Combi boiler, last radiator in the system not hot

abankerbutnotafatcat

Looking for MSE advice that will either prevent me from needing to get a central heating engineer/plumber out or if I do then will arm me with the knowledge to not be fleeced!!

We have a 3 storey house and with the loft that makes 4. We have a c8 year old Halstead Ace High combi boiler in the ground floor. There is a small double panel radiator in the loft and I think it's the last in the system.

If water pressure on the gauge on the boiler drops below one then the radiators on the top two floors don't get hot. I know how to raise the water pressure to 2 and it works but it adds air to the system and I need to bleed them. Eventually, I get floor 3's rads really hot but in the loft the best I can get is back panel hot, bottom of front panel hot but top of front panel cold.

Is there anything I can do? Is radiator broken?

All help appreciated!!

macman

If you have bled the top rad without resolution then there is another problem.
Topping up the pressure does not add air-it sounds as if the is air getting in anyway, then is then pushed to the top when the pressure is increased.
If you have to keep topping up the pressure there is either a leak on the CH circuit, or it is losing water through the pressure relief valve which vents to the outside-have you checked that?

keystone

Was the rad in the roof added after the boiler and the rest of the system were put in? Have you got another bathroom up there too? You may possibly have a system design issue.

Is/has the PRV operating(ed)?

Cheers

PS In all honesty though I find this:

Looking for MSE advice that will either prevent me from needing to get a central heating engineer/plumber out or if I do then will arm me with the knowledge to not be fleeced!!

rather a damned cheek as its most likely that the only sensible advice, if it is a system design issue, will come from people that operate in the trade so what you are asking for is free advice from those whom you believe will automatically fleece you if they were paid for helping you. Not a particularly good demonstration of first class inter-personal skills is it?

Now you may not have meant it that way but thats certainly the way it reads.

abankerbutnotafatcat

keystone wrote: »

PS In all honesty though I find this:

rather a damned cheek as its most likely that the only sensible advice, if it is a system design issue, will come from people that operate in the trade so what you are asking for is free advice from those whom you believe will automatically fleece you if they were paid for helping you. Not a particularly good demonstration of first class inter-personal skills is it?

Now you may not have meant it that way but thats certainly the way it reads.

So you are suggesting there aren't any tradespeople out there who try to take advantage of ill informed people?? I highly value honest and skilled professional tradespeople but I want to make sure that i'm prepared in case I meet the cowboy element.

abankerbutnotafatcat

macman wrote: »

If you have bled the top rad without resolution then there is another problem.
Topping up the pressure does not add air-it sounds as if the is air getting in anyway, then is then pushed to the top when the pressure is increased.
If you have to keep topping up the pressure there is either a leak on the CH circuit, or it is losing water through the pressure relief valve which vents to the outside-have you checked that?

Thanks. There is a LOT of water coming out of a thin plastic pipe to outside, so much so that i put a container under it because i was worried about it turning to ice (it drains onto steps). In which case is it something I can do or do I need to get the professionals in? It was checked over by Npower as part of their boiler cover service a couple of months ago.

I only thought that topping up the pressure added air to the system because i'd read it on this forum somewhere and it did seem to be the case (you've explained why) that there was a lot of air so I thought it must be that.

keystone

abankerbutnotafatcat wrote: »

So you are suggesting there aren't any tradespeople out there who try to take advantage of ill informed people?? I highly value honest and skilled professional tradespeople but I want to make sure that i'm prepared in case I meet the cowboy element.

No I didn't say that at all. Please read it again. Ta.

Cheers

macman

If it's a condensing combi, that is the condensate drain, not the PRV overflow. It's supposed to discharge condensate, but into a drain or soakaway, not over a step. It should also be lagged, not bare plastic-sounds like a very shoddy install.
A second pipe in copper should be present for the PRV overflow.
If the plastic pipe is the overflow, it is blowing off due to excess pressure or a faulty PRV-usually due to grit in the valve.

keystone

abankerbutnotafatcat wrote: »

Thanks. There is a LOT of water coming out of a thin plastic pipe to outside, so much so that i put a container under it because i was worried about it turning to ice (it drains onto steps). In which case is it something I can do or do I need to get the professionals in? It was checked over by Npower as part of their boiler cover service a couple of months ago.

The plastic pipe is probably the condensate drain as the pressure relief drain should be in copper.

A combi boiler can generate 6 - 7 litres of condensate per day (from the condensing flue gasses - not from the system water). If this is your condensate drain it should NOT be left running over the step - it should have been directed to a foul drain.

I only thought that topping up the pressure added air to the system because i'd read it on this forum somewhere and it did seem to be the case (you've explained why) that there was a lot of air so I thought it must be that.

You add air when you repressurise the expansion vessel but it doesn't get anywhere near the system water unless the diaphragm is knackered. When you top up the boiler pressure you add water from mains via the filling loop.

Cheers

EDIT: Hang on - I'm talking bollix. The Ace isn't a condensing boiler so won't have a condensate drain. So it probably is the PRV drain.

macman

I'm a bit worried by 'thin' plastic pipe too-what diameter is this pipe?

Canucklehead

Hi.

Do you have a water softener? The salt in a bucket type.


GSR

abankerbutnotafatcat

Thanks for your help.

Sorry, bf has just informed me that it's a metal pipe (painted white so I thought it was plastic). It's about 2cm wide. The Npower guy did say something about that pipe not meeting current regulations -something about it rising (internally) before falling so the water could potentially freeze.

Yes, we'd like it to go down to the drain (there is one about 1.2m away) - the container under it is just a fix so that there's not sitting water to turn to ice. We've only been here six months so still finding our feet with the new place. At a guestimate probably 300ml of water comes out of it per day.