Outdoor wood furnace backup

[Sukhoi29SU]

FNG here, planning extensive home remodel in north central Illinois. Currently heat home primarily with two Avalon Olympic wood stoves, and propane backup. I’m away from home militarily and with an airline job very often, and sometimes my wife falls behind with keeping the stoves going. House is extremely inefficient right now, but plan on making it really tight and doing a good job insulating it with the remodel. Considering the idea of removing all duct work and installing radiant heat throughout the house , fed by an outdoor wood burning furnace / boiler. I’d keep the wood burning stoves as well, but like the idea of having the flexibility to not always have to get the wood into the house. What I’m trying to figure out, however, is what a backup source of heat should be if the duct work is removed from the house. Is there a way to have propane feed the radiant heat when the outdoor wood furnace / boiler doesn’t meet a certain demand? Natural gas is not available in my area.
Thanks in advance for the advice!

 

[jwfirebird]

just speaking from my own experience here, if she doesn't want to feed the stove in the house she certainly is not going to want to when its outside in the cold and snow, why I don't have a owb. I just optimized getting wood to the racks, shoots and such, and when the basement is more than 30 she uses the stove on the first floor, she don't like the basement and I have to be home if I want that one used.

personally would leave the propane and ducts, you already paid for it, spend a ton on insulation and good windows installed very well, that's the best way to get the most from your dollar on most older homes. and the wood units you have will be more effective at keeping the house comfy

 

[maple1]

You can heat water with NG, LP or oil. All kinds of choices.

Is a/c in the summer a consideration or possible desirable thing? Consider ductless heat pump if so.

Or just keep your LP as-is. There is no way my wife would be keeping an OWB going if we had one & I wasn't here to do it - I am quite sure. I would plan the system the other way around - something else as primary heat source, and wood as secondary. Then the more wood you can burn the less other stuff you will. Of course that might mean your OWB would be going cold if you're away for long - which might be a reason to reconsider having an OWB in the first place.

 

[Sukhoi29SU]

Thanks for the responses, fellas.
It takes a special kind of woman to keep wood burners fed, that’s for sure.
My plan was to keep the house stocked with plenty of wood before I go away on trips. If she has wood readily available to her right by the stove, she does a good job keeping them going. I think once I get proper insulation and windows in here, these Avalon Olympic stoves will provide plenty of heat. They are sitting in the center of each floor (one in basement , one on main level). When they are going, they will practically heat you out of the room they are in, but I haven’t found a good way to get the air pushed to other areas of the house, yet. Hopefully the remodel , which will make the floor plan open concept, will clear some walls and make hot air easier to travel - however, some of the bedrooms on the sides of the house might still have trouble getting air. That’s one main reason I’m looking towards a radiant heat throughout the house with an OWB. Perhaps I’ll keep my propane tank, and have propane feed it’s own boiler. I just didn’t know if there was a way that could be set to a thermostat and only kick on when owb stopped being fed by my wife, but then work to maintain the same temp the owb did. I’d like to minimize this propane use as much as possible.
Also, to answer your question, Maple— I live out in the woods in a heavily shaded area, so even though I currently have AC installed, it rarely gets used. I’m thinking that I could live without it, or maybe just get a couple small mini-splits for the very hot / muggy days. Lower level stays plenty cool.
Thanks again

 

[leon]

Another option could be a bituminous coal stoker in a separate building to heat your home with steel or reclaimed/cleaned cast iron radiators
at a lower temperature (if desired).



The EFM DF520 underfed coal stoker will burn bituminous rice coal and provide all your heat and domestic hot water if desired and you can have air conditioning.

Bituminous coal is very economical and the underfed coal stoker will only require tending once a day depending on the weather where end user can fill a 55 gallon barrel with coal and remove one ash basket and replace it with an empty one for the next days use.

 

[jwfirebird]

indoor furnace of whatever fuel is going to be the most efficient, in the basement. the heat lost to the ducts and heater go up into the living space anyway. if you have circulation issues, sounds like you have planed to fix that. you could just add or resize ducts to bedrooms when the walls are open.

i dont have to run anything, ducts, any of that when we run the stove 1st floor to keep second warm, just no insulation or sound proofing between the floors when you redo it

 

[Bad LP]

I'm not sure my wife will feed the indoor wood boiler but I know for sure if it was outside she would not nor would I. Below zero is normal up there then add the blowing wind.

I went indoors with the boiler and tanks in the basement and the heat loss even with the tanks in an insulated room has the basement at 70 in no time.
My system does not care what heat source is running. What ever boiler is hot is being used used. I'm on LP as well.
Duct work could be used for an air source heat pump for shoulder seasons down to 25 or so plus having AC is a no brainer. No need to rip it out for wood boiler heat not to mention you could add a water to air exchanger from the wood boiler as a dump zone or again for quick recovery and shoulder seasons.

