Combi Boiler not activated by Hot Tap

11 Jul 2007
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United Kingdom
Recently moved into a house with a Worcester Greenstar high flow 440
We have hive installed
Scheduled hot water mornings and evenings, are get hot water for the shower and rads.

In between, when we turn the tap on full in the kitchen, or mixer shower, we don't get hot water, lukewarm at best.

I presume, (knowing nothing) that the taps aren't creating enough demand for the combi to kick into life??
Any easy settings to check?

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I suspect that your boiler can be scheduled for times for hot water production.

You indeed say that it is scheduled for morning and evenings.

Why not set it for all day and see if you then get the HW all day?
I thought one of the benefits of a combi is it produces hot water on demand.
You use the schedule to create a back-up store when you have a lot of demand i.e. in the mornings when everyone uses the shower.

I would expect the boiler should provide hot water on demand without the schedule being set to 24/7
Your expectation is not the same as mine.

A random use of hot water will encounter a cold store and not give terribly good hot water temperatures!

Try to understand how the store is connected in the boiler.

But it is not very large and will probably reach its normal temperature within say 10 minutes of hot water use providing the hot water flow is less than the maximum that the boiler can heat.
Last edited:
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Cheers for the replies, a quick call to Hive and it could be the controller they have installed.
They do 2 versions, 1 for hot water and heating, 1 for just heating (which I presume passes through the hot water request direct to the combi).
This could be the issue. They are sending someone out tomorrow to check and if necessary install the correct one.
An update for anyone that comes across this.
For Hive there are two types of Hive Receiver, that connect your Hive thermostat to your boiler.
1 is for your standard Combi and handles only central heating programming,
the 2nd handles both central heating and hot water, so you can schedule filling the hot water tank.

My Combi boiler is a little unusual, in that it has it's own water store, to supply multiple showers at once.

In short we should set the hot water to constant on the Hive Receiver and App, to act like a standard combi
Is it now working?
On another tack, there should be a flow (or pressure?) switch on the boiler to sense hot water demand, therefore kicking the boiler hot water heating into life. Maybe this isn't working properly. If the boiler starts but doesn't heat the water up properly, maybe its the heat exchanger.

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