Any advice before we majorly rearrange our in floor heat system?
We have found a lot of great insight on this site. We have a bit of a unique situation so we would greatly appreciate any thoughts before we majorly rearrange our in floor heat system. Thank you in advance for any thoughts!
We did a new build in the North East a few years ago. We have cold winters so the thought by the original plumber was that in floor alone wouldn’t be responsive enough. Given this we added in floor heat “just to keep the floors warm” and then added two air handlers to pick up the extra demands as needed (and circulate fresh air). The in floor and air handlers all run off a single indirect loop heated by the boiler.
For the floors one zone is in an insulated slab in the basement, and three zones are for the main floor. The main floor zones are staple up piping between the floor joists with no heat plates, just stapled up to the sub floor with an air gap and cardboard underneath, and insulation below that (we were told heat plates weren’t necessary, which was maybe a mistake in hindsight).
The four zones are controlled with floor sensors and thermostats. When calling for heat the boiler turns on, which heats up the indirect loop to a specified temp, which is then circulated through the floors with the four circulation pumps. So it is an on/off system.
Originally the in floor loops were set at 160 degrees “so that the heat would get through the floor” but we worried this might be putting too much stress on the glue down vinyl plank flooring above so we lowered the temp to 130.
The three problems we see are 1) we get cold spots near windows because the in floor circulation is off most of the time, 2) we are running the boiler on and off at what seems to be a relatively low temperature so we worry about boiler efficiency, and 3) we worry about the stress this high temp on/off cycle might be putting on the floors.
Given this we are considering adding an indirect HW tank, and then running the in floor heat off this tank with the four circulator pumps running continuously. The thought is that this should give a more even heat, and also put less stress on the boiler as there is a better heat sink with the tank and therefore hopefully less cycling of the boiler. We would then use the thermostat on the indirect tank to control the temperature of the floors, with outdoor temp info being used to maximize the floor temp without overheating the space. The air handlers would continue to be used to pick up any extra heat needed.
That said we aren’t sure if this is a good idea or not. Any thoughts or advice would be greatly appreciated.
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