efficient use of wood heat

[farmerpsv]

hey all
am going to build a house and have been thiinking about ways to heat it, so i thought i'd ask the most knowledgable people out there, my friends at tractorbynet. i will probably go with a heat 2 zone heat pump system or radient for my primary, and wood for secondary. i like the idea of being able to use the btu's from my heat source to be able to heat the house and water. my floor plan isn't really open, so putting in a wood stove ( i favor the soap stone) won't really heat the house, but will do in a pinch. using a stove though tends to preclude heating water as well. i know there are some stoves with that ability, but they are limited. outdoor boilers are nice for their ability to adapt as a secondary or primary source in conjunction with a heat pump or radient but seem to me to be overkill...lots of btu's up the chimney. anyway what are y'alls thoughts? what are some of the solutions you've come up with?
thanks
paul

 

[bczoom]

Paul,

A couple question if I may...
Approx. how many sq/ft will this house be? What style and # of floors? Basement?

I have a heat pump connected to an indoor furnace as well as a wood stove. I use the woodstove as primary heat, heat pump second and furnace last. The indoor furnace is electric and I try to never let the thing kick on as it will make the electric meter spin so fast that it may fly off the house.

If you go with the heat pump (or other forced air setup), heat from the woodstove can be pumped through the house by turning the fan on. You don't need the heat pump itself on, but there should be a FAN switch on the thermostat with an AUTO or ON setting. I use the ON setting and let the fan run constantly. Using the fan circulates the woodstove heat throughout the house (although the room with the woodstove will obviously remain warmer).

In the summer, I use the A/C from the heat pump as the dehumidifier in the basement. The conditioned air is drier so I don't have to use a stand-alone dehumidifier. Since the basement is cool anyway, the air being pulled out helps cool the rest of the house.

 

[farmerpsv]

bczoom,
the house will be about 2400+basement w/9' ceilings. it's a colonial, so alot of separate rooms with one over the garage. do you have a return near your stove, or is the fan circulation enough? heat pumps are a decent method in VA, not as cold as PA, still, you can get slumps where your below 35 and suplimental heat is a good idea...i hate when the heat strip kicks in. i'm still toying with the idea of radiant heat, with new construction it's pretty easy for me to install, it is redundant because i would have the ac for summer and adding a heat pump to that is pretty cheap. you can get the hot water off the ac in the summer, with an exchanger...anyone do that?
paul

 

[bczoom]

</font><font color="blue" class="small">( do you have a return near your stove, or is the fan circulation enough?)</font>

Paul,

The room the wood burner is in does have 2 cold air returns into the furnace.

I have a multi-story house (split front to back) with a total of 4 levels. The wood stove I have is on the 2nd lowest level.

Without running the house fan, I can stick a candle near the ceiling as it is going up the stairs and it will blow the candle out. Ditto when I put near the steps (cold air coming down will extinguish the candle). I do run the house fan to get the warm air up to the uppermost floor as well as equalize the temp across the entire house. I have considered cutting floor grates between the level the woodstove is on and the one above it to get more direct heating to the upper level.

Question.
Using the heat pump and A/C, I assume you're going with a forced air system.
For radiant heat, you'll be using a water piping system.

Won't that get a bit pricy to install since you're running both types of systems?

As for "you can get the hot water off the ac in the summer, with an exchanger...anyone do that?", I have never heard that was possible. Even if "doable", is it practical? You would have to run your A/C to generate hot water. What would you do in the spring/fall?

 

[farmerpsv]

bczoom,
i would not install 2 systems, it would be either radiant or heat pump. In va you pretty much need ac in the summer, adding a heat pump to a system is a negligible cost, having ac and radiant w/o the heat pump would be more costly...two systems. re the hot water from ac, there's a heat exchanger you can attact to the condenser coil that suplements hot water during the summer, you still have a hot water heater.
paul

 

[Varmintmist]

I have heard of using the ac to heat your hot water. I assume it is like my heat exchanger from the OD woodburner. You have a heat exchanger and the hot water tank. Should work, even if it does nothing but bring your water temp up by 10 degrees it will save $$ in electric.

