worcester 28i rsf. hot water isusse !

[plumbbobshan]

hello ,
Boiler worcester 28i has gone off. Get to the job and do the checks aps and fan , fan goosed and seized solid , fit a new fan. All ok leave the job .
Two days later she phones the boiler is working fine(heating) but, NO hot water. The thermostat had triped out, so i reset it and ran a bath of water. All ok and left the job.
Next day same again, so put in a new thermostat, still tripping out .
Then changed the DHW flow sensor (thermistor) still the same results after running hot for 10/15 sec then tripping out !!!!!!!! .
ANY IDEAS LADS

 

[wnjswozo]

you need a multimeter,mi and run throu fault finding chart,my be aps,check tubes not crossed,
always the way,straight forward job ,turns into nightmare

 

[plumbbobshan]

not got a book for the boiler, but will look to get one . It works fine on the heating fine, runs all day long !!! so the aps is ok !

 

[clydey]

its not on the wb site only the user manual
pm me for a copy
cheers

 

[clydey]

book not on wb site - only user manual pm me your e-mail address for a copy
cheers

 

[clydey]

plumbbobshan i cannot get into my e-mails until i reboot my computer but running kaspersky for a facebook bug as i opened; ive just seen whos checking out which is a malware program
as soon as i boot down ( about 6 hours) i will send manual
sent it yesterday to another op scan down threads need 28i rsf
cheers

 

[plumbbobshan]

ok no probs cheers.

 

[gasmarc]

is it over heating and tripping out ?

 

[plumbbobshan]

yes , heating perfect , 10/15 sec's of hot water demand and it trips out !!!!!!

 

[RoryD]

Sounds like a blockage on DHW side of things

 

[plumbbobshan]

i have checked for blockages in dhw side pipework from inlet to flowswitch to heat ex to dhw outlet and all are clear. all the readings on the elec side of things are ok . boiler in a million bits now and the heat exchanger is being descaled as a last resort . i will post results later.

 

[plumbbobshan]

well it descaled and rebuilt , all working fine . stll not convinced it is the end of the matter !!! or any being to harsh on myself. i dont feel i have done anything other than strip down and rebuild a combi !!!!
BIG THANKS to wnjswozo, clydey, gasmarc and roryd .

 

[wnjswozo]

hope its ok ,i,ve been there,stripping down boilers,job turns into a mare,so your not alone mate,all part of fun

 

[clydey]

treat yourself to a pint at least if its a callback you know what its not
well done

 

[Eddie Charlton]

Gas rate with hot water on?burner pressure? (full as with hot water)could there be a partial blockage in the main heat exchanger? not enough to affect heating but could affect primary for hot water?

 

[plumbbobshan]

just having a pint ;-)and the call came,---- it doing the same again!

gas rate with hot water on ? Burner pressure ? why would these change????? it was all ok till i changed the fan!
as for blockage not a chance, descaled and hose pipe attached ,clear as a bell .
at my wits end now HELP!