New boiler installed - rads hot downstairs cold upstairs

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Hi all

had a new boiler installed during the week and converted from an old gravity hot water system with a circulating pump on the return converted to a Y plan system. To reduce the costs I've done the pipe work and the plumber will be back to check everything over.

Radiators upstairs and downstairs bled. Boiler fires and radiators downstairs get hot, but radiators upstairs remain cold. When turning the hot water on, a big gurgle of air went through the cylinder.

I think there is air in the system causing the upstairs rads to be cold even though they are full of water. The house has been extended twice with pipe work added on and added on.

The plumber will be back tomorrow to check everything, just need to get the rads upstairs heating.

I was planning on shutting down the rads downstairs and forcing the flow upstairs and seeing if that had any effect. The other plan was to drain the system, re fill it and see if that had any effect. Finally I was thinking of back filling the system.

Anything else I could try?
Tks
 
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Anti gravity valve left in position possibly ? Worth trying what you suggest first though as it might just need balancing properly. Is the pump up or downstairs ?
 
Assuming no anti-gravity and pipework OK, most likely to be airlock. I think balancing less probable as usually it's the downstairs rads that usually suffer more in this case.

Try the suggestions that you have made whilst also temporarily turning pump speed up to max. Should shift any airlocks. If not, backfill with hose to lowest drain-off point.
 
Thanks

Pump is downstairs and is fitted before the 3 port on the flow. Originally the CH was pumped, and strangely the gravity HW also had a pump which was wired into a cylinder stat and a 3 pin plug. I guess this was done as the run from the original boiler was lengthy and to aid a rapid recovery. No original roomstat either so everything was run off the boiler stat.

Any ideas where a anti gravity valve would be? Seems strange as the system worked fine on the pumped CH, but now doesn't. I'm still hoping for an airlock somewhere :D
 
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An anti-gravity or featherlight valve will be fitted on a vertical pipe from boiler to radiators. I don't think that it is likely to be your problem. The airlock is favourite.

What happened when you turned the working rads off?
 
Circulating pump turned up to 3, hot rads downstairs balanced and air bled from the rads upstairs! All up and working now after the airlock was removed!

Thanks for the help
 

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