Baxi Boiler Cutting Out

I have a Baxi Solo 2 40 RS that has worked with out a problem for about 8 years. At its last service, repair man said over heat cut out was disconnected (not me by me). He reconnected it. Now it often trips out just after the boiler has a long run. It is a pumped system and manual says pump should run on for a few minutes after boiler shuts down. (It doesn't) I presume this is to prevent over heating?

On gravity system it says to disconnect the over heat thermostat.

My questions are:

Am I likely to be right about why it is tripping. If so is it easy to wire the pump into to run on or do I need to get an extra part fitted to circuit board?

Also if it is safe to have the trip disconnected for gravity feed, is it really needed for pumped system (or how dangerous was my installation without it?)

The question you have to ask yourself is how long has it been in and working perfectly ok, i bet about ten years..

The reason on this particular boiler for having it on pumped and not gravity system is on a pumped system the pipes are usually 22mm and struggle to get rid of excess heat when boiler turns off .so needs the pump to pump heat away around the bypass

Where as on gravity the pipes are 28mm and the heat can get away.

If the heat stays in the boiler too long scale can form and you get a noisy heat exchanger..

If you want to wire it right you need a permanent live and a switched to the boiler and pump wired from boiler .

Also these should be fitted with a 3 port motorised valve as opposed to 2 two ports as they need a bypass of about 27 feet in length.

So if it worked ok it is up to you there is loads out there like it with no problems

Namsag - thanks advice sounds spot on.

System is being cleaned at the moment and will then be drained, flushed through etc. Banging noises from noisy heat exchanger have reduced alot already.

when the system clean is complete, will boiler then run without triping out (given that pump is not wired to run on) until scale builds up again or is it "safe" to continue with overheat protection disconnected?

I've never seen a Solo on anything other than a fully pumped system

Bryen if you are going to the expense of getting it descaled etc pay that wee bit extra and get it wired properly as yours has been affected by being left with no pump over run(not all are)..

www.partsarena.com/baxi then click on boiler then solo and it will give you the wiring diagram