Loud Radiators

[LisaWiddi]

How can I stop the really loud "rushing water" noise coming from my Radiators?
I had a brand new system fitted 2 months ago (new Worcester Bosch Combi Boiler, 7 Radiators, New Towel Rail and new pipework).
The noise is so loud, that it wakes my children and I up and then can't get back to sleep. I really need some advice.
Ps...it happens on numbers 4,5 and 6 on the TRV. If I put the TRV on 3, 2 or 1 the Radiators don't come on at all!

 

[twgas]

adjust the timer so it wakes you up just before it's getting up time, then you wont need an alarm clock

 

[LisaWiddi]

Thanks Mick. Whilst that may seem like a great idea, it would be nice to have the house wRmed up before we wake! It's only October and its freezing at 5am, so god only knows how bad it will be by January!

 

[seco services]

It's only October and its freezing at 5am

Freezing where are you north pole ?

 

[calorific]

Have you asked the installers what they think?

 

[LisaWiddi]

Yes, the Installer came out and agreed that it's not "normal", but wasn't sure how to correct it. He thinks the water is rushing too fast through the TRV into the Radiator. He said he would ask around, then get back to us. That was nearly 2 weeks ago and now he's impossible to get hold of. So, I was hoping it was something that I could sort myself.

 

[calorific]

Changing the pump setting might do the trick.

Am a bit concerned about the TRV's not functioning on low settings Hope he's not scrimped on them

 

[LisaWiddi]

The TRVs are Draytons. Is that good or bad?

 

[45yearsagasman]

It may be that the lockshield valves are closed too much. These valves are used for balancing water flow through the system. I hope your installer has checked this. From your other post, 7 rads is considered a small system and depending on system layout it should be possible to open up L/S valves a bit without affecting system performance. I would register a complaint with your installer and insist he remedies the problem. I would not advise adjusting things yourself as it may invalidate warranties. I assume the system is vented of any air and is up to correct pressure. Drayton valves are usually good, and do not adjust any pump settings. Good luck.

 

[LisaWiddi]

The noise is at its worse with the Lockshield valves fully open. My husband has closed them slightly and the noise is now better. However, my downstairs radiators are scolding hot on number 4, but freezing cold on number 3. What does that mean? Number 4 is just nice warm upstairs!

 

[D_Hailsham]

The problem is probably caused by the system not being correctly balanced; and possibly by the boiler oversized for the heating requirement.

Which model WB boiler do you have?

Use Whole House Boiler Size Calculator to find the heating requirement.

 

[LisaWiddi]

We have a Worcester Bosch Greenstar 27 cdi. We didn't select this boiler specifically. This was recommended by the installer. I did ask him if it needed balancing and he said no. Could it be the pump speed?

 

[D_Hailsham]

We have a Worcester Bosch Greenstar 27 cdi.

What's the required output according to the link I gave?

I did ask him if it needed balancing and he said no.

Then he was talking nonsense.

 

[LisaWiddi]

The required output is 13.89 KW. (Bearing in mind, I have put estimated measurements of my house size on there).
If it needs balancing, how do I do that? As I said before, I can't seem to get hold of my installer anymore

 

[D_Hailsham]

The required output is 13.89 KW. (Bearing in mind, I have put estimated measurements of my house size on there).

Is that because you are not at home or you do not have a tape measure??

The output of your boiler modulates (varies) between 8 kW and 26kW, so even in the coldest weather it can produce about twice what you really need. It would be ideal if the temperature went down to -20C in the winter!!

Fortunately the output can be adjusted. It's best to get this done by a qualified person.

If it needs balancing, how do I do that?

The full details are in How to balance a CH system, but there is a quick way:

Turn boiler off
Remove all TRV heads (Draytons are good, by the way)
Set all lockshield valves to half a turn open from closed
Start boiler and let it get up to full temperature.
It needs to be kept going, so you may have to turn the room stat up.

Check each rad by feeling the flow (hotter) and return (cooler) pipes.

There should be a noticeable temperature difference between them but all rads should have approximately the same difference. Feeling the flow and return at the boiler will give you a good idea of what it should be.

If any rad is way out - large or small drop - close the LS valve slightly (1/8 turn) to increase the drop and open slightly (1/8 turn) to reduce the drop. A small difference in the LS valve can have a big effect on the temperature drop.

You will have to wait 10-15 minutes for the change to be noticeable.

When all rads are approximately the same, replace the TRV heads and set them as required.