Radiant Floor compatibility question
I’m curious if anyone has radiant floor heat but also uses another type of heat, like a wood stove? I’d like to be able to augment a radiant floor system in that way but I’m not sure that the RF thermostat would respond correctly or that there might not be other problems, trying the keep the house comfortable.
Replies
You have a real puzzle on your hands, I don't see any way you can control a wood stove without causing the thermo. of the RF to quit working unless you have a zoned system. Maybe someone else has a idea. Luck.
"If all else fails, read the directions"
It may not be such a puzzle, if oil prices continue to rise as they have. After considering what I've read on that subject, just in the last week or two, it's looking more like I'd be better off super insulating my next home and heating it with alternate energies of various kinds, instead of fossil fuels. Living near NE PA, where anthracite coal is still mined, makes that a likely resource. Having several acres of hardwood trees on site has always been helpful.
Anyway, I'm still sold on radiant floor but maybe I should consider a coal fired and/or a wood fired boiler.
As long as radiant heat is sized correctly it works like a charm. I still think that any system should be zoned; that way you can control the different areas with separate thermos. They do make multipal fuel boilers, check on that. Lots of luck......................................
"If all else fails, read the directions"
I agree with you completely about zoning. It's just a couple more hours work and few hundred bucks to do it right.
What brought up the original question was remembering a radiant floor seminar I attended some years ago. The company spokesperson said that adding convective heat to a radiant floor system would throw off the radiant system's thermos.
The radiant floor system takes much longer to respond to air temperature changes. So if the convective heat source took over and shut off the radiant system, then the convective heat crapped out...the woodstove burning down...it would take some time for the radiant floor to begin heating up again.
So the effect might be that the warmth and comfort of radiant floor would disappear in an inpredictable manner.
So I'd like to hear from anyone who has experience, trying to use both heat sources in the same home.
I hope someone else posts on the forum, I'm out of ideas, luck.
"If all else fails, read the directions"Thank goodness for those 'Wet Nap' directions.
"Open. Use."
Color me stupid, but I don't have a clue what "Wet Nap" means, therefore I don't know what your post is supposed to mean, sorry.
Wet Naps are those moist towelettes for cleaning your hands. They come individually packaged in a little foil wrapper with directions, Open. Use.Found that funny.
I get it now!
We have a masonry heater along with radiant floor heat. Installed in a newly built passive solar house in '89. I have a zone for the upstairs bath, a zone for two 4' pcs of HW basebd in two of the bedrooms, and 2 zones downstairs, along with the dom. HW heated by the boiler.
The mas. htr is located in the center of the "great room" and with an open floor plan down, is adequate to heat the home except in the below zero (rare) highs. The up is open to below and draws heat from there also.
I do not have any sensing thermo's outside, that would be a smart move for the floor heat. If it was cold and the boiler on overnight and the sun is out all day-we accumulate some nice warmth. The outdoor sensing would conserve fuel.
Both systems in the house require some common sense. We use the mas htr. totally in the late fall/early spring for our heat. The floor takes to long to bring up to temp in that moderate time when no heat is needed during the day. It would just get up to temp and then shut down and end up starting up again to begin the cycle. Learning the output of the mas. htr and how much fueling will be necessary is a sort of art form-or you might end up opening the windows in early dec. or late feb. to get the proper comfort. Same with the passive solar-you need to keep an eye on the weather report.
That's the basics, anything else - feel free to ask.
A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Calvin,
That's the kind of experience which I'd hoped to hear from my question. This is the first I've heard of outside thermostats for radiant floor heat. Considering the long response time, outside thermos make a lot of sense...to keep enough heat in the floor in order to stay ahead of the heat loss during colder periods.
I like the idea of a masonry heater too. It's only been recently, since I began researching newer products and materials in preparation for building my next home, that I've become aware of modern masonry heaters.
I lived for many years with a very simple passive solar design of my own which was not very efficient. That's largely because, in my area of New York State, the winter weather patterns only give us one sunny day in three. So my little wood stove, also not very efficient, had to work pretty hard on colder nights in order to keep the electric baseboard from eating up too much of the winter budget.
I'm interested to learn several more things from you.
I'd really like to have a masonry heater but where to put that big beauty becomes the question. My new home will be on a hillside, three stories including a basement which will be fully exposed on the downhill, eastern, side. I could add some space for the masonry heater(s), putting one in the basement level and adding a second flue for another, perhaps smaller heater-stove-oven in the third floor kitchen. The one in the basement, at present the recreational area, could also be positioned to absorb heat from the sun as well. That would be the more efficient heater and the most easily accessed for supplying fuel too.
What sort of masonry heater do you have? What are all it's functions? Who designed it? Who built it? Does my proposal sound workable to you? Is it too expensive to consider having two masonry heaters? Would it be simpler and more efficient to use a cast iron stove in the kitchen, as a second cook stove and auxiliary heater?
We have a 2 story, imbedded in the hill and open on the downhill (south) side. Sounds like the same orientation (if facing south) as you will have. Remember, to get the optimum direction for the sun heat, you can excavate a bit more and cock that house on the angle. Nothing says the orientation has to be perpendicular to downhill.
