Radiators hot upstairs BUT cold downstairs?

[charlie]

Hi,

I moved into a new house 5 months ago and the downstairs rads never get hot, whilst the upstairs ones get warmish. It's an 'open' system that's around 15 years old and I don't know if inhibitor was used correctly. I decided to drain the system down and remove all the rads, flush them out with a hose, replace them and add some sentinel x400. The upstairs ones are definitely warmer and I'm happy with them, but the downstairs ones are still stone cold, so I'm not sure where to go next? There was some very black sediment in all the radiators, but this mainly came out in suspension when flushing through, rather than really thick sludge that I'd been expecting. I only refilled the system last night so should I wait and see if the Sentinel does anything? The fact that the downstairs rads are stone cold makes me think that this is a long shot! The pump has 3 settings and it's currently on the lowest- I was advised not to turn this up but could that be the problem?

This is my first attempt at plumbing and I was prompted by the high quotes and un-convincing advice given by the plumbers that I've had round (no offence to all you decent proffesionals out there!)

thanks Charlie

[Andrew Welham]

When you re connected the rads down stairs, did all the rad fill with water ?

[charlie]

Yes, I bled the downstairs rads first then the upstairs ones- they all filled OK.

[charlie]

Yes, I bled the downstairs rads first then the upstairs ones- they all filled OK.

[Andrew Welham]

I asked in case one of the valves on the rads was closed stopping the flow of water.

Are all the manual values (used to adjust the heat) open ?

Do any of the pipes leading to any of the rads get warm down stairs ?

Can you hear any water movement in the rad down stairs ?

[Cats Whiskers]

Where's the pump, is it nearest the upstairs rads or the downstairs rads? If the pump is nearest the upstairs rads it might be that the lock shield valves on the upstairs rads are fully open or open too far so that they are hogging the hot water and there is not enough pressure for hot water to reach the downstairs rads. In that case all the rads MAY need balancing. But that doesn't explain why the upstairs ones are only warm if their control valves are fully open. What happens to the upstairs rads when you turn the pump up to 3 and turn the control valves on all the downstairs rads completely off? Do the upstairs rads get hot?

[charlie]

Hi Andrew,

All the TRV's are set to open- maybe I should check that some are not stuck closed? I'm not actually sure how the pipes are set up- each downstairs rad has a pipe coming down from the ceiling and one going back up- I kind of thought there would be 'horizontal' pipes downstairs? All other valves are open. The pipes leading to the rads are all cold.

thanks Charlie

[charlie]

BTW, I'll see if I can hear any movement in the rads tonight. C

[charlie]

Hi,

Just to clarify, the upstairs rads are fine after I cleaned them out- they get nice and hot. I'll try your suggestion tonight.

thanks

[PM]

Another thing it could be is an airlock in one of the pipes going to the cold rads. The rad would fill OK through the other pipe but water would not be able to circulate.

You can try and cure this by turning all the rads off except one of the cold ones, turn off the circuit for hot water if possible (if you have motorised valves just make sure there is no HW demand), if you have an auto bypass valve turn it to the highest setting after making a note of the current setting, switch the pump to its fastest setting and then turn the heating on.

If this doesn't work and you have a F&E tank, you could try the same but using a hose blast some mains pressure water down the F&E outlet, or take the rad(s) off again, open each valve and use the hose to try and clear the air lock (this last one is likely to get you wet!)

[Sparks]

Is the pump actually working, you should be able to hear it running if you put a screwdriver on it, and the handle on your ear (You can just stick your ear on the pump, but it will probably be hot!) - if not, then the pump is shot and your upstairs rads are getting heated by gravity circulation.

If the pump is running, turn off the rads upstairs, all but one downstairs - does this cause the downstairs rad to heat up?

Sparks...

[Roger Mills]

As others have said, you may be able to clear the airlocks in the downstairs rads by applying *all* the urge to one rad at a time - by turning all the others off. If that doesn't work, try this:

On each cold rad, turn off one valve. Open the bleed screw and bleed off a couple of litres of water (into a suitable container!). Then close that valve and open the other one, and repeat the bleeding operation. That will ensure that the flow and return pipes are *both* full of water. [If you bleed with both valves open, the water only needs *one* path - and there can still be an airlock.] If your system has inhibitor in it, pour the 2 litres back into the F&E tank after each operation to avoid wasting it.

One other thing to check: I think you mentioned earlier that the rads are fitted with TRVs. Remove the thermostatic heads and make sure that the pins move up and down smoothly, and are not stuck down.