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- 18 Oct 2021
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Hello Group,
I originally posted this a couple of months ago:-
https://www.diynot.com/diy/threads/...our-boiler-does-not-fire-up-on-demand.579594/
and I had some degree of success thanks to your kind help. I changed the jumpers on the controller to the correct setting and I also bled all the radiators throughout the house, and for several weeks I was getting heat on when I needed it.
Today I have largely been sitting in a cold house, even though the room thermostat is way up and calling for heat.
One thing I have noticed though is that if I gently turn up the hot water cylinder thermostat (this):-
then the boiler will fire up, radiators will come on and normal service is resumed. This has worked more than once.
What I think is happening is that the cylinder thermostat thinks there's already enough hot water in the system and is therefore doing nothing. When I turn it up a bit, it calls for more (hotter) water, signals the boiler to come on, and also triggers more (hotter) water to go through the radiators.
What I don't get is that it's not as if I have some "warm" water in the radiators. When they're not on, they are properly cold, it's seemingly "all or nothing". Therefore, I don't understand why the trigger to push hot water around the central heating system is not happening anyway even with a temp setting of (say) 50 degrees.
I can live with the minor inconvenience of adjusting the cylinder temperature but it would be nice not to have to do it. I'm keen also not to have to "ratchet" up the cylinder to hotter and hotter temperatures each time, as this would make my hot water way too hot to use.
Am interested to know, do these cylinder thermostats tend to fail this way after a time? Can they be replaced or are they integral to the cylinder?
Thoughts welcome and appreciated.
I originally posted this a couple of months ago:-
https://www.diynot.com/diy/threads/...our-boiler-does-not-fire-up-on-demand.579594/
and I had some degree of success thanks to your kind help. I changed the jumpers on the controller to the correct setting and I also bled all the radiators throughout the house, and for several weeks I was getting heat on when I needed it.
Today I have largely been sitting in a cold house, even though the room thermostat is way up and calling for heat.
One thing I have noticed though is that if I gently turn up the hot water cylinder thermostat (this):-
then the boiler will fire up, radiators will come on and normal service is resumed. This has worked more than once.
What I think is happening is that the cylinder thermostat thinks there's already enough hot water in the system and is therefore doing nothing. When I turn it up a bit, it calls for more (hotter) water, signals the boiler to come on, and also triggers more (hotter) water to go through the radiators.
What I don't get is that it's not as if I have some "warm" water in the radiators. When they're not on, they are properly cold, it's seemingly "all or nothing". Therefore, I don't understand why the trigger to push hot water around the central heating system is not happening anyway even with a temp setting of (say) 50 degrees.
I can live with the minor inconvenience of adjusting the cylinder temperature but it would be nice not to have to do it. I'm keen also not to have to "ratchet" up the cylinder to hotter and hotter temperatures each time, as this would make my hot water way too hot to use.
Am interested to know, do these cylinder thermostats tend to fail this way after a time? Can they be replaced or are they integral to the cylinder?
Thoughts welcome and appreciated.