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I live in the Chicago area and have brick ranch with block walls and no insulation other than a 3/4 airspace between the concrete block and the plaster walls. A lot of large windows in each room.
Currently I have radiant heat in my ceiling consisting of 1/2 copper tubing approx. 6-8 inches o/c imbedded in about an inch of plaster. It’s being fed with approx 120 deg. water which is measured directly from the boiler. I’m in the process of doing some extensive remodeling and would like to move the radiant heat into the floor. I think gypcrete is going to weigh too much so I’m considering aluminum plates with PEX on top of the subfloor with sleepers.
My biggest concern is that I get at least the same heat output with the aluminum as with the plaster. I was told from Radiantec that I would get around 35 btu/sq.ft with their plates which are 8 inches wide and about the same thickness as flashing. I have a sample of a Thermofin channel which is much thicker and 4 inches wide.
Is there a way of calculating the BTU output of my plaster ceiling? Since the Thermofin is much thicker and not much more expensive, would that be a better way to go. I’ve been following the other RFH postings and have pretty much ruled out the Warmboard due to the very high cost.
Thanks for any help that you guys can provide.
Ed
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Buy the thermofin and be done.
*Your house sounds like it would need about 70 BTU/hour at 0F outside temperature. Maybe more if it is isn't very tight (air-infiltration-wise). But you have an easy way to now for sure. Look at your gas (?) bill for a month in which you can estimate the temperature (e.g. last November averaged, let's say, 20F, day and night). Subtract from that gas usage your summer time gas usage (which would be showers, laundry, kitchen baseline usage). What remains is your average heat demand for the month (with a 70-20=50F temperature differential in this case). Divide by 50 and multiple by your design (worst case) temperature differential, probably between 70 (for 0F) and 90 (for -20F outside temp). So you'll get a number like 120,000 BTU/hour. Then you need the square footage of RFH and the output per square foot to achieve that.You can almost read the meter yourself over a 1 to 3 day period to get heating demand over a period of known otuside temepature. Again, subtract the daily summertime gas use to take the Domestic HW usage.If you use fuel oil, sorry. Not an easy way to track energy usage over a short period.Seems that it might be borderline to not feasible for an uninsulated in a climate that sometimes gets somewhat cold. If you go with RFH, it may dictate non-insulative floor covering (vinyl, tile, bare concrete) or at least miminally insulating ones (floating, manufactured pseudo-wood, e.g. Prego, flooring). Good Luck
*Ed,Just saw your post. I'm thinking I may need to put radiant heat in the ceiling of a 13' high room, which is north facing with nearly floor to ceiling windows. I'm wondering how well your ceiling system worked?
*Arvid,It works extremely well considering I have alot of large windows and no insulation in my exterior walls. My only complaint is the cracks that have developed in the plaster ceilings. This could have been due to the fact that previous home owners were running the water temp too high. I have never had a problem heating the house even when the temps have gone in the negative digits. Why don't you want to put the heat in the floor?-Ed
*Ed,Thanks for the response. We are putting heat in the floor. But one room has massive windows and 13' high ceilings. So we were thinking we may have to put some pipes in the ceiling as well, for this one room.Arvid