Larry Peterson
New Member
Hi All,
We recently finished an addition and whole house remodel. We opted for a tile floor in our new bathroom.
Initially we were interested in doing electrical radiant heat in the bathroom but our contractor convinced us we would be better off with tying in a radiant heating zone on our new propane furnace.
Now that the weather has stayed cold for a couple months here in Massachusetts, we are finding out a few things we werent expecting.
1. Propane is costing us a fortune. $200 every 2-3 weeks.
2. The radiant heating in our bathroom will never reach its setpoint if the rest of the house is set below its setpoint. Even when the house is warmer than the bathroom setpoint, the bathroom zone is on far more than it is off. We have tried keeping the doors shut to the bathroom but it doesnt seem to make a difference.
We have a wall mounted honeywell standard thermostat
on the wall about 5' off of the floor. The floor has 2 layers of 1/2" plywood, a layer of durarock and then the porcelain tile on top of that. The floor joists below are on 16" centers with one loop (2 lines) in each of the 6 bays. I insulated each bay with the foil backed insulation and tried as best i could to keep a 2" air gap where i could. I then put in some R15 non faced insulation bats as shown in the photos.
The zone feeding the radiant heat runs at about 120 degrees when its calling for heat.
So my questions are as follows.
1. Is there just too much mass to heat?
2. Should i have used a different thermostat with a thermocouple located on or near the floor?
3. There is only R15 insulation above this bathroom in the attic. I just went out today and picked up 27 rolls of R30 unfaced fiberglass insulation and ill be installing all of that tomorrow in the attic above the original part of the house. I did have a double layer of R15 up there but a lot of it got trashed during the remodel. Some areas, particularly the area above the bathroom will end up with the 2 layers of the R15 and one layer of the R30 when all is said and done tomorrow. I dont expect all that to change the issues im having in the bathroom that drastically. I do hope that itll help cut down on the heating costs overall as a single layer of R15 just isnt sufficient.
4. How critical is it to have the 2" air gap between the reflective insulation and the radiant lines?
5. Should i consider raising the temp up another 10 degrees to 130 degrees? This seems like a bandaid approach and that there is some other bigger issue here.
6. In the attached pictures, you can see where the plumber ran the lines under the floor joists and into the next bay. Should there have been holes drilled through the floor joists and the lines ran through them?
Would that have made much of a difference?
7. I read about the use of heat exchanger plates. Is that easy enough to do after the fact and would they make that much of a difference?
Any help would be appreciated.
We recently finished an addition and whole house remodel. We opted for a tile floor in our new bathroom.
Initially we were interested in doing electrical radiant heat in the bathroom but our contractor convinced us we would be better off with tying in a radiant heating zone on our new propane furnace.
Now that the weather has stayed cold for a couple months here in Massachusetts, we are finding out a few things we werent expecting.
1. Propane is costing us a fortune. $200 every 2-3 weeks.
2. The radiant heating in our bathroom will never reach its setpoint if the rest of the house is set below its setpoint. Even when the house is warmer than the bathroom setpoint, the bathroom zone is on far more than it is off. We have tried keeping the doors shut to the bathroom but it doesnt seem to make a difference.
We have a wall mounted honeywell standard thermostat

The zone feeding the radiant heat runs at about 120 degrees when its calling for heat.
So my questions are as follows.
1. Is there just too much mass to heat?
2. Should i have used a different thermostat with a thermocouple located on or near the floor?
3. There is only R15 insulation above this bathroom in the attic. I just went out today and picked up 27 rolls of R30 unfaced fiberglass insulation and ill be installing all of that tomorrow in the attic above the original part of the house. I did have a double layer of R15 up there but a lot of it got trashed during the remodel. Some areas, particularly the area above the bathroom will end up with the 2 layers of the R15 and one layer of the R30 when all is said and done tomorrow. I dont expect all that to change the issues im having in the bathroom that drastically. I do hope that itll help cut down on the heating costs overall as a single layer of R15 just isnt sufficient.
4. How critical is it to have the 2" air gap between the reflective insulation and the radiant lines?
5. Should i consider raising the temp up another 10 degrees to 130 degrees? This seems like a bandaid approach and that there is some other bigger issue here.
6. In the attached pictures, you can see where the plumber ran the lines under the floor joists and into the next bay. Should there have been holes drilled through the floor joists and the lines ran through them?
Would that have made much of a difference?
7. I read about the use of heat exchanger plates. Is that easy enough to do after the fact and would they make that much of a difference?
Any help would be appreciated.
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