Bleeding radiators, still don't get warm

Igotadose

I have 35 feet of radiator in my bungalow. I have 3 radiators that just won't get warm. If I bleed them, it makes no difference - I have bled them for 1/2 hour at a time with the heating system running, and they don't warm up. If I close off 1/2 of the radiators in the rest of the house, then they warm up.

I am thinking that it's the case that the boiler, which is original to the house (so, 13 years old) just simply isn't pumping enough water - I touch the 'feed' pipe from the boiler to one of the pesky radiators, it's warm, but the outlet pipe isn't, as if the water cools off in the radiator quickly and it simply won't warm up before the water cools.

Should I be looking to replace my boiler with a new one? Or, just the radiators in question? The boiler is a 'firebird 90s' which is very common here on the Dingle Peninsula. The radiators look like this one: https://www.plumbingproducts.ie/imperial-300mm-high-double-panel-radiators-ireland/2246-imperial-double-convector-radiator-300h-x-1000l.html

Jayop

Is there a little valve and Guage in beside your hot water tank? I know on my system the upstairs heaters don't heat up unless there's pressure built up showing on that Guage. I have to add pressure every few weeks.

Wearb

Has any new radiators been added to the system ? Did the ever work properly? Has the boiler been serviced? Is it an open system?

Damokc

Having a similar problem with a new house/system. We have an open system though. Should it be bled when the system is cold or hot for best results?

Igotadose

Jayop wrote: »

Is there a little valve and Guage in beside your hot water tank? I know on my system the upstairs heaters don't heat up unless there's pressure built up showing on that Guage. I have to add pressure every few weeks.

No, there's no gauge that I see.

Igotadose

Wearb wrote: »

Has any new radiators been added to the system ? Did the ever work properly? Has the boiler been serviced? Is it an open system?

Nothing new added, was serviced a few months back. Not sure what's meant by 'open system' though. I'm thinking it's time to get the serviceman back.

flaneur

It could be lots of things.

1. Failed circulation pump. These are almost a consumable in the heating system and typically last about 10 years at most.

2. An airlock. Was the system fully drained recently? Some systems can tend to have issues with air locks, depending on how they’re laid out.

3. A failed / stuck actuated valve if your system has them.

4. A stuck non return valve. Some multi zone systems use large flapper valves after the pumps to prevent back flow.

Either of these could be stuck halfway open.

I think to be honest if you haven’t managed to clear the issue now, you need a central hearing plumber / RGI if it’s gas.

If you’ve access to the pump(s) set it to maximum speed and that might help push any airlock out.

Igotadose

flaneur wrote: »

It could be lots of things.

1. Failed circulation pump. These are almost a consumable in the heating system and typically last about 10 years at most.

2. An airlock. Was the system fully drained recently? Some systems can tend to have issues with air locks, depending on how they’re laid out.

3. A failed / stuck actuated valve if your system has them.

4. A stuck non return valve. Some multi zone systems use large flapper valves after the pumps to prevent back flow.

Either of these could be stuck halfway open.

I think to be honest if you haven’t managed to clear the issue now, you need a central hearing plumber / RGI if it’s gas.

If you’ve access to the pump(s) set it to maximum speed and that might help push any airlock out.

Thanks I think the pump is likely to be the problem - it works a little, some of the baseboards heat just fine. I've had to replace other pumps like the biocycle, septic, power shower since we moved in a few years back. Further, the heating system has had a lot of work - the old owner barely lived here and I think kept warm with a fire in the fireplace and a small electric heater; the oil tank had fallen off its supports and was 1/2 full of rainwater but all that's been rectified and repaired, and the last couple winters the heating system's been o.k. except for the baseboards that won't warm up, unless all the others are closed. It's probably time to get the pump replaced.

agusta

You probably just have to balance the system
Firstly see if you can locate the copper cylinder balance valve . it probably is a red wheel gate valve.it will be on one of the two hot pipes feeding the cylinder.Close the valve fully and reopen the valve 1 1/4 turns