Heat not moving through zones properly

Toshiro88

Good morning,

I have a hot water baseboard fed by a oil burner, Kerr Comet, with 4 zones. I noticed one of zone valves was stuck open, and then noticed that water was not moving through any of the zones, or very little movement.

My father in law determined that no power was getting to the circulator pump, a Grundfos UP 15-42F 59896161 and being an electrician setup another relay to bypass the board.

We turned it all back on and heat went up into each zone, and we thought we were done. But i note that although the zone valves open up and heat does travel up the pipes that after 10-20 minutes the radiators are barely warm and the return pipe registers the smallest amount of heat. So that makes me think the circulator pump is not working.

I closed all the zones and then opened each one up on its own, just to make sure it was not something wrong with one or combination of the zones that was messing things up, but each zone on its own does the same thing, once the valve is open, heat travels up the pipe but after 10-20-30 mins the is just a little bit of heat on the return and the radiators are lukewarm to the touch at best.

Although i would love general help with the issue, i was really curious why i cant seem to find a Grundfos UP 15-42 F pump with the same p/n as the one i have. I have a 59896161 but i see very little of it listed online, whereas it seems that the 59896155 seems to have the exact same UP 15-42 f designation. I would like to be able to buy the exact replacement, my thinking being that i could replace the circ pump in its place in the system with the least amount of work. It seems to make sense to me that if i had a 1 for 1 replacement i could unscrew the pump from the housing and then just slot in the new one. But please tell me i am wrong.

Long story short is the 59896161 the same as the 58896155? or similar enough to be interchanged. And if not why can i not find the 58896161 - was it discontinued? replace?

Thanks in advance for any help you can provide.

STEVEusaPA

A 15-42f is a 15-42f
Maybe you just don't have enough water in the system, or air in the system.
Or the impeller is damaged not moving water.
I don't agree with a relay to bypass the board. If something was wrong with the board, replace the board.
And if constantly power the circulator didn't help, time to bring in a professional to check that and the other things I mentioned.
What did you do about the 'stuck open' zone valve?

Toshiro88

One of the zone valve motors seized, leaving the valve in a open position.

My take is that the impeller is damaged. Seems to make the most sense. Seems unlikely the isolating each zone and attempting to push water through the zone would result in the same result, if only one had an air block.

Jamie Hall

Toshiro88 said:

One of the zone valve motors seized, leaving the valve in a open position.

My take is that the impeller is damaged. Seems to make the most sense. Seems unlikely the isolating each zone and attempting to push water through the zone would result in the same result, if only one had an air block.

If the pump is getting power... and if the motor is actually running... and if there isn't a valve hiding somewhere which is closed... you may be right.

How is the pump piped in relation to the expansion tank? Specifically, is the expansion tank on or very near the inlet to the pump? Or is it somewhere else? If it's somewhere else, you may have damaged the pump impeller through cavitation -- which can ruin an impeller in a remarkably short time (and would do the same thing to a new one).

HotanCool

Agree with Steve. I vote for air. Have your system evaluated by a professional. It will pay off.