Critique my plan please

[JeepDoug]

Well, spring is almost here . . . so who's planning the installation of a wood boiler? Yup, This guy . . . Doing my homework, I settled on a Varm from Dean at Smokless heat, so now I'm finishing up my design before I pull the trigger and start assembling all the pieces . . . I've attached a sketch of my plan for the hydronics. I've based it mostly on what others have already done and posted here and elsewhere, but I would appreciate if some of you guys who have done a lot more of this then I to take a look and make changes. I am not an HVAC pro, I'm not a plumber, but I am proficient in the basics of both, and have worked installations as the labor on several jobs. . this is my first time designing a system on my own . . . I am kind of stuck with the 2 zones being separated like they are in the sketch, i know, not ideal, but it's what I've got for now. My goal is to install a Vedolux 37 with 2@ 250 gallons of storage while still using my existing oil HW boiler as the backup into the existing 2 zone baseboard system . . .

my big questions for now:
1. how do the 2 buffer tanks ideally connect to each other?
2. what type of check valves should I specify, and are they in the correct locations in the sketch?
3. where does the boiler system fill enter the system? (I call it the auto fill)?
4. where is the appropriate location to put the air scoops, and what type are recommended? (I do have loop purge valves already at each loop not indicated in the sketch)
5. Of course, what have I done wrong, and what mistakes have I made? what have I overlooked?

Thanks again for any help any of you can provide!!

 

[JeepDoug]

PS, I would be glad to send an email copy PDF of the sketch to anyone if you would be willing to mark it up and send back . . . or even mark it up and Re-post it here for others to see . . . not sure how this sort of thing is usually done . . . just PM me an email address and I'll shoot it out to you.
-Doug.

And I guess I should have included a key: The Z things are Check valves, the Circle with 2 lines are ball valves, the squiggle on top of the boilers is a blow off valve . . . sorry if the symbols are not standard . . .

 

[JeepDoug]

Ok, sorry about another thought, but i tend to get obsessed and can't focus or sleep until an issue is resolved . . . I just saw a system design sketch posted by woodwacker . . . . and he uses a heat exchanger to isolate the house zones from the buffer tank storage / boiler loop . . . does this simplify the design or istallation at all? Wonder if this is a better way to go then sending every drop of buffer tank water thru the house . . . and does using one drop the efficiency of the system (thru loss in heat transfer) enough to matter?

 

[leon]

Well, spring is almost here . . . so who's planning the installation of a wood boiler? Yup, This guy . . . Doing my homework, I settled on a Varm from Dean at Smokless heat, so now I'm finishing up my design before I pull the trigger and start assembling all the pieces . . . I've attached a sketch of my plan for the hydronics. I've based it mostly on what others have already done and posted here and elsewhere, but I would appreciate if some of you guys who have done a lot more of this then I to take a look and make changes. I am not an HVAC pro, I'm not a plumber, but I am proficient in the basics of both, and have worked installations as the labor on several jobs. . this is my first time designing a system on my own . . . I am kind of stuck with the 2 zones being separated like they are in the sketch, i know, not ideal, but it's what I've got for now. My goal is to install a Vedolux 37 with 2@ 250 gallons of storage while still using my existing oil HW boiler as the backup into the existing 2 zone baseboard system . . .

my big questions for now:
1. how do the 2 buffer tanks ideally connect to each other?
2. what type of check valves should I specify, and are they in the correct locations in the sketch?
3. where does the boiler system fill enter the system? (I call it the auto fill)?
4. where is the appropriate location to put the air scoops, and what type are recommended? (I do have loop purge valves already at each loop not indicated in the sketch)
5. Of course, what have I done wrong, and what mistakes have I made? what have I overlooked?

Thanks again for any help any of you can provide!!

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As you are in Pottstown, PA., have you considered a coal stoker????? Its a lot less work and plumbing and you do not need storage tanks.


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If you are really going to do this your plumbing can be cut in half.

There is no reason you cannot connect the boilers in series and simply use the buffer tanks for BUFFER TANKS with the cooler return water being stored in the tanks and simply reheated. Do not forget that your radiation can only provide you with so much heat per gallon of hot water.

2 expansion tanks are a no no and your circulator should be pumping away from the boiler to the zones. by using two expansion tanks your circulator will have no point of pressure change.

You can use one steel expansion tank for all this and not have to bleed radiators as long as you have boiler drains on the return loops to vent all the air and the remaining air bubbles are absorbed by the water in the steel expansion tank.

