CH not coming on, but HW is fine


Postby diyjunky » Sat Oct 03, 2009 10:11 am

Hi all,

I've just come back from holiday and now the weather is turning decided to stick my CH on for a while. Unfortunately, even though my HW is fine, the CH refuses to come on. I haven't used the heating since around early May but it was working fine at the time.

I have a wireless thermostat (British Gas T4RF) connected to a WR1 receiver which is in turn connected to a Honeywell ST9400C programmer:

[IMG]http://i38.tinypic.com/beiil4.jpg[/IMG]


Thermostat appears to be working fine, and the wireless receiver successfully receives signal and in turn the "ON" LED light comes on to call for heat.

I've got the programmer set to constant for both CH and HW right now to try and eliminate the unit as the issue.

It's here that it goes a bit pear shaped, with the WR1 showing a call for heat (ON) the boiler fails to ignite, but I'm almost certain that the problem lies with the valve. I have two two-way Honeywell valves, left one for HW and right one for CH:

[IMG]http://i34.tinypic.com/104ql36.jpg[/IMG]

The only difference between the two is that the lever on the left is slack when the HW is on, the lever on the right valve (circled in red) is constantly stiff.

I have manually pushed the lever over to the left (opening the valve) and held it - at which point the rads started to heat up.

I'm no brain surgeon but I presume this might indicate that the electronic valve is broken perhaps? is there any way I can test this to make sure thats the case or are my above steps sufficent to diagnose?

My plumber can't come out until Monday so I just thought I'd check if there's anything I can do beforehand.

Thanks.
diyjunky
Rank: Labourer
Progress to next rank:
25%
Posts: 2
Joined: Sat Oct 03, 2009 9:42 am

Sponsor

Simply Build It

Postby diyjunky » Sat Oct 03, 2009 5:12 pm

Not sure why the images aren't working :? guess you'll need to cut and paste the image URLs if you want to see them.
diyjunky
Rank: Labourer
Progress to next rank:
25%
Posts: 2
Joined: Sat Oct 03, 2009 9:42 am

Postby plumbbob » Sat Oct 03, 2009 8:25 pm

Switch everything off at the main switch and compare the two levers on the valves. Obviously they should both now feel identical. Are they?

If the feel of the gears is the same for each, there is little more you can do to identify the problem without electrical test equipment. As I see it, everything you have explained and done is correct and the heating should be on.

If you need the heating on whilst waiting for the repair, the lever can be hooked in a slot at the end of it's travel keeping the heat in the "on" position.
plumbbob
Rank: Project Manager
Posts: 1873
Joined: Wed May 07, 2008 9:59 pm

Display posts from previous
Sort by
Order by



  • DIY How to Project Guides

  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!



 


  • Related Topics