Hot water runs dry at the taps.

[jeremy hughes]

I drained down the water at my mother in laws to move a basin and radiator. Now the central heating seems to run fine, however the hot water to all the taps keeps running dry after only a minute or so.

What I do know is the copper cylinder in the airing cupboard is filling up, as water is reaching the drain valve before it enters the cylinder although this maybe at a slow rate as when the drain tap is fully opened the water comes out at a slow enough rate that you can easily stop it by pressing your finger over it so not sure if that is normal.

I did not touch the gate valve in the water supply from the water tank in the loft to the copper cylinder in the tank when I drained the system down, and have subsequently checked the tap and fron an initial inspection by turning this it appears to operate fine.

I did notice that the hot water overflow pipe did actually bend over and go below the water level in the water tank in the loft, pressume the ballcock need adjusting however I have lifted the pipe up enough so now it is not in the water as wondered if this was causing an air lock of sort and in doing do pressuring the cylinder in the airing cupboard, however this has not cured the problem.

Any help would be very much appreciated.

Thanks

Jeremy

 

[seco services]

sounds like you may have an airlock in the pipework out of the top of the cylinder.

 

[twgas]

or even in the cold feed to the cylinder, or both

 

[jeremy hughes]

Thanks for the speedy replies, and I am of this opinion too, however how can I get rid of these airlocks?

 

[seco services]

have you a mixer tap in the bathroom that has cold mains feed ?
you can use the cold to force the hot backwards forcing the air out if airlocked at top of cylinder

 

[jeremy hughes]

have you a mixer tap in the bathroom that has cold mains feed ?
you can use the cold to force the hot backwards forcing the air out if airlocked at top of cylinder

Yes I do, also when doing this should I leave the hot tap on the sink open to see if this helps/cures the problem, or should all the hot taps be in their closed positions? I assume you turn the hot on the bath mixer tap when doing this!?!?

 

[twgas]

try it first with other taps off, then try opening other taps and repeating as required

 

[seco services]

only open the mixer hot tap block the spout with hand or rag turn on the mains cold and that will push the hot backwards releasing any air up vent.
try for a min or two then shut the cold and the hot should run on its own and leave running for a while and then try your basin tap etc to get any air out of cylinder.

make sure the cylinder is all full first. which it should be by now.