Taco Pump Running

Joe Mattiello

The pump will run as long as it has 120 volts supplied to the pump through a relay. If the circulator is connected to the C1,C2 terminals on the boiler aquastat/relay, then there has to be a call for heat through the TT terminals at the top of that control. If the circulator has its own relay the relay could be faulty keeping the circulator energized. Another potential culprit to the circulator running continuously would be blatant with no relay, pump directly wired to a 120 volt power source. Hopefully, this helps you.

Bob Oras

Pump keeps running

I recently had the taco pump repaced on a Peerless PDE 130 boiler and since the replacement it comtinues to run even when none of the 3 zones are calling for heat.

The old taco pump only ran when there was a call for heat.

I've had two opinions so far from licensed plumbers.

1. They all do that. They're supposed to run to keep sediment from building up.

2. It's not supposed to run unless there is a call for heat to a zone.

I side with the second opinion as the old pump functioned that way.

Any help is appreciated.

Big Ed

Bad End Switch

My guess you have zone valves ?


You may have a bad end switch..They are the red leads,wired in parrell.Disconnect one set at a time to find the culprit...

Relay clapper could also be fused.Diconnect TT which would be at the other end of the red wires. The end switches control the circulator through the relay.

There could be a cross in wires bypassing the relay also...

These are the normal problems I would check first