Radiators working lovely, But No Hot Water?

[markymarkuk]

Any advise appreciated...
All my radiators upstairs and down all get hot, don't have the master bedroom one turned on (maybe this is an issue), but the Indirect Cylinder in the airing cupboard is cold, so too are the pipes leading in and out. I've checked the 2 tanks in the loft, they both have water in.

Any hints or tips on what to test or check would be good. thanks

btw its an old potterton boiler from 1970s, but works good as rads get hot!!

diagram of my system
//media.diynot.com/209000_208117_66208_76806473_thumb.jpg

tank in airing cupboard
//media.diynot.com/209000_208117_66210_63202706_thumb.jpg

 

[easyflow]

Sounds like a motorised valve packed up.

 

[markymarkuk]

The system has no motorised value. The system cannot be switched to Hot water and/or Heating... Old system from the 70s so when the boiler is turned on, it puts rads on and heats water, there is no option to switch between the two. But thanks for suggestion anyway.

 

[boabcelt]

Sounds to me like an air locked or blocked gravity coil in the cylinder.

 

[picasso]

Blocked cold feed ?

 

[MANDATE]

from the limited information, I would think you have a fully pumped system with two 2port valves. One for CH which is functioning ok and one for HW which is not functioning. When receiving power from the cylinder stat the valve should open and it would appear it does not in your case.
So either no power to valve, or more likely a faulty motor

 

[boabcelt]

from the limited information, I would think you have a fully pumped system with two 2port valves. One for CH which is functioning ok and one for HW which is not functioning. When receiving power from the cylinder stat the valve should open and it would appear it does not in your case.
So either no power to valve, or more likely a faulty motor

The op has put up a diagram showing a gravity system, and has confirmed there is no dhw motorised valve.

 

[markymarkuk]

Thanks for all the replies. Any way I can check for blocked cold feed or coil blockage - Alternatively, would it just be easier to replace the whole cylinder?

Thanks

 

[john4703]

I dealt with a fault like this some 25 years ago and it was a build up of sludge in the feed to the coil in the cylinder. I fixed it by draining the system, cutting the pipe and putting two hoses on the cut ends and flushing it through so all the muck went out through the hoses, I seem to remember one ran clear quickly and so I stopped that flow then let the other run until it was clear. Afterwards all it need was a compression fitting and a dose of anti-corrosion treatment

 

[markymarkuk]

thanks I'll give that a go