Strange combi problem

Hi,

I have an intermitant problem with my ideal response 120 combi where when running the hot water after a few minutes :-

1 The hot water flow slows right down 2 The water then runs cold 3 I then turn of the tap, wait a few minutes. normal flow and hot water return

what would cause this and what would reduce the flow rate?

many thanks

Reply to
Block
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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).

Reply to
Ed Sirett

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

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Reply to
1501

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

Reply to
Block

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.

Reply to
Ed Sirett

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

Reply to
Davao

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

Reply to
Block

< snip problem about HW flow going cold after a short while>

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?

Reply to
Ed Sirett

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

thanks

Reply to
Block

No.

Reply to
Doctor Drivel

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.

Reply to
Doctor Drivel

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