Central heating fine but no hot water after fitting new rad

[pootie]

Hi

We recently had a plumber round to fit a new radiator. He drained the central heating system to do so (though not by doing anything with the header tank as I have read in a few FAQs - he turned the mains supply off instead). Anyway - the central heating is now working fine. However we have had no hot water since he left - a couple of days now. We did not realise this for a while since there was a full tank of water when he finished and when this ran out we each thought the other was using up all the hot water. The pipes leading to the hot water tank are not hot either. The boiler & system are pretty old (maybe the wrong side of 20 years old).

I am trying to contact the plumber but there is no answer so I thought I would try here in case it is a simple matter.

Please let me know if I need to provide more details.

 

[weareleeds]

If it is a gravity system check to see if header tank is full if fully pumped see if there are any air vents on circs to cylinder as you probably have air in dhw circ pipes

 

[pootie]

Thanks for replying weareleeds

I cannot see any vents. There is a large bolt head on the top of the cylinder that is marked where it has been opened previously. There is also a valve on the pipe leading into the top of the cylinder. Nothing else that I can spot.

 

[Danielh1664]

If the system is over 20 years old there may be a blockage somewhere along the way.
Check the basics such as
1. On the mains water pipe that feeds the header tank there should be a isolation value, check it is open.
2. Limescale build up can cause real problems with the gate valves (I have just had the problem myself) where if closed and then reopened the shaft can shear off from the gate itself and cause the gate to stay closed. This is usually easy to check by rotating the wheel anti-clockwise until fully open and if it stops valve should be fine, if continues rotating with little resistance - sheared off. Don't apply too much pressure when testing as you may cause the problem yourself!
3. Ball valve - Is it being held closed to prevent header tank fill?

Basic stuff i know - but may save some money

 

[sime10]

If you have a facility on your timeswitch turn it on to hotwater only if you get a loud banging noise give us another shout

 

[sime10]

If the system is over 20 years old there may be a blockage somewhere along the way.
Check the basics such as
1. On the mains water pipe that feeds the header tank there should be a isolation value, check it is open.
2. Limescale build up can cause real problems with the gate valves (I have just had the problem myself) where if closed and then reopened the shaft can shear off from the gate itself and cause the gate to stay closed. This is usually easy to check by rotating the wheel anti-clockwise until fully open and if it stops valve should be fine, if continues rotating with little resistance - sheared off. Don't apply too much pressure when testing as you may cause the problem yourself!
3. Ball valve - Is it being held closed to prevent header tank fill?

Basic stuff i know - but may save some money

I think they have got water but its not hot

Got heating so header tank is ok

Basic stuff I know but may not complicate matters

 

[pootie]

Thanks guys.

Header tank is full and refills & we have a good flow of cold water through all hot taps so does that cover Daniel's points 1 & 3? I think the gate valve is ok but I will double check.

I will try re hotwater only on the time switch. We have had some banging last two days in any case as it happens.

Cheers

 

[pootie]

Thanks for your help guys.

It turned out it was air in the system. The plumber came round eventually. There is no blead valve so he "cracked" the joint to release the air and we now have hot water.

We initially had some joy just setting the thermostat to hot water only (some gurgling and a little hot water) but it did not fully clear. Apparently it is a gravity system which is "very old fashioned".

Thank you again for your help.