Combi boiler - CH going cold after a while

KiKi

Hi, TIA if anyone can help!

I have an Ideal Logic 24 combi. Hot water works fine.

I noticed the other day that the boiler was on (it's in the loft but I can clearly hear it), but the radiators which had been previously hot, were cool. I popped into the loft, boiler status was 'Pump overrun' which is a normal operation status, and I topped up the pressure as well (it was at 1, I topped it up to 1.5). I noticed that when I topped the pressure up, it took a long time, and there was no real noise, it was very quiet - usually when topping up it's quick and you can hear the water rushing through.

I thought perhaps the temp had been reached, that the rads were therefore cooling, and the boiler was just spending some time making noise before it switched off - so I ignored it. (In retrospect the rads would have taken a long time to cool, so there's no way the boiler should still have been running if it were switching off!)

Yesterday the rads were cool again after running the CH for a couple of hours - and the same again today. I usually have to stick the thermostat on 19-21 to get the CH to even come on, despite the fact that it feels much colder, but this has always been the case. Today it was on 21.

I have NO idea about boilers other than how to top the pressure up. The water pressure from the tap / shower has always been fairly low for the hot water as well - if I run the kitchen tap with hot and cold, then the cold completely takes over. When I switch the cold off, there's no water at all from the tap - and then slowly the hot water starts to come through.

Showers are no problem - they remain hot.

Any ideas, or is this a 'call my plumber' jobbie?! If it is, is it an expensive one?!

If it makes a difference, I'm in a three floored house, boiler's in the loft, I only put CH on in 1 rad on the middle floor and 1 in the basement - none in the top except the heated towel rail.

Thanks so much
KiKi

thescouselander

So, had the room where the thermostat is located reached the required temperature when the radiators went off?

Norman_Castle

It sounds like the temperature has been reached so the boiler has shut down. Completely normal. If you turn the thermostat up do they heat up again?.

KiKi

No - obviously if the radiators were cool because they were meant to be, then that would be fine! That's what I meant in my first post where I said I thought perhaps the temp had been reached and the boiler was shutting down.

But the boiler is STILL running, and there is still water running through the radiators - I can hear it - but they're not hot anymore. If I turn the thermostat up, nothing happens. I have to get the boiler to switch off (by turning the thermostat down) then turn the thermostat up again.

And since last night whilst the heating's not been on at all, one of my radiators is now leaking cold water from both ends, which it's never done before, so I think I'll just call my plumber tomorrow!

Thanks
KiKi

Norman_Castle

But the boiler is STILL running, and there is still water running through the radiators - I can hear it - but they're not hot anymore.

The pump will continue to run after the room temperature has been reached. It will switch off after a set amount of time until the boiler fires again.

p00hsticks

Are the radiators ever getting hot ?
Have you tried bleeding them ?

Gordon_Hose

Norman_Castle wrote: »

The pump will continue to run after the room temperature has been reached. It will switch off after a set amount of time until the boiler fires again.

If the pump was still running then it suggest the boiler has only just stopped firing. I wouldn't expect the radiators to be "cool" so soon after the boiler had switched off?

My rads stay hot for a while after the boiler (and pump) have stopped running. They don't become "cool" immediately.

KiKi

Gordon_Hose wrote: »

If the pump was still running then it suggest the boiler has only just stopped firing. I wouldn't expect the radiators to be "cool" so soon after the boiler had switched off?

My rads stay hot for a while after the boiler (and pump) have stopped running. They don't become "cool" immediately.

Thank you - that's exactly what I was trying to say in the third paragraph of my first post. I understand that the boiler runs for a bit afterwards, but they are so cool, that there's no way this is just the boiler running down. What I'm observing is *not* normal on radiators - I don't understand boilers, but I do understand how my CH system works, and it's going cold whilst the boiler is running.

I can now see that the radiator leak has been going on for a while - the skirting board is splitting, but it can only have been a maximum of 7 weeks, as when I painted the room 7 weeks ago it was fine, so I wonder if this leak has caused this problem.

My plumber's coming on Friday.
Thanks anyway for your help
KiKi

southcoastrgi

Oh the stupid idea of fitting a boiler in the loft so you can't see what it's doing

KiKi

Back again! My plumber fixed the leaks and pressure issues. However, I'm still 'concerned' about the boiler - although perhaps I don't need to be. If anyone could offer advice or reassurance that would be great.

When the temp is met, the boiler cools down - and displays the message 'pump overrun'. I understand that it runs for a bit to cool itself down, and this is what my plumber also explained it's doing. Sometimes this lasts 4-6 minutes and then switches off, which is what I understand to be normal. Sometimes, it just goes on and on and on.

Today the boiler was in pump overrun mode for so long, that the rads had cooled down completely. They weren't stone cold, but they were cool.

Is this normal? It doesn't always happen, and I can't see a pattern, either. Is it possibly because I'm only heating two of six rads in the house and therefore the whole system is really hot and the boiler needs a really long time to cool down?

I guess I just want some reassurance - if it's normal for the boiler to pump for so long, then okay. My plumber says it's fine - that the pump running isn't going to damage anything. But from everything I've read on the net, it's usually a case of between 4-15 minutes. I just want to check that my plumber's not telling me something just to shut me up!!!

Thanks if anyone can advise.
KiKi

p.s. Does anyone know what the red light means, over a large circle, when you pull the front boiler flap down? There's nothing in the manual or online to explain what it means! It's not the burner light.

Norman_Castle

Today the boiler was in pump overrun mode for so long, that the rads had cooled down completely. They weren't stone cold, but they were cool.

With the current warm weather once the room has warmed to the correct temperature it will take a long time to cool enough for the heating to be needed again. When this winter gets colder your boiler will be working more often and your radiators will be warm more often.

http://idealboilers.com/wp-content/uploads/sites/2/2013/08/Logic-Combi-ES-User-Guide1.pdf