stove btu rating - per hour? per day?

[PaulLovesJamie]

My hearthstone wood stove is rated at 55,000 BTUs. Is that per hour? per day? Per what?? I'm looking at adding a solar system for hot water, it is rated at 35,000 btu per 5 hour period, I'm need to compare that to my wood stove to get a better feel for how much heat it will really give me.

 

[KsWoodsMan]

That 55,000 BTU rating is per hour. A pound of seasoned wood holds between 6800 and 8400 BTU's depending on it's Moisture Content. It isn't unreal for a wood stove to consume 6-10 pounds in an hour in the dead of winter.

Hope that helps

 

[PaulLovesJamie]

Yes, that helps - its exactly what I needed to know. Thank you sir.

 

[Wood Doctor]

That 55,000 BTU rating is per hour. A pound of seasoned wood holds between 6800 and 8400 BTU's depending on it's Moisture Content. It isn't unreal for a wood stove to consume 6-10 pounds in an hour in the dead of winter.

Hope that helps.

:agree2: I use 100 lb/day as my average consumption, so for a 200-day heating season, that means 20,000 lb of wood required. Five cords will usually make it, but last year I needed 7. That heating season last year never seemed to end.

 

[KsWoodsMan]

You are very welcome.

As a comparasion to a gas water heater, the ones I am familiar with are 38,000 BTU's Per hour. I never check to see how long they run each day but have a recovery time of approx 20 minutes for a 40 gallon tank set at 110* F.

I'm interested in hearing more about the sytem you intend to install. Is it just for your Domestic Hot Water ? or will it be used to supplement heat to your home also ?

 

[avalancher]

My hearthstone wood stove is rated at 55,000 BTUs. Is that per hour? per day? Per what?? I'm looking at adding a solar system for hot water, it is rated at 35,000 btu per 5 hour period, I'm need to compare that to my wood stove to get a better feel for how much heat it will really give me.

What kind of solar heater are you looking at? I have looked at quite a few, and dollar for dollar I wondered if they are worth it.
I have signed up for the Federal Alternative Energy grant, and the program doesnt offer any grant money for solar water heating.

 

[PaulLovesJamie]

The dealers here are saying that you can get up to $2000 back from the federal govt on a solar water system, supposedly all their customers are getting it. Which leaves my cost somewhere around 4 - 5000.

Sunda and apricus are the 2 brands I'm seeing here in PA. I agree, the numbers dont pencil out. I figure my water heating costs are about $600/year, and since they tell me I'll save 75% of that I figure it'll be closer to 50%. So I'd be investing $5000 to save $300 per year ... not a very good move financially.

When I built my house I insulated under and around the basement floor and put pex tubing into the slab - so my basement floor could be one huge heat sink. My intention is to put in solar for hot water, and also use it to heat the basement floor, letting it radiate into the house all night. Unfortunately, now I'm finding out that I'll only get about 35000 btu's/day total out of the solar, so not much at all will be left to go into the floor after the water is hot.

My conclusion: not worth it. Unless I can save an awful lot by doing it myself.

 

[Wood Doctor]

The dealers here are saying that you can get up to $2000 back from the federal govt on a solar water system, supposedly all their customers are getting it. Which leaves my cost somewhere around 4 - 5000.

Sunda and apricus are the 2 brands I'm seeing here in PA. I agree, the numbers dont pencil out. I figure my water heating costs are about $600/year, and since they tell me I'll save 75% of that I figure it'll be closer to 50%. So I'd be investing $5000 to save $300 per year ... not a very good move financially.

When I built my house I insulated under and around the basement floor and put pex tubing into the slab - so my basement floor could be one huge heat sink. My intention is to put in solar for hot water, and also use it to heat the basement floor, letting it radiate into the house all night. Unfortunately, now I'm finding out that I'll only get about 35000 btu's/day total out of the solar, so not much at all will be left to go into the floor after the water is hot.

My conclusion: not worth it. Unless I can save an awful lot by doing it myself.

:agree2: You are correct on all counts. Passive solar retrofits can be harnessed most effectively to heat air but not water. Heating the floor by circulating water through the ground to ultimately heat the house is the most cost effective energy saver you can do because the ground does not rely on continuous solar and does not shut down during cloudy conditions.

Tapping the "heat sink" stored in the ground works, but a ground water piping system should be installed when the house is first built. Unfortunately, retrofitting one is seldom cost effective because the payback is too long.

 

[KsWoodsMan]

Ed , I think you missed the part where he said pex was installed in the basement floor when his house was built. Like Prego, it's in there. No retro fit needed.

I guess to get the grant you have to purchase new equipment ? Thats how it was with wind powered generators years ago.

For the cost, 35,000 to 40,000 BTUs per day doesnt seem justifiable for supplemental heat or DHW.

 

[Wood Doctor]

Ed , I think you missed the part where he said pex was installed in the basement floor when his house was built. Like Prego, it's in there. No retro fit needed.

I guess to get the grant you have to purchase new equipment ? Thats how it was with wind powered generators years ago.

For the cost, 35,000 to 40,000 BTUs per day doesnt seem justifiable for supplemental heat or DHW.

Well, perhaps. The groundwater piping system I am referring to goes out into the yard and taps the heat sink that way, usually using a circulating pump, hence the term "groundwater heat pump". That's not really the same as passive solar units that heat embedded floor pipes as OP is mentioning.

My biggest concern on any passive solar unit is that the sun can disappear for several days a time, and these systems all tend to diminish rapidly when that occurs. Groundwater piping, on the other hand, is rather stable all the way through the winter.

Twenty years ago I came within an eyelash of buying a home with one of these groundwater systems installed. Owners have claimed an average of $1,200 a year for both heating and cooling a house that is pushing 4,000 sq ft--not too shabby. Also, when the temp hits 0 F, that system still works when all typical electric heat pumps fail.

 

[mranum]

One thing to keep in mind is that the farther south in the U.S. you are the better solar works. Here in central Wisconsin they do work but the benefit is a longer road to get there since the sun is farther to the south especially in winter.

I have some experience with alternative energy in trying to get a power source that was off grid. Which is different than trying to collect solar for heat units rather than generating electricity which was our case. For solar powered voltage units the dealers even told us given our latitude that if we didn't put in a tracking unit that would have the panels follow the sun across the sky we were wasting our time. We ended up with a wind generator to suit our needs.

 

[PaulLovesJamie]

Ed , I think you missed the part where he said pex was installed in the basement floor when his house was built. Like Prego, it's in there. No retro fit needed.

I guess to get the grant you have to purchase new equipment ? Thats how it was with wind powered generators years ago.

For the cost, 35,000 to 40,000 BTUs per day doesnt seem justifiable for supplemental heat or DHW.

correct on all 3 counts.

 

[PaulLovesJamie]

Heating the floor by circulating water through the ground to ultimately heat the house is the most cost effective energy saver you can do

Well, actually I disagree. I installed a ground source heat pump when I designed/built my 4000 sq ft house 5 years ago, and yes you are correct that it is incredibly efficient, I spend approx $1000 per year for heating and cooling.

But: a geothermal system does have an operating cost - for every btu you bring into the house, you have to operate a compressor and pump. Cheap, yes. Free, no. Solar on the other hand is cheaper to operate. You get less heat out of it, but you put less energy (percentage-wise) in to get that heat.

Ultimately though, I've concluded that the solar doesnt get me enough btus to justify the up-front cost.

I may simply buy a new chainsaw and a second wood stove for the basement, that'd be cheaper.