No hot water but heating works fine

[stufft]

Over the past day or so I have had a problem with my hot water. I have a stelrad Ideal Mexico RS55 slimline boiler (gas), hot water tank and 6 radiators with thermostatic valves.

The problem being that the hot water is not heating up, I get luke warm water coming out the tap but the radiators are working fine. I tried switching off the heating and just have the hot water on, this resulted in a very slight increase in temp but it's still not hot.

Any ideas what could be wrong and do I need a plumber/heating engineer or is there a simple fix?

Stu

 

[andsam]

Could be a few things.
Firstly on the flow and return pipes to the cylinder there is normaly a bleed valve on a length of pipe 6 to 12 inchs long try bleeding this.
secondly if the system cannot be bled, It could be an empty c/h header tank or blocked cold feed.

 

[stufft]

There is no sign of a bleed valve on any of the pipes leading to the cylinder. There is a header tank but it has plenty water in it and the ball valve appears to be working fine.

I think I've narrowed it down to a stuck 3-way motorised valve but I have yet to locate it. It's possibly under the kitchen floor (laminate). Here goes lifting some of it.

 

[andsam]

This will all depend on the type of system you have. I was thinking you had gravity hot water and pumped heating. If you have a 3 port valve and it fails, normaly it will give dhw and no rads ( I could be wrong ).You could have 2 zone valves and one of these could be faulty.

 

[stufft]

I lifted some flooring in the kitchen and found a motorised 2 port valve whicj I think controls the flow to the rads. This may be sticking, I gave it a gentle thunk with a hammer to see if that freed it and am now waiting to see if it worked

 

[andsam]

look for the manual over ride on the side ,its a little metal arm that you can lock in the open position.

 

[stufft]

The motorised valve was working fine. Traced the problem to a blockage in the hot water circuit. Switched heating off but kept water on. Increased the pump power to MAX and that blew through the obstruction and it's all working fine now. In fact better than before.