Do yourself a favor and send your diagram to the local B+G or TACO technical rep and they will correct the diagram for you to do this with little fuss if you are going to burn wood. BUT as I said a coal stoker boiler is easier to plumb up and you do not need storage and the extra plumbing.

 

[maple1]

Dean should be able to give some input or suggestions.

 

[JeepDoug]

Hi Leon, thanks for the input . . . Wood is a waste product for me . . . so I am using it as free fuel . . .
Let me make sure I understand: you say the circulators should be on the SUPPLY side, pumping HOT water to the zone? I was under the assumption that they PULLED water from the zone and were placed on the RETURN side feeding into the boiler?

Thanks for the info on the expansion tanks, I'll look at that and make the change . . .

 

[leon]

Hi Leon, thanks for the input . . . Wood is a waste product for me . . . so I am using it as free fuel . . .
Let me make sure I understand: you say the circulators should be on the SUPPLY side, pumping HOT water to the zone? I was under the assumption that they PULLED water from the zone and were placed on the RETURN side feeding into the boiler?

Thanks for the info on the expansion tanks, I'll look at that and make the change . . .

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Yes, that is how I have my single circulator and It works perfectly fine and it helps to pull any remaining micro air bubbles out and into the steel expansion tank as there is no need for the air scoop.

You can plumb the circulator any way Doug, but the ideal way is to install them on the top of the boiler with isolation flanges preferably with the isolation flanges with drain cocks so you can drain the water in the impeller chamber into a bucket before you unbolt the circulator from the flanges.

I have a vacuum gauge on the suction side of the circulator and a pressure gauge on the discharge side of the circulator and that lets me know if the circulator is going bad because it will be pulling a large vacuum pressure gradient "Hg". I also have a pressure and temperature gauge on the return line to the sump of the coal stoker to keep track of water temperatures.

I also have a 4 inch square bottom tapping Marsh instruments Marshalltown pressure and altitude gauge in the steam chest
of my coal stoker because Keystoker has been using junk Chinese Gauges and digital boiler controls and I almost had my house get blown up because the Hydrolevel 3250 Plus did not shut my boiler down when it had a low water condition.

The use of a true triple gauge lets you set your operating pressure with a manually adjusted pointer on the dial and you can always see how the boiler(s) is/are working and you can operate at a very low pressure at all times- mine runs between 4-12 pounds at all times and you can run at very low operating temperatures too. I have run my system at 140 low 160 since I installed the old hand fed wood and coal boiler and it works fine it only does not heat well when I use oil as I have no additional storage but I do not burn that much oil anyway so....

I got rid of all that digital junk and installed a Honeywell L8124L1011 triple aquastat and a B+G Bulldog RB-122-E low water cut off after the replacement Hydrolevel 3250 Plus turned the Low Water cut off function off while I ran the boiler on oil to test it.

The Hand fed wood and coal boiler I had which was tied into the oil boiler for back up had 2 simple strap on honeywell aquastats and a Honeywell L8214 triple aquastat to control the oil boiler if the wood and coal hand fed boiler got too cold if the fire went out and I never had an issue using that set up for 33 years.
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As I said plumbing the boilers in series saves money and work and if you want to use oil just shut off the wood boiler and let the all water flow through the oil boiler unhindered without installing boiler to boiler bypass plumbing. Just be sure isolate the boilers with 4 good ball valves and 4 unions to allow for any forseable repairs or an oil boiler change outs
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The boiler builders installed circulators on the bottom pumping to the boiler that way years ago to simply save crating cost when they shipped the packaged boilers they designed for one story homes using hot water heat.

The plumber or homeowner had to drain the boilers to change circulators which becomes messy at times and can cause electrical problems too if you have a leak as well as cause accidental electrocutions.


I will suggest very very strongly that you order two paper back books "Pumping Away" and "Classic Hydronics" written by Dan Holohan. Dan is a former plumbers helper, plumber and HVAC technical sales rep that has been in the business for many years and when he writes about plumbing and heating he makes it fun to read and easy to understand for both the layperson/homeowner and plumber.

Pumping Away is a small paperback with large type and Classic Hydronics is a wire bound book which make it easy to
rear and show the many plumbing designs that have been invented and it has larger type as well.


You can purchase his paperback books directly from him at www.dansbooks.com and eliminate the middleman.