If you are adding RFH in a major remodel you could bury the PEX in gypcrete on top of the floor. Much better system IMO due to mass. My second choice is warmboard and third is staple up. Both option 1 and 3 require insulating the under side of the floor. A very good friend went the warmboard route after asking my advice (he hates me because I cost him money yet he knows I'm right) and the end result was very, very good. He used tile throughout his major mud/laundry/kitchen/dining room. Due to the lack of mass you can tell where all the pipes are unlike my gypcrete where you must use an IR thermometer. Warm floors encourage people to take off their shoes and that helps keeping your house clean.

Ohhh. Our boxer loved sleeping on the warm floor in front of the LR fireplace insert and frankly I didn't blame him.

 

[Sukhoi29SU]

I'm not sure my wife will feed the indoor wood boiler but I know for sure if it was outside she would not nor would I. Below zero is normal up there then add the blowing wind.

I went indoors with the boiler and tanks in the basement and the heat loss even with the tanks in an insulated room has the basement at 70 in no time.
My system does not care what heat source is running. What ever boiler is hot is being used used. I'm on LP as well.
Duct work could be used for an air source heat pump for shoulder seasons down to 25 or so plus having AC is a no brainer. No need to rip it out for wood boiler heat not to mention you could add a water to air exchanger from the wood boiler as a dump zone or again for quick recovery and shoulder seasons.

If you are adding RFH in a major remodel you could bury the PEX in gypcrete on top of the floor. Much better system IMO due to mass. My second choice is warmboard and third is staple up. Both option 1 and 3 require insulating the under side of the floor. A very good friend went the warmboard route after asking my advice (he hates me because I cost him money yet he knows I'm right) and the end result was very, very good. He used tile throughout his major mud/laundry/kitchen/dining room. Due to the lack of mass you can tell where all the pipes are unlike my gypcrete where you must use an IR thermometer. Warm floors encourage people to take off their shoes and that helps keeping your house clean.

Ohhh. Our boxer loved sleeping on the warm floor in front of the LR fireplace insert and frankly I didn't blame him.

Thanks for reply.

I guess I didn’t know that indoor wood boilers were a thing- I thought that systems like these had to be placed a certain distance away from the house for safety reasons. Glad I’m doing the research and getting smart on this prior to remodel

I like the idea of a wood boiler in my garage, as the source for radiant heat. And propane backup for the boiler, for heated floors.

Ideally, I’d really like to take the ducting out of the house- providing much more ceiling height in the lower level. Plus, from everything I’ve read, the radiant heat is very efficient if installed correctly with insulation and vapor barrier- and provides a more evenly distributed heat throughout the house. I also will keep my indoor wood burning stoves for the really cold days.

So, if I understand correctly, I can have an indoor wood boiler connected to radiant floor heat system; (gypcrete) and if the wood boiler isn’t supplying proper demand (we go on vacation for a week) a propane backup system automatically takes over to heat the PEX?

Any opinions on best indoor wood boiler for large house?

Thanks again

 

[leon]

All depends on your wallet and how thick it is as you are talking about a huge amount of money with the EPA rated wood boilers with a secondary burn chamber/afterburner

You will have a lot of difficulty from your insurance company with putting a boiler of any type in your garage UNLESS you have a dedicated separate room for your wood boiler with a block wall separated boiler room and a steel fire proof door.and an overhead door to load wood in the room.

You have to do a lot more work and remember that you need to think about it as something you will have feed 10 years from now with the idea that you want something that will be a forest eaters little brother.

 

[Bad LP]

Thanks for reply.

I guess I didn’t know that indoor wood boilers were a thing- I thought that systems like these had to be placed a certain distance away from the house for safety reasons. Glad I’m doing the research and getting smart on this prior to remodel

I like the idea of a wood boiler in my garage, as the source for radiant heat. And propane backup for the boiler, for heated floors.

Ideally, I’d really like to take the ducting out of the house- providing much more ceiling height in the lower level. Plus, from everything I’ve read, the radiant heat is very efficient if installed correctly with insulation and vapor barrier- and provides a more evenly distributed heat throughout the house. I also will keep my indoor wood burning stoves for the really cold days.

So, if I understand correctly, I can have an indoor wood boiler connected to radiant floor heat system; (gypcrete) and if the wood boiler isn’t supplying proper demand (we go on vacation for a week) a propane backup system automatically takes over to heat the PEX?

Any opinions on best indoor wood boiler for large house?

