Worcester 40 cdi combi.

[John.B]

Just fitted a Worcester 40 cdi combi today and was doing usual installer checks for commisioning. Noticed that heating was still on even though room stat was off. Checked switched live on honeywell stat (240v) with neon tester and showed dead. Checked live return on boiler and again showed dead. So I tried testing with multimeter and was getting 24 volts returning from room stat to boiler. Turn up the boiler stat and the boiler fires up. Seems the boiler is responding with a return of 24 volts. Have Worcester got a problem as one of their engineers told me that early Ri models were experiencing problems when fitted in conjunction with Honeywell y-plans. It was too late to call Worcester as it was 6.30 and I was wondering if anybody else has had any similar problems.

 

[John.B]

Spoke to Worcester and it would seem I have answered my own question in that the latest Worcester boilers are sensitive to low voltage returns. The cure is to install a 0.47 microfarin capacitor between LS and LR on the terminal block. This blocks out voltage leakage from cables and will hopefully on monday cure my boiler problem. I will post a reply to let you know.

 

[Paul Barker]

That would be 0.47 microfarad, or 470 nanofarad (or nuf). Mostly these are ac rated but make sure you do get ac rated ones. There are special quality ones made as components in mains supressors X or Y rated. Either would do you.

Wha the heck if you have trouble I could post you one.

 

[John.B]

Thanks for your kind offer Paul, I have already been given the correct Worcester part by an engineer a couple of months ago for the Ri but could n't find it in the van last night as it was pitch black and torch was failing. As usually happens, went to my van this morning, first thing I picked out of the racks was the capacitor. I'm sure my vans got a poltergiest! Going to stock this part from now on as this is obviosly going to happen again. Apparently the same part that they fit to the Ri to stop the Honeywell problem occurring will do the job on the system boiler as well. It now looks like it will do the cdi's. Sorry about my spelling but I was only repeating the information from the Worcester technical guy and he was unsure of it's spelling as well. Found out from another fellow installer today that the latest instructions are starting to mention the problem and it's cure. Obviously my boiler has been an earlier built example and been stood in merchants for a while. Looks like Worcester pcb's do not require much voltage to fire up the boiler. Last night I thought the boiler had a poltergiest as well, kept waking up thinking about the problem, glad to say after speaking with tech help that I was on the right track with my thoughts after all. You would think Worcester would send out a letter telling us to watch out for this possible problem, after all they have our details on their mailing lists from the business club. Once again thanks Paul.