Downstairs RADs go hot then cold

[TimperleyCH]

Hi,

We've recently moved into a house with an old glowworm boiler.

We had problems with the central heating at the start - some of the upstairs radiators weren't getting hot. An engineer fitted a new pump and that problem has been solved. The upstairs radiators now all get hot.

However, we've now developed another problem.

When the heating comes on, all the radiators get hot - upstairs and downstairs.

However, after a few hours, the downstairs radiators go cold. The upstairs ones remain hot. The central heating is turned on and boiler is still firing up.

None of the radiators have thermostatic values, so that's not the cause of the problem.

Any one any ideas please?

Thanks.

 

[bookahandyman]

Is it a combi or gravity pumped system?have you tried to balance the rads to get an even temp across the lot, this is done by adjusting one valve on each rad up or down depending on the temp of that rad. if all upstairs stay warm then turn them down and open up downstairs. it will take a while playing around with each one but should work. also check what speed your pump is set at.

 

[TimperleyCH]

Is it a combi or gravity pumped system?have you tried to balance the rads to get an even temp across the lot, this is done by adjusting one valve on each rad up or down depending on the temp of that rad. if all upstairs stay warm then turn them down and open up downstairs. it will take a while playing around with each one but should work. also check what speed your pump is set at.

It's not a combi. We've a hot water tank upstairs.

What difference will the pump speed make?

I've 7 radiators downstairs. They all do get hot for a few hours, then all go off at the same time. Upstairs isn't impacted.

I'm assuming the pump is OK, since the radiators which didn't get hot upstairs prior to the pump being replaced are staying hot (these radiators are the furthest away from the pump). Might this not be the case?

 

[bookahandyman]

Is your pump downstairs ? If so it could be just gravity heating upstairs.

 

[TimperleyCH]

Is your pump downstairs ? If so it could be just gravity heating upstairs.

Hi,

Yes, the pump is downstairs with the boiler.

We've no problem with hot water.

If the pump isn't working, then how is hot water getting upstairs into the tank and upstairs RADs?

Or do you mean that the pressure of the water in the central heating system is pushing all the hot water into the upstairs rads?

I checked a few downstairs RADs this morning - they were piping hot first thing, but they'll go cold quite quickly in a bit, but the upstairs ones will be fine.

Sorry if these are simple questions - as you can tell, I've haven't a clue on this sort of stuff.

 

[bookahandyman]

Close one side of the upstairs rads and see if downstairs stay hot. If they do then pump is working. Hot water rises hence the upstairs staying hot if pump isn't running properly.

 

[Morris40]

what happens if you turn off the upstairs rads and leave the downstairs open ?, does the downstairs rads going cold coincide with anything like the hot water demand coming on ?, do you have a 3 port valve or 2x2 port valves

 

[TimperleyCH]

what happens if you turn off the upstairs rads and leave the downstairs open ?, does the downstairs rads going cold coincide with anything like the hot water demand coming on ?, do you have a 3 port valve or 2x2 port valves

Thanks for the reply.

However, I don't know what you mean. I've not got a clue about CH, so I wouldn't know if I've a 3 port valve or 2x2 port values. What do I need to look at?

We do have a remote digital thermostat. However, the temperature on this shows lower than what we've got the thermostat set at. We are asking for 19C and it's showing that the temperature is 16C, so it should be asking for the pump to run.

The upstairs rads don't go cold until the CH cuts out at 10:30pm, in accordance to the timer.