New to in floor heat

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New Member
Nov 24, 2022
I bought a home on a slab with in floor heat. I have some questions and would really like to hear your thoughts.

Home: 32x48 living area that is broke into 2 zones, and a 32x32 attached garage consisting of 1 zone. House was new in 2011, post and beam structure with 4" slab. Under slab is 2" foam board. Walls are 4" closed cell spray foam and ceiling has 15" of blow in insulation. Guessing an R32?

System: The system looks well put together. 3 zones all consisting of 250' loops of 1/2" pex on 12" centers. Zones are/were all utilizing Taco 007 pumps. The boiler is a Quietside LP boiler with a max btu output of 120,000. Manifolds are stainless with flow valves on each zone. Pumps are controlled by a Taco relay board. Thermostats in each zone that are measuring floor temp, not air temp. Boiler is set on 130 degrees but never see that at the manifolds.

Zone1: living area/kitchen - 4 runs. Floor covering mostly carpet and hardwood flooring
Zone 2: Bedrooms - 3 runs. Floor covering mostly carpet and Tile in the bathroom
Zone 3: Garage - 5 runs. all concrete floor

I have been doing some testing in the garage, mainly because we can eliminate floor covering as a factor. Zone 3.

I have been watching my temps this winter and have seen very high delta t temps. We are about 120 degrees on the supply side and 80 degrees on the return side. GPM is running around 0.5. I thought maybe we needed to bump up the GPM to get a better delta t variance so i switched to a 011 pump. GPM did increase to .75 on each run but the delta t did not change. Boiler seamed to run "smoother". The boiler temp was set to max of 130degrees for this test. Floor temp at 68 degrees with an air temp of about 68 degrees. The garage seems to run 1:1 ratio of floor to ambient temps. It's in the 50's outside currently.

The other Zones are the same. Even the 3 run zone with the 007 pump. low GPM's and high delta t temps. I would think that the 007 pump could handle this small zone.

My question, is this something that I should be concerned about? Does this sound normal?

I'm learning as I go and am really excited to get this system dialed in and make as efficient as possible. I am not new to unconventional heating sources. We have wood stoves and wood boilers as well in our shop and other out buildings at the farm. I love working through issues to make the most out of these systems.

Thanks for your help!

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