Combi boiler; PRV leaking??

[Laurence Harvey]

My son has an Ideal Logic Combi ES30 boiler and the it would appear that the external pipe from the pressure relief valve has been dripping constantly for quite some time...several weeks at least. His wife noticed the dripping a few weeks ago but didn’t think anything of it as she’s aware that the plastic condensate pipe drips as well and assumed all was ok !

However, the boiler itself is functioning normally and the pressure is at just over 1.5bar and hasn’t needed to be re-pressurized. The fill-loop is definitely closed tight. The hot water for sink/bath/shower etc is being delivered ’hot’ as per usual.

The rads are working fine and all of them are heated all the way to the way up i.e. no cold section at the top.

Question: is the pressure relief faulty and if so what would be a ball-park figure to get it replaced by a heating engineer?;...or is there another fault?

As ever, all replies gratefully received.

 

[terryplumb]

If the PRV is passing ,and water has been dripping from its external pipe for several weeks ,the pressure would drop significantly. So water would have to be continually going into the system to maintain the pressure . Are you sure the pipe outside is actually the PRV pipework not something else ?

 

[Laurence Harvey]

Thanks so much for the reply tp;...yes, it's defo the prv outlet,...it comes through the wall in exactly the right place,...can't be anything else.

The lack of pressure drop is the thing that's puzzling me;...it's just a standard 3 bed detached house with 10 rads in total and I know for a fact that to drain even a pint of water from any rad is enough to drop the water pressure on the meter significantly and also enough to prevent the boiler igniting. The PRV external drip would probably fill a bucket in a day quite easily.

I've been scratching my head as to where the water can be coming from. Is it possible the valves on the filling loop pipe are both leaking slightly and allowing the cold water mains pressure to continually top-up the C/H water that is being lost through the PRV?

Maybe one filling loop valve has always been faulty/leaky from day one and the other one has recently failed as well;...I'm just clutching at straws really.

p.s. the boiler was installed about 4 years ago before my son moved in.

 

[terryplumb]

The cold mains water would have to be entering the sealed central heating system ,and the filling loop is a possibility. I assume the filling loop is external to the boiler ,and disconnecting it would be a first step.

 

[Laurence Harvey]

The cold mains water would have to be entering the sealed central heating system ,and the filling loop is a possibility. I assume the filling loop is external to the boiler ,and disconnecting it would be a first step.

The filling loop/pipe looks similar to this and sits at the base of the boiler chassis adjacent to the water pressure gauge.

https://i.postimg.cc/DmFN3Nqm/ideal-combi-loop.jpg[/img][/URL]


I might try running the C/H with the cold water mains stopcock shut-off completely and leave the filling valves untouched just to see what happens. Does that seem like a good idea, or not?

Thanks.

 

[terryplumb]

If that pic is a true representation of actually what you have ,removing the copper link would disconnect the mains water . If water flows out a valve,it's obviously passing ,and the other one would have to be kaput as well !!
Turning off the mains stopcock wouldn't necessarily stop water dripping from the PRV pipework outside for a while ,as there is still pressure in the system.

 

[Laurence Harvey]

Thanks tp ;...I'l be at my sons house on monday doing a bit of double glazing work so I'll have a jiggle around with this problem while I'm there.

 

[terryplumb]

The PRV will need replacing in due course ,as it shouldn't pass water at 1.5 bar ( around 3 bar it should). But you need to sort out the main issue first.
Good luck.

 

[Harry Bloomfield]

I might try running the C/H with the cold water mains stopcock shut-off completely and leave the filling valves untouched just to see what happens. Does that seem like a good idea, or not?

Odd that it drips, without showing loss of pressure.

Just turn both valves to off and carefully remove the loop. Off is with the valve handle at right angles to the pipe/valve.

Then keep an eye on the pressure, if it suddenly shows a drop, after the heating has run then cooled down/ combined with it still dripping when the heating is running, it could be the pressure vessel has lost air pressure. Pressure vessel may need repressurising with air, or the rubber diaphragm inside may have burst.

 

[terryplumb]

Odd that it drips, without showing loss of pressure.

Just turn both valves to off and carefully remove the loop. Off is with the valve handle at right angles to the pipe/valve.

Then keep an eye on the pressure, if it suddenly shows a drop, after the heating has run then cooled down/ combined with it still dripping when the heating is running, it could be the pressure vessel has lost air pressure. Pressure vessel may need repressurising with air, or the rubber diaphragm inside may have burst.

The issue of water continually being lost from the system ,without pressure drop ,or manually topping up , has nothing to do with the expansion vessel.
It may be the plate hex ,but the filling loop would be the first thing to rule out.

 

[Harry Bloomfield]

The issue of water continually being lost from the system ,without pressure drop ,or manually topping up , has nothing to do with the expansion vessel.
It may be the plate hex ,but the filling loop would be the first thing to rule out.

I know, but I didn't want to scare the OP by mentioning that possibility immediately.

 

[terryplumb]

I know, but I didn't want to scare the OP by mentioning that possibility immediately.

Did you decide to confuse him instead ,with irrelevant reference to the expansion vessel Harry

 

[Laurence Harvey]

The issue of water continually being lost from the system ,without pressure drop ,or manually topping up , has nothing to do with the expansion vessel.
It may be the plate hex ,but the filling loop would be the first thing to rule out.

Bleedin’ell, that’s sounds ominous,...and expensive,...is it?

 

[terryplumb]

Fairly expensive ,but may not even be that.

 

[Harry Bloomfield]

Fairly expensive ,but may not even be that.

Then why scare him by mentioning it :-} Long way to go yet, before it can be determined what the actual issue is...