Worcester greenflow 440

[mcdryburn69]

Hi

I've a Worcester Greenflow 440 combi that was in the house I live in before we moved in (so by my reckoning could be 7 to 10 years old). We've just had it serviced under a annual contract from British Gas and there were no problems reported.

The problem I have is that the water from the taps gets scalding hot but the water from the shower while it starts hot soon becomes look warm.

I've been having problems with the temperature in my shower for a couple of years (again probably 7 to 10 years old) and so have just replaced the cartridge. Now while this has helped in that the shower seems to stay warm a little longer and the temperature regulator now seems to actually allow the temperature to be made hotter or colder the fact remains that the water temperature ends up lookwarm.

I did a little test and found that the temp of the water coming out of the taps is also lookwarm once the shower temp drops off.

All this leads me to think that although I think my shower cartridge was shot and needed replacing there may actually also be an issue with the boiler.

Can anyone suggest what it might be and whether there is any chance I could sort this myself or whether British Gas should have picked this up during their service last week?

Many thanks

Mark

 

[picasso]

Check to see if the hot out pipe on the boiler becomes lukewarm when the shower is running, if it stays hot you could have the cold supply passing into the hot supply making the hot lukewarm, its normally a passing mixer tap or stuck non return valve in shower valves.

 

[mcdryburn69]

Thanks Picasso I'll do that. One thing I'd say is that the thermostatic mixer shower I have has a main cartridge and two separate pistons (a hot one and cold one). I've just replaced the hot one and the main cartridge as I thought that these were the problem. When you say cold could be passing into the hot supply could that be from a faulty cold water piston?

 

[picasso]

No if anything it will be a faulty/stuck hot nrv, check the boiler output first to rule it in or out.

 

[mcdryburn69]

There are various pipes that are hot - which one should I be concerned with?

See attached photos below.

Also is the nrv part of the shower fitting? or is it part of the plumbing for the boiler?

Best

Mark

 

[picasso]

nrv is normally part of the shower (do you have more than one shower ?) the pipe I have marked should get hot and not fluctuate when a hot tap/shower is running.

 

[picasso]

Your boiler is running rather hot (87c) seems likely your system is needing a clean.

 

[mcdryburn69]

Thanks.

No we've only one shower but the bath does have a mixer tap with a shower attachment (not sure if that is of any importance).

So I've checked the tempo that pipe you highlighted and it was really hot when I switched the hot taps on but then after running them for 5 minutes the water temp dropped and the pipe temp also dropped.

Bristan say the nrvs are in the elbows of my mixer shower. Is it a big job to get at these and replace them?

Mark

 

[picasso]

If the pipe I highlighted went lukewarm then you have a boiler problem.

 

[mcdryburn69]

So part 15 on this diagram is the nrv. it has a grub screw holding the elbow in pace. If I isolate the mains do you think it would be as easy as taking the grub out and removing the nrv or will the whole shower mixer have to be disassembled to get at the nrv?

 

[picasso]

Its a boiler problem ! (posts crossed ?)

 

[mcdryburn69]

Thanks

I just had British Gas out last week and they did their annual service and passed it. Should I get them back? What sort of thing could be causing this?

 

[picasso]

Probably the store ntc or the hot water ntc or sludge or main ntc or .........

 

[mcdryburn69]

thanks so much for your help Picasso.