Pressure drop in central heating system

[neomagik]

Hi,

I have recently added a wetroom ensuite which involved adding a new heated towel rail.

For a few months while I was building it I had the chrome heating pipes sticking out of the floor with isolating valves to stop the water, this way I could regularly check for leaks before I finally laid the wetroom floor.

Up until this point I had no problems with pressure in the system but as soon as I filled the towel rail it started to loose pressure and has done ever since.

It takes about 8 hours for the pressure to go to zero so I'm filling the system up to twice a day. This has been going on for a week now!

So far I have tied a bag around the copper overflow outside to see if the prv is stuck open, after 8 hours it was empty, I've done the same with the condensate pipe overnight with the boiler switched off to check for internal leaks within the boiler, again empty. There are no visible leaks, no damp patches in ceilings or walls. I'm able to look under the wetroom by lifting floorboards and shining a torch and all is dry.

I'm beginning to wonder whether I drew in air when I filled the towel rail and it's just moving around the system but I've bled all the radiators and as far as I know removed all the air.

I'm at a loss as to what's going on Can anyone suggest anything?

 

[flameport]

If the pressure drops all the time, there is a leak.

As this only started when the towel rad was fitted, seems likely that the towel rad is leaking - and in a wetroom, the leaking water would just flow away into the drain and therefore not be noticed.

 

[arfurrrr]

Have you tried isolating the towel rad and running the system to confirm if towel rad is the problem

 

[neomagik]

flameport, if the towel rad was leaking above floor level I would see the water making its way to the drain. As I said before I can see under the wetroom and it's dry.

Arfurrrr, yes I have tried isolating the towel rad and no difference.

 

[arfurrrr]

Arfurrrr, yes I have tried isolating the towel rad and no difference.

prob leak under ground floor then , if you have excluded boiler and just a coincidence .

you could isolate all rads . if it leaks boiler and or pipework .

 

[NEALDEAN]

What boiler is it.
Have you ruled out a faulty gauge ?
Does the boiler shut down when it reads zero ?

 

[neomagik]

You've just reminded me, when I first noticed the pressure drop, I filled it back up, turned off the boiler and isolated the heating flow and return using the valves under the boiler. I then left it for a couple of hours and when I returned the pressure gauge hadn't moved. I then opened the valves and the gauge dropped imediately about 1/4 bar. I am sure that this means a leak somewhere in the system??

The only place I know that the pipes run under the ground floor I have checked and are not leaking.

 

[neomagik]

Its a Potterton Promax HE and I think it shuts down at 0.5 bar with an error code. Does this rule out a faulty gauge?

 

[NEALDEAN]

Its a Potterton Promax HE and I think it shuts down at 0.5 bar with an error code. Does this rule out a faulty gauge?

Yes the gauge seems to be working correctly.
it would be normal for it to drop when you said you opened the iso valves after a few hours as it will have been drawn into the system after you worked on it.
You need to recheck the installation as it has to be a leak somewhere !!!!

 

[neomagik]

Thanks,

I suspected so. I guess I'll just have to wait for it to show itself because I'm out of ideas where to look

 

[NEALDEAN]

Just out of curiosity what did you use to connect the copper to the chrome ?

 

[neomagik]

It was plastic to chrome and I used compression nevertheless I can see the joints and all is good.

 

[NEALDEAN]

Did you use an insert in the plastic side ?

 

[neomagik]

If you mean an olive, then yes I did.

 

[NEALDEAN]

No the insert that goes inside the plastic pipe end before you put the fitting onto it.