Potterton boiler Myson pump problems

Hello all, new here, great site, need help!
A few months ago my Myson pump started making strange noises, I've gone through as many threads as possible without getting square eyes and can't find a definate answer. Sometimes is ok then all of a sudden it will start sounding like someones put ball bearings in my system.

I've bled all the radiators (got a fair bit out of the upstairs ones) and also bled the pump through the black screw until I got a little trickle off water out but it's no better.

It's now making an intermittent humming sound which can be heard quite loudly when the house is quiet.

Could the moving parts inside the pump have been damaged by sludge etc?

I read about the pump having to be lubricated by the water itself, could a lack of this before I bled it have caused some damage?

Any help at all is much appriciated!!!!

Cheers, Karl.

Could the moving parts inside the pump have been damaged by sludge etc?

I read about the pump having to be lubricated by the water itself, could a lack of this before I bled it have caused some damage?

Click to expand...

yes and yes

Cheers mate, so am I looking at a new pump or can it be taken apart and repaired? I just can't understand how this could have happened all of a sudden, how has the crap got in the pump in the first place?

I've got a combi boiler so i'm presumming that it will pump my hot water to the taps aswell?? Because I've noticed that the shower ain't getting that hot any more and the flow speeds up and slows down slightly, is this right?

Cheers, Karl.

The bearings wear out, and get noisy. Replace the pump.
What boiler is it - Puma?

The boiler pump doesn't pump the tap water

flush your system out using your filling loop and open the drain valve. close drain off fill up and then drain, do this a couple of times. because you have to drain down, why not change the pump as well. i usually just change the front of the pump providing the back is not all crudded up, 4 allen screws usually. the back of the pump is only a casing with no moving parts, quicker and easier. when this is done start up system making sure to get all the air out. and if the problem is cured, then make sure you put some inhibitor in. some of the other things you said like warm water and loss of pressure could be pointing to a dhw heat exchanger depending on what boiler it is... but obviously try the pump first.

Thanks for the help guys!
Yeah it's a Puma, I think about ten years old.

Will I be able to buy only the front half of the pump?

When refilling or topping up the system do I need to shut off the valves that are on the flow and return pipes for the CH to stop fresh water going straight in to the boiler? I have topped it up about twice is three years but havn't closed these off?

Finally, when topping back up do I get the air out from the radiators and the pump only? Is there anywhere else air can collect?

Many thanks, karl.

i suggest you read up a bit about boilers. I'm not being rude but my advice is for someone at least part competent, i dont want to be responsible for you flooding your place. but it is a diy forum so i will answer your question.

no you cannot buy the front of a pump, at least not from my local plumbing merchants, but when i worked for bg, they used to just give us front of pumps. i suggest changing the front because sometimes the nuts on the pump casing are a bugger, sometimes they come straight off.

dont worry about fresh water going into the boiler. you are flushing out. its not going to stay there, on a combi your heating is on its own circuit. so open all valves. as you drain down, undo the bleed screw in top rads so that the water does not "lockup" meaning stays in there. and as the water drains out, undo more bleed screws from the top of the house. when you have drained out, flush through using filling loop. then fill system again and dont forget to close bleed screws, and open bleed screws as system fills up from bottom upwards this time.

do this a couple of times, if you can give it a hot flush, (fill system and put boiler on ) then even better,, and having changed your pump, is the boiler better now, if so drain down one last time, and fill up having put in a quality inhibitor, check the inhibitor is for an old system.

and if you do know someone who has rudimentary knowledge, getem round, but this job is bread and butter to a plumber or gas engineer. why not watch him do it and then youll know next time.

one last word of warning, there is an automatic air vent in the boiler, youll know it because ifs got a car valve dust cap on it, this should be loose. not tightened up.( the valve cap that is)

Ok, thanks for the advise, I ain't taking anything apart until i'm sure I can do it.
I feel confident enough to do the job apart from one other thing. I've had an engineer out to it before for a different reason, think it was a sensor that wasn't working properly, and when he came he couldn't find a drain other than one on the boiler itself (watched him drain it from there), so to be sure that any radiators below the boiler are clear would I have to disconnect them and drain or would flushing it out from the filler tap get it out (boiler is in a downstairs kitchen half way up the wall)?#

It seems to be worse when the pump first starts up after being off for 30mins or so, is this because the crap is settling back down into the pump?

Karl.

engineer working on boiler does not need to drain system down, however if you want to drain your system, you must fit a drain off valve, you can buy them now where you just screw into the rad pipe, usually used on washing machine tap off. ask at your local plumbing merchants. pick a rad nearest the back door or a drain. ideally you should solder a drain off valve on, but in the absence of the proper tools, the tap in will do and is also quick and easy. noises as you describe are usually if something has disintegrated or a load of solder is floating round the system where it has not been flushed. like you are about to do now.

Ok pal, thanks for the advice, it does sound a lot better since I bled the radioators the other day but it will need sorting soon!!