problem with combi boiler filling loop

[electroman68]

Hi There,

The filling loop has been left connected to my boiler by the previous occupants and I would like to disconnect one end of it in order to avoid 'accidental' pressurising of the system, and also to comply with regs.

So, what I have done is ensure that isolation valve on filling loop (mains water side) is closed and then disconnected other end of hose via wing nut coupling. However, when I did this water was coming out at a fair rate so I quickly reconnected it again. I was wondering whether the isolation valve on mains water end of filling loop is shutting off properly? When I close the valve with an adjustable spanner (the black lever part is missing) it certainly appears to be turned fully and won't go any further.

Also, I recently had a leak in a radiator pipe that caused a complete loss of boiler pressure. I had this repaired by a heating engineer, who then repressurised the system to 1 bar. He stayed for a short while to ensure that pressure stayed at 1bar and then left. However, when I looked a week later the pressure gauge was reading around 2 bar. My first thought is that perhaps the filling loop isn't completely closed but it did take a long time to increase from 1 to 2 bar so not sure.

Any thoughts on this would be most appreciated. Any suggestions on what I should check also greatly appreciated.

As my name suggests, I am a qualified engineer but of the electronics variety so my plumbing skills are somewhat limited!

Cheers.

 

[Charnwood]

Turn off water at main stop cock.
Take filling loop off iso valve, does it look closed? If yes then its seal may have failed. Fiddling with cheap isos can cause all sorts of problems.

If the above is the case, replace iso (or whole filling loop).

 

[electroman68]

Thanks charnwood. I will check this tonight.

Am I right in assuming that, all being well, I should be able to disconnect the loop on the central heating return side without water leaking out all over the place? Could it be that the DCV is faulty, as this is on the CH return side? How could I check this?

Thanks.

 

[Charnwood]

The DCV is to stop water going from the heating system to the mains.
If the iso is letting by it will come out of the DCV, if you remove the DCV from the system. That's regardless of whether it is usually attached to the flow or return.

If the DCV is not faulty it will allow water to flow in one direction only.
If it was faulty it would either not let water through at all or it would allow water to 'backflow'.

Turn water off at main stop cock, remove iso, screw inlet end of DCV into nut at mains end of iso. Turn on stop cock. If DCV OK you will have a wet floor.

Turn off stop cock, turn DCV round so t'other end is attached, turn on stopcock. If OK you will have a wet floor...still, but it should be no wetter than before you turned the DCV round.

Turn off stop cock, put everything back, get missus to mop floor.

 

[electroman68]

Hi Charnwood.

Right, I firstly tried disconnecting the filling loop via the wing nut coupling, I.e leaving the DCV connected to the heating return pipe. Water was flowing out of the end of the loop. This suggests that the Iso valve is not closing properly.

I have turned stock cock off and removed filling loop from mains side. Valve appears to be closed. By strange coincidence I have found another filling loop in the garage. I remember keeping this from when having a boiler replaced in a previous property. I am going to replace the existing one with this one and see what happens. I'll try to do this sometime this week and will post back here to let you know how I get on.

Many thanks for all your help so far, it's much appreciated.

Regards.

 

[electroman68]

I should clarify that when I mention that the water is 'flowing out' it is actually a very small trickle, which indicates that the ISP valve is almost closed completely, which also explains why boiler pressure has been increasing but only very gradually over a few days.

 

[Charnwood]

The PTFE seals (3 on diagram) can fail, or they can get caught when the ball (4) turns past them whilst being closed, causing a trickle like yours.