Loud noise through pipes

Hi All / Mike!

This boiler has been installed in my house for 7 years with no real problems, and it actually does seem to be working fine heating / water wise.

However, I have an intermittent issue that's been getting worse for the last 6 months. It's a very loud vibration type noise that comes from the boiler several times per day.

Now, 6 months ago this would ONLY occur when I'm running a hot water tap, usually after a few minutes. The noise would normally go away by itself after 60-90 seconds or so, but turning off the tap would stop it instantly. Also, turning the tap down gradually would result in the noise reducing as well, suggesting the noise is linked to water flow.

Since about 3 weeks ago though, it's also been happening randomly during boiler operation. It woke me up with a start at 3am today! I had my thermostat set at 14 degrees last night, so I can't say for sure if the central heating would have kicked in at that time, or whether the boiler just decided it's thermal store needed a bit of heating.

I had a local gas engineer service the boiler yesterday, and he found no problems, however I wasn't able to reproduce the problem in front of him. He's not a gledhill specialist though which is why I am posting here.

Has this been seen before, or do you have any ideas?

I'm in Swindon by the way.

Cheers,
James

Hi James,

I have to say I'm puzzled. I can't think of ANY expanation for this and I've never experienced it.

The first step in tracing a fault is to reproduce it, Until you are able to discober a way to do this, try things which may or may not interfere with the noise. Do things like turning the mains water tap OFF overnight and seeing if the noise continues, or stops. The result will be good information. Checking if there any overflow or warning pipes dripping outside. Looking for evidence of them dripping in the past. Stuff like that. A technician can make some educated guesses based on good investigation work by the user!

I have now found that the vibration is coming from the automatic fill system above the boiler. I cant tell of it's the backflow valve or the pressure reducing valve that's doing it though.

The noise only happens when the pressure of the system is just above 1 bar. Above this it's fine and below this the automatic fill kicks in and the vibration only starts around 1 bar.

So I have a couple of issues, the vibration and the frequent reduction of pressure that results in the auto fill kicking in.

It's happening many times per day at the moment!

Also the vibration happens when I run any other cold tap if the system pressure is at the requisite 1.2 bar.

The noise doesn't happen at all if I isolate the backflow valve / prv but I do get pressure loss.

Will hopefully get this looked at next week but it's always pot luck with heating engineers!

James