Thanks again

You understand correctly. You will want a buffer tank for the RFH system if you use a low mass LP boiler. I'm running a System 2000 in part because the local company sells a ton of them and all the techs know them inside and and out. My buffer tank is an electric (not wired in) 42 gallon hot water tank The short cycling of the boiler feeding the RFH was driving me crazy!! If I had to do that over I would get a cast iron boiler and ditch the tank.

When I was looking at boilers and talking to people I narrowed it down to Tarm or Varm. A used Tarm became available so that settled it. I don't regret my choice and the dealer is kind of local to me, very responsive and well stocked. I really didn't want the hi tech units coming out when I was shopping but today you have no choice in the matter.
That all said I'm betting Varm would have been an equally good unit and they were also very good to talk to. They spoke clearly and off the hip about all of the competition. I really liked their honesty and frankness.

I will say this... It's not a cheap investment. I built the house 10 years ago and the HVAC systems were 30K and this boiler project was another 18K installed. When I started out LP was nearly 4.00 a gallon along with oil so the math made it easy. Last month I topped off the tank at 1.99. The ROI is a long way out IF prices remain low. We have 14 acres of woods here and I always have the options of cutting and splitting my own, buy log length truck loads, buy cut only or cut, split and delivered. With 3 million acres of paper company land in my back yard I'm not worried about running out of supply. I won't lie to you when I say I never thought about pellets. Storage and handling sure would be a whole lot less work but the exercise won't kill me and I do enjoy being outdoors. Its a Maine tradition.

 

[Sukhoi29SU]

You understand correctly. You will want a buffer tank for the RFH system if you use a low mass LP boiler. I'm running a System 2000 in part because the local company sells a ton of them and all the techs know them inside and and out. My buffer tank is an electric (not wired in) 42 gallon hot water tank The short cycling of the boiler feeding the RFH was driving me crazy!! If I had to do that over I would get a cast iron boiler and ditch the tank.

When I was looking at boilers and talking to people I narrowed it down to Tarm or Varm. A used Tarm became available so that settled it. I don't regret my choice and the dealer is kind of local to me, very responsive and well stocked. I really didn't want the hi tech units coming out when I was shopping but today you have no choice in the matter.
That all said I'm betting Varm would have been an equally good unit and they were also very good to talk to. They spoke clearly and off the hip about all of the competition. I really liked their honesty and frankness.

I will say this... It's not a cheap investment. I built the house 10 years ago and the HVAC systems were 30K and this boiler project was another 18K installed. When I started out LP was nearly 4.00 a gallon along with oil so the math made it easy. Last month I topped off the tank at 1.99. The ROI is a long way out IF prices remain low. We have 14 acres of woods here and I always have the options of cutting and splitting my own, buy log length truck loads, buy cut only or cut, split and delivered. With 3 million acres of paper company land in my back yard I'm not worried about running out of supply. I won't lie to you when I say I never thought about pellets. Storage and handling sure would be a whole lot less work but the exercise won't kill me and I do enjoy being outdoors. Its a Maine tradition.

Thanks again, guys. I enjoy being outdoors, too. I like the idea of using downed trees that would otherwise rot away, as a source of fuel. I'm on 12 acres and my Dad, who's heated with wood for 40+ years, is on 80 acres of woods and lives just down the road from me. As much as I like the idea of radiant heat and an indoor boiler, those are big numbers you're talking about and I'd really want to be able to justify the decision, financially. I think simply by insulating this house properly during the remodel, I will be able to heat this house mainly with these wood burning stoves I have in the house, and drastically reduce the propane burn. I've considered putting some spiral ducting in the lower level and keeping the propane as my backup. The floor vents actually sit within the concrete slab in the basement, too - so someone put some thought into the system when the house was built in the late 70s.
I do really like the idea of radiant heat, however. One of the main reasons is that the heat would be more evenly distributed throughout the house - instead of it being 90 degrees in front of the stove and 60 degrees over in the corner bedroom in the lower level. Is there any system where I could heat a radiant system with my downstairs wood burning stove? If not, how much money would be saved with an OWB furnace vs. one that sits in my garage? If I can keep the OWB furnace relatively close to my house - I don't mind the idea of walking outside in the morning for a couple minutes to put some more wood in it. I don't mind putting some money up front for the right system - but it has to make some financial sense to me...

 

[Bad LP]

To be clear you can spend less and many do. Recycle a LP tank for water and do some work yourself.

LP boiler system in gypcrete plus a full central AC system was my design from the start when building the house.
I used vertical ASME rated tanks and they are $$$. Much of the labor in pipe work I could have done but between the tank rating and having the system installed by a licensed boiler tech my insurance will never be compromised. That's a risk I was not willing to take.