Boiler Not heating water to correct temperature

[SquiddlyDiddly]

We have a Worcester CDi Conventional Condensing Boiler

My central heating and hot water system was changed a couple of years ago when I needed a new boiler.

Previously, the system was pumped CH and gravity HW.

The plumber that installed the new conventional condensing boiler gave me a fully pumped S plan system. However, it was clear that he was not familiar with the system and admitted he usually only installed combination boilers.

The system never worked properly and needed a fair amount of manual intervention although it would provide the heat to the radiators and hot water tank.

Over the last couple of years I have eradicated most of the problems which included incorrect electrics and an incorrectly placed vent pipe - left over from the gravity system..

The final thing to do was to reverse the pump as the installer had put it in upside down so it pumped into the return of the bolier rather that out to the motorized valves. This I did yesterday.

Since righting the pump I cannot get the boiler to heat the water up to temperature. The boiler comes on, fires for 30 seconds or so and then switches off. It then comes back on after a minute or so and switches off again. The temerature of the water is not much better than lukewarm with the temperature showing as 36C on the boiler.

The motorized valves open correctly and the pump comes on so the problem must be something to do with the boiler. I have also blead all the radiators and the Hot Water circuit too.

Has anyone got any ideas? I expect you will say I need to get the man out and now that I have solved all the other problems I can do that but was just looking for an interim solution.

 

[Agile]

Sounds like you may have a circulation problem as well as a boiler problem.

Why dont you just get a competent engineer like most people?

It seems clear to me that you knew the installer was very limited in his capabilities but still used him. Was he very cheap indeed?

Tony

 

[Dan Robinson]

So, the boiler worked.

You changed the pump around.

The boiler doesn't work.


And you think it's rt he boiler at fault?

 

[SquiddlyDiddly]

To Tony,

The original installer was recommended and I didn't know he had limited knowledge until he was into the job installing the new boiler.

My concerns are that how do I know whether the next plumber I consult with doesn't also have limitations.

To Dan,

I question the boiler as the pump and motorized valves are working. And to be fair the boiler is working just not getting up to correct temperature.

Anyway I will bite the bullet and call in another plumber.

Andy

 

[oldbuffer]

As you used to have a gravity hot water system it is possible there is a non return valve installed to prevent gravity heating of the radiators.

If this is the case, once you have changed the direction of water circulation this valve will always be forced closed, restricting the flow and causing the boiler to overheat very quickly.

A lot of older systems were installed with the pump on the return rather than flow, and, subject to correct installation of feed and expansion pipe(s), there's not much wrong with this arrangement.

 

[SquiddlyDiddly]

Oldbuffer your suggestion is possible but if that was the case, I wouldn't get any flow of water through the radiators and I do. It is just that it is lukewarm.

I would agree that the boiler is shutting off because it has got up to temperature but it doen't show that on the temperature indicator which stays at about 36-38C.

Is it possible that the condensate pipe is blocked and so the boiler effectively shuts down?

But that would be coincidence as this has only really occurred since the pump was reversed.

Oh well I will have another look at it tonight when I get home from work and try and find a relaible plumber in the morning.

Andy

 

[Agile]

All very well but this boiler is only getting up to 36 C.

I think he needs a heating engineer!

Tony