The inlet of the house water heater (green arrow) is branched, goes through a backflow preventer, and what I believe is a pressure regulator (red arrows). The backflow preventer is vented to the floor (blue arrow).
After the pressure regulator, the branch is connected to the TPR valve on the water heater serving the in-floor heat (red arrow). What is the idea behind this configuration?
Because I see a shut off valve along with a pressure regulator I think that pipe may be the make up water for the system. Is that water heater manufactured and approved to be used as a component in a hydronic heating system? It may be best to just ask a local plumber to confirm the installation methods are acceptable. It’s difficult to see what’s going on with the limited photographs.
So if the secondary tank overheats, the pressure/steam/hot water will travel to the pressure regulator, then to the backflow preventer. Not really sure why that would be desirable.
That is probably correct now that you mention it. I was thinking because the secondary water heater had a pipe connected to the inlet, it wouldn’t need make up water. But that pipe connected to the inlet isn’t actually supply water, it is return water. Now it makes sense. Thanks!
