Looking For Some Boiler Advice

[CT-Mike]

So I am currently heating my home with a Lopi insert. As expected there are some definite cold spots at the opposite end of the house and upstairs. Because of this I am thinking of installing a gassification boiler such as a Garn, etc. I want the boiler installed in a shed to be built to minimize the amount of handling of wood I have to do, and to minimize the chance of getting carpenter ants, termites, etc in the house.

The house is approx. 2400 sq ft, and I would like to heat the garage, my 525 gal hot tub, and a future workshop. House currenly has an oil fired FHA system as primary heat source.

Hot water is currently an oil fired hot water heater.

So what I am looking to do is this:

- Install boiler such as a Garn WHS2000.
- Pre-heat incoming water to hot water heater with a plate heat exchanger.
- Boiler outlet of plate heat exchanger goes to another heat exchanger in the FHA plenum and then return to the boiler.
- Another loop feeds a shell and tube type heat exchanger for the hot tub.
- Another loop to the garage where I plan to add radiant floor loops and pour some additional concrete over the top.
- Another loop for the future workshop to be built.
- An additional loop to another heat exchanger and a fan on the second floor to finally give me two zone heat.

I guess my biggest question is would the heat exchanger in the FHA plenum be efficient enough to make this worthwhile?

Would I be better off installing either radiant floor loops under the floors in the basement?

If I did that what would I do to heat the second floor? Would the heat exchanger fan combo be good enough considering the second floor would be kept cooler than the ground floor?

Any help and other high level design ideas would be greatly appreciated.

Thanks,

Mike

 

[Piker]

We are using a heat exchanger/forced air system on our Froling/1000 gallon storage. It works well, though as the tank temps start to drop, the blower runs for longer cycles, just like any other high temp emitter hooked to storage. Our goal is to eventually move the entire house over to radiant floor to increase comfort as well as effective use of heat storage. I don't, however, plan on removing the forced air altogether. I'll do a plateless radiant install on the first floor... according to my calculations, the 15 or so btu's per square foot that this will produce will be enough radiation for 90 or 95% of the season. With a two stage thermostat setup, I can easily add the output of the forced air for the few days per year that the radiant won't be able to keep up. This saves me quite a bit of money on the radiant installation, plus I have the forced air for those shoulder season days where you might just want to take the chill off in the evening for a little while.

One thing about your dhw preheat... this doesn't really work great on a system that uses thermal storage. You will want to leave the water in the garn sit without circulation when there is no call for heat. This keeps the water stratified, and also reduces transmission loss to the house... but it also means there isn't hot water going through your preheat exchanger unless there is a call for heat in the house. Basically, i think you will want to put some sort of control on your dhw just like your other zones.

cheers

 

[CT-Mike]

Thanks for the quick reply. Good to hear that your plenum heat exchanger works fairly well. Also that is good to know about the DHW system, putting it on a separate loop makes much more sense.

 

[Piker]

Thanks for the quick reply. Good to hear that your plenum heat exchanger works fairly well. Also that is good to know about the DHW system, putting it on a separate loop makes much more sense.

Not a problem... there are quite a few knowledgeable folks on the forums here that are more than willing to help, so I am sure you will receive some more input. When you're talking about thermal storage, you want to use emitters that produce the greatest amount of temperature differential as possible. Radiant floor is best as supply temps are already low at 120° or less. With your forced air heat exchange, try to size the exchanger as large as possible... this will give you the greatest delta t and allow the use of cooler water temps to maintain temperature inside the home. You can also slow flow rates through your heat exchanger to increase delta t ... this will cause your fan to run a little more though.

there are lots of options... take your time... read up... ask questions.

cheers

 

[pybyr]

Definitely aim for abundant size on your water-air HX. They are typically rated (and systems designed for) assumptions of 180 degree water in, with a 20 degree drop in water temperature coming out. Actual BTU/hr capability then drops rapidly when you have lower input temperatures, which you _will_ have with storage- so the off-the shelf units and their ratings really aren't cut out for service with storage.

The good news is that by upsizing the water-air HX, you can get high BTU/hr outputs even with lower temperature water.

Here's a past thread with some useful info and links to a prior thread:

https://www.hearth.com/econtent/index.php/forums/viewthread/47737/

Good luck, and there are lots of good folks here to help.

