worcester 25si

Hoping someone can provide insight on issues as we've had plumbers come out 3/4 times and not being able to diagnose. 10 yr old boiler, Worcester Greenstar 25si , hot water runs fine, when heating turns on it causes a lockout/reset required, after 1-3 times of reset it then works fine. Pressure...

Hi, I am installing a Nest onto a Worcester 25Si combi. It is to replace a Drayton SCR/ Digistat +3RF. I wanted to double check the wiring- ie. can I swap it like-for-like? Wiring, as shown in the pics (http://imgur.com/a/Ri7GW), is currently: Blue- N Brown- L Black- 1 (C) Grey- 3 (Call) Earth...