Humming in central heating pipes

[Adamski]

Complete novice here so apologies for any incorrect terminology etc!

I have a Baxi Bermuda back boiler - I've looked at the piping and the outlet from the boiler directly after the pump seems to split into a circuit for the downstairs radiators and one for upstairs.

Everything was OK until I recently moved a radiator from one wall to another in the bathroom. To do this I drained the system, relocated the radiator (this included having to put in 3 elbows quite close together resulting in what's best described as a tight turn!) and then refilled the system.

The system is working again heat-wise, but now I have an annoying humming noise apparently coming from the central heating pipes and I can feel the vibration in the upstairs radiators. The humming only seems loud in the master bedroom - this is the first room upstairs that the pipes go to from the boiler. The pipes then lead through to the bathroom in which I moved the radiator.

The pump doesn't seem especially noisy, the humming isn't as bad downstairs and doesn't seem as bad in any of the other bedrooms. I've tried turning the speed of the pump down but is doesn't have much effect - I've also bled the pump. Any ideas on what I may have done wrong or what might need replacing?

 

[ChrisR]

Pump bearing may be getting worn. Use a stick or similar with your ear on one end to probe around.

 

[Adamski]

Can't really locate any particular worn bearing type sound from the pump. In fact when I turn the pump down to it's lowest speed the humming sounds clearer, as though the sound of the pump is drowning out what's really causing the hum.

Is it possible for the boiler itself to hum?

 

[Adamski]

Ignore last post about boiler humming - the sound is only audible when the pump is running so it's not the boiler.

The system has been running today for about 2 hours, and the humming noise now seems to be coming and going. This hasn't happened before today... the humming periodically (and randomly) stops for about 10 seconds and then gradually starts up again.

Could these symptoms confirm a possible pump bearing failure, or maybe an airlock? Not sure how an airlock may cause a humming noise so that may be a daft question!

I'm tempted to replace the pump anyway - it looks fairly old and the joints either side are well rusted. I'm not sure what the current make/model is offhand and it's under the house so is a bugger to get to. If I do replace it, am I best getting the same make/model of pump or can I use any? Most pumps these days look nothing like the one I've currently got.

 

[breezer]

if its that old then yes change it, i recall years ago i had a big green c/h pump it gave up, i had to change the pipe work slightly, put in pump isolators, but all worked fine, oh, and it was a normal pump from q & B

 

[Adamski]

Wow! Thanks for the v prompt reply breezer, I think I'll change the pump.

On that note, what's the correct procedure? I'm probably being lazy as I'm sure I could find the answer in the forum somewhere! There are already isolator valves on either side of the pump and I think it's standard 22mm piping. Am I right in thinking I:

1) Turn off the heating
2) Turn off the electric
3) Shut off both valves
4) Remove the old pump
5) Fit new one
6) Turn on both valves (any order?)
7) Bleed pump
8) Turn on electric
9) Turn on heating
10) Sit back in hum-less ecstasy (I hope!)

 

[breezer]

apart from dissconecting/ recoonecting pump yes, but if it has 22m valves already it cant be that old

oh, and make a note (put arrow on wall / floor) which way it pumps now