Is my COP rubbish?

[Beelbeebub]

Don't most HP controllers allow for different zones of heating with different WC curves?

[RobLe]

38 minutes ago, Beelbeebub said:

Don't most HP controllers allow for different zones of heating with different WC curves?

I’m sure you could run it this way.  But if you run half the time into one emitter, half into the other, then both emitters will need to be twice as hot (2x the Tflow-Troom), to get the same average heat flow.  It’s likely to be counterproductive - better to run everything on together.  

[sharpener]

The OP is charging the floor slab with the UFH during cheap rate and then switching to the rads to heat the bedrooms. There seems to be little point in having the water un-necessarily hot for the UFH (and then tempering it with a mixing valve!) when the rads are anyway not going to be on at the time in question.

 

1 hour ago, Beelbeebub said:

Don't most HP controllers allow for different zones of heating with different WC curves?

 

I think so, Vaillant Arotherm + certainly, don't know about the OP's Daikin.

 

Presumably when zones are on together the one demanding the highest temp has priority, hence the need for the mechanical mixing valve.

 

Or you can control zones separately with electronic mixing valves but AIUI the HP will still have the leaving temp of the highest circuit, and so involve an increase in entropy for the others hence less than ideal CoP.

 

So turning off the UFH for an hour while you heat the bedrooms would give you a small improvement and you probably wouldn't notice the gap.

 

Edited November 10, 2023 by sharpener

[Bob77]

4 hours ago, sharpener said:

The OP is charging the floor slab with the UFH during cheap rate and then switching to the rads to heat the bedrooms. There seems to be little point in having the water un-necessarily hot for the UFH (and then tempering it with a mixing valve!) when the rads are anyway not going to be on at the time in question.

 

 

I think so, Vaillant Arotherm + certainly, don't know about the OP's Daikin.

 

Presumably when zones are on together the one demanding the highest temp has priority, hence the need for the mechanical mixing valve.

 

Or you can control zones separately with electronic mixing valves but AIUI the HP will still have the leaving temp of the highest circuit, and so involve an increase in entropy for the others hence less than ideal CoP.

 

So turning off the UFH for an hour while you heat the bedrooms would give you a small improvement and you probably wouldn't notice the gap.

 

 

My heat pump is capable of having two separate heating zones (plus DHW), but the installer set it all up as one zone, for reasons known only to himself. I think a lot of installers just want to keep things simple and not have to explain complex stuff, as most of their customers are probably in the gas boiler mindset.

 

As far as I know there is no way of changing the flow temperature automatically at different times. The flow temp for a given zone is either set at a constant or on a WC curve.

Edited November 10, 2023 by Bob77

[JohnMo]

50 minutes ago, Bob77 said:

heat pump is capable of having two separate heating zones (plus DHW)

 

6 hours ago, Beelbeebub said:

Don't most HP controllers allow for different zones of heating with different WC curves?

All heat pump have one inlet and one outlet. The only way it can supply two different temperatures at the same time is with mixing valves. So at any given time the output will fixed to give the highest temp required.

 

Any heat pump can do as many or few zones as you like mostly via external controls.

 

All the above impact CoP - but not in a good way.

1 hour ago, Bob77 said:

set it all up as one zone, for reasons known only to himself.

 

For efficiency?

 

[sharpener]

1 hour ago, Bob77 said:

As far as I know there is no way of changing the flow temperature automatically at different times. The flow temp for a given zone is either set at a constant or on a WC curve.

 

Am surprised there is no night setback possible. Or a low-noise setting which would limit the heating available during night-time hours.

 

1 hour ago, Bob77 said:

My heat pump is capable of having two separate heating zones (plus DHW), but the installer set it all up as one zone, for reasons known only to himself. I think a lot of installers just want to keep things simple and not have to explain complex stuff, as most of their customers are probably in the gas boiler mindset.

 

Maybe you could make use of this to simulate two zones with different temp/time settings? You might need to use both outputs but connect them to the same actuator. With or without two relays.

[ReedRichards]

17 hours ago, sharpener said:

 

19 hours ago, Beelbeebub said:

Don't most HP controllers allow for different zones of heating with different WC curves?

 

I think so, Vaillant Arotherm + certainly, don't know about the OP's Daikin.

 

I think most HP controllers probably cannot do different WC curves for different zones.  I have an LG Therma V; it can do different zones but not with different WC curves.  Nor can it do a programmed set-back, although you can do this manually very easily. 

 

And you only benefit from different WC curves for different zones when one of the zones is off, not demanding heat.

[Beelbeebub]

5 hours ago, ReedRichards said:

 

I think most HP controllers probably cannot do different WC curves for different zones.  I have an LG Therma V; it can do different zones but not with different WC curves.  Nor can it do a programmed set-back, although you can do this manually very easily. 

 

And you only benefit from different WC curves for different zones when one of the zones is off, not demanding heat.

You might be right.

 

I think the Grant/Chofu units so have that function, though as an undocumented (from Grant's perspective) feature.

 

They seem very capable units. Grant have made them as simple as possible for existing boiler installers to use which ignores a lot of functionality.

 

I'm really intested in what the next gen r290 units will do.

[JohnMo]

1 hour ago, Beelbeebub said:

think the Grant/Chofu units so have that function

They do, but is only by the zone of highest demand that controls the temp output, the other zone is just a mixer valve.

 

and