Worcester 28si II hot water problem HELP!

[stantb]

Hi I have a 28si II that was installed 14 months ago and has suddenly become unreliable on the hot water side. The central heating seams to work fine but the hw starts hot for 5 secs then turns mildly warm and stays like this indefinetely, is there a valve that controls the water temp? could this be it or would it be the diverter valve? Thanks in advance if anyone can help

 

[COG]

You dont have a diverter valve so thats easy. A basic test is to turn off you CH timer turn off theCH dial on the front of the boiler and wait for any fan or pump overruns to stop, then have someone turn on a hot tap in another room if your flow turbine (spinning flow switch) is working then you will hear various clicks from relays and the demand should start if nothing happens then your flow turbine will probably be faulty to be sure leave the tap running for say 2 mins then turn on the CH to full at all switches if the heating comes on the flow turbine must be faulty as it should overide the ch and stop it comeing on when you run a hot tap.Simple to replace .If your competent.

 

[stantb]

Hi, thanks for the reply.
I tried that, when a tap is turned on there are clicks and whiring noises coming from the boiler (with the ch off) it just doesn't get hot (just warm) with the rotory switch at maximum. The ch however get nice and toasty.

 

[ChrisR]

Does the boiler light to (try to heat the water) or is it just residual heat you're getting, from when the heating was on? IN other words if you leave the tap on for say a minute does the water go completely cold?

 

[stantb]

yes the boiler does light so it is warming the water up slightly on the hw system but fully on the ch system

 

[COG]

If it fires on hot water but not enough it could be that the gas pressure is to low, but thats not very likely and reguires a corgi eng to check but test your flow rate at the taps on full it should be 9lt per min so find a jug and a stop watch.

 

[COG]

If it fires on hot water but not enough it could be that the gas pressure is to low, but thats not very likely and reguires a corgi eng to check but test your flow rate at the taps on full it should be 9lt per min so find a jug and a stop watch.

 

[COG]

My mistake that should be 10 lt per min at max flow.

 

[stantb]

Just thought i'd post a final reply, I sorted it out myself a couple of weeks ago. It was the turbine (flow switch) on the cold water inlet!

 

[AlanE]

"I sorted it out myself "????

Funny I thought Cog suggested checking flow switch in first post after your original question.

Alan