Strange combi problem

Very likely this is a *tap* problem. You open the tap a small way (because you have good water pressure) and the DHW start to flow, the boiler does it's stuff and the water and tap becomes hot.

The hot tap head expands and closes down the flow of DHW to the point where the boiler cuts out...

All this might be aggravated by an insensitive DHW flow detector in the boiler (I've not got a Response manual so can't remember or guess the mechanism).

I trust it isn't preparing to depart this world. . . .

Gives me something to go on should it become a nuisance.

Search around on the archives and you'll know the score. Keep boiler on high settting, all TRVs to max and control with wall thermostat. This boiler must not be allowed to condense.

This has always been the case with my bathroom basin hot tap since installing a new W/B 28i . My taps are cheap crap.

Arthur

of the taps, could they all be at "fault" ?

Does anyone know if the Response 120 has a built-in store? (IIRC it doesn't).

What's the cold water pressure and flow like?

flow seems good (sorry for lack of detail) havent actually measured any of these.

thanks

No.

Does this dropping off of flow happen with the cold water too? If so, then look at the main stop tap.

The Response has no 3-valve and the DHW is activated via a flow switch.

The heat exchanger may be blocked. When off, the pressure is high, then stays high for awhile until the dynamic pressure falls off because of the blockage. This boiler should always have a strainer to catch solids on the cold water feed - as should all combis.