Help: Circulator shuts off when burner shuts off

[Pat Thompson]

Hi All,

I have a Crown Boiler with a Honeywell Aquastat L8148E Relay. This unit is used for domestic single family baseboard hot water heating only, with no zone valves.

I noticed that the circulator shots off when the burner shuts off at the high water temp limit, even though the thermostat is still calling for heat. I thought this strange, thinking it should circulate water as long as the water is hot and the thermostat is calling for heat, instead of letting it just set there in the tank to cool down and wasting $s.

I looked at the instruction sheet for the Aquastat and it says under "Application": "If boiler water temperature exceeds the high limit setting, the burner circuit is broken; the circulator continues to operate during thermostat call for heat."

Any thoughts as to what may be wrong? Faulty Aquastat perhaps? Or are some systems operated like this?

Thanks for any help.

[Stormin Mormon]

Sounds like a wiring problem. Call a technician.

[ForEverNJersey]

Thats exactly how mine operates NOW. I had the opposite problem you do. My circulator WAS ALWAYS RUNNING, RUNNING FOR APPROX 8 SEASONS, it never shut off. Turns out the relay was shot FROM DAY 1 and the installers simply connected it to the hot wire without finding out what the problem was. I replaced the relay, all is well. Good Luck.

[Paul Franklin]

In your setup, the circulator should run anytime the thermostat is calling for heat. The burner should fire anytime the water temp is below high setpoint and thermostat is calling for heat. (Which is what you said you expected.)

Has it always done this? It's possible that it's wired incorrectly. It could be a bad aquastat, but it seem unlikely given that that portion of the circuit is simple. It's obvious that the transformer is ok, the circulator relay functions, and the high limit functions. There's not much else in the circuit.

Are you sure the stat is still calling for heat? Just because it's below setpoint doesn't always mean the contacts will be closed.....

Is there a separate high safety? Perhaps that is wired to shut everything down (which would be wrong, but...) and that's what is tripping.

I'd check the wiring against the drawing in the manual, then do a test with the stat contacts jumpered. The circulator should run steady, and the burner will fire until the high setpoint is reached and then cycle on and off.

HTH,

Paul

[mark Ransley]

Try turning up your wall thermostat, 5` and turn down the stat on the boiler to 100 , see if that makes the pump stay on when your house calls for heat , but water temp shuts down fire, May be out of calibration, but this way you will know if it operates properly.

[kjpro]

And he returns with an acceptable answer!!!! :-)

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