To your other questions. We have a tulikivi. A good mason friend of mine was just getting started in masonry heating and decided to set up one of them in a home show. He laid it up dry, disassembled it and brought it up to Ohio. A great deal for us at the time. Still, far from cheap. It was a big decision that we are glad we made. Our heating systems were not cheap then, but the savings in fuel over the years has been good. Our design for energy conservation (rudimentary at the time) looks to have a good future.
My friend now is an educated source for anything to do with masonry heating-stoves, bake ovens etc. He's made it a career and has studied with some of the best here and in Europe. He builds some beautiful things, your imagination is the only limit. And, the savings in wood is GREAT. We heat 2600 ft with two firings of about 15/18 lbs of wood. In the fall/spring-one firing. And clean heat too. We get a bit of smoke at start up, then nothing visible out the chimney for the rest of the burn. Flue-never been cleaned in 18 yrs and nothing on the sides except for a lite grey "ash". No creosote to contend with, the fire burns too hot for it to form.
A masonry heater has some tonnage. You'd have some engineering to get it up on the 2nd floor-or you'd have to block up to that level and then add the mass. Give some thought to maybe using a high efficiency stove on the second fl. Or, how bout this. Open that level up to the basement a bit on the down hill side. Figure a way to convection that heat up and to the back, returning it down to the bsmt level.
Isn't planning a build fun?
If I didn't answer em all, ask again.A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
<<Isn't planning a build fun?>>
Yes it is. I'm particularly impressed with the many fine proven methods for energy conservation which now exist. ICFs have come along way since their inception. I'm planning to build the entire exterior of my next home using them. For a wood loving carpenter whose experience in building new homes over the last forty years has been strictly western framing, that's a huge departure.
But the demand for fossil fuels will not decrease so, in order to avoid one consequence of that fact, I'm looking at any means to conserve energy and augment my new home's heating.
Your masonry heater sounds like a near perfect match for my new home. I'm impressed by the hot fire-thermal mass concept. As you probably know, the history of wood stoves in the last fifty years has been mostly slow burning semi-automated furnace types which inevitably produced a lot of pollution and dangerous creosote. Your masonry heater not only answers those concerns but addresses a number of other PIA problems which arose with those older wood stoves.
Thanks for sharing your experience. I'm sure to have more questions so I'll plan to keep in touch.
If you haven't yet, check out the masonry heater association website. See if you can find any of the work pictured with the name Tom Trout.
http://mha-net.org/A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
I was thinking that if you couldn't have a zoned system, maybe you could put the thermostat for the radiant system as far away from the wood stove as you could get it--in as cool a location as you could thing of--maybe near an outside door.
Edit: Was also wondering if you could put it on a timer so it is set higher for times the stove would normally be on, and then is lower for when the stove is not normally burning.
Edited 4/22/2007 1:43 pm ET by Danno
Danno,
Your thoughts are similar to mine. Good thing that others have gone ahead of us, huh? The outside thermostat and the embeded sensory suggested by Globaldiver sound like effective ways to deal with that problem.
Edited 4/22/2007 3:17 pm ET by Hudson Valley Carpenter
If you're pre-pour stage on the radiant floor, you can embed temperature sensors in the floor and measure that temperature directly.
Hudson Valley,
I have an ICF house which is a basement and two storeys. The basement and main floor are hydronic in concrete. The top floor, bedrooms and bathrooms, is a single loop of hot water baseboard convectors with a few runs of pex under the bathroom floors at the end of the loop. This is a high mass house which responds very slowly to changes in outdoor temperatures. It is also nearly airtight, ventilated by HRV. We have a wood stove on the main level. The boiler is a Toyotomi "Oil Miser". There are five zones controlled by digital non-programmable thermostats, four hydronic radiant zones plus the baseboard zone.
I've lived in this house for only a little over a year, but I have drawn some conclusions. One is that I am glad I didn't spend a lot of money on control systems; what we have works perfectly well. The reason it works well is that the top floor of the house, which is where most of the heat loss occurs, is heated by a low mass system which responds quickly to demand or to heat inputs. If I fire up the wood stove, the concrete main floor stays warm for quite a long time but the house doesn't overheat because the upper floor system has no heat storage capacity.
Another is that I should have gotten a smaller oil tank and saved some space. I have a 900 litre tank, which is probably enough oil for two years.
I think that if you are going to have a fast heat input like a wood stove then you should have a fast response main heat system or some other fast response heat control mechanism, like a window that opens.
This is a design solution to the potential problem, rather than a hardware solution.
Ron
An ICF home with two poured hydronic floors? That's one good lesson. I hadn't thought about supporting a hydronic floor with ICF walls, nor of having that much thermal mass surrounding the radian floor. BTW what's the span of the suspended floor?
I checked the Toyotomi web site. Which boiler or water heater is installed in your home?
I'm impressed by the efficiency of your system. Thanks for telling me about it.
Hudson Valley,
I was less clear than I should have been.
