Worcester 28 CDi RSF HW fault

[PaulT]

Having a bit of a head scratching moment and would appreciate some advice. I've just been called out to a Worcester 28 CDi RSF, the problem is that boiler will not fire when there is a demand for hot water only, however, if the central heating is turned on for approx 10-15 minutes it will fire and provide hot water. It will continue to fire for hot water when a demand is created for about 10-15 minutes after the central heating has been turned off, but once the system cools it refuses to fire for hot water only. I initially thought the diverter valve was faulty (as did the last 3 GSR engineers that had looked at it). I followed the fault finding guide and whilst I was testing for continuity at ST16 (2 x pink wires) the boiler instantly fired for hot water when I connected the terminals. Now thinking there's a problem with the PCB but would appreciate your thoughts as the customer is an elderly lady and I don't want to replace an expensive PCB if you guys think the problem lies elsewhere. I'd really appreciate your opinions.

 

[Billy Bob Bob]

post your details to mr doberman that way we all know your GSR,you need 10 posts first,as what your asking is not directly safety related test the continuity of the dhw divertor flowswitch

 

[buckley plumb]

sometimes it can be cheaper to call worcester in on a one off fix price as pcb can be expensive.think about £220 for call and 3 major parts

 

[PaulT]

Thanks gas man much appreciated I will post my details to mr doberman once I hit the 10 posts mark.

 

[PaulT]

Thanks buckley plumb good point

 

[PaulT]

I just double checked the manufacturers instructions and it looks like the 2 pink wires at ST16 that I tested for continuity where for the DHW diverter and flow switch. As soon as I touched the terminals with the probes of my multi meter (with hot tap running) the boiler fired, as soon as I removed the probes it shut down again.

 

[Billy Bob Bob]

I just double checked the manufacturers instructions and it looks like the 2 pink wires at ST16 that I tested for continuity where for the DHW diverter and flow switch. As soon as I touched the terminals with the probes of my multi meter (with hot tap running) the boiler fired, as soon as I removed the probes it shut down again.

flow switch or divertor down by putting your meter in continuity and touching the 2 pink wires it becomes the flowswitch,is the plunger on the divertor lifting?

 

[PaulT]

It was providing hot water (no heat creeping up central heating flow) so I'm guessing it was lifting, I'm not at the property now so can't check though. Why do you think it would fire to meet the demand for hot water only whilst central heating was on or whilst boiler was still hot for a short period after central heating was turned off? Thanks for all the help so far.

 

[PaulT]

gas man your a star thanks a lot. I'll let you know how it goes.

 

[Billy Bob Bob]

now i have told you this take it on board because its being moved to the GSR only forum,i know your registerd but others may use this thread for wrong doing this thread will disappear in 5 seconds 5-4-3-2 gone

 

[PaulT]

now i have told you this take it on board because its being moved to the GSR only forum,i know your registerd but others may use this thread for wrong doing this thread will disappear in 5 seconds 5-4-3-2 gone

Totally understand, once again many thanks.