Water hot - heating not switching on

[xxjinx]

Central heating working perfectly Friday evening.

I have my heating on constant and just control it by turning down the heating switch.

Turned up heating switch yesterday and nothing happened. Red light on in boiler cupboard which says heating on.

I have had no problems with water - still hot.

Boiler seems to be working perfectly as flame comes on when I presume heating water.

Any ideas - or should I stop stressing and call someone in - if it is something simple would prefer to try and solve as money very tight at the moment.

Thank you for any help

 

[tryitandsee]

The little 'motor' in the motorised three way valve has packed up. Easy to change, look in FAQs number 3.

 

[bengasman]

read announcement at top of forum called: "read this first"

 

[adam7]

The central heating system is 2 1/2 year old and until now have had no problems with it, typically warrenty ran out after 2 years and now having a problem!
The hot water is still working fine, although central heating is working sporadically, therefore discribing the system is difficult but here goes!

The heating system is an open vented with a cylinder for the hot water.
Problems started about 6 months ago when the central heating did not come on, we had a engineer called out but again typically the heating fully worked and therefore he couldn't diagnose any problems. Since them it's worked fine until a couple of weeks ago when we came home to find the house cold with no central heating working.

As the timer appeared to work and the room thermostat didn't have any effect, I presumed knowing little about central heating systems, that we may have a faulty stat. I purchased a sunvic 7501 www.sunvic.co.uk/tlx7501rt.html and pressuming I have wired this up correctly (2 live and 1 neutral wire - live to C, neutral to ON and second live to OFF, - i did try the live wires the other way but this blew the fuse on the timer switch).
This new stat had no effect and the central heating continues to not work on demand, while the hot water works fine. But the heating does work occasionally when I turn the Cylinder stat up and turn the heating off/on at the timer - but as I said this is very sporadic and doesn't work every time.

I then found this website and after reading many of the posts, in particular the FAQs sticky, I'm learning it may be a motorised valve problem.
However, the motorised valve on my system has 2 LEDs and both are lit?

Does the LEDs being lit have any significance and have I wired the new room stat correctly? Any further advice and checks I could do would be very much appreciated - before I call out an engineer.
Many thanks for reading my post.[/img]

 

[bengasman]

Chances are your original stat was fine and you have changed a perfectly fine Honeywell for a cheap piece of junk from sunvic, which you have wired up wrong; neutral ALWAYS goes to neutral.
Would you have an Ideal or a Potty by any chance?

 

[adam7]

Chances are your original stat was fine and you have changed a perfectly fine Honeywell for a cheap piece of junk from sunvic, which you have wired up wrong; neutral ALWAYS goes to neutral.

Previous stat was a Myson, and just bought a cheap stat as I wanted to check if this was the problem not to upgrade.

Can't understand if your trying to be helpful or sarcastic.

I only posted on this site for a bit of advice not for comments like

neutral ALWAYS goes to neutral

 

[adam7]

Rewired the sunvic stat after finding the following post on this forum; //www.diynot.com/forums/viewtopic.php?p=414252#414252

However, boiler still does not fire up for central heating, only firing up when hot water cylinder thermostat is turned up.

 

[xxjinx]

The little 'motor' in the motorised three way valve has packed up. Easy to change, look in FAQs number 3.

Many thanks 'tryitandsee' at least when telephoning someone stating problem and they come up - with the same answer fills me with far more confidence - thank you again.