Combi boiler making a loud noise early morning need 2nd opinion!

JanG_5

Hi, looking for advice as my plumber thinks I need a new boiler. It’s a MAIN Combi Eco , nearly 10 yrs old. Making a loud ‘zhoom zhoom’ noise when idle, particularly first thing in morning. Only cure is to run hot tap. Otherwise working fine, no error messages. Plumber has replaced heat sensor twice, hasn’t helped. He suggests next step is a new Circuit board which is uneconomical to replace. I realise this is a specific question but any advice gratefully received. Thanks

macman

Kettling when cold? Your RGI sounds like he's just guessing, not fault finding.

Grenage

I'm with Macman; I'd get another engineer in.

Alex1983

Does it sound like the boiler is trying to run? If so it could well be the PCB, sensor was probably changed to overcome it, his thinking could of been it acting as a frost stat and telling the boiler to run to stop freezing. Could be a few other things.

As others have said get someone else in to give a second opinion. If it is the PCB it shouldn't be that expensive that it makes it uneconomical to repair.

alanobrien

Sounds like kettling to me, i would be using some of this in the system before i did anything else

https://www.screwfix.com/p/sentinel-x200-boiler-descaler-1ltr/43140

JanG_5

Thanks for everyone’s replies, plumber did seem stumped to be honest. Will google ‘kettling’ and look at Screwfix link too. Looks like I need a second opinion!

Alex1983

It's not going to kettle unless the boiler is running for hot water or heating....

JanG_5

Thanks Alex1983. It makes the noise in the dead of night when the boiler is cold (and the noise therefore wakes us up) and the only way to stop the noise is to jump up and turn on the hot tap....

southcoastrgi

Turn your hot water temp control knob to the 12 o'clock position (fully anti-clockwise) & see if it does it the following morning,

If that doesn't work turn the control knob to the 0 position before you go to bed & see if that works, come back & let us know if either of those work

JanG_5

Thanks, will give that a try. We have noticed the water I is heating to 70 degrees even though we have it set at 55 so you might be on to something. Fault is intermittent and hasn’t happened since I posted my question on the website .... typical. Will try the heating up high/ low and will let you know.