I need a boiler to heat domestic hot water and radiant floor. The space is 352 sq. ft. with a volume of 2,500 cu. ft. It is fairly well insulated. As best I can figure, I need to generate about 21,120 BTUs. This is a very small space. I will be doing the installation myself. I would prefer a pellet boiler though I have no experience with pellet stoves. I can't find an appliance online small enough to fit my needs. Please advise.
think smaller
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A Windhager BioWin 100/150 will modulate down to the 10,000 btu range. Add a small thermal storage tank of some type, in the 40-60 gallon range and you are good to go.
In the 100 configuration it will fire from right at 10,000 up to 30,000. Perfect for your application. Depending on what type of radiant floor you have, you may not even need the thermal storage tank.
In the 100 configuration it will fire from right at 10,000 up to 30,000. Perfect for your application. Depending on what type of radiant floor you have, you may not even need the thermal storage tank.
Do you mean this one?: (broken link removed to http://www.windhager.com/int_en/products/pellets/variowin-xs-25/)
I am only familiar with the pex tubing and aluminum reflector style of radiant heat between joists under wooden floors.
I am only familiar with the pex tubing and aluminum reflector style of radiant heat between joists under wooden floors.
This one is available here in the US. Check the specs on the BW-100. It will fire from 2.9 to 9.9 KW which translates to around 10,000-30,000 btu.
For your application with plates under the floor rather than a thick slab type radiant I'd recommend using a small buffer/thermal storage tank.
(broken link removed to http://www.windhager.com/int_en/products/pellets/biowin-3/)
For your application with plates under the floor rather than a thick slab type radiant I'd recommend using a small buffer/thermal storage tank.
(broken link removed to http://www.windhager.com/int_en/products/pellets/biowin-3/)
An eko 25 might work . My EKO puts out about 25k btu when it is turned down to not put out so much heat. My heat load is about the same as yours on a cold winter night. I tune it so it doesn't get much air and put the fan speed on minimum. The reason I do this is cause I don't have storage but have 1,000 ft. of 1/2" pex stapled up to the floor in the basement. A steady supply of heat works well. Many people here don't think this is a good set up and say I should have storage.. They are most likely right but it works well and I am happy with it for the most part.
Before we got our boiler fired up, we heated 924s/f - 7900 c/f with a small, milk crate size 7500 watt plug in electric heater with a fan & t/stat. It did cycle off! We're well insulated also, but only so-so Andersen 200 series windows, also in ME. My primary duty for my boiler is for the attached 2432 s/f shop & dhw for all. I think with you're small space, you need to be careful sizing the system (see my 7500 watt heater in a bigger space above) and although I don't have it (yet), storage will be required. Heck you'll warm up you're space cooking dinner, and might be the first here to have one fire a week in the dead of winter! Welcome to Hearth.
Could it have been 7500 btu's? It was my cousin's (also the electrician), he rigged it up for us.
Max space heater allowed by law is 1,500 watts. 5,000 btus.
7,500 watts would be something like 63 amps.
7,500 watts would be something like 63 amps.
21,000 btu/hr sounds way to large for a tightly insulated building?
352 square feet x 12 btu/ sq. ft would be a load of 4224 BTU per hour on a design day. A refrigerator and some light bulb would heat that space. If it is really well insulated we have seen heat loads in the single digits. Run another heat load calc.
Install electric radiant mat or cable in the slab and grid tied PV modules
Thanks for all your suggestions.
I spoke with the New England regional rep regarding the Windhanger and plan to visit his demonstration model when I am in Massachusetts. He informed me of Maine's $5,000 rebate for whole house conversion to pellet boiler's - nonetheless the cost of the appliance and installation (which must be contracted to qualify for the rebate) is excessive. I underestimated how expensive these boilers are.
One thing I don't like about electronically operated boilers is their sophistication, so many parts to go wrong and their dependence upon electricity.
It is tempting to take advantage of Maine's rebate and buy a pellet boiler with the capacity to heat the entire house but there is no one to heat it for at the present time.
