Boiler - Hot water problems

[Moonmaiden]

I have been having problems with my Ravenheat CSI 85T boiler for some time... boiler cycling on/off when running DHW.

First fix (about a year ago) - replaced both thermistors.... seemed to do the trick for a while

Then it started all over again.... only worse... and suffered tepid-cold-tepid-cold showers all summer... replaced thermistors again.... no better.....

Second fix (last week) replaced heat exchanger and diverter valve (bathroom radiator was also getting warm when hot water was on) and... great celebrations.... I had my first, full power, HOT shower for months!!

This lasted about a week.... but it's now back up to it's old tricks again... on for 20 seconds.... off for 20 seconds....

Any ideas where to look next...?

 

[Youllneverguess]

What was wrong with the heat exchanger?

Was it full of crud?

If so, then so is your new one now.

 

[Moonmaiden]

What was wrong with the heat exchanger?

Was it full of crud?

If so, then so is your new one now.

Surely can't be crudded up in just a week?

 

[Servotech]

I have been having problems with my Ravenheat CSI 85T boiler for some time... boiler cycling on/off when running DHW.

First fix (about a year ago) - replaced both thermistors.... seemed to do the trick for a while

Then it started all over again.... only worse... and suffered tepid-cold-tepid-cold showers all summer... replaced thermistors again.... no better.....

Second fix (last week) replaced heat exchanger and diverter valve (bathroom radiator was also getting warm when hot water was on) and... great celebrations.... I had my first, full power, HOT shower for months!!

This lasted about a week.... but it's now back up to it's old tricks again... on for 20 seconds.... off for 20 seconds....

Any ideas where to look next...?

1. Try removing the purple wire off the gas valve and run the hot tap.
2. If the boiler stays on with a low flame put the purple wire back.
3. If the flame then goes out it's probally the callibation of the gas valve that needs re-setting.
servotech,

 

[Moonmaiden]

Thanks for the replies.....

Went and had a little play and it turned out to be the CH thermistor... again!!

Think I need to buy me a box load of spares... seems he likes to eat them!!! (fortunately had a few old ones lying about.... usually replace both of them so chances were that one of the old ones would be alive!)

See how long this fix lasts....!!!!