Central heating - no hot water

[peterpjr40]

We have a Baxi back boiler running the central heating and providing hot water to a cylinder. Yesterday I bled the radiators and got some air out of most of them. Now the radiators heat up but the tank doesn't. Have I caused this? If not anyone got any ideas of what I should be investigating?

 

[chrishutt]

Check the CH feed tank (small tank in roof space?). It may be empty of water (stuck float valve).

 

[andsam]

Or the dreaded blocked cold feed.

 

[bobw1956]

Try bleeding air from the manual air bleed valve at the hot water cylinder

 

[peterpjr40]

Thanks for quick replies. The header tank is working ok so it's not that.

"Dreaded blocked cold feed". Can you tell me more please.


Bleed valve on hot water cylinder. I'll have a look for that, didn't know such a thing existed.

Thanks again everyone.

 

[andsam]

This answer depends on the type of system you have. I am assuming it is gravity hot water and pumped heating. Where your cylinder(tank) is you will have at one side, 2 pipes that enter the cylinder one higher than the other. Sometimes the cold feed that comes from the bottom of the expansion joins the system at these points (normaly 15mm pipe) If it is a blocked cold feed or there is a partial blockage it can be found by placing a magnet near the connection of the cold feed to the system. If the magnet is pulled towards the pipe it is possible there is a blockage.

You can either cut the pipe and remove the blockage or back fill the system by filling the sytem at a different ,point for eg. open vent.

 

[peterpjr40]

Thanks for that Andsam. I will do some further investigation tomorrow. As far as I know the system is as you describe "gravity hot water and pumped heating".

Had a quick look for a bleed valve on the cylinder with no luck. There is just the immersion heater to one side and a big pipe coming out of the top of the cylinder.

May be of interest, the immersion heater works fine!

 

[peterpjr40]

Done some more investigation.

The magnet didn't show anything - I don't pretend to understand the logic of this test but if you told me to stand on my head while doing it I probably would .

The bathroom radiator warms up when the immersion heater is on.

The bathroom radiator keeps bleeding a bit more air when I try it, but I never get any trickle of water. With the heating on this rad seems perfectly ok.

Any other suggestions please?

Thanks for all advice so far.

Peter

 

[peterpjr40]

Success! The system is working fine now. I have spent the last few days bleeding radiators, for some reason two upstairs wouldn't fully bleed. Then this afternoon I tried again and they all fully bled, the hot water is working again.

Thanks everyone for the advice given.

Peter