Noisy ch/rad valves and mysterious object....

Hi Guys,

I live in a housing association property and we recently had a refurb. Our old style boiler with cold & hot water tanks was replaced with a Worcester Bosch GreenstarHE, all rads replaced, all valves replaced and some pipework near old boiler & tank sites replaced.

My issues are;

1. Some valves noisy, particularly when close to being shut.
2. At night the whole system sounds noisy, sounds like a cross between a humming and the flow of water.
3. A few months after the install someone turned up and fitted a round metal thing on a pipe near the boiler.

1 - On the bedroom rads we have Drayton TRV4 and other rads Peglar standard valves. Both are noisy particularly the closer to being off you adjust them. I've read there are two types of valve and some brands noisier than others.

What is the silentest and best valve to go for?

2. With the old boiler everything was almost silent with usual knock as pipes/rads warmed up and cooled. Now there seems to general and quite audible humming/flowing sound from pipes leading to rads which are turned on. When the boiler shuts off everything goes silent. I noticed the pressure was out of the green zone so I topped it up and now its quieter but not silent.

What could be the cause of the noise?

3. I've read that building regulation L states an automatic bypass valve must be fitted to systems after 2001.
Where would this valve be fitted on a system?
What is the round metal thing in the picture below? (was fitted month after boiler swap)?
(is it something important that should have been there from the start?)


Any help much appreciated as my ch noise is eating into my good nights sleep.

Thanks,

Mark.

Its a shock arrestor on the cold water pipe.

You should have an auto bypass valve. Ideally fitted at the far end of the heating circuit but usually fitted near the boiler.

Tony

Hi,

Sounds like the pump has been left set to max, (as usual), if you have small hands you can adjust it on these without opening the casing, make sure you turn the leccy off and let it cool down, its the black thing on the right side of the boiler near the bottom, look in the manual and try it on a lower setting, personally I would set it to one and if all rads still heat up leave it there.

AFAIK this boiler is obsolete and hasn't been in production for a number of years - strange how it's a fairly recent installation.

The boiler does not appear to have an internal bypass valve therefore fit an automatic bypass valve - the manual does not mention this.

Are TRV's fittted to all radiators? one radiator should be uncontrolled (ie have lockshields both ends) and in the same room (normally hall or perhaps living room if a flat etc) the room thermostat will be sited.

The ticking noise when heating up that is more noticable now with the combi may be due to the boiler having its radiator heat output being left on maximum. This results in a faster warm up and hence more pronounced expansion noise. From the manual it appears the heating output can be lowered (range rated) to suit the property.

Unusually the manual also states the pump speed can be lowered to speed 2. This may reduce the hot water output a little - it's not clear. Do NOT set the speed to 1. Most combi boilers must not have the pump speed lowered.

OOI, what happens if you lower the pump speed on a combi?

Hi,

Many apologies, just checked the MI's if this is the correct boiler the pump shouldn't be set to one but can be set to 2 or 3. It will provide full hot water on setting 2.

Perhaps you could tell us exactly which model it is because some have automatic bypasses installed and some have modulating pumps and must not be installed with a system bypass! Greenstar HE actually covers quite a wide range of appliances.

Less heat transfer across the plate heat exchanger, reduced hot water output, I suspect plenty of modern combis would throw up allsorts of fault codes since the differential temperatures may not be as expected.

Gasguru said:

AFAIK this boiler is obsolete and hasn't been in production for a number of years - strange how it's a fairly recent installation.

Click to expand...

Geoff, I think that they are still putting the word Greenstar on at least the manuals for some of the latest boilers.

I think that the manual for the 12Ri for example says Greenstar.

Tony

This is a Greenstar HE 30 Combi from the other posting and looking at the image which is why I though it was obsolete.

Hi Guys,

Thank you for your replys.

More info you requested;

1. The serial label says ZWB 7-30 R30 HE Greenstar HE. Since the council handed us over to the housing association nothing surprises me if it is an obsolete model.

2. We have 6 radiators, 4 have TRV 4 valves and 2 have plain valves (Hall & Bathroom) I think the kitchen radiator is the first in the system as it is the closest to the pipe which comes out of the boiler. What is the silent rolls royce of valves?

3. With the new boiler we don't get any warmup/cool ticking/knocking like we used to. Just a minimal amount from the pipe feeding a stone cold radiator when you first turn on the vlave. Although we do sometimes get a single thud as if somebody had hit a rad with a hammer.

4. I will check the pump setting (for 2 or 3) at the weekend.

5. I will have a hunt for the automatic bypass valve, because apart from the double check loop and valve there doesn't seem to be anything else fitted near the boiler. If I suspect an automatic bypass valve hasn't been fitted in line with building regs, do I contact a council inspector?

6. With the shock arrester - we hear pipe thud noise from the flat below each time they use their taps - is this what needs to be fitted there to cure that?

Thanks again for your efforts.


Mark.