Noisy Neighbours...

[TrentW]

I thought the neighbours were up at all hours doing DIY, but it turns out it's our boiler in the loft making a noise

We've moved into a house with a 3 year old Worcester 28i Junior that's installed in the loft.

Whenever the heating comes on, the boiler makes a racket for a short time (sometimes up to 5 mins) before going quiet.
It sounds like air is being forced through the boiler.

The heating and hot water systems work OK - It's just the noise, which I'm sure will damage the boiler eventually.

Turning on the Hot tap stops the noise, but it starts again as soon as you turn the tap off.
It seems that the noise is only with the heating side of things and only when the water is cold (noise goes away once the heating has been on for approx 5 mins)

The pressure is set to around 1.3 cold and rises to around 2.6 hot - I'm not sure if this is normal - could it be the expansion tank at fault?

I've tried adjusting the pump speed, but it didn't make a difference.
We've bled the rads a number of times and got a small amount of air out each time, but it doesn't fix the problem.

I've put a video of the boiler and noise on YouTube here:
http://www.youtube.com/watch?v=NUMrNeXg9tk

The noise starts about 50 seconds into the video.

I've booked an engineer who's coming in a weeks time, but if I can fix it in the mean time...

Any ideas?

Cheers
Trent

 

[Deleted member 105431]

the boiler is overheating. do all the rads have trv's on? You should have one that doesn't. the pump should be on max.

 

[TrentW]

Pump was on Max, and it didn't make a difference when I changed it, so left it on Max.

Yes, all rads (except towel rail) have TRV's and all are fully open at the moment.

The towel rail in the bathroom doesn't have a TRV - In fact it doesn't have any valves - All it has are in line taps (the ones with the screwdriver slot to turn them off) the same as you would put on a cistern or sink so you can easily turn the water off for repairs.

I thought that this might be the problem, so turned both taps off to isolate the towel rail, but it didn't make any difference (although by doing this, I've removed the 1 rad that didn't have a TRV)

What is happening for it to be overheating? (eg not enough water flow?, Pressure not high enough?)
If it's overheating, shouldn't it lockout and need to be reset?

 

[picbits]

The sound is a bit distorted but could that be air in the system ?

If the boiler is the highest part of the system, any air is prone to collect at the top.

I could be totally wrong but its worth a check.

 

[TrentW]

Yes, that what it sounds like to me as well... My gut feel is that there's air in the system, but I'm not sure how to get it out...

The Boiler has an Automatic air bleed valve. I drained the system completely and while refilling it, could hear the air escaping from the valve in the boiler, so it appears to be working OK.

The fact that we get a little bit of air each time we bleed the rads seems to indicate that there's air trapped somewhere, but how do you get it to flow to the rads or boiler so we can get rid of it?

 

[TrentW]

I've found that If I turn off all the TRV's on all the rads and only leave the Non TRV heated towel rail running, the noise stops - If I turn one of the TRVs back on, the noise starts again...

Not sure if that points to anything??

I'm going to try turning all rads off, then turn one rad on and leave the system running for a few hours, then bleed that Rad, turn it off and move on to the next rad.

I hope it may shift any air that's trapped. Any other ideas?

 

[seco services]

what happens if you shut that trv again and open another trv ?

 

[Timmyturtle]

There should be an air bleed in the loft ,possibly within the boiler casing(no experience of model) the bleed can be either manually operated or automatic.
The automatic one possibly has been closed by mistake?

 

[Timmyturtle]

Holy cow! just watched the video
Sounds like air that after a while moves itself away from the boiler ,only to return when turned off
Need to check for air bleeds

 

[TrentW]

what happens if you shut that trv again and open another trv ?

Same thing - Doesn't matter which TRV I turn off / on the noise comes back straight away.

I've also noticed that when I turn the hot tap on while the noise is happening, the water splurts out of the tap as if there's air locks in it - The pressure also seems to be much higher than normal.

Once the noise stops the hot water goes back to normal pressure, non splurting etc.

Holy cow! just watched the video
Sounds like air that after a while moves itself away from the boiler ,only to return when turned off
Need to check for air bleeds

Sounds like I'll need to let the system cool down, let the air move back to the boiler, then try to bleed it off from there.

 

[heatingman]

Must agree its a racket, have you tried turning the boiler thermostat down, is it still noisey.

 

[superdupergasman]

IMHO a blocked main heat exchanger, pump does sound likes its pumping against itself tho therefor is not the problem.

 

[TrentW]

Thanks for all the replies...

Turning down the temp dial didn't seem to make any difference.

The engineer will be here on Wednesday, so I'll post a reply about what he finds then...

Cheers
Trent

 

[jiminblack]

My money is on a new heat exchanger. Changed loads when I worked for Worcester.

 

[TrentW]

Right... So the boiler man came today...

He listened to it and said "It sounds like there's a block in the heat exchanger"
He then said you can't replace the heat exchanger on this model (Worcester 28i Junior) and we need a new boiler

You can buy the heat exchanger as a spare part, so I'm thinking he just didn't want to do the job (or didn't know how)

So... what do you guys think... Is he taking the ****? It's a reputable company, but he didn't fill me with confidence (especially when he rammed a screw driver into the end of the pump to see if it was turning!)

Can I replace the heat exchanger myself? I used to be a mechanic, so very handy with tools etc - but I don't want to fiddle with the gas side of things...