Radiant Heat and Soapstone Fireplaces
thorn
| Posted in Energy, Heating & Insulation on
My wife and I are going to be building a house next year, and have been looking at a lot of information relating to radiant heat systems. We have also read quite a bit about soapstone fireplaces. We really like both concepts, but have been unable to find any literature that suggests they can be used in conjunction, rather than either one or the other.
Does anyone have experience using soapstone fireplaces to heat the water for radiant heat flooring systems.
Thanks,
Dave
Replies
Welcome to Breaktime. Participants HAVE been known to assist.
On first blush, I think using a fireplace to heat for a radiant water system would be massively inefficient. Also, the fireplace would have to be on for you to get heat - and not knowing where you live, and what kind of fuel you are using and its' prices, nobody can give you much advice.
I did read of a Swedish (I think) fireplace which is incredibly efficient, but the cost is quite high. Trying to engineer a heat exchange system into that would also be costly.
Are you sure you don't want to be like the other kids?
Quality repairs for your home.
Aaron the Handyman
Vancouver, Canada
Aaron, Bob, Calvin, and Paula:
Thanks very much for your comments, they were thought provoking for us. I wanted to interject a few more thoughts and here what you had to say.
First of all, we live in Maine and will building by the coast. We really like the idea of radiant flooring, with it's even heating and efficiency, and thought that by using a soapstove fireplace (also reportedly very efficient see http://www.tulikivi.com) to actually heat the water for the system we could capitalize on the heating of the fireplace twice over. However, as you have pointed out, it might be cost prohibitive as well as redundant.
Having thought about this more, what we are really trying to do is find the most efficient way to heat the water system for radiant heating. We have thought of using an oil fired burner to heat the water, and perhaps couple that with a wood-burning stove. What would be your thoughts on that approach?
We have also given some thought to using solar panels to heat the water in the system. Has anyone had any experience with this approach?
Thanks again for you thoughts.
Dave
thorn, our heater is a tulikivi. Very efficient and clean burning. If you fire it twice a day, sized right, it will heat a house at least 2500 sf. As has been pointed out, you won't "see" heat off of it for a couple hours. Once you get it going and providing heat, it might confuse the floor, telling it there is no need for heating water. Both would "die" at about the same time-12-24 hours later. This is the reason I gave myself for not going down that path. I wouldn't say either or as far as the primary heat source. The cost would be pretty steep I suspect. The tulikivi we have was purchased through a mason buddy that used it set up dry at a home show, we then re-assembled here. He gave me his intro price from the manu. The boiler and tube set up with controls is an equal cost. Both put together, costly as if two heating systems were being installed.
Seems to me there was something about a custom built Masonry Heater that did what you propose, I know in old Europe water heating by the masonry heater is common place, stands to reason you could do it and it would work. Retrofitting the tulikivi would seem possible too. Check out the Masonry Heater Association, nice people there. Look for a builder called Tom Trout, he's the guy I spoke of above. I'm sure they have some members up Maine way. Ask Tom for a referral.
http://mha-net.org/
Remodeling Contractor just outside the Glass City.
Quittin' Time
With regard to price - setting up the hydronic cost about 3,500$ CND including slab insulation, the wood stove with the water heater insert, SS chimney( 30feet long) cost about 3,600$ CND.
I figured that the wood heated hot water portion of the system added about 600$CND to the cost.
The addition is also heated with forced air. We do have winter power failures about once every two winters. I do like the idea of having a back up heat source not dependent on 110v electricity. Is it worth the extra cost of 600$ or so for the wood heated hydronic? Hard to say. We had planned to have a woodstove in the addition any way so it seems logical to try and extract and distribute as much heat from it as possible.
Re:belts and suspenders, we can in an emergency heat the hydronic with our domestic gas water heater as well as it does not require 110 v power to operate.An ex-boat builder treading water!
