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Help me figure out my system

nickybotz Member Posts: 27
Hey all I'm going to try and explain as best I can. I have a Lochinvar whb110 boiler and radiant heat on 3 floors. Two of the floors are installed with pex in slab one on grade one on a framed subfloor. The third floor is staple up under hardwood in-between joists with heat transfer plates and very well insulated.

I jsut turned on my system for the first time being it's starting to get into the 30-50 degree range here in NYC.

What I'm noticing is the house is warm very warm the floors I have on (the two tile floors) seem to be warm in some spots and colder in others. On both manifold returns the returns are bout 75-80 degrees and the supplies are 100 or so. 

My installer who is extremely knowledgeable and did a great job is telling me the system is designed to work that way saying all the heat is being outputed thus saving energy, and as it gets colder the water temps will rsisee do to out door reset and it does makes sense .

I'm just trying to understand how my system works and is there a way to make the zones circulate longer to feel a difference in the floor.


  • hot_rod
    hot_rod Member Posts: 16,554
    Looks like it is a single temperature system?

    The floor coverings have a lot to do with output, do the staple up zones have carpet? Those zones may require a higher supply temperature. On one hand the carpet or throw rugs help spread the heat across the surface evenly. On the other it adds some R value and as such may need warmer supply temperature.

    Slab systems can take hours, maybe a day to ramp up, especially with low supply temperatures. It also takes some time for the slab surface temperature to even out.

    Shoulder seasons can be a challenge if the system shuts down when outdoor temperature is in the 50's. during the day then on again at night. Ideally the boiler temperature will modulate closely with load conditions and the system will not have a lot of stop/ starts. The best way to run radiant, especially the slabs is to set a comfortable temperature and let them run.

    Wait till you get some days where the system has some longer run cycles. Anytime the surface temperature is warmer than the ambient room temperature, heat energy is being added. 80- 82F is a good surface temperature, warm enough to feel nice, not too hot to be uncomfortable on bare feet.

    On well insulated homes the radiant floors may never feel warm :( The heat load can be covered with very low supply temperatures. Great for efficiency, not always customer friendly.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream