Noisly-Boiler Steam Bubbles

sknight · 26 Oct 2004

I have Potterton boiler that is very noisy.
The system is gravity fed.
System has been drained and also Sentinel X200 has been added. I have also used Other de-scalers and drained the system twice before.
The noise seems to have got worse since I added thermostatic radiator valves. I have left 2 radiators without TRV’s to allow a good flow of water.
The noise seems to be coming from the boiler and seems to be banging created from steam bubbles.
The funny thing is that it seems to be worse when the central heating pump is on.
When the system is just on HW the banging seems to be virtually non existent.
Switch on the CH pump and when the boiler kicks in the banging starts.
The banging noise only seems to start once the water temp gets to near the boiler thermostat setting.
Ie if the CH has just come on there is no banging, give it 10mins for the system to get hot and the banging starts every time the Boiler kicks in.
I have tried opening all the TRV’s to increase the water flow but this does not seem to cure the problem.
What else can I do to try and diagnose the problem?
The pump that I have only seems to have one speed setting, there is no adjustment. The pump also makes quite a loud humming noise. (thought this means there is too much flow?)
Any ideas or information would be greatly appreciated
Thanks

sknight · 26 Oct 2004

PS I have bled all the rads.
I have read on some more posts about bleeding the pump. any one have some hints on how to do this.
I have two isolations valves either side but no bleed nipple anywhere near the pump?
thanks

ChrisR · 26 Oct 2004

WHich potterton, they made a few..
Many pumps have a big screw in the middle for bleeding. If yours is an oldie like an SMC it may not have one.

Sounds a bit like your pump draws air bubbles into the boiler. Check for signsof having leaked on the input side of the pump - all the pipe/valves/rads etc you can see. Is the pump on the flow from the boiler or the return ot it? return to it?

sknight · 26 Oct 2004

There is a screw in the middly of the pump but this just lets me turn the pump if the thing is ceased.
If I had an air leak would I have to keep bleeding the rads (I do not have to keep bleeding)
Not sure on the potterton boiler or the pump position. I will check tonight.
I am sure there are no leaks as I have cehcked and double checked for leaks.
Thanks

kevplumb · 26 Oct 2004

when you take the screw out of the pump does it leak water ?

sknight · 26 Oct 2004

Yes It does leek water when the screw is taken out.

The boiler model is a Potterton Kingfisher II.

breezer · 26 Oct 2004

just a thought since the poster said

The noise seems to have got worse since I added thermostatic radiator valves

could the trvs be on the wrong end?

kevplumb · 26 Oct 2004

check the pump is pumping in the right direction (arrow on case )

sknight · 26 Oct 2004

More info,
The pump is on the return, aslo the pump does have 3 speeds, oops!.

kevplumb · 26 Oct 2004

turn it down 1

sknight · 26 Oct 2004

After looking more closely at the system.
The boiler seems to have two systems. Is this the case for the KingfisherII.
There are 4 connections to the boiler. Looks like gravity fed HW feed and return and also pumped CH feed an return.
The boiler is definitely making noises with Only HW and with both HW and CH.
Could scaling cause the banging? Listening right next to the boiler it does sound a little scaled.
The pump is turning the correct way, also the TRV's are feed or return type.
What is the best de-scaler for this type of system? How long should I leave it in for. Dont think I will try the type that you can leave permanently in the system again(Sentinel).
The are no air bleed valves on the system so should the air on the HW circuit just rise to the overflow. The CH system I suppose can only be bled from the Rads?
See this link for diagram of my system
Open vented system, with pumped central heating and gravity domestic hot water
http://www.discountedheating.co.uk/whichboiler.htm
Kev, you mention turning the pump down to 1. Is this to stop the humming, will this not reduce the flow back to the boiler.

kevplumb · 26 Oct 2004

yes i was going on your orig post
you could try fernox silencer has worked for me in the past

sknight · 27 Oct 2004

Kev you mentioned about the pump leaking when the screw cap is taken off.
Should this leak or not? Is the small leak actually creating a seal for the pump?
The leak from my pump is only a very light trickly (a bit more than a drip)
I have had the boiler making a very load kettling noise before and used Fernox silencer. This did the job in minutes.
Not sure if it has fully cleaned the system as when you get right near the boiler you can hear a slight kettling noise once it gets upto temp ie just before the thermotstat cuts the boiler off.
Does fernox silencer really give the boiler a proper de-scale?

raykeeley · 1 Nov 2004

when was the boilers last service

sknight · 4 Nov 2004

Bolier Last serviced about 6 yrs ago.
I have checked out the burners and they all seem to have a good flame distribution.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Noisly-Boiler Steam Bubbles

breezer

Similar threads