Hi Dave,
You might try Albert Barden at http://www.mainewoodheat.com/ . He did considerable research on masonry heaters, and wrote a construction manual.
kestrel
Dave - I have lived with a radiant slab system for 20 years now. Currently heated with a wood boiler and (more & more) with off-peak electric (I get lazy & it's nice to come home to a warm house). Solar input works pretty well, from what I understand (no first hand experience, my solar input is passive direct gain) - provides a direct heat storage medium for the solar heat and effectively creates a several hour time delay for the delivery of the solar heat, which is good in most cases.
I started out not knowing much about radiant slabs (I try to do my experimenting on my own home first ...), and tried to heat the slab with two heat exchangers inside the firebox of a wood stove. Didn't ever get enough heat into the water to effectively heat the slab. I would guess that this would be a similar thing with your soapstone fireplace. By the time the slab gets heated up you've overheated the house with the fireplace - because most of the heat comes out through the fireplace rather than going into the water.
My thought is that the ideal combination is one high-thermal-mass system (slab) and one quick-responding relatively low-mass heater (woodstove). Gives you the best of both worlds. The radiant slab is easiest to do with an automatic controllable heat source - but if you're willing to futz with it - a wood boiler can do it.
Roy
Thorn, welcome.
We've got a soapstone heater and hydronic heat from a boiler in the floor. We use one, the other or both. I gave some thought when we did this to perhaps run some coils through the heater, but quickly abandoned that idea when it appeared too complicated for my pea brain. However, I think it is possible with the right controls etc.
Here's how we use our system. In the fall and spring when the passive solar isn't enough to take the chill off, we fire up the heater with maybe a 10/15 pound charge of wood (about 2/3's of a log bag) in the evening. The mass of the soapstone radiates the heat 24 hrs, stone still warm the next evening. In winter, we would charge twice a day to provide the heat, which we might do on weekends. Throughout the winter the floor heat takes over, with the heater used in the evening quite often to really toast it up. Best of luck on your project, those two heat sources are very nice. Radiant heat is just the best heat IMO. Higher start up cost, better operation cost. Do the two pay back? Beats me, comfort is king.
Remodeling Contractor just outside the Glass City.
Quittin' Time
Edited 11/4/2004 6:48 am ET by calvin
Edited 11/4/2004 6:50 am ET by calvin
I've got a Pacific Energy woodstove with a SS water pipe in it that I use as a heat supply to the hydronic heating in a house addition I'm building.
A local firm designed the system for me.
The water pipe is connected (looped) to a 40 gal(CND) hot water tank. There is a pump with thermostat to pump water to the cold side of the tank. The thermocouple for the thermostat is located just where the waterpipe exits the stove. When the water in the pipe hits 65 c the pump kicks in and pumps a shot of hot water into the tank. It takes about 48 hours to heat the tank from 10 c to 50 c.
Another pump connected to a room thermostat pumps water from the tank through a manifold to the hydronic pex pipes.
I don't know how efficient it is energy wise. It does store heat and it certainly distributes the heat from the woodstove around the house, and down low in the floor where it is most useful.
Last year I kept the woodstove going 24/7 for most of the winter.
The hot water tank is an electric one which I turn on if i am going to to out of town for a few days. As the addition project proceeds I'll add a gas fired boiler to the system and use the woodstove set up as a preheater.
I can tell you that at our house, we already have so much radiant mass that a soaptstone fireplace would be too much. We have radiant heat in concrete (basement) and soon to have it in gypcrete (main level). (We have lived in our basement for 2 years while working on the upstairs levels.) Anyway, what we have learned with our radiant heat in concrete (and gypcrete will be similar) is that you set the temperature and you leave it....forever. The responsiveness of radiant heat in concrete is very slow. We realized that we needed a fireplace that would give us quicker heat after the sun goes down and before the radiant heat kicked on. I think a big, massive, soapstone fireplace would react more like the floor...slowly.
Our hope is that the quick response fireplace and the slow response radiant heat will compliment each other.