Circulator pump humming

Shadowdoc

I have a 2 zone system that are about equal, upstairs and down. Upstairs is living space and heated more constantly.

2 identical circulator pumps. The upstairs one has a humming sound coming from what I think is the motor housing when running. Heats fine though. Vibration transfers to the pipes (all copper) Making the humming more noticeable upstairs. 

The other pump has no sound or vibration at all when running. 

I gently tap the motor housing with a wooden dowel and the humming ‘almost’ disappears until it starts again later on. 

I’m just trying to get a feel for what it may be and how to mitigate it. 

Thanks in advance. Merry Christmas. 

Gilmorrie

So, both pumps are running and both zones are heating? If so, then it's probably not a big deal.

These Taco pumps have only one moving part - the cartridge - which can be replaced for the pump you think is noisy. Depending on whether you have isolation valves on each side of the pump, you may have to at least partially drain the system to replace the cartridge - and then bleed air from the system.

PC7060

Sounds like a bearing is wearing out.  You may be able to get a rebuild pack for it based on the model. 

Edit: what @Gilmorrie said! 

HomerJSmith

It is almost as cost effective to replace the pump than to just replace the cartridge. The pump may just be moving too much water (GPM). A 0010 is just a lot of pump. I would replace it with a Grundfos 15-58FC which has multiple speeds if you decide to replace the pump. I like isolation flanges, too, which makes changing pump a lot easier.

Shadowdoc

Thanks for the input.

Although it’s still working, and has been, I was worried if it’s a sign of pending failure, I didn’t want to be caught without heat since it’s winter here in NY. 

I can isolate the pump pretty much if needed. 

As far as the size, it’s a pretty big system. I live in a church and the 2 pumps each feed about 3000 sq ft each. One for each floor of the fellowship hall (my home). I figured since the other one makes no noise and works, it was the right size pump. 

Maybe I’ll just purchase a pump and keep it on hand. 

Thanks again. 

PC7060

How large is the piping? My system with 2” mains was severely over pumped with a large red B&G circulator, Ive forgotten the model number.  Currently running a Grundfos Alpha2 at the lowest speed. The system also services about 3000 SFT. How many radiators do you have on each zone. 

Shadowdoc

It’s 1 1/2” pipe. Its two zones with each zone covering about 3200 ft.². So it’s a total of almost 7000 ft.² between the two zones.

And it’s all baseboard heating, hot water.

hot_rod

Could be a piece of debris in the circ. Banging on it moves it around, but still in the impeller, off balance. The high head, higher rpm circs are more sensitive to out of balance conditions

I too think it is oversized from the info you have shared