Condenser boiler and pump problem

dewsbury · Nov 26, 2008

Hi,
I am not a plumber as you will see !

3-storey house being heated.
I have a condenser boiler for my underfloor heating system.
(There is a pump in the boiler - perhaps there always is!).
The boiler then immediately feeds a separate grundfos pump (which is electrically independent of the boiler).

Here lies the problem!
Yesterday I noticed that the house was not as warm upstairs and realised that the independent pump was not turned on. When I switched the pump ON the boiler reacted by virtually shutting down!! The temperature of the boiler dropped to 10 degrees and the boiler generally stops producing hot water.

Question: Why does switching on the independent pump cause the boiler to die?

Excuse the lack of detail but it may mean something to somebody!

Mike Jackson · Nov 27, 2008

Without looking at the system it is not possible to diagnose a problem like this. With underfloor it's common to have two pumps. The one in the boiler runs a primary water circuit and the other circulates cooler mixed water round the underfloor circuit.

You're going to have to bite the bullet and get some in.

Mike

dewsbury · Nov 27, 2008

Thanks Mike,

I will get somebody in to look at it - again!

Unfortunately, the boiler people say it is not their fault and the underfloor heating people say it is the fault of the boiler people etc.

As you may gather there is some history associated with this problem.

Watch this space!

Thanks again.