Rads downstairs not working

[Bobl]

Heating was working well apart from the furthest two rads which needed bleeding. Once I bled them no heating anywhere. I turned off all the rads and then turned them on again gradually, now the rads upstairs are on but none downstairs. We had a new Boiler 2 years ago which is working fine, I have tried turning the pressure release valve at the boiler (which worked when I had a similar problem a while ago) but there was no air released. The system is an open vented system with an expansion tank in the loft (which occasionally overflows). My local plumber has been out a few times but he is stumped by the problem. Any advice gratefully received.

 

[Keentolearn]

Do you have any additional zone valves or thermostats (zoned heating)?

 

[Gasmk1]

Pump faulty or air lock

 

[Bobl]

Do you have any additional zone valves or thermostats (zoned heating)?

Hi, no zone valves, we have TRV's on all the rads.
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Pump faulty or air lock

The pump appears to be working fine, I have turned it off and on again and can hear it turning. I suspect you are right with air lock, just not sure how to fix it.

 

[Gasmk1]

What make of pump also what speed setting just because you can hear don't assume it's working to its full capacity

 

[Bobl]

What make of pump also what speed setting just because you can hear don't assume it's working to its full capacity

It's an Evosta, I have tried all three settings, currently on three lights.

 

[centralheatking]

Hi, no zone valves, we have TRV's on all the rads.
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The pump appears to be working fine, I have turned it off and on again and can hear it turning. I suspect you are right with air lock, just not sure how to fix it.

Air locks can be solved by shooting up the system with mains pressure. Connect the lowest drain off with a jubilee clip to a garden hose to an outside tap. When the system is cold turn on outside tap Gently check for leaks etc. open the drain off and then go round your rads etc lowest nearest to highest furthest in turn And bleed. blip the pump. Watch out if it’s an open vented system as you can overfill the f&e tank and it might overflow out the wall upstairs. It’s a great way to get rid of air and you can flush a system this way using another drain off to let the dirty water out. Tried and tested for 30 years plus. Centralheatking

 

[John.g]

It's an Evosta, I have tried all three settings, currently on three lights.

Failing all else and before you try centralheatking's remedy you might just drain down the system and refill it very slowly and keep the d/stairs rad vents cracked open while doing so, just put a few old towels underneath to catch any water while running about.
I have a combined cold feed and vent and I had to carry out this procedure once when I drained down the whole system many years ago.

Even though air is the most likely culprit, you might look at your pump again. Your pump looks as if it is pumping downwards, just check that this is correct, the pump head orientation doesn,t really matter, just that the settings are "upside down" (or maybe its just the picture that's upside down). I'm just stating the obvious but also check that the pump isolating valves are opened and that it is vented via the brass vent/degassing screw. This pump has 9 settings, 3 constant curve and 6 proportional pressure settings, it appears that you have it on PP6 which a very high setting but if there is air in the system then it won,t shift it as the pump will just ramp down. I would suggest trying it on constant curve CS2 which because of the pump head orientation is the two top solid green LEDs illuminated and a illuminated arrow (on the top) pointing to the right but you probably have tried all these settings anyway.
The international symbol for constant curve operation is a pump curve and a "arrow" for PP operation but the DAB seems to have these reversed if I am interpreting their manual correctly.

 

[Bobl]

Failing all else and before you try centralheatking's remedy you might just drain down the system and refill it very slowly and keep the d/stairs rad vents cracked open while doing so, just put a few old towels underneath to catch any water while running about.
I have a combined cold feed and vent and I had to carry out this procedure once when I drained down the whole system many years ago.

Even though air is the most likely culprit, you might look at your pump again. Your pump looks as if it is pumping downwards, just check that this is correct, the pump head orientation doesn,t really matter, just that the settings are "upside down" (or maybe its just the picture that's upside down). I'm just stating the obvious but also check that the pump isolating valves are opened and that it is vented via the brass vent/degassing screw. This pump has 9 settings, 3 constant curve and 6 proportional pressure settings, it appears that you have it on PP6 which a very high setting but if there is air in the system then it won,t shift it as the pump will just ramp down. I would suggest trying it on constant curve CS2 which because of the pump head orientation is the two top solid green LEDs illuminated and a illuminated arrow (on the top) pointing to the right but you probably have tried all these settings anyway.
The international symbol for constant curve operation is a pump curve and a "arrow" for PP operation but the DAB seems to have these reversed if I am interpreting their manual correctly.

Thanks for this, the rads are now all working. Apart from turning off the rads a turning them on again I have done nothing. However I did change the settings on the pump and perhaps that sorted it (I may have had it on the wrong setting). However, this was clearly not the initial problem - I will just have to wait to see if it happens again. Thank you to everyone who gave advice.

 

[John.g]

Glad to hear you are sorted out. If you don't mind, you might post a close up photo of your present pump setting while its running.