Worcester Bosh 24i (RSF)

[fuzzy]

Got this off a mate, any ideas?

Worcester Bosh 24i (RSF)
This boiler when switched on stays on for approximately seven minutes then shuts itself off.
After about eleven minutes it starts up again and then cuts off again after about another seven minutes.
When the boiler is on some heat comes into the radiators and a small amount of hot water is produced.
No constant hot water is produced.


Its quite far away so i dont want to go and look at it but any advice would help him

 

[mike_s]

Pretty sure it's a crossflow heat exchanger and they have a manual overheat reset button on top of case?
So if its resetting itself maybe not overheating but cycling due to a water or gas supply issue?
It could just be blocked up and cycling as per usual thinking it is reaching temperature.
I could be talking nonesense, they're just my thoughts of the top of my head.I'd speak to Worcester Technical as they are very good but they'll probs say it could be anything until you test all the sensors.

 

[Billy Bob Bob]

as above if it has a manual o/h stat buy i presume you would have said if its being reset tell your mate to check the resistance of the ch thermistor its about 11k at cold if its the boiler i am thinking of take a look at the aps/venturies/y piece hose connector

 

[gasmarc]

it could be a gas issue more so than venturi but have had a part melted APS and that plastic tee piece now that was a learning curve :17:I have had similar but stuffed if i can remember at the minute

 

[diamondgas]

Realy need a bit more info fuzzy ... but you're looking for something that's conected to both heating and water and it sounds like a temp sensor from what you've posted ... Best guess

 

[gasmarc]

it could be the fan

 

[Puddle]

Sounds like going to low flame only,possible faulty thermistors,check resistances as said,also not uncommon for diverter valves due to age,not switching fully to heating mode,causing restriction maybe

 

[gasmarc]

that could explain not getting either fully by the sounds of it which could signify 2 faults perhaps

 

[Kev the gas]

Ive had this before.

The over heat stat wet pocket thermostat will be blocked with sludge/crap ect.

Before draining down to prove,

Remove the wet pocket wiring and link into the dry pocket stat ( ie take out of the circuit)

Rerun the boiler and check correct operation.

If all works well, drain system and boiler remove wet pocket overheat thermostat and clear of all sludge/crap.

Reassemble and fill and test.

Sell them a Magnaclean !!

Kev.

 

[gasmarc]

is it not a manual reset stat on these i thought?

 

[Kev the gas]

"After about eleven minutes it starts up again and then cuts off again after about another seven minutes.
When the boiler is on some heat comes into the radiators and a small amount of hot water is produced.
No constant hot water is produced."

 

[gasmarc]

he does not mention having to reset it or have i missed it lol

 

[Billy Bob Bob]

its confusing with worcester models they have similar sounding names

 

[Kev the gas]

This model has a manual reset but this problem is not overheating this thermostat.

It is resetting itself.

I cant name exact thermostat names at the mo, but the thermostats in question are at the top right side of heat exchanger
accessible inside the combustion casing.

 

[gasmarc]

Ah that makes sense 8m I thought you were talking about the manual reset one , Now that would be very satisfying sussing that one , I suppose a quick continuity test would prove that , happy days nice one

 

[Kev the gas]

Got this off a mate, any ideas?

Worcester Bosh 24i (RSF)
This boiler when switched on stays on for approximately seven minutes then shuts itself off.
After about eleven minutes it starts up again and then cuts off again after about another seven minutes.
When the boiler is on some heat comes into the radiators and a small amount of hot water is produced.
No constant hot water is produced.


Its quite far away so i dont want to go and look at it but any advice would help him

Fuzzy

Tell your friend to buy himself a new watch as well.

I spent half a morning timing the above problems and promise it was 5 mins running before shutting off :winkiss:

 

[fuzzy]

thanks guys, my mates not gsr so wont be doing work himself, he asked me for advice but im not very experienced in fault finding on boilers although ive been corgi and gsr for years i used to pass faults on most the time to a mate who did that full time, hes no longer doing it though, hence asking you guys

Thought of all the usual like fan, venturi etc but tbh never heard of wet pocket dry pocket stats? can someone help me here please, i wouldnt know where to look. If i aint sure ill tell him to pass it on, but before i do i owe it to him to try to find out

thanks

 

[fuzzy]

"After about eleven minutes it starts up again and then cuts off again after about another seven minutes.
When the boiler is on some heat comes into the radiators and a small amount of hot water is produced.
No constant hot water is produced."

yes ive questioned him on that, i dont think he knows whats happening tbh, ive asked for clarification as it dont make sense

 

[gasmarc]

It could be numerous things like dirty system for starters which may cause other issues

 

[Billy Bob Bob]

thanks guys, my mates not gsr so wont be doing work himself, he asked me for advice but im not very experienced in fault finding on boilers although ive been corgi and gsr for years i used to pass faults on most the time to a mate who did that full time, hes no longer doing it though, hence asking you guys

Thought of all the usual like fan, venturi etc but tbh never heard of wet pocket dry pocket stats? can someone help me here please, i wouldnt know where to look. If i aint sure ill tell him to pass it on, but before i do i owe it to him to try to find out

thanks

a dry pocket thermistor simply clips on to the pipework a wet pocket stat screws in and normally involves a drain down

 

[Garyb]

I've worked on some of these can't give a definite answer.There is a hot water & c heating thermostat both dry pocket.If it had been ahot water problem i would have said flow switch.The overheat stat is top left in the chamber and reset button on top of the casing.Sorry cant help more.

 

[fuzzy]

a dry pocket thermistor simply clips on to the pipework a wet pocket stat screws in and normally involves a drain down

thank you

 

[gasmarc]

yes that is one mistake you dont want to make which I did on a saunier duval years ago . I had spoken to the technical bloke and he guaranteed me it was a dry pocket so I pulled it out fortunately it was over a sink and the customer was cool so no major damaged done ,but i had to ring them again and the tech guy said they are dry pockets on the newer version,