Delco-Heat GM gas furnace (radiant heat) recirculator pump

Old 04-27-06, 07:41 AM
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Delco-Heat GM gas furnace (radiant heat) recirculator pump

I’ve recently moved into an old house and I’m trying to figure out some aspects of the heating system.

The recirculator pump on the water return line into the furnace seems to run constantly (and its getting hot to the touch). How long should this recirculator pump continue to run after the furnace has turned off? The hot supply and cold return water lines seem to be cool for several hours – but the recirculator pumps keeps going.

The electric line into the recirculator pump passes through what appears to be a temperature probe attached to the hot suppy water line exiting the furnace, then to a transformer and an on/off switch. But the on/off switch doesn’t seem to effect the operation of the pump.???

Also – does anyone know where I can get manuals for the following parts:
Furnace: Delco-Heat GM gas furnace
Ricirculator pump: White-Rodgers

Any thoughts/advice and prior experience would be appreciated…
Old 04-27-06, 12:50 PM
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Some old forced-hot-water (hydronic) systems had a constantly running circulator, yours may be one of them. In these old systems the room thermostat would control the firing of the burner. These systems were generally slow responding and they also had a tendency to wildly overshoot the desired temperature set on the thermostat.

Technically the correct terminology for your "furnace" is a boiler.

As for the circulator pump motor being hot to the may be completely normal.

Before any attempt can be made to help you find any manuals you need to supply the complete model numbers for the boiler, circulator and control boxes.
Old 04-27-06, 03:52 PM
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They have been out of the heater business for probably 40 years.
The probe on the pipe is called an aquastat. Frequently in old systems they were surface mounted. When the pipe dropped below a certain temperature, the circulator would shut off.
Old 04-27-06, 09:24 PM
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thanks for info

Thanks to both of you for helping me with my terminology and info on my boiler.

- the aquastat is surface mounted as you noted.

- I'll try to find model numbers, some of these parts are pretty old, and they are in a dark part of the basement, so I'll have to get some good lighting (and better eye-balls).

When I checked a few hours later the circulator pump had turned itself off and was no-longer hot to the touch.

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