central heating pressure loss

hehaen

I have a large central heating system fired by two glow worm flexicom 35X condensor boilers. it was been losing pressure for many months and now is getting a lot worse. typically 1 full bar a day. it is a closed system so i have to top it up daily. I have tried to isolate the different sections of the heating (2 radiator circuits and also an underfloor circuit) but the pressure seems to drop no matter what is turned off. No apparent leaks anywhere. Upstairs rads have old gun barrel piping but you would see a leak that big downstairs. The boilers are not connected to the hot water cyclinder. The pressure also seems to drop when EVERYTHING is off. no one can give me any solutions! ideas?

Billy Bunting

What pressure are you putting into it ??

hehaen

I am filling it to between 1.0 and 2.0 bars, seems to make no difference to rate of dropping. someone tried leak sealer in december, no change at all.

heinbloed

Unless the gauge is faulty or you have a direct connection to the mains without a proper working non-return valve you certainly have a leak in the system.

What does the plumber recommend?

heinbloed

Double posting, sorry.

JohnnieK

Do you have any sections of pipe that are buried in the ground? Has anyone checked the pressure relief valves on the boilers?

hehaen

yes the ground floor pipes are underground but leak still continues when ground floor section shut off at valves. Leak also continues when first floor section shut off at valve. The boilers do not have their own pressure valves, there is an expansion vessel.

hehaen

no plumber has made any sense of it so far. i have a non-return valve alright connected to the mains - perhaps that is faulty, but it has a butterfly valve as well as a screw valve, so even if one part not working right the other would be...

JohnnieK

The boilers would (should) still have a pressure relief valve some where on them. What model of Flexicom are they?

hehaen

the plumber who i had look at them says they don't - they are flexicom 35hx condenser boilers. There is a safety valve but doesn't appear to be a flow control valve on the pipes either.

JohnnieK

Your going to have to take a few pics and post them on here for us to have a look at I'm afraid.

hehaen

Ironically when all the valves to the heating circuits are opened up, the pressure holds longer, though still slowly drops. I put a basin under the top boiler drain pipe and it lost over 2ltrs of water overnight. I wonder if this is the source of the problem? As per request, i am posting some photos of the system as well as the drain pipes on the back outside wall. Any ideas?

hehaen

outside drain pipes - wonder if that should have been installed at all if i have a closed water system?
also close up of mains fill into system.

heinbloed

Seing the pictures:
all mighty!

I wouldn't want to live with such an installation. Get a real plumber in. And a skip.
There are to many build-in faults obvious to my amateur's view that there is no doubt to me someone in the scrap trade emptied a skip and sold you a heating system.

JohnnieK

WTF hehaen. Who installed that for you? They should be shot. No regard for there own work. The 2 litres of water your talking about is coming from the condens drain from the boiler which is normal but it should be going to outside via the white drain pipe which you obviously have a leak from. You should get that addressed quickly because it will rote the copper pipes beneath it in a couple of years. Another note on the drain pipes outside, they should be going to a foul drain or a purpose made soak away not just looking out onto the ground. There should also be a terminal guard on the bottom terminal also. The safety valve is not piped to outside and terminating 150mm from the ground, also why is there a radiator valve between the pipe and the safety valve??

On the 11/4 inch pipe by the top boiler the fittings a very stained, you could have a slow leak from the compression joints, also the automatic air vent at the top looks dodgy. Take the insulation off and inspect with your fingers around the joints for water. Also it is possible that a fitting might only be leaking when the system is cold and not when warm. Also you could top it up and remove the flexible link on the filling loop blanking off the non-return valve thus eliminating the possibility of the valve letting by.

If I think of something else i'll let you know.