A slight twist on a common problem...

[hooper]

I have an Ideal mini C24 boiler installed and am having a problem with the heating. I have searched and searched about this but have only found info regarding a similar but opposite problem to mine....

The central heating timer will switch on and a noise comes from the boiler, not sure if its the fan or pump, but it never actually fires therefore the heating doesn't come on. I can then go and turn on a hot tap which fires the boiler, then turn the tap off and the heating stays on! What i have started doing is leaving the heating ON all day and regulate it with the thermostat. Now, when the thermostat requires the boiler to come back on again it usually does, although sometimes it doesn't.

Now, i'm no expert, but logically (in my thoughts anyway!) it sounds like something to do with the diverter (or something connected to it). This is how i see it....

1. Heating wants to come on, so diverter needs to be in CH only position. It can't so boiler doesn't fire.

2. Turn the hot tap on and the valve moves to CH and DHW enabling both to work.

3. Turn hot tap off and valve either moves to CH only or stays at CH and DHW.

Does that make sense or have i got it completely wrong? Any help would be massively appreciated.

 

[Agile]

Completely wrong I expect!

You should be concentrating on the system flow switch!

I expect it is not quite making on CH but does make on DHW and stays made after DHW.

You can take the switch off and see how far the pin projects on DHW and on CH when they are each activated independently.

There is either a too low resistance in the heating circuit because the rad lockshields have been opened fully or too far OR the pump may have the eye of the impeller partially blocked with dirt OR the ports to the flow switch or the diaphragm may have a problem although thats far less likely.

Tony

 

[hooper]

thanks, and as usual i was a barn door off!

 

[gas4you]

These have a ch diaphragm as well, rare occurence, but this could have perished and weakened.