 

[woodsmaster]

I'd consider radiator panels if you have a way to run the lines. Then you can use lower temp water, dont have a energy hungry fan running , blowing dust around, and you dont have to listen to a fan run.

 

[jebatty]

Very much encourage you to move towards abundant, low temperature emitters, as much as possible. With 1850 gal of storage in the WHS2000, you will have abundant storage to greatly lengthen times between burns, depending on your demand. With my system, a Tarm and 1000 gal storage, I easily can run the storage down to as low as 85F with usable btu's, although 100F would be a pretty normal low temp point in the storage. The Garn also appears to be most efficient with water temperatures of 140 or lower, as Garn has advised, although you certainly can run it at higher temps.

Since you're looking to put the boiler in an outbuilding, I also would encourage you to look at other gasification boilers with separate pressurized storage, including possibly storage in your home to capture heat that otherwise would be wasted. Your flexibility in operation increases with this kind of installation and you may avoid expense and efficiency loss that accompanies use of a heat exchanger to operate a non-pressurized boiler with a pressurized system.

 

[jebatty]

Think about your boiler outbuilding being the first stage of your future shop, so that when the shop is built, the boiler system will be in the shop. Then whenever your fire the boiler, you will capture a lot of otherwise wasted btu's to heat your shop for many hours without drawing on the storage. At outside temperaures in the 0-30F range, my boiler firing alone provides 8-20 hours of a heated shop without the radiant floor ever calling for heat. The benefits of the boiler being in the heated space are substantial.

 

[CT-Mike]

I am definitely thinking that installing baseboard heat would be the best way to go, at least for the first floor. But the wife doesn't want to go that route for several reasons. So I am looking into putting radiant loops as someone mentioned above.

 

[Hunderliggur]

Look at some of the "modern" flat plat radiator panels. I know there is one that comes in widths of 4" or so multiples by whatever length. Would fit in well with regular baseboards. Do not fall into the assumption that all radiators are lke the days of old with big cast iron units or finned tube baseboards. You can also do some nice architectual designs (like wall screens, etc.). Tell your wife yu'll throw in a heated towel rack to boot!.

 

[CT-Mike]

Thanks for the tip about the new flat panel radiators. I did not know they existed and so I showed them to the wife and she is happy with them. We were both thinking about the old style finned pipe with the ugly sheet metal covers.

 

[Hunderliggur]

Does she still get the heated towel rack in the bathroom?

 

[CT-Mike]

Yah she will get that if I can figure a way to get the hot water upstairs to the bathroom.

 

[Chris Hoskin]

Think about your boiler outbuilding being the first stage of your future shop, so that when the shop is built, the boiler system will be in the shop. Then whenever your fire the boiler, you will capture a lot of otherwise wasted btu's to heat your shop for many hours without drawing on the storage. At outside temperaures in the 0-30F range, my boiler firing alone provides 8-20 hours of a heated shop without the radiant floor ever calling for heat. The benefits of the boiler being in the heated space are substantial.

+1

 

[Hunderliggur]

Yah she will get that if I can figure a way to get the hot water upstairs to the bathroom.

You may be able to fish PEX (1/2) through the wall like electrical lines. I haven't tried it and I sure wouldn't with 7/8" PEX.

 

[ewdudley]

Yah she will get that if I can figure a way to get the hot water upstairs to the bathroom.

You may be able to fish PEX (1/2) through the wall like electrical lines. I haven't tried it and I sure wouldn't with 7/8" PEX.

Search:

Seigenthaler homerun ecm

Recommended for retrofits.

-ewd

 

[heaterman]

With hot water as your heat moving/transfer medium, your heating options are limited only by your imagination and your budget.

I am a huge fan of panel rads. When controlled by a room sensing TRV (thermostatic radiator valve) you can have individual room by room temperature control. The beauty of a TRV controlled rad is that once the room is initially heated they never turn all the way off. The valve will throttle closed until it reaches a balance point proportional to the heat loss of the room. You will find that the rad is always warm to some degree or another depending on the outdoor temp. Variable heat output is a lot like having a wood stove in every room. The heat is always "on", it just matches what is needed to heat the space it's in. Extremely comfortable heat. Unlike baseboard which is 100% convective heat, a radiator provides some of its output in the form of radiant energy the same as a heated floor or wall.
Another nice thing about rads when you pipe them individually off a central manifold is that the whole house can be heated with one circ and no zone valves of any kind. Each TRV is its own "zone valve". Also, provided you are not trying to heat a 500 sq ft room, 3/8" tubing will easily flow all the water the rad needs. That can make a big difference in whether you can get the tube where you need it or not.

