so far above it. I could envision it running out of the top of the boiler.

    I think with that much underground I would heavily consider spraying in trench - depending on what kind of a deal you can get from a local spray foam guy. Usually the cost/foot might come down a bit with more footage to do.

    Also one more on your DHW comment - DHW is a very small part of a heating load compared to what your other HXs & houses will be using. So I would expect you could heat your DHW pretty well no matter what else you do. I can heat our DHW for a month with resistance electric for what it would cost to heat our house for only one day the same way. Unless of course you are rather off the charts with your DHW use.
     
  22. jebatty

    jebatty
    Minister of Fire 2.
    NULL
    

    Jan 1, 2008
    5,459
    758
    Loc:
    Northern MN
    That ID indeed is important, glad you noticed that.

    Keep in mind that although the Garn WHS2000 carries a 325,000 btuh maximum output, it probably is unrealistic to expect to see that for extended periods of time. My rule of thumb for gasification wood boilers is that average output over a burn is about 70% of rated output. Also keep in mind the Garn is best operated in batch burn mode: burn a load (or a couple of loads), let the fire go out, clean the ash and dead coals, and then the Garn is ready for another batch burn.

    A couple of years ago I did extended and intensive data logging on a Garn WHS3200, rated at 700,000 btuh. Over an 18 hour period I was able to keep the Garn fueled at the rate of 100 lbs of wood per hour, and by the end of the period the Garn had to be allowed to burn out because the firebox bed was loaded with coals and additional wood could not be added. Also, actual output over the 18 hour period was measured at 500,000 btuh, which is almost exactly 70% of the rated output.

    Also keep in mind that if you need consistently very hot water, 160F minimum, even as low as 140F minimum, your Garn will need to be fired pretty consistently to provide that hot water. That also would be true of other gasification boilers. If you can use water down to 120F or lower, then you have a lot more flexibility in firing your boiler. Of course, heat loads play a big role in this.
     
  23. leon

    leon
    Feeling the Heat 2.
    NULL
    

    Feb 3, 2013
    426
    17
    Loc:
    Southern Finger Lakes Region of New York
    I wish I could say definitely that your going to have enough hot water but you are going
    run out of hot water unless you the 3/4 pex in two loops passing through a water to water heat exchanger in the carriage house.

    Saying that I believe your going to run out of hot water quickly with that pex ID as you will be pushing 900 gallons per hour when calling for heat where you will have a complete exchange in 2 hours and 16 minutes+-.

    The laws of thermodynamics are against you unless you use 3/4 pex for both loops and circulate 8 gallons per minute "in total" with a water to water heat exchanger and in combination with a 140 low and 160 high aquastat temperature setting.
    =======================================================================
    Quoting from Danholohans book "Classic Hydronics" from Page 17;


    Quote:

    " When your sizing that new boiler"


    Boiler manufacturers rate their boilers they use a bunch of terms to do this.
    Let me take a minute to explain (or at lest try to explain) what thats all about.

    When you look at a boiler manufacturers catalog you'll see that there are seveveral types
    of ratings for each boiler. Theres the Input rating, The Gross Output rating, which they call the
    DOE Heating Capacity nowadays (DOE is the U.S. Department of Energy) and then there's the
    Net Output rating. You pick one or another to size a boiler. But are you sure you picked the right one?

    To make things even more confusing, some of the ratings are shown as Btuh (British Thermal Units per Hour),
    while others are listed as Square Foot Equivalent Direct Radiation or EDR for short (and here you'll find different numbers for water and steam boilers). Then we have this other column for Gallons Per Hour, which applies to fuel oil,
    and another for Therms, which applies to gas.

    OKay here is whats going on. You have three basic columns. First theres Input, Thats where you'll probably find the ratings in Gallons Per Hour or Therms because this column has to do with fire. What you're seeing here is the amount of heat that the fire is putting into the boiler. You PUT the fire IN and thats what they call Input.

    But, not all the heat that enters the boiler winds up in the water. Some of that heat goes up the chimney and is lost forever. There's alos some more heat lost through the boiler's jacket, but this is one of those vague areas because if the boiler is in the house, can we really say that the jacket losses are gone for good?. And there are some boiler manufacturers who will tell you that thier jacket insulation is so fabulous that British thermal units hardy ever choseto leave that way, but whatever.

    Next, we get to Gross Output (or DOE Heating Capacity). Gross is what's left over after the boiler has suffered the heat loss up the cminey and through the jacket. Now this term can be a bit confusing because Gross usually implies that you're dealing with the whol enchilad, as in Gross Income (which means before taxes, right?). But in the world of hydrononics Gross means, "whats leftover" instead of "what you start with." Or to put it another way Gross means "after taxes." "Taxes" in this case, being the price you pay when you send heat up the chimney and through the boiler jacket. Just remember this:
    Gross Output is the amount of heat that rideson the water that's flowingout of the boiler. It's the heat that's available to the whoel system(and maybe that's why they call it Gross).

    Ready for the next factoid? Here goes: The difference between the the Input and the Gross Output represents the combustion efficiency of the boiler. For instance, if a boiler has an input of 200,000 Btuh and a gross output of 160,000 Btuh, that boiler would be running at 80% combustion efficiency. It's not that hard to figure this out. Just divide the larger number into the smaller number and then multiply the result by 100 to get a percentage.

    Unquote:


    This is the reason I mentioned the surplus insulated railroad tank car body as a buffer in your installation.

    This buffer would let you heat the water in the buffer tank at a high temperature and the Garn would continue to circulate 4 gallons per minute of very hot boiler water into heat exchanger for the the buffer tank and have a complete exchange in 200 minutes.

    When the buffer tank comes up to temperature, lets say 160 degrees that 8 thousand gallons would be able to shed the heat through the heat exchanger that is shedding the heat to both loops at 8 GPM in total for 1,000 minutes or 2 hours and five minutes. The amount would probably be much less once the buffer tank comes up to temperature of course becuase the buffer tank is insulated and sealed from heat loss.

    surplus insulated tank cars are available for sale and you can sell the trucks and axles to defray some of the cost.

    Buying a big buffer tank "Uninsulated and new will cost much, MUCH more money than a surplus insulated railroad tank car at the end of its service life which is typically 40-45 years of service.

    I want to help you not hinder you, I want you to suceed not fail.
     
  24. maple1

    maple1
    Minister of Fire 2.
    NULL
    

    Sep 15, 2011
    7,490
    1,307
    Loc:
    Nova Scotia
    Where & how did you come up with 900 gallons per hour & 3/4" lines?

    EDIT: Nevermind on the 900 gph, I see that in the 15gpm mentioned earlier.
     
  25. maple1

    maple1
    Minister of Fire 2.
    NULL
    

    Sep 15, 2011
    7,490
    1,307
    Loc:
    Nova Scotia
    I'm kind of wondering about those heat loads.

    150,000 btu/hr seems like a lot for a place that doesn't get colder than 20f.

    From my burning habits here the past couple of years, I think I'm in the area of somewhere between 500,000 & 600,000 btu per day. It was -18c here this morning (0°f). It is now -12c (10°f). I'm in a 20 year old 2700 sq.ft two storey (plus 1500 sq.ft. basement), on an open hilltop.

    Unless I missed something along the way...
     

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