Help me understand my system? Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[supersadie]

Hi
Mystified by my own heating system!
I have a fortic supercal indirect combination tank on the first floor with a vertical pipe leading into the loft. There is no header tank in the loft. Have a fanned flue Ideal boiler. Is this an indirect vented system and if so, where is it getting its water from if no tank in loft?

Heating won't come on (boiler won't fire) unless water heating set to some on simultaneously. Is this wrong? If so, is it a wiring or valve issue?

BTW, all rads that are on are warm when the hot water comes on, even if the CH is not on.

Posting this altogether in case it's all relevant, apologies if this is poor etiquette. Can anyone give me an idea how the thing is put together?
Thank you kindly

[squaddie_plumber]

ok thats a combi cylinder, not a tank. the water supply for that is directly on top of the cylinder in the small cistern. you don't give much details on your boiler, it could be a combi or system boiler; hence no feed and expansion tank.
the problem you are having(but this depends on what type of boiler it is) sounds like a problem with the motorised valve (3 port), or valves, I would say the Heating motorised valve isn't opening fully and touching the little micro switch; which in turn tells the boiler to kick in. If you carefully open the switch cover (when boiler power is off!) then turn it on, turn heating on and try and look with a little mirror to see if the switch gets depressed by the arm of the brass lever as it slowly turns ( this is why it takes a few seconds for the boiler to fire after you turn heating/hot water on) please be careful as there are exposed live 240v connections there. you could try flicking the micro switch with an insulated screwdriver and get your partner to stand by the boiler to listen to it kick in.
I hope this helps a bit.

[supersadie]

Thanks for your advice. Perhaps it could be as simple as that. I'll investigate.

:)