Please help! Combi boiler overflow leaks, low pressure

[rtuk85]

Hello, I feel like I've searched everywhere but couldn't find a similar problem to this! We've just bought a house, and although the electric and gas aren't yet connected, whenever we turn the water supply on at the mains, the boiler overflow starts to drip/mini stream outside the house. The boiler is a Britony Combi 80 SE. We'll be moving to the house in a couple of weeks.

Now, when I first checked it, the filling hose was closed at the water inlet valve, but open at the CH return, so I hoped that closing both of these would solve the problem in terms of isolating the water supply to the boiler. However it didn't.

What's more strange is that the pressure gauge is within the red at approximately 0.8 bar. We even tried opening the filling loop for about 10-20 secs to raise the pressure but it didn't seem to move (we didn't hear any water either, so closed them again).

I am so stumped by this. To start with I just need a way of stopping the drip (metered water) but I don't want to call anyone out until we've fully moved in and got the electric and gas back on!

Could it be that the pressure gauge is mis-reading, and/or the filling loop is passing water? I haven't tried removing the filling loop completely yet to test for this. Or could it sort itself out once the electricity is back on, in terms of "activating" valves etc?

Hoping someone has experience with this problem - appreciate your help and happy to supply any other info.

 

[davebgas]

Try disconnecting the filling loop to see if its passing... the guage could well be faulty also yes.
Could also be the plate heat exchanger is passing, coupled with a faulty guage.

Isolate the cold mains into the boiler using the isolation valve underneath if you prove the filling loop isnt passing.

Sounds though from reading your post that the guage is knackered.... could be the case that the reason you arent hearing water enter the boiler is because the system pressure is right up at mains pressure.

1st check filling loop isnt passing.
2nd isolate cold mains underneath the boiler.

 

[rtuk85]

Thanks for your fast reply. I'm assuming the "cold mains" is different to the "cold water inlet" (i.e. which links the filling loop to CH return)?

If so where is the cold mains isolator likely be located and is this easily turned off?

At the minute the CH flow, water inlet and CH return valves are all turned at right angles to the pipe so assuming they are closed.

 

[davebgas]

Look for the pipe that the filling loop connects from.... one will probably be 22mm - thats the CH and the smaller probably 15mm is the cold inlet to the boiler. Follow it up to under the boiler and turn that valve off

 

[rtuk85]

Look for the pipe that the filling loop connects from.... one will probably be 22mm - thats the CH and the smaller probably 15mm is the cold inlet to the boiler. Follow it up to under the boiler and turn that valve off

Do you mean the DHW flow valve needs turning off?

 

[davebgas]

Yes, the cold mains inlet to the boiler.

 

[rtuk85]

Yes, the cold mains inlet to the boiler.

ok thanks, i've only really developed my knowledge of boilers over the past week! From what I could see there doesn't appear to be a black in-line isolating tap for the mains inlet, does this look different on the Britony 80? Is it something you twist or need a screwdriver for?

 

[davebgas]

Can you post a photo of the underneath?

 

[rtuk85]

unfortunately don't have a picture, as away from the house at the minute, but the pdf installation manual can be downloaded here

http://www.google.co.uk/url?sa=t&so...ht1BGPYjVzd2GJIGQ&sig2=VQi80NrD7kEeP8z60ZObrQ[/url]

I was looking on page 20 and assuming you meant item K needs isolating? As J, M and N are all turned off

 

[davebgas]

Its the 2nd one in from the right.

View media item 14073

 

[rtuk85]

Its the 2nd one in from the right.

View media item 14073

That valve is closed. As I thought that when that and the one next to it on the right were open, the CH system would top up via the filling loop?

Or am I getting confused?

 

[davebgas]

That last post confused me a bit..

The isolation valves underneath purely isolate the boiler..... the filling loop would STILL fill the system if the valves were turned off......

Open the CH flow and return valves on the boiler..... see if the pressure gauge goes up...

 

[rtuk85]

... but if the mains water to the boiler had been isolated surely there wouldn't be any water to draw to fill the system?

We tried a combination of the valves but pressure didn't increase.

The scary thing is the overflow still drips when all 3 black valves are closed?!

 

[davebgas]

Sounds like your going to have to get someone in to have a look at it in the flesh so to speak.

Try this....

Disconnect the filling loop and check its not passing.... if its not, reconnect it.

Open ALL the boiler isolation valves, does the pressure increase at all when this happens?

Now, try filling the system slowly and see if the pressure rises.
If it doesnt seem to rise, then most likely the small tube to the pressure gauge is blocked.

The overflow, or pressure relief valve as its called, opens when the system pressure reaches about 3bar.
If the gauge is faulty, it may just need a clean or replacing.

The plate heat exchanger can also pass, but the best way to test this is with a working pressure gauge.

 

[kevplumb]

FWIW

i think the plate and gauge are u s and the prv is dripping cos its at or over 3 thats why it wont fill