Hydronic heat air handler

I came across one of these today, the t-stat had problems so I did not get to do much testing.

Anyone have any experience with these?

It was plumbed to the gas water heater in a small home.



Not much to say about them. They’re just a hot water coil, not unlike the radiator in your car, that is inside an air handler (blower). The stat will most often open a zone valve to the coil, and a little pipe mounted thermostat on the outlet of the coil will bring the blower on when the coil has heated a little bit (so you don’t blow cold air right away). Connected to a domestic water heater is a tad weird, but that’s the way things are done in small dwellings sometimes to save the cost of a proper hot water furnace.

Was this the same water heater that they were using for domestic hot water? If so, I’m not so sure that hydronic coils and zone valves, as well as the circulators typically used, are NSF rated. That would be my personal concern with your particular setup.