Room stat turns on pump but not boiler

[Jonks]

Hi guys

I'm afraid this is the latest chapter on my plumbing (see my posts in July). Briefly, plumber managed to fuse various bits and changed wiring but didn't sort it out.

All other DHW parts work but room stat turns on pump but not boiler. Temporary fix by electrician means I can switch it on manually via zone valve wiring. No good long term because CH isn't now managed by timer or room stat.

I have C plan (gravity DHW and pumped CH) but must have been modified originally. Zone valve only has 5 wires, ie not white live to room stat. Had always worked - must have been linked in programmer. Recently found stray orange wire discarded by plumber - must be reason for problem. I have always been able to run systems separately. Turning up room stat used to immediately fire boiler and start pump. (The pump did not run unless the CH was on.)

Question is can I link something in programmer so room stat will fire boiler as well as pump? Programmer is Potterton EP2000/3000 and I have installer's guide/wiring diagrams.

I've had various plumbers and electricians out but they give up and want to rewire everything. I think the simple link would work (it must have done for the last 20 years) but not sure where to put it!

Any help appreciated!!

 

[gas4you]

What circuit is the zone valve controlling? I take it is the DHW.

 

[ChrisR]

http://content.honeywell.com/uk/homes/Catalogue/Sundial Plans/3.1 C Plan.pdf

 

[Terrywookfit]

Do you have a 28mm valve with c/o contacts??

n/o goes to perm live

common feeds boiler

n/c feeds pump

If not you need to install a relay !!

 

[Jonks]

Hi Dave and Chris R
Yes the zone valve is managing the hot water and it's working OK. It's a replacement one and I know from the diagrams (yes I had these Chris but thanks) that it should have been the 6-wire version but obviously never was.

 

[Jonks]

Do you have a 28mm valve with c/o contacts??

n/o goes to perm live

common feeds boiler

n/c feeds pump

If not you need to install a relay !!

No! The 28mm pipe has been reduced to 22mm. The zone valve responds to the cyl stat only. There is a junction box nearby but with only 5 wires, so it must have always been like this. (As I said in a previous post - I'm blaming the ex!) I'm not an electrician or plumber but I'm beginning to understand quite a lot.