Boiler not working -Leaky radiator valve, now pressure has gone down

[Startingagainandagain]

I had a new combo boiler installed about 2 months ago. Was working fine until today.

Two days ago I did notice that one of the radiator in the kitchen had a leak at the valve (see pic, I think it is leaking at that metal bit just above the red arrow) which must have gone on for a little while as there was damp under the kitchen vinyl floor but I did not notice it.

My usual plumber and is on holiday and can't come in until Thursday.

Could that leak have cause the pressure to drop (0.2 this morning)?

I was going to use my usual plumber but I also coverage from Homeserve. Anyone knows if they cover leak detection if there is another leak somewhere else? am I safe to wait until my plumber is back from holiday (he installed the boiler and bled the radiators two months ago so I would prefer him to come and check it)

I was starting to finally have managed to fix everything in my upper fixer (aka the House of Horror) and this has knocked me back.

Any advice much welcome...maybe @pigletjohn?

I have a couple of electric heaters so at least I won't freeze...water is working fine in sink and so on.

You could try some plumbers tape around the leak area and then top up the boiler as a temporary/quick fix. A leak can absolutely cause the pressure to drop which will stop the boiler working if it's too low.

When was the last time you checked the pressure on the boiler? It could have been a gradual drop if the leak was small but ongoing.

Disclaimer: no expert, just experience of stupid boilers

If the pressure has dropped, then there must be a leak somewhere. The one you have found is the likely culprit and will have allowed the pressure to leak out over time.

Was the previous boiler a combi too, or has the system been modified from a non pressurised one? If the latter, it is not unusual to discover leaks of this sort that were not manifesting previously because there was only atmospheric pressure in the system.

Have a good look around as there may be other weeps.

If you are feeling brave, you could tighten the nut a little (1/8 of a turn) and remember that the nut will do up clockwise from underneath, or anticlockwise as you look down from the top. You should only need to nip it up.

If you get that far, and are feeling braver, the system will need to be topped up. There is normally a mechanism to do this at the boiler where two valves need to be opened allowing water to feed into the system from the mains. There will be a pressure gauge on the boiler. Open the valves very slowly and allow the pressure to rise to about 0.8 bar, then close the valves. You should then be able to fire up your heating. Then check the radiator valve for continuing leak.

I'd still get your plumber to look over it when you can, and check that any corrosion inhibitor is unaffected.

Thanks everyone for the feedback so far!

I don't think I am not brave enough to start poking around/topping the water pressure (I have an absolute hatred of central heating systems and boilers...) but I will ask the plumber to show me how to do it when he comes in so I can do that in the future.

That leak has definitely been on for a while, maybe a month or so when I last checked the valves for leaks and the pressure on the boiler.

I only noticed the leak two days ago randomly as I was doing a little check to see whether there was any leaks in my radiators valves...

I really hope that will be it and there are no other leaks anywhere else...

Yes the previous was a combi but it was a much older one.

Yes it can cause the pressure to go down and if the radiator is on the heat will evaporate the water so it seems like there is much less than there is. Before the plumber comes round though I would check all the other joints on all the radiators with a bit of paper towel which will show any slight leak. It's probably from just that one radiator though

I have checked the others and could not see anything but will another go. Of course it could be something under the floorboard but I guess the plumber will need to repair the leak first and restore the pressure to see if there could be leaks anywhere else...

Have I mentioned how much I hate boilers and central heating...

It’s really straight forward to top up the pressure and get your boiler going until the plumber can get there. If I can manage to do it on ours then anyone can - I’m a complete numpty when it comes to understanding how anything like that works!

Here’s some useful advice from EDF - it tells you how to do it.

https://www.edfenergy.com/heating/advice/boiler-pressure-everything-you-need-know

Good luck! 😊

Our radiators are about 25 years old and our boiler is about 6 years old and we have had about 4 leaks in the past and they have all been from either where yours is or from the bleed valve at the top of the radiator

if your boiler is new it should be easy to top up and it should be in your manual what to do, I would give it a go

I have just this morning had a plumber in to fix a leak on a valve like this. It was causing our boiler pressure to drop. It took him 2 minutes. It might be the nut, you can try tightening it or it could be the gland on the valve (this was our problem) which I don’t know how to fix. Ours needed topping up fairly frequently, once the drip became noticeable we had to top up every day you may find it drips less when the system is hot because everything expands and seals better.

If you take a photo of the bottom of your boiler and post it, most likely people on here will be able to tell you which is the fill/pressurise control.

The worst thing you could probably do is turn the gas off. This is normally the yellow lever, so it's pretty obvious not to touch this.

as above, my last two boilers have been turn the right tap on, turn the left slightly to top up to 1.5 bar. Close the left tap, close the right tap. Boiler working.

I've had the same issue, the valve needed replacing in the end because every time the radiator came on it would leak until the boiler lost pressure and stopped working. Repressurising the boiler was very straightforward, though, and once the plumber replaced the valve it all settled and is now watertight again. runs to touch wood

To update everyone the plumber bled all the radiator to remove the air and fixed the leaky valve which had caused the loss of pressure. Everything is working fine again :).

That's good news. Did your plumber show you how to repressurise the boiler? If so, it's a good idea to write the instructions down as next time could be months or years in the future. I have a little notebook that I write things like this in. Also where the stopcock is, emergency numbers for utilities etc. But then I live in the middle of nowhere so have to be somewhat self reliant.

There should be a filling loop (picture attached). On that filling loop should be a tap/valve. Following the rule of righty-tighty/lefty-loosey, you should be able to pull the tap/valve towards you, slowly, and you should hear water going in. I say to do it slowly, because it can fill up super fast and you'd have to bleed a radiator to drain the excess water if it does. You don't want too much pressure in your system.