Worcester Bosch 28 CDi

[Minder]

Hello

I have a Worcester Bosch 28 CDi boiler and have a recurring problem. The boiler works fine for hot water during the months where the central heating is not being used. But as soon as I switch the CH on, the DHW starts to play up. Last winter I had the unit serviced and flushed, but typically it would perform properly when the plumber was in the house. Getting the plumber to move in is not an option, so am I left with a lottery of replacement parts until it starts to work properly? Which parts could be causing the problem?

Many thanks.

 

[nickso]

what does play up mean?

doesnt work at all or hot/cold or intermittent operation?

 

[Minder]

When the CH is in use, the DHW doesn't work properly. Sometimes the hot tap can run cold from the moment it is turned on and no hot water comes through. Other times, the DHW will start but run to cold after about a minute. The problem is consistent with the CH being used. I have the CH turned off for the last two days and the demand for DHW is always met continuously.