boiler bother - Halstead Hi Ace

[Vickster]

I have a Halstead Hi Ace boiler for HW and CH - probably 6 years old, serviced only last month, new diaphragm fitted for hot water also. Water pressure usually at 1.25 bar rising to 2.5 when the heating comes on. Problem is over the past couple of days i've noticed the heating going off after about 1.5hrs, the heating led indicator stays on and the power led flashes. If i then run some hot water for a few minutes the heating kicks back in and works fine! What gives? Any thoughts? Should i get the plumber back who serviced it or is it something i can deal with?
Cheers in advance

 

[Billy Bob Bob]

Sounds like a expansion vessel issue and over heating poss ntc

 

[Vickster]

Thanks Gas Man. Whats ntc mean, is that a technical term? Is 6 years old for a boiler of this type?

 

[Billy Bob Bob]

Thanks Gas Man. Whats ntc mean, is that a technical term? Is 6 years old for a boiler of this type?

ntc is basicly the thermister ch i would go for but it may just be the ev causing it to kick in