wood stove with central air

[reffug]

Has anybody here incorporated a wood stove somehow into there central air ducting system. With the new house construction we did a heat pump with a gas furnace backup system. But the truly cold temps here lately and how much the gas is actually kicking on and the $ has made me long for my wood stoves I had in the old house. Got a friend building a new house and he is willing to sell me his big wood stove(one of the floor standing ones) that is capable of heating a whole house. Just not sure how one would go about incorporating the heat from said unit throughout the entire house efficiently. Thoughts anybody done anything like this?

 

[reffug]

Nevermind fella's after some more searching I have discovered that this is basically impossible to accomplish because of some serious safety issues as well as code violations. Looks like the only viable option is to look into a wood burning furnace located outside the home that would use H20 baseboard type heat. Which would kick some serious ass. Now its just a question of the $ involved.

 

[firetruck41]

What about just using your woodstove and turning the fan (only) on, on your central furnace, that will circulate air through the house. Your thermostat should have a switch that says "on-off-auto" or something like that, "on" will turn the fan on until you switch it off, "auto" will just turn it on when your furnace lights up and is heating (or cooling, with AC).

 

[osagecruiser]

look at the nu air fireplaces...thats what we have and it is ducted around the house...really nice...and saves heating dollars

osagecruiser

 

[VTFJ40]

What about just using your woodstove and turning the fan (only) on, on your central furnace, that will circulate air through the house. Your thermostat should have a switch that says "on-off-auto" or something like that, "on" will turn the fan on until you switch it off, "auto" will just turn it on when your furnace lights up and is heating (or cooling, with AC).

I do this. One of the intakes for the forced hot air is near (not too close) to the stove. Had to get a thermostat that allowed for just the fan to run, but it works great.

 

[reffug]

What about just using your woodstove and turning the fan (only) on, on your central furnace, that will circulate air through the house. Your thermostat should have a switch that says "on-off-auto" or something like that, "on" will turn the fan on until you switch it off, "auto" will just turn it on when your furnace lights up and is heating (or cooling, with AC).

Good thought but the problem therein would be logistics. Air intake for the furnace is located upstairs with the actual unit being located in the basement. Placement of a wood stove would have to be in the basement just do to the layout of the house. So even though I appreciate the idea I don't think it is feasible at this point. I'll look into the nu air though.

 

[John Smith]

Good thought but the problem therein would be logistics. Air intake for the furnace is located upstairs with the actual unit being located in the basement. Placement of a wood stove would have to be in the basement just do to the layout of the house. So even though I appreciate the idea I don't think it is feasible at this point. I'll look into the nu air though.

Huh? There is no way you only have one return in a modern forced air HVAC system unless it was designed and installed by a crackhead. As you have found out heatpumps suck in this region.

 

[firetruck41]

Huh? There is no way you only have one return in a modern forced air HVAC system unless it was designed and installed by a crackhead. As you have found out heatpumps suck in this region.

Almost all new homes I see, have one return, unbelieveable isn't it? Even the $500k-600k homes usually have one, around here.

 

[reffug]

Huh? There is no way you only have one return in a modern forced air HVAC system unless it was designed and installed by a crackhead. As you have found out heatpumps suck in this region.

Yes there is only one return. The installer wasn't a crackhead as a matter of fact he is the son of a very good friend of mine and the actual owner of the company. He tried to talk me out of gas as a backup but I can be kinda stubborn that way. Also the house is single floor sitting on a full basement so a single return which is central in location does make good sense and the house has excellent airflow. The heatpump actually doesn't suck to bad unless its cold like it has been here lately and I go to gas backup. Which is awesome and the reason I installed it but man does the $ add up quickly.

Almost all new homes I see, have one return, unbelieveable isn't it? Even the $500k-600k homes usually have one, around here.

True dat, I asked around with several people in the industry and they told me if its set up correctly and everything figured properly this is a very efficient set up depending on house design.

 

[firetruck41]

I've got 5 returns in my 1900 sq ft house, because I designed the system. It circulates all the air in the house. A single return just isn't really very good, except that it is easy, and you don't have to find space to run the return ductwork, and it is cheaper. HVAC design is often overlooked by HVAC techs that use simple rule-of-thumb and "standard" layouts. A properly designed system will tailor each duct size and each vent/return opening for the specific room and CFMs desired CFM neede are calculated byeach room's insulation, window area, floor covering, compass orientation, exterior siding, etc...

 

[John Smith]

Wow! New construction practices never cease to amaze me. I can't believe that one return would be acceptable in a residence unless it is very small sq footage. Around here they are putting in two and three zone systems in all the McMansions complete with atriums and cathederal ceilings. Too bad they don't tell the poor bastards what their heating and cooling bills will be.

I think I will stick with my 1930s gas fired hydronic system. I <3 radiators.

 

[Toyo FJ40]

If you do a wood boiler you can put a fan coil in your air handler to heat the house and even run baseboard around your basement. I had my wood boiler set up to heat my pool with a heat exchanger.


Kevin

 

[Lugboot]

I have the system you speak of--heat pump main, propane furnace back up, and I have a woodstove installed in the great room. Our floor plan is pretty open (it's a timber frame). Oh yeah, also have a humidifier on the propane furnace and an outside air exchanger. We usually heat the house with just the woodstove and leave the t-stat set at around 60 to account for the times we may not be home and the fire goes down. The gas furnace has been kicking on once in a while, sometimes in the middle of the night. I will sometimes run the central air system fan when the woodstove is burning to help pull outside air into the house through the exchanger but when it's really cold, the air exchanger has to be turned off.