The main level of this house has a concrete overpour on top of wood framing. It isn't a suspended slab solid concrete floor system. The framing is dimensional lumber. I ususally recommend strongly against using lumber framing for floors in ICF structures, but I was prepared to put up with the consequences in my own house to save a few bucks. The longest spans are 15', done with 2x12 @ 12"
The Toyotomi is model OM-180. It is a 150,000/btu/hr unit. No annual service requirement, which is a bit of a subsidy on the cost of the thing. The local distributor can't tell me anything about the expected lifespan of these things from his own experience as the oldest unit he has installed is only ten years old and he hasn't yet had a service call.
The machine is the size of a two-drawer filing cabinet and makes about as much noise as a refrigerator.
Ron
Ron,
The Toyotomi sounds like a dream come true. Thanks for that information. That alone will change my heating plans.
As I'm just getting acquainted with all the advantages of current ICFs, I appreciate some guidance. Other than wooden floor systems, what would you recommend for spans of twenty feet or more?
My new home will be three stories, including what I'm calling the basement.
Peter
Hudson valley,
I don't know much about spans that long.
The only reason for not using lumber in ICF construction is that shrinkage in the floor framing is not matched by shrinkage in the walls so you will get a lot of door openings warping, floor slopes developing, drywall cracks and that sort of thing.
Wood trusses would work, maybe, depending on your loading. Talk to a truss designer.
I think TJI might go to spans like that too, but I think they are too difficult to bother with. Running services with them is always a hassle.
As for a heating plant, I wouldn't even think about buying anything that didn't have local support. Ask around for local experience.
I am very happy with the Toyotomi. When it's running, you can put your hand on the exhaust pipe. It's uncomfortably hot, but not enough to burn, so it isn't pumping a lot of expensive heat out of the house.
Ron
Toyotomi update?
Ron, Do you have anything to add about your experience with the toyotomi, now that it has a few more years of use? I'm stuck with oil, and my prospective radiant supplier is steering me toward a Bock water heater. Whe I suggested the Toyotomi, he said there was some issue with the temperature differences that might affect longevity, but I couldn't really follow the logic. The toyotomi venting is a more attractive solution.
I live in Montana. Our house is radiant floor, tubing set in 1/12" mortar with tile on top. The hydronic system is an LP fired boiler. We use a wood stove extensively. The problems I've encountered are that the slab gets cold if the floor doesn't run, this means that when the floor does come on it takes quite a while to warm the slab, then the room. The best solution I found was to use an automatic thermostat and have the floor come on twice a day even if the stove was heating the whole area. I'd set the floor to come on at 4:30 am for a half hour, then again at 4:30 pm for a half hour. This way the floor was not cold when we get up in the morning or at night when we kick back.
Like I said, the biggest problem is the recovery time from a very cold slab, if you avoid letting the slab get very cold recovery times will be much quicker.
Lee
If you are using a mass emitter (concrete), then you do two things.1. Zone the entire area that will get heat quickly from the intermittant source (woodstove) by itself. The stove can shut down that zone whenever it likes, without the rest of the house getting cold. If other zones get heat at some point, fine.. they can shut down when they do finally get that heat.2. Use a slab sensor to maintain a minimum slab temperature of room temp, or room temp plus one or two. That way, if the wood stove cools down faster than the concrete can heat up, you aren't starting from "cold". This is less critical if the slab is above all heated space, but it's not too expensive to do and it is a good idea anyway.These sensors can run into good thermostats, like a tekmar 541 or 508water temperature control is part two of the puzzle can be done with an outdoor sensor controlling a mixing device, or with outdoor and indoor sensors (like the 541, which is a smart thermostat).-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Thanks to all for your thoughtful replies and for sharing your experience. It feels great to be in contact with some end users of products I've only read about. Relieves doubt about the hype with which all products seem to be sold.
If you use a slab sensor, as opposed to a thermastat, you can control the temp. of the slab, regardless of the room temp.
Karp,
That makes a lot of sense to me. Radiant heat, particularly radiant floor, doesn't really need an air temperature reading to make the room comfortable for people. So a wall thermostat is about two steps removed from the information needed by a radiant floor system, for it to respond to human needs.
I suppose that eventually someone will write a radiant floor software program, with temperature sensors in several locations, which will make it possible for the floor to be kept at a very precise temperature setting, moment by moment.
Uh, that's not correct at all.You'll find it's nearly impossible to control a room temp by floor temperature alone. The floor needs to be a different temperature depending upon the current load conditions. The more heat the room is losing, the warmer the floor has to be. It's not the floor you're trying to keep warm, remember... it's you, and all the other surfaces of the room. The floor has to radiate that energy intensely enough to provide that heat to the objects that need it. When your load is 10 BTUs/sq ft, that's a very different intensity than 20 BTUs/sq ft. Using the same temperature floor in both conditions will not generate good results.A floor sensor WITH a thermostat... now you're talking. as I noted before there are thermostats that can take auxiliary sensors. Then you have some control over both the mass directly, and the room temperature which is ultimately what you wish to control.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Thanks for jumpin' in, Rob. I was making a suggestion based on the woodstove being the primary heat source. The important thing to remember is both Hudson and myself are Carpenters, who have no business designing radiant heat systems. Not that I'll let that stop me, but its nice to know you'll set us staight.