Thanks too for pointing out that a well insulated space the size of mine can be heated by less expensive means. And that is probably the way I will go. To be more specific, the space is a small part of a much larger old house. There are existing electric baseboard heating units already installed in the space although I have never used them and they won't heat the water. The space was damaged by a roof leak that persisted for many years and caused extensive rot in the eve wall which must be torn out and replaced. I am attempting to create a warm space for one person within the building.
The whole-house heater is an oil fired boiler with two zones neither of which include the space I am trying to heat. The oil fired boiler has not been fired in six years due to the cost of oil. A wood stove and electric water heater have been my heat sources. I also have a small Sears coal stove (without a coil or hot water storage) which I have considered moving into the small space but am unsure how to vent it as the roofs would block the chimney. Unlike pellet stoves which can be vented through a wall, this coal stove has a five inch stove pipe and I believe the clearances required are the same as for a conventional wood stove, though I have not researched this.
How can I use my existing coal stove to heat domestic hot water? I know how to solder copper pipe. Can I add on a coil / heat exchanger and a pressure relief tank. Enough hot water to shower and wash dishes would suit me and I can forgo the radiant floor.
I spoke with the New England regional rep regarding the Windhanger and plan to visit his demonstration model when I am in Massachusetts. He informed me of Maine's $5,000 rebate for whole house conversion to pellet boiler's - nonetheless the cost of the appliance and installation (which must be contracted to qualify for the rebate) is excessive. I underestimated how expensive these boilers are.
One thing I don't like about electronically operated boilers is their sophistication, so many parts to go wrong and their dependence upon electricity.
It is tempting to take advantage of Maine's rebate and buy a pellet boiler with the capacity to heat the entire house but there is no one to heat it for at the present time.
Thanks too for pointing out that a well insulated space the size of mine can be heated by less expensive means. And that is probably the way I will go. To be more specific, the space is a small part of a much larger old house. There are existing electric baseboard heating units already installed in the space although I have never used them and they won't heat the water. The space was damaged by a roof leak that persisted for many years and caused extensive rot in the eve wall which must be torn out and replaced. I am attempting to create a warm space for one person within the building.
The whole-house heater is an oil fired boiler with two zones neither of which include the space I am trying to heat. The oil fired boiler has not been fired in six years due to the cost of oil. A wood stove and electric water heater have been my heat sources. I also have a small Sears coal stove (without a coil or hot water storage) which I have considered moving into the small space but am unsure how to vent it as the roofs would block the chimney. Unlike pellet stoves which can be vented through a wall, this coal stove has a five inch stove pipe and I believe the clearances required are the same as for a conventional wood stove, though I have not researched this.
How can I use my existing coal stove to heat domestic hot water? I know how to solder copper pipe. Can I add on a coil / heat exchanger and a pressure relief tank. Enough hot water to shower and wash dishes would suit me and I can forgo the radiant floor.
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Would probably heat just fine but will only provide a limited amount of hot water.
A small active dog, funny. Limited hot water, funnier.
To reiterate my last question:
How can I use my existing coal stove to heat domestic hot water? I know how to solder copper pipe. Can I clamp a coil of quarter inch copper tubing to the back of the stove to function as a heat exchanger. Enough hot water to shower and wash dishes would suit me and I can forgo the radiant floor. Anyone familiar with a hillbilly set up like this?
To reiterate my last question:
How can I use my existing coal stove to heat domestic hot water? I know how to solder copper pipe. Can I clamp a coil of quarter inch copper tubing to the back of the stove to function as a heat exchanger. Enough hot water to shower and wash dishes would suit me and I can forgo the radiant floor. Anyone familiar with a hillbilly set up like this?
If you are using a coal stove, why not use a heat pump water heater or even just a straight electric heater. This is such a small building, your DHW load cannot be too much, no?
Tying your coal stove in with a DHW heat exchanger is apt to overheat the storage tank. There are safety issues as well.
If your DHW load is small enough a small electric tank is likely a better choice.
Tying your coal stove in with a DHW heat exchanger is apt to overheat the storage tank. There are safety issues as well.
If your DHW load is small enough a small electric tank is likely a better choice.
I watched a video describing the heat pump water heater - it might suffice if it were in close enough proximity to the coal stove. I already have a forty gallon electric hot water heater but I don't use enough hot water to warrant the expense of operating it 24/7 or even intermittently - I never need forty gallons of hot water at any given time.