In a nutshell, I'm glad we use the woodstove as a primary. We wanted to go geothermal but couldn't take the price tag. The heat pump/propane furnace combo seemed the best efficiency bang for the buck. We can usually easily keep it around 70 in the house with the woodstove--it's a Quadrafire 3100 Steptop, btw.

 

[photogod]

I've got 5 returns in my 1900 sq ft house, because I designed the system. It circulates all the air in the house. A single return just isn't really very good, except that it is easy, and you don't have to find space to run the return ductwork, and it is cheaper. HVAC design is often overlooked by HVAC techs that use simple rule-of-thumb and "standard" layouts. A properly designed system will tailor each duct size and each vent/return opening for the specific room and CFMs desired CFM neede are calculated byeach room's insulation, window area, floor covering, compass orientation, exterior siding, etc...

One hot air and one return in every bedroom and enclosed space and one return on the main floor and one return in the basement here. I can't imagine only one return for an entire house. I wouls think it would get kinda stale inside. Differnt codes for different climates, I guess.

 

[Arya Ebrahimi]

What's forced air?

Seriously though, what is the feasibility of adding a second return to the ductwork in the basement at the heatpump near where the woodstove would be? I don't think it would be all that difficult to tap into the side of the trunk, and you could incorporate a damper for times when you're not utilizing the woodstove and don't want to pull air from the basement, although in the summer it should be cooler which would theoretically lower your cooling bill

Ary

 

[reffug]

I've got 5 returns in my 1900 sq ft house, because I designed the system. It circulates all the air in the house. A single return just isn't really very good, except that it is easy, and you don't have to find space to run the return ductwork, and it is cheaper.

Ben,
OK this is all stuff that I can buy. How hard do you think it would be to vamp an existing system to make it more efficient? Do you think it is practical to look into changing what is already in the house to make it more efficient and eliminate what one would consider cold spots etc...? How would you suggest I go about it, what steps would you take, and do you think in the long run the efficiency would outweight the cost in fuel consumption for the system as a whole?

Oh yeah, also have a humidifier on the propane furnace and an outside air exchanger.

Lug,
Tell me more about this particular addition to your system if you don't mind. I considered and spoke to my HVAC guy about a humidifier but not an air exchanger. He persuaded me not to use a humidifier due to mold build up in the ducting that would occur with such an addition. Sometimes the air in the house is particuarly dry but the mold build up did make sense to my limited brain and my GC on the project agreed with the HVAC guy and told me that it would cause more air quality problems than it would help.

 

[firetruck41]

Ben,
OK this is all stuff that I can buy. How hard do you think it would be to vamp an existing system to make it more efficient? Do you think it is practical to look into changing what is already in the house to make it more efficient and eliminate what one would consider cold spots etc...? How would you suggest I go about it, what steps would you take, and do you think in the long run the efficiency would outweight the cost in fuel consumption for the system as a whole?

Let me first say, I am not a HVAC pro, I used the HVAC Calc program (~$40) to determine all my duct sizes and all my register sizes, I researched the web and some books at the library, and am fortunate enough to have a HVAC/sheetmetal shop nearby that caters to DIYers. I had to retrofit an entire gas forced air system to our 10 yr old house, it just had individual electric wall heaters before. It was a big pain in the @$$ to install, though worth it in the end to convert to forced air (and AC).

If you have easy access to the main return in your basement, it may not be too bad to retrofit some additional returns. There are so many variables, it would be hard to say if it will make a marked improvement in your house. But if you have easy access to the return trunk and to the locations for the return ductwork and registers, it would not be that expensive. Is your basement finished or unfinished?

 

[reffug]

Is your basement finished or unfinished?

2300 sq. feet completely unfinished at this point. Wife is lobbying hard for me to consider finishing the basement before building the 2 car / workshop / garage. Don't think that is gonna happen though. I ask myself where will I spend more time, in a finished basement or in a heated garage/workshop? Its kinda a no brainer..............

 

[Lugboot]

Lug,
Tell me more about this particular addition to your system if you don't mind. I considered and spoke to my HVAC guy about a humidifier but not an air exchanger. He persuaded me not to use a humidifier due to mold build up in the ducting that would occur with such an addition. Sometimes the air in the house is particuarly dry but the mold build up did make sense to my limited brain and my GC on the project agreed with the HVAC guy and told me that it would cause more air quality problems than it would help.

Reffug,

We were told there are mainly three different types of humidifiers for whole-house central heating/cooling systems. The cheapest one would definitely accelerate throwing liquid water into your ductwork and promote mold, to my knowledge. The second tier is a better system, which is what we have, and the best is a steam system, very expensive. My apologies that I don't have more definitive info for you on this--I'll edit this when I check our system at home tonight.

The outside air exchanger was recommended for our type of construction--we have a timberframe with SIPs--Structural Insulated Panels. The SIP construction creates a very, very tight and efficient house. It's nice to know you can pull fresh air into the house when your firing the woodstove for extended periods when you don't have an outside air source for the stove.

I'll get you more info on the humidifier tonight.

 

[ff347]

You would want to build a minature "water oven", sort of the same idea as one of those fancy sheds in the yard. If the floor stove has the area on the top you could form a exchange to go on top of it. Tubing to transport the fluid, a Grundfos/Taco pump to move the fluid and a radiator with fan at the airhandler end of things. It might look a little frankenstein but if you look at the websites that have the outdoor sheds you will see what I mean. Yours would just be on a smaller scale, I helped a man source the parts to do just that the other day. You would probably want some sort of snap switch to control the fan and the pump.

I told him to get back with me, as of yet he has not.

Scott