w/bosch 400 rsf over heating

[joserulz73]

hello people

i have a highflow 400 rsf (non electectronic) that cuts out on dhw.Safety
Temperature Limiter has to reset in order for it to work again, but cuts out gain a few hours.

i have replaced the pump, water - water heat exchanger, Safety Temperature Limiter,HW Thermostat, i have checked the filter in the white manifold, i have checked the 6mm swan neck pipe,
the boiler still has the problem!
the pump does over run

has anyone had this problem?
thanks
jose ,

 

[ollski]

Have you replaced the dhw hx for a new one?, I always replace the top manifold aswell (and the bottom as I might aswell). There isn't much to knock these out for hw only except what you have already done

 

[joserulz73]

hey there

i have changed the dhw hx and the two manifolds are clear.
any other ideas?

 

[Dan Robinson]

A little rusty on these but does the priamry temperature sensor play a part on the hot water generation too?

 

[joserulz73]

not to sure m8

 

[ollski]

Have you been running heating demands at all?, poss. gas valve sticking.

 

[joserulz73]

hey
the boiler runs fine on heating its only dhw it cuts out.
how would i check if gas valve is sticking?
cheers