Expansion tank feed tap open or closed?

[alpinejim]

In response to another topic i started someone wrote that the cold feed FROM the expansion tank to the CH system should not be closed.

I have just got my system up and running again after draining it completely, and during this time i found the tap on the feed from the expansion tank was closed and jammed solid. I replaced this and cleaned the expansion tank - it was thick with orange gue, lord knows how long it had been like this (i'm new to this house by the way).

Upon filling the system and getting the heat going i found that upstairs rads were ok but downstairs were cold. I closed the tap from the expansion tank and downstairs started to warm up.

Can anyone explain what state the tap should be in, open or closed?

I am guessing that when open there is enough pressure to defeat the power of the pump (which is on level 1 of 3) therefore blocking the flow of hot water round the system. I have only noticed the downstairs rads going cold but maybe after enough time the upstairs rads will go cold as well.

Maybe someone can clarify this and advise as to whether to leave the valve closed or open it and turn up the pump?

Many thanks.

 

[oilman]

The tap should be open.

The pressure exerted by the water will not affect the load on the pump as the pump is only circulating water, and it doesn't have to lift water.

Try closing the lockshield valves on the upstairs radiators, as it sounds like the system needs balancing.