This is what I'm thinking except I can't see the benefit of two storage tanks: http://www.motherearthnews.com/diy/woodstove-water-heating.aspx#axzz38mnELTa6
This is what I'm thinking except I can't see the benefit of two storage tanks: http://www.motherearthnews.com/diy/woodstove-water-heating.aspx#axzz38mnELTa6
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I would look for a smaller DHW tank and just run that with electricity. I am not sure the HP is a good fit with such a small building. The only thing that makes it worth thinking about is if a coal stove is overheating the space. Even then, in the non-heating times of year, the HP will overcool the space.
Resistance water heaters are something I've never heard of before. I found this: "Point-Of-Use Electric Resistance Water Heater. This model is installed near the point where hot water is used. Due to the proximity of the heater and the location, the time required to get hot water is shortened. There is no need for a pumped recirculation loop and the associated heat loss is eliminated. Units usually include a one- to 20-gallon tank." here: http://energywisepa.org/category/fa...ric/electric-resistance-storage-water-heaters
Other than being lined with glass, how are these heaters different from conventional electric water heaters?
Other than being lined with glass, how are these heaters different from conventional electric water heaters?
A resistance heater can be an electric tank water heater or an instant one that uses no tank. Instant ones usually have durability issues and require some high power to deliver reasonable performance. If you take low flow showers a smaller instant unit might work.
If you have a 200 amp electrical service, an electric tankless (instantaneous) water heater would be a great choice. They take very little space and there are little or no standby losses that waste energy and add heat to the living space during Summer like you would have with a tank-type water heater.
I have no great suggestions for how to heat such a small space. You might consider a small, high efficiency propane boiler combined with a buffer tank (to minimize short-cycling) and one or two panel radiators. There are some pretty small LP fired space heaters out there too that might be worth considering (Ecotherm, Orbis, Robur, Rinnai). Do NOT use so-called "vent-free" units in such a small space.
A coal stove would be a horrible way to try to heat this space. The stove will put out much too much heat and does not operate well at low burn rates. As Tom indicates, a stove is not a great way to make domestic hot water either.
If you are committed to a renewable fuel source, a solar thermal collector (hot water, not PV) may do the job for you. If you are still interested in wood as a fuel, the smallest cord wood or wood pellet boiler with a very generous buffer tank could do a great job for you, but might be difficult to justify the expense of the system for such a small heating load.
Hope this helps,
Chris
I have no great suggestions for how to heat such a small space. You might consider a small, high efficiency propane boiler combined with a buffer tank (to minimize short-cycling) and one or two panel radiators. There are some pretty small LP fired space heaters out there too that might be worth considering (Ecotherm, Orbis, Robur, Rinnai). Do NOT use so-called "vent-free" units in such a small space.
A coal stove would be a horrible way to try to heat this space. The stove will put out much too much heat and does not operate well at low burn rates. As Tom indicates, a stove is not a great way to make domestic hot water either.
If you are committed to a renewable fuel source, a solar thermal collector (hot water, not PV) may do the job for you. If you are still interested in wood as a fuel, the smallest cord wood or wood pellet boiler with a very generous buffer tank could do a great job for you, but might be difficult to justify the expense of the system for such a small heating load.
Hope this helps,
Chris
maple1
Minister of Fire
I would just stick with a regular electric hot water heater.
Very hard to beat on a bang-for-buck basis, both up front & ongoing. Our 2 year old 80 gallon one uses no more than $25/mo. in electricity for a family of 5.
Maybe get a new smallish one if yours is near the end of its life. Get it up off the ground on top of some foamboard, and maybe even put more insulation around it. Add heat traps up top if there aren't any, maybe add some pipe insulation.
Very hard to beat on a bang-for-buck basis, both up front & ongoing. Our 2 year old 80 gallon one uses no more than $25/mo. in electricity for a family of 5.
Maybe get a new smallish one if yours is near the end of its life. Get it up off the ground on top of some foamboard, and maybe even put more insulation around it. Add heat traps up top if there aren't any, maybe add some pipe insulation.
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