Hot water plumbed backwards now no heating

[Underpressure]

Hi all,

right, so, please help a man out here

my plumber for some unknown reason whilst plumbing the kitchen in that we have just fit confused the hot feed from the boiler and put a cold feed onto it......
the heating was working fine and as normal,
until...
my heating guy came out, attempted to isolate the boiler to change a suspected flow turbine as this is what tech support said to change, and water :nono: everywhere as the pipe was still live due to being plumbed backwards..
he got it swapped, however, we now have lovely hot water, but, the :nono: heating wont come on!
if you demand heating through thermostat it talks to the boiler, pump comes on etc, but does not fire up just pump keeps running?
he's saying to now change the diverter valve as that could have failed and the symptoms match that

no warning lights or flashing ones on boiler

worcester bosch greenstar 24i approx 5 years old

customer is being very patient, but its causing me mega stress

please advise

cheers guys

 

[drip-dry]

It is not this diverter valve,which would be easy to check anyway.best he re checks his diagnosis..maybe your heating lad is related to your plumber,or you just have split personalities ...

 

[Underpressure]

It is not this diverter valve,which would be easy to check anyway.best he re checks his diagnosis..maybe your heating lad is related to your plumber,or you just have split personalities ...

Any idea what it could be?

 

[drip-dry]

You need to be gas safe to work on the boiler,am sure a qualified engineer will sort out OK,

 

[Dotty]

As above. You need a competent gsr to look at this.