Help with central heating

knightstyle

My DD bought a new build 8 years ago and has had nothing but trouble and numerous visits from so called experts trying to sort it out.
Now she has been told she will have to pay for any faults to be rectified.
I have had a look and this valve keeps letting water down the drain so I assume it is a pressure safety valve but what pressure should it stop letting water out?
Plus what do I ask for when I buy a new one?
Pics show the valve and the system, any idea what the system is called so I can try to work out how it should work?

http://s1040.photobucket.com/user/mycaravan/media/IMG_20170307_171819492_zpsxaaln2zs.jpg.html?sort=3&o=0

http://s1040.photobucket.com/user/mycaravan/media/IMG_20170307_171754577_zpswckw2ifl.jpg.html?sort=3&o=1

Owain_Moneysaver

That's an Range Tribune HE unvented hot water cylinder and it must only be repaired by a plumber with an Unvented Hot Water qualification. It must also have an annual safety inspection.

It appears to use the RWC safety products (other versions of the Tribune HE used Caleffi). The pressure relief valve should probably be set at 3 or 3.5 bar but that must be verified by a qualified plumber referring to the manufacturer's instructions.

Do you have a pressure reducing valve on the cold water inlet to the cylinder or at the main stopcock? That might have failed (or be missing) allowing the pressure to rise above that permitted by the pressure relief valve, rather than the pressure relief valve being faulty.

knightstyle

Thanks, yes I understand the implications of DIY but the so called experts have been many many times and never got the system to work for more than a month or two before it broke again and each said different things to my DD.
Water is flowing continuously, the pressure when I looked was 1.2 bar.
DD has to re-pressurise every week, but I cannot see any other leaks.
Where is the requirement for an annual inspection?
She has no paperwork as her ex. threw it all away, bless him!

Alex1983

If your topping the heating system up every week then the water that is running down the drain is probably heating water and not connected to your unvented cylinder, the picture isn't very clear to see very well but I would check the expansion vessels 1st.

keith969

When you say water is running down the drain, do you mean you can see water dripping/flowing in the tundish (a thing in the pipe from the pressure relief valve to the drain that allows you to see any water flow)? Is the flow continuous, or does it happen when the boiler is operating and heating the water? If the latter it's probably the diaphragm in the expansion vessel, which will need replacing; if it leaks all the time the valve may be faulty (I had that problem once). Either way as mentioned you need a plumber with an unvented cert, make sure you ask them. Don't do it yourself, you would be messing with scalding hot water under pressure, not nice if it all goes pear shaped.

knightstyle

Hi, thanks again. There seem to be two problems, DD says the downstairs toilet wall is always damp by the radiator so that may be the heating water pressure problem.
The other problem is more urgent and I will go round today. Yes there is a constant flow of cold water to waste from the pressure relief valve, when I was there I twiddled the knob on it and tapped it a few times but the water still flowed constantly, this is a flow not a drip.
So I will make sure things are isolated and replace it. I will also look for the pressure reduction valve and check that.
If you look at the pic. you will see the white expansion tank has fallen off the wall and is supported by a piece of wood so I will fix that as well. What plumber thinks that is an acceptable way to leave an installation?

Alex1983

Cold water continually flowing is a problem with the pressure reducing vavle. It has a filter called a line strainer, which is removable and can be cleaned but to be honest they are normally seized in.
Get someone who is unvented qualified to replace the complete vavle and you will likely fix your problem.

Alex1983

Cold water continually flowing is a problem with the pressure reducing vavle. It has a filter called a line strainer, which is removable and can be cleaned but to be honest they are normally seized in.
Get someone who is unvented qualified to replace the complete vavle and you will likely fix your problem.

knightstyle

Where will it be? The water meter is under the pavement, there is no reducing valve by the stop !!!! which is under the kitchen sink.
Will the reducing valve be on the incoming mains or will it be on the cold feed to the water tank?
The house is a three story town house and the hot water tank is on the middle floor.

Alex1983

It's the brass vavle in the right of the airing cupboard. The one with the white expansion vessels flexiable hose attached. The strainer is built into the black plastic cartridge, the cartridge is the reducer and it will have the pressure it is set to printed on top

Alex1983

You really need to unvented trained and qualified to do this. Get someone who is qualified to te replace complete vavle and I'm sure it will fix your problem