OK, I'm dealing with a 1996-vintage stadler-product radiant hot-water install.

Outdoor reset runs the pump continuously below 60F outside, thermostat in the heated area sends a call-for-heat to the boiler.

Circulator for this loop is located at the loop instead of at the boiler, but I believe the pump is outside the loop (not sure).

There is a stadler powerhead (says stadler, white doohickey connected to the 4-way valve with a pair of wires coming off it) connected to the 4-way valve, and it looks like it is wired in parallel with the thermostat contacts. It has the stadler thermostat with seperate 24VAC feed, setback, their standard little square box thermostat.

It doesn't seem right that the powerhead would be in parallel with the thermostat contacts- was there a stadler thermostat that attached to the 4-way valve?

The hardware is exactly what was offered in the kit in the pic.

Thanks,
Dave

Wellll... Crap.

Hoped someone would have a clue about the stadler stuff.

Dave

Hi Dave,

Not sure I get it, but that may be an on-off injection setup. the zone valve allows hot water into the radiant system? and when it's closed, you don't get "ghost flow".

Just guessing..

I'm not sure it has a zone valve at all, unless the valve that's wired to the thermostat is wired wrong.

That's the main thing tripping me up.

We are looking for a radiant outfit that will service in the cortland NY area, and not having much luck.

The heated area only gets used 2x/week, so we are looking to modify the system (if need be) to handle as deep a setback as feasible with a radiant system.

Thx-
Dave