Heating only working when Hot Water Required Danfoss FP75

[M Mannas]

I have a Danfoss 75 controller for Heating and Hot water.

The water works fine but the heating only works if hot water is also requested and required.
What I mean by this is first thing in the morning if we have not used hot water the night before the tank is full therefore hot water does not come on. Even though I have set the heating to come on it does not. The heating will however come on once I use the shower or run hot water as then the systems say it needs more and the bolier run also kicking in the heating.

The problem is that if on a very cold day I have enough HW but want heating it comes on for a couple of seconds then goes off. I can run a bit of HW to get it to run but as soon as it is back up to temp/level it trips out even though the house is still cold.

 

[Prof.plumb]

What boiler have you got?

 

[M Mannas]

Sorry its a
Ideal Classic LXFF & FF Fanned flue gas boiler
Boiler size FF270

 

[Prof.plumb]

This may be down to the way in which the system is wired/designed. How many motorised valves if any are in the airing cupboard?

 

[M Mannas]

There are two

One is a Honey well f-8

The other is a Barlo 2PV-2.

Both seem to have switches on the back of them

 

[Prof.plumb]

ok. And you say that the heating will only come on when the how water is required?

 

[M Mannas]

Yes thats correct.
I can turn the CH on only when HW is required but as soon as there is enough HW the CH goes off even though the house is cold.

If left on timed the heating will not come back on until water is also required.

I can get the CH back on but only by running the HW again.

turning both CH and HW to on constantly only works if HW is required and again cuts off.

If i manually try to turn CH on I can hear the boiler start then go back off.

 

[alok]

I have the same problem with a Potterton Netaheat Electronic boiler. It seems to have 2 of these synchro valve boxes and I had one replaced but this does not seem to help.. Any ideas anyine ??

I have set them both to manual and this still does not work.

 

[alok]

Has anyone have any odeas to why the Heating does not work if the hot water is not being heated. Any help/suggestions would be welcome..

Also, I have a feeling that there may be some sludge in the system as some of the radiators are not coming on.. could this be the course.. should I be looking to get a power flush done ??

Thanks