Isar

[hammers4spanner]

Went to service one of these nails tonight , all worked fine on service nothing showing odd but customer said boiler fires up on heating randomly for about 3 or 4 mins then shuts off again . She said no demand on heating yet still does it .

Any ideas chaps normally just rip these models out .

 

[newcastle phill]

Inbuilt Frost protection ?? Faulty.

 

[Billy Bob Bob]

sure its on heating? has a built in pre heat,could be heating plate

 

[hammers4spanner]

She said it just does it randomly had a honeywell cm whatever wireless stat. But that was off yet she says it still ramps up for few mins and is getting more frequent however when i serviced it nothing like that happened .

 

[hammers4spanner]

sure its on heating? has a built in pre heat,could be heating plate

She said rads get hot , thing is i can only go off what she said as all seemed ok when there.

 

[AMGasServices]

Stuck diverter ?

 

[Billy Bob Bob]

Stuck diverter ?

likely suspect,or blocked PHEX causing it to dump down

 

[hammers4spanner]

Did questioning the diverter was a touch of tracking down the flow pipe when hot water was running but nothing than was overly hot , i asked her if all the rads got hot when this issue happens and she reckons so .

 

[Billy Bob Bob]

Did questioning the diverter was a touch of tracking down the flow pipe when hot water was running but nothing than was overly hot , i asked her if all the rads got hot when this issue happens and she reckons so .

sounds like dv failing or phex blocked causing it to dump down on preheat

 

[gassafe]

I'm not sure on the isars, but it does sound like a preheat symptom... I thought it was a common fault on these types of things probs as gas man says...

Was probs doing it before, custard always asks for a service thinking its a repair!!

 

[Billy Bob Bob]

I'm not sure on the isars, but it does sound like a preheat symptom... I thought it was a common fault on these types of things probs as gas man says...

Was probs doing it before, custard always asks for a service thinking its a repair!!

oh how often do we find that,they think a service will cure it,then the bads ones we occasionally get who say it was fine before you serviced it

 

[GrahamM]

As per gasman preheat kicking in but div valve cartridge has had it so dumping down heating.
Check motorised head operating ok and change the div cartridge.

 

[jonnyswamp]

Agree with above, also check the rf stat isn't playing up
I haven't fitted the Honeywell ones, but some of the others need the frequency altered to stop any interfence which can cause intermittent firing

 

[buckley plumb]

Ask what symbol comes up when it fires. Known for diverter if it's the honeywell unit.

 

[arran197]

Ye, preheat coming on, either a t or a d. There's a couple of different diverter valves on these. I've had several with the red top Honeywell actuator that has failed. The rest position on the diverter is ch. So the diverter doesn't push the pin in and the ch comes on, but the DHW never gets to temp.