If you go with a coil in the plenum of the furnace just check the btu output and flow rate required to get sufficient btu's into the house using 140* water. In a system like a Garn, or any system using storage, you will find this greatly increases the period of time between firings and take full advantage of the storage capacity offered by it. I have several Garn installs that never see water temp above 160-170* because the heat emitters were designed to provide sufficient output at that temp range or less. Other Garn users have elected to go another step and add a mixing valve, either variable temp or fixed in order to regulate the water temp going to the system while running the Garn at full swing from 120* up to 200*. This has advantages in some situations because the emitters (rads, baseboard or heat exchanger coils) are always seeing the same water temp.

As a design option you could use a main piping system circulated by 1 variable speed pump and use a zone valve for your water heater, furnace coil and / or other additional zones. I am continually amazed by how much water those things will move on an extremely small amount of electricity. The key with any boiler piping is correct diameter for the flow rate needed. It makes me grind my teeth when I see people trying to get 10gpm+ through 1" pex. T'aint gonna happen without a high head circ that uses way more energy than needed if the tube or piping would have been 1-1/4" or 1-1/2". Bear in mind that if your system is designed around 201-20 degree temp drops you can get by with much lower flow rates and smaller diameter tube. It is routine to see a 30-40* temp drop in a European style system using panel rads with water just trickling through them. Amazing to see when you consider that most US designed systems rarely see a 10* drop due mainly to scrimping on emitters and trying to compensate by upping the flow. Stupid, Stupid, stupid.

AFA placing the Garn or other unit in an out building, I would heartily recommend it for all the reasons you mentioned. Just pay attention to your underground lines and how they are insulated and sized. This is probably the area I see people have the most trouble with due to bad advice or trying to "save" money. Just remember this simple axiom when buying insulated underground tube "Price is what you pay, Value is what you get."

If you need help finding panel rads send me a PM. I have a very good friend on the East coast who imports them directly from a manufacturer in Europe.

 

[CT-Mike]

Well after doing some research and budget analysis, I think I am going to go with an EKO instead of the GARN for several reasons. First I can install the EKO in the basement, saving on the cost of an outbuilding. Additionally, the EKO is about 1/3 the price of the GARN. And lastly, my wife's cousin is an EKO dealer and can get me the boiler at cost.

So I am looking at initially installing the boiler with a plate heat exchanger loop on the hot water tank, a heat exchanger in the FHA plenum, a heat exchanger loop to heat the hot tub, and some finned radiator tubing in the basement as a gravity flow dump zone. Eventually I will add 1,000 gallons of storage.

 

[flyingcow]

Good post Heaterman!

CT-MIKE,

Good luck with you install. Keep in mind, you will get some smoke roll back from the boiler. Exhaust hood or not. You will still get the smoke smell in the house from time to time. Best way to operate is, fill it and forget about it. Once you get tuned in on loading times, try to load when unit is down to just coals.

 

[CT-Mike]

So I have been doing more research. Talked to the wife's cousin, and he feels the EKO 60 is too large for my needs (2500sq ft home). The FHA furnace in the basement is rated at 115K, so it seems the 25 would be too small. So I am looking at getting the 40. It should be able to heat both floors of the house, the hot tub, and DHW with no problem.

Since I currently have supply and return ducting for the second floor originating in the basement, I will just install a hydro-air setup in the basement and finally get twonzone heat. In the future another Ac system will get installed to get two zone cooling.

For the first floor I will go with a heat exchanger initially to cut down on installation costs, and then eventually move over to baseboard radiator panels.

The beauty of having the chase with the ducting in it is I can easily run a loop to the master bath for a towel warmer to keep SWMBO happy.

I stopped at a propane dealer and was told $1500 for 500 gallon tanks. Is that a reasonable price? The plan is to buy two and have 1,000 gallons of storage.

Also, when I do add the storage, what are the benefits of pressurized vs unpressurized? If pressurized is the way to go, what is used to maintain proper system pressure? Obviously there will need to be a relief valve to prevent system damage.

I am looking to purchase this in late February and I need to start figuring out what I need for circulators, control valves, etc