grant combi oil boiler 90 mk 11

[garden]

keeps going into lock out after heating on timed for an hour, had new expansion vessel fitted, then sometimes will reset straight away then the next time it wont .Getting stressed and broke, could it be the thermostat or i did see on the forun the heat exchanger plate might be blocked up with gunge,pumps sounds ok can any one help g

 

[Tipper]

When was it last serviced?

It should be done every year. You need to get it sorted before the real hard weather hits because it's bound to fail if you don't!

 

[simond]

burner lockout or overheat lockout (the burner lockout is located on .....the burner.)?

The servicing advice is very relevant for an oil boiler.

 

[dcawkwell]

When was it last serviced?

It should be done every year. You need to get it sorted before the real hard weather hits because it's bound to fail if you don't!

When have people ever thought of that?
Sitting there all summer long knowing the heating has problems.
Knowing they need more radiators. Do they think
of getting that done in the summer?
No it's when the boiler gives up and there is 2ft of snow outside.

 

[Boilerman2]

Some reasons for overheat trip on a Grant 90 MkII Combi

Store Stat not correctly set to cut in at 78'c
Control Stat not set at 82'c +/- 2'c
Plate HE Scaled
faulty circulating pump
Thermostatic Blending Valve "Shocked"
Faulty Overheat Stat
Low water pressure in Primary system

It will be one of the above

 

[garden]

Thanks for the advice, boiler gets serviced every year. So will get plumber to try these the ones we havent thought about. Thanks again G