Hydronic system hum

[P7rancher]

When running the furnace (hydronic heat), we hear a loud hum coming from the forward bay, likely in the electrical bay. Any ideas as it is loud enough to be annoying and we have not noticed before this last trip?

Is there a recirculating pump in this area that could be going out? Only hear when the hydronic heat is on and it does not matter which zone is on.

Thanks in advance for any help

Tammy

[docj]

Sounds like you're hearing the burner and/or the circulating pump. Although it's possible something is going wrong, is it also possible you didn't notice it before because the temperatures were higher and the furnace didn't run as often and as long? Ours is definitely noticeable when running, but it's reassuring to know that we will stay warm at night.

[P7rancher]

We can barely hear the burner in the back which is a good thing. This hum is in the front of the coach and with the front bay door open, it is definitely in the front area of the coach. We do not have a plumbing schematic and were wondering if the recirculating pump is in the front of the coach and if so, why the loud hum?

Thanks, Tammy

[ottffss]

You got Oasis or AquaHot?

Either one, the recirculating pumps (and stir pump) are all inside the actual furnace housing. Put your ear up to the furnace housing and see if that's where it's coming from. These units use magnetic drive pumps and are highly unlikely to become overly loud. Yes, they do/can hum a little like any motor but it's usually mostly contained inside the furnace housing. There are no "external" pumps (unless you call the engine pre-heat pump on the back of the AquaHot "external."

Could it be a fan motor for the front heat registers? It might also be the relay for the electric side of the hydronic. Turn off the electric side of the hydronic and run only diesel and see what that does.

Hum sounds can transmit in funny ways sounding like they are coming from one place when in fact they are originating elsewhere (due to the nature of low frequency sound waves - like a sub-woofer). Can you poke your head into the basement doors and also place your ear to the floor inside and try to narrow down where it sounds like it's coming from?

[P7rancher]

We have a Webastco, no electric element. The hum is definitely in the front bay, cannot hear in the back of the coach.

Thanks,
Tammy

[dons2346]

There is a circulating pump up front that runs when the heater is running. It will also continue to run for awhile after the burner quits.