I have both of these paperback books as well as "What Hydronics Taught Dan Holohan" and they are well written and easy to understand and he goes into detail talking about plumbing and heating and the history of plumbing and heating and he makes it fun to read and he brings real world examples to show the reader about plumbing history of all types and as I said you will have fun reading these books.

 

[velvetfoot]

Hi. I also think you should contact the distributor.

I think you could get a lot of different responses.

On the autofill valve, I had an issue where the boiler protection valve closed when the boiler cooled off and isolated it. Then the pressure would drop as it continued to cool. The autofill valve would open and repressurize the isolated loop. The cycle would continue until eventually the pressure relief valve popped during a cycle. I have the autofill connected to both sides of the boiler prot. valve now, but there is some flow bypassing the valve now through the .5" line. Probably not ideal, but that's all I could figure out.

I think maybe spring operated check valves may be what you want.

I'd say, why not another large diameter connecting pipe on the other end of the tank? The more the merrier, I'd say.

The Spirovent bubble remover is nice. I'd say put it/them on a hot supply pipe coming out of the boiler. The hotter the better.

On the tank and oil boiler pumps, I'm wondering if you might not want to use those fancy pumps that maintain constant pressure. So, if only one zone valve opens, ORRR, if the loading pump is on and a zone valve or two is open.

I think you might want the tank pump on the discharge side of the tank, but I don't know why, ha ha.

I think parallel is generally considered better for heat loss. My pellet boiler is stone cold when on oil mode.

Anyway, there are some sample diagrams in the sticky, and I'd contact the distributor. Good Luck!

 

[maple1]

From a quick look, I see quite a few similarities with my setup.

My circs are down low on the returns - no issues. Well, my main zone one is. (Also the loading unit circ). The one on my backup electric boiler is on that boiler outlet - gets used very little.

Highly recommend Grundfos Alpha for load circs, when there are multiple zones with one circ.

I would perhaps suggest putting the top tank load outlet at the same end as the boiler supply inlet (top right looking at the diagram), and similarly the bottom tank return inlet on the same end as the outlet to the boiler return (bottom right). Otherwise water might short circuit when drawing from storage (the right side of the tanks might not get fully utilized). I use just one tapping for both for these purposes, with a T just outside the tank, but there are subtleties in the way you would pipe to help prevent drawing through a cold wood boiler when drawing from storage when not burning.

Autofill can go pretty well anywhere, mine is hooked into the bottom left front small tapping on mine. But I keep it valved off, unless I need to add some water for some reason (maybe after bleeding some air) - then do it manually by opening an isolation valve then closing it again after I've let enough in.

As said, quite similar to mine, which I set up at first to not draw any water through storage when the backup is going. But I ended up drilling a small hole in a check valve flapper (I just used 'cheap' swing checks) to let just a little through, to reduce short cycling of my backup boiler and it also keeps some heat in my storage to reduce risk of pressures dropping out too much & make it quicker to recharge when I burn again.

I'll repeat - Dean should be able to help.

 

[dogwood]

Tarm Biomass has a lot of plumbing schematics you can check against yours.
http://www.woodboilers.com/images/stories/document/woodboilerplumbingschematic1211.pdf

My Taco 4900 Series Air Separator (fancy air scoop) is located close to the boiler on its supply line https://www.taco-hvac.com/uploads/FileLibrary/AirElimination.pdf. I've got my feed line flowing through a backflow preventer, then a feed water pressure regulator, then into the bottom of the Taco Air Separator. My two expansion tanks are teed off right after the pressure regulator, before the air separator. I got this setup off the Tarm Biomass PT3 diagram. Been working fine for two seasons now.

My Termovar loading unit is on the return line, like in your diagram, right next to the boiler. Like Maple, no issue there. Unlike Maple I leave my fill line open. No issues there with the backflow preventer, called for by code, and pressure regulator in place. Check out the Watts Series 1156F Feed Water Pressure Regulator. It has a built in bypass for your initial fill. Automatic air vents are needed at each high point in your system. I've got about six Watts Series FV-4M1 Automatic Air Vent valves in place.

I didn't notice an overheat zone in your diagram for power outage situations. Are you handling this some other way, as some do? Also I didn't spot any cleanouts or wye traps to catch any system debris before it fouls your circs. I've got a couple of Jomar T-100FB Filter ball valves, which are ball valves with integrated clean-outs, plus one wye valve to protect my DHW flat plate hx. I cleaned them after the initial fill, and once a year thereafter. No idea where your check valves should be. Looks like your doing a great job planning. Good luck with your install.

Mike