Cold Rads - tried all FAQs - help pls

[Blue_Manc]

V old system and Old boiler - Oil fired with four pipes exiting from it, top L+R both hot, Bottom L+R usually cold (I think from memory?).

Control panel only allows Hot water, or Hot water + heating - no Heating only option.

**Boiler working okay but rads stopped heating up**. Hot water fine.

Went through a few things and pump not working - no flow on anything but "3" - changed pump. New pump flowing fine and fast on all settings.

Still no heat in rads.

Bled everything to death. No joy.

Finally drained down system to see if it would clear any blockage/airlock. No joy.

At a loss now - any suggestions to try today before I call someone out tomorrow?

 

[easyflow]

If you are sure there is no blockage/no airlock, check you have put the pump on the right way round (easy mistake) if all ok there check for a motorised valve not working there will be a manual operated lever to open valve.
If that works change motorised valve.

 

[Agile]

Or call a professional?

 

[HERTS P&D]

Or call a professional?

Tony do you know anyone? and their hourly charge?



Andy

 

[Blue_Manc]

Motorised valve - where is it likely to be located? Cant see anything either near the boiler or near the hot water tank? Do all systems have them?

 

[Hugh Jaleak]

Yours is a gravity hot water/pumped central heating going by your description, unlikely to have a motorised valve. Have you checked pump is the right way around, pump valves are open, and water in the system?

These are simple systems, did the heating stop working suddenly or has it been a gradual decline?

 

[Blue_Manc]

Pump taken off - replaced unit but not pipework by removing 4 allen keys and replacing - so could not be 'wrong' way round in that circumstance no? Or could it?

It stopped working suddenly - but pump had only been workign on setting 3 for years. Assumed pump had just failed/siezed. When I took it out pretty stiff.

Edit to add - can hear water flowing pretty freely thorugh the pump and pipes when on

 

[Hugh Jaleak]

Rotation would still be correct if head only was removed. Assuming it is still rotating. If you can hear water flowing with it on, where is this water going? Rads will be a closed circuit, if its going in, it's got to be coming back out!

Not unknown for a pump to be 'working' but not actually moving any water. Valves both open either side of pump? Pipework clear?

 

[Norcon]

It's the summer time. Your rads should be cold.
If you need heat this time of year there's something wrong with you!

 

[MANDATE]

It's not clear if the whole pump has been replaced with a new one or just the pump head.
I removed a pump couple of years ago and the 20mm inlet and outlets were silted so much they were down to about 8mm creating resistance.
The isolating valves either side of the pump were also in similar condition.
If the system has been drained and refilled, there could well be an air lock preventing the water from circulating.
You did not mentioned bleeding the pump, but I thought it worth mentioning.
When bleeding a radiator it's worth doing it twice, with one valve open and one closed and then reverse the valves opening/closing
If there is a blockage it will affect the flow from radiator when bleeding in one of the two ways.
If the problem is 'air lock' it will not have adverse affect.
If the problem is a 'air lock' it would be near impossible to get rid of it by bleeding radiators.

 

[Slugbabydotcom]

Pick an easy to remove downstairs radiator and take it off the wall.

Flush some water through each valve at least a couple of washing up bowls full. Or better still if you can get a hose on it.

Do not let the water come out of the system faster than it is filling or you could re-introduce an airlock.

Try running the system again when you have the rad back on the wall.

Report back with findings or you should be able to figure out yourself where to go from there

 

[hazetimesfive]

It's the summer time. Your rads should be cold.
If you need heat this time of year there's something wrong with you!

mine is still on.