High limit stat tripping on a warmflow oil boiler

[tickdoc]

Good evening, about 2 years ago a customers high limit stat was tripping every so ofte,n not a sealed system. I turned the circulating pump speed up to 3 from 2 and seemed to cure it , until recently. Tripping again and hes now saying when he turned the Boiler on didn't heat water but rads were hotter than normal. I service and repair oil boilers and have replaced pumps, motorized valves etc many times but I'm not a plumber with a plumbers knowledge. Originally I thought pump for sure, possibly the boiler stat but now I'm thinking motorized valve also, and maybe more than 1 of them. 1 last thing, warmflow boilers have their own stat, I have changed imit stat like for like, is it ok to change a warmflow stat with a imit stat, no point in stocking everything, many thanks.

 

[dancinplumba]

is boiler kettling ? could be sludged up more than before

 

[Best]

Warmflow boilers used Imit stats for decades, but now use a different (French made I think) stat which I find gives trouble.
The control stat is almost certainly faulty and probably boiler is running too hot and close to limit stat cut off temperature. Less likely to be the limit stat.
You need to replace the entire stat. The pocket is slightly different and although it could still do an Imit stat, you might want to replace everything, or just buy an identical replacement stat to make life easy for yourself.
I have a customer on texting with identical problem on a Warmflow as I type this.

 

[tickdoc]

Warmflow boilers used Imit stats for decades, but now use a different (French made I think) stat which I find gives trouble.
The control stat is almost certainly faulty and probably boiler is running too hot and close to limit stat cut off temperature. Less likely to be the limit stat.
You need to replace the entire stat. The pocket is slightly different and although it could still do an Imit stat, you might want to replace everything, or just buy an identical replacement stat to make life easy for yourself.
I have a customer on texting with identical problem on a Warmflow as I type this.

 

[tickdoc]

Ye I'm told the Boiler is probably kettling ,ye I know what you mean Best about the stats, years ago I've saw warmflow boilers with imit stats fitted, but now seems to be their own. Just a hassle having to stock or go get a warmflow stat, if things were kept more universal, be easier all round.

 

[tickdoc]

I know it's very hard to know for sure but what about the pump, increasing the pump speed sorted the problem for about 2 years.