What sort of heating system do I have

[stem]

The current system is probably configured so that the room thermostat only operates the pump marked CH that circulates the hot water around the radiators. So unless the thermal store is also hot, the pump will only circulate cold water around the radiators. [The other pump marked HW is a bit of a misnomer, it is responsible for heating the Heat Store which is required for both CH & HW, so 'HS' (Heat Store) would be more appropriate.]

One of the features of Hive / Nest is that they are controllable remotely, so if you wanted to use it to turn the heating on as you were heading back home after a few days away for example, you wouldn't get any heat unless the heat store was on and hot, but from what you say yours doesn't have a timer and is on 24/7 anyway, so shouldn't be a problem for you.

The NestE is a good suggestion if you don't want to install a mains supply, but it is a 'cut down' version of the standard Nest, and doesn't have all of the functions of the standard Nest, as a result, some have been disappointed with it. And it is just a single channel to replace a standard room thermostat.

 

[con1_uk]

Thanks for all the replies so far, you have been really helpful and patient.

So the hot water for taps and showers comes from the heat store which also supplies the radiators?

as soon as I flick the stat to 21 the boiler kicks in, should it still do that if the hot water was supplied from the heat store? If the heat store is on 24-7 does this use a lot of energy?
Does the heat store heat the water as well? Is it run of electricity?

Thanks.

 

[ianmcd]

No the boiler heats the water that is inside your heatstore, there is a coil of pipework inside the heat store, when you open a hot tap, the cold water runs throught the coile and picks up the heat from the hot water inside the store and comes out the other end hot, the two waters never meet, the stat does not bring the boiler on, it brings the CH pump on and the hot water is transferred to your radiators, the boiler will sense this and will come on to maintain the temperature of the heat store, no the boiler is not heated electrically but some have an emergency immersion back up

 

[stem]

If the heat store is on 24-7 does this use a lot of energy?

Not a lot, but some. The heat store should be well insulated and keep most of the heat inside, just like a traditional hot water cylinder, but there will still be some heat losses. Although in the winter those losses would contribute to heating your home.

I've not worked much on systems with heat stores, but those that I have seen, unlike yours, did have a timeswitch for the heat store that controlled when the boiler heated it. Many are left on 24/7 so the store is always hot and ready to provide hot water and heating at any time. Once there is no demand for heating or any hot water being used, the store heats up and the boiler shuts down anyway. I have seen the timeswitch set to be off for a few hours during the night so that sleep isn't disturbed should the heat store request a top up in the middle of the night due to its natural heat losses.

The problem with energy is that as @ianmcd said, the boiler should be set to its maximum setting. Modern condensing boilers work more efficiently at lower temperatures so don't give their best efficiency with heat stores. That wouldn't apply to solid fuel boilers of course.