Loud banging from Worcester Bosch Greenstar 24i Junior

[M.Joshi]

Hello All,

We have a small Worcester Bosch Junior 24i boiler which is making a loud banging noise when operating.

If a radiator valve or TRV is adjusted (turned), the noise disappears.

Is this likely to be a faulty radiator valve, TRV or something else?

The boiler has 3 radiators attached to it (2 normal, 1 towel). The towel radiator does not have a TRV fitted.

Thanks.

 

[SimonJohns]

You have a faulty trv valve. Need a new one

You could DIY it using YouTube or you can post it on here and someone local will be able to help you out

 

[M.Joshi]

Thanks for your reply SimonJohns.

The reason why I wasn't 100% certain it was a TRV is because the banging also disappears if a radiator valve is adjusted.

How do I determine which TRV is faulty? Adjusting any radiator TRV or valve seems to temporarily stop the banging noise.

 

[dancinplumba]

When you say turned, do you mean on or off ?

 

[M.Joshi]

You have a faulty trv valve. Need a new one

The reason why I am not 100% sure it is a TRV is because the noise disappears when a valve or TRV is turned (slight turn clockwise or anti-clockwise). This can be on any radiator valve or TRV and not a specific one.

 

[Roger Welton]

Is there a radiator with out a TRV to act as a bypass?

 

[glenno1]

if they are poor quality valves they tend to do this ive changed a few

 

[M.Joshi]

Is there a radiator with out a TRV to act as a bypass?

The boiler has 3 radiators attached to it (2 normal, 1 towel). The towel radiator does not have a TRV fitted.

glenno1 - I think you may be right. The TRV could be a cheap one! It looks very similar to this:

[DLMURL]http://lpssupplies.com/images/Angle-trv-image-for-box.jpg[/DLMURL]

 

[M.Joshi]

Is there a radiator with out a TRV to act as a bypass?

The boiler has 3 radiators attached to it (2 normal, 1 towel). The towel radiator does not have a TRV fitted.

glenno1 - I think you may be right. The TRV could be a cheap one! It looks very similar to this:

[DLMURL]http://lpssupplies.com/images/Angle-trv-image-for-box.jpg[/DLMURL]

 

[M.Joshi]

OK, for some reason the 2 replies I posted last week on this thread haven't been moderated and posted on here? Here they are again:

Is there a radiator with out a TRV to act as a bypass?

The boiler has 3 radiators attached to it (2 normal, 1 towel). The towel radiator does not have a TRV fitted.

Why does the noise disappear if any valve/TRV is adjusted?

I believe the TRVs fitted are cheap - they are similar to this one:

[DLMURL]http://lpssupplies.com/images/Straight-trv-image-for-box.jpg[/DLMURL]

Does anyone know if the Danfoss RAS-D2 liquid TRVs are reliable?

 

[M.Joshi]

Anyone?

 

[Roger Welton]

At a guess boiler overheating due to lack of circulation, you open trv circulation restarts and boiler cools.

 

[M.Joshi]

But as I mentioned, there is one radiator (towel) without a TRV fitted so there still should be circulation?

We also have another issue which has occurred recently - the hot water from the tap is occasionally very hot. There is no hot water temperature adjustment on the front of this boiler.

 

[dancinplumba]

now not enuff circulation ?? needs a fush ?

 

[M.Joshi]

A flush on a new boiler and system that was installed only around 5/6 years ago?

 

[dancinplumba]

why not ? some heat exchangers very susceptable to smalll particles of dirt which will cause overheating, is there a filter on the return pipe to boiler

 

[M.Joshi]

No filter on the return. We have booked a full service for Wednesday - what should this involve on this model of boiler? I am wary that some companies quote for a service but in fact it's only an inspection and checking emissions comply with the regulations.

Also, any comments on Danfoss liquid C2/D2 TRVs?

 

[cdodds2004]

i use danfoss Trvs they are excellent, make sure you set the manual flow direction when fitted! i never get any chattering with these! what is the radiator stat set to on the front of the boiler! if its overheating and only 3 rads on the system, i think you could run this on 2-3 and sysytem would be fine!

 

[Roger Welton]

Danfoss TRV's are good, I think the only differance between the C and D is the look, they use the same valve.

 

[Millsy 82]

Are the lock shield valves fully open,

Start system from cold and see which valves get hot first trv or lockshield, Try removing the trv heads and run it without them to see if it carries on it may be that because its a small system the flow and returns are the wrong way round when they start shutting off they start vibrating due to the pressure from the pump forcing them down.

Failing that give it a good flush out doesnt matter how old the system is I have seen 3 month old systems need flushing due to not being properley flushed at time of install.

 

[M.Joshi]

Thanks for everyone's replies so far.

We've just had a service on the boiler today - the D2 TRVs have been ordered.

I am a bit concerned that the service wasn't done properly. We paid £60 +VAT and this is all that was carried out:

Remove cover
Check gas pressure / boiler output
Clean out condensate trap
Visually inspect heat exchanger from outside

I mentioned that the hot water was extremely hot at the time of booking the service but, they were not able to find out what was causing this? They only identified that the hot water pressure was lower than the cold water pressure, the hot water was cloudy and that a filter? may be blocked in the boiler.

I thought that during a service the boiler should be stripped down and the heat exchanger inspected for any corrosion. Does £60 +VAT seem expensive for this service (NW London)?

They didn't carry out a flue combustion analysis - when I asked why not, they said it wasn't required on a standard service. Their meter was away for cal. but they could do this at a later date!

So, is the above list all that is required for a full service?

 

[Millsy 82]

If you carry out a full strip down service you have to swap all the gaskets/seals that are touched. They should have carried out a flue analysis as you cant see the flame in the boiler so have no way of telling if it is burning correctly. My company charge £70 and thats not in London (so a fair price but has not been carried out correctly) and unless it doesnt look right on analysis I dont strip them.

 

[RPG 80]

If you carry out a full strip down service you have to swap all the gaskets/seals that are touched. They should have carried out a flue analysis as you cant see the flame in the boiler so have no way of telling if it is burning correctly. My company charge £70 and thats not in London (so a fair price but has not been carried out correctly) and unless it doesnt look right on analysis I dont strip them.

Agreed its best practice to use a gas analyiser, but the reason you gas rate the appliance is to tell if it is burning correctly ie +/- 5% of heat input.

 

[Millsy 82]

I was always taught that the gas rate just shows you that its using the correct amount of gas not that its burning correctly.

On these boilers I do
1.Flue analysis on high flame (case off) adjust as needed
2.Flue analysis on low flame (case off) adjust as needed
3.Gas rate
4.Flue analysis on both high and low flame case on if a seal has gone in the boiler or flue the co/co2 will start to rise. you do tend to find quite alot of problems Ive had split flues, split seals, flues not put together correctly etc.

I might just be being fussy but better to cover yourself

 

[M.Joshi]

Does anyone have an idea what might be causing the excessively hot water?

Thanks.