 

[dmccarty]

Farmerpsv,

We are almost finished with our new house. One of our original ideas was to put in a radiant floor that was heated with solar. NC will help pay for the installation and we liked the idea of having a heat source for water during power outages. We also are putting in a wood stove and a heat pump. To put in the radiant flooring with solar was going to be in the neighborhood of $7,000 for our house. Our house is about 2,540 sf on a single floor.

The thing that finally hit me is that it it ain't worth 7K to put in the solar radient floor. 7K is about what we paid of the heat pump system. Then you add the wood stove to the cost. Do we really need three ways to heat the house? Yes solar would be cheap but it cost me 7K to be cheap. That aint cheap. So solar was thrown out the window.

Then we went down the path of putting in a wood burning boiler to heat the water. Fast forward to the end. It was not worth the cost either.

For us it just did not make money sense to put in radient. And we don't have it in the house. If lived farther north AND we heated with oil or gas it would be a different story. Part of our heating plan is the wood stove. It should easily heat everything but the kids bedrooms and maybe the dining room. If we really have heating problems we will put in one more wood stove near the kids rooms.

The origonal plan called for R30 in the ceiling. For my area this has been upped to R40 or R49 depending on who you read. Or heat pump was sized for R30 but the contactor said we could go as high as R40 before we had issues with the heatpump. Going from R30 to R40 was about $200. Going to R50 was about $600. You might want to see if you can put in more insulation to lower the cost of installation of the heatpump.

I think we have a 3.5 ton heat pump in a 2,540 sf house. I know the builder priced a 5 ton unit at the start but the HVAC installer said we only needed a smaller unit because of the R30 in the attic and R26ish in the walls.

I'm really hoping that the wood stove and the passive solar design, as minimal as it is, will help keep the house warm. We have put in lots of mass in the house to moderate temperature changes. The floor is a slab and the stove sits on and is backed into a corner wall made of two layers of brick. Once that warms up it should throw heat into three other rooms... At least that is the plan. My point is that if you are still at the planning stages maybe you can incorporate some design issues to help heat or retain the heat in the house. NC State University has a Solar Design cernter to help people plan their houses. Mabye VA does as well?

Later,
Dan

 

[sherpa]

bczoom,

(I use the ON setting and let the fan run constantly)

Do you run the fan constantly? I run my fan some to spread my wood heat but not constantly, althought I have thought about running it all the time. It would be nice to have some kind of timmer device on that fan switch.

Sherpa

 

[farmerpsv]

Dan,
thanks for the reply. yeah, i go back and forth about cost as well, i do like the idea of sustainability though, just because i like the notion of independence. i'm one of those nuts who grows his own grain and grinds it and makes his own bread. i'm looking to do one of two houses, one is a dry in, the other a SIPS house. with the stick built dry in i will use icynene insulation. i've restored several old houses and used it to retro insulate, and it works very well. you can almost get the same effect as a SIPS house. i tend to agree though, a wood stove or two is probably going to be the ticket, water can be heated using solar or ac heat exchanger, either of which will be cheaper than radiant. we are a bit colder here than NC. last year my heat strip kicked in quite a bit and ran my costs through the roof, but it is an old house and i hadn't built out the second floor yet, so this year will be better. another fun thing about the land i'm building on is the opportunity to do some hydro electric, just in the beginning phase of researching that one.
paul

 

[bczoom]

</font><font color="blue" class="small">( bczoom,

(I use the ON setting and let the fan run constantly)

Do you run the fan constantly? I run my fan some to spread my wood heat but not constantly, althought I have thought about running it all the time. It would be nice to have some kind of timmer device on that fan switch.

Sherpa )</font>

Sherpa,

Yep, I pretty much run it all the time. On occasion, I'll turn it off based on my current heating needs from the wood stove. If I want more heat quickly in the vicinity of the stove and the next floor up, I might turn the fan off for awhile.

I would "think" that a timer could be incorporated into the fan. I'm not a HVAC and/or electrical expert but I would think it would need to be wired in parallel to and separate from the thermostat. Reason being is you'll need the AUTO function to work in the event the furnace or heat pump needs to come on during your "fan off" timer hours.