OK - thanks @vanq

What we're (jointly) about to say here, might sound contrary to the way in which you've imagined your heat-pump works.
Please don't immediately rush to a specific conclusion because the underlying concepts are more important than "How do I add Homely"!

I'm going to tag @jamespa and @majordennisbloodnok initially, but others might join in.

Your heat pump is unable to perform as it should because it's having external controls imposed upon it.
The present arrangement is what we'd expect to see for a boiler running on gas or oil.

The basic idea is that the Areona 3 is meant to run continuously, and not have thermostats and time-clocks switching it on/off.
Its own native firmware will adjust the Flow to meet the heat demands of the house.

The ground floor UFH manifold needs those valve actuators removed, and replaced with the manual knobs which it probably came with.

Those knobs are then turned so that the flow through each loop is balanced.
That's where the sight-glasses at the top are needed.

Each pipe loop will have a different length, and might also be constrained by having more bends than the others.
You will end up having the manual knob fully open for the longest pipe-loop, which is the one with the most resistance to flow.

By this stage you will be picking up something heavy to throw in my direction...
... because all those thermostatic controls don't come cheap!

You will wondering how the Heat Pump "knows" how much heat to send into each room.

The answer lies in the original Heat Loss Survey which was completed before the system was designed and installed.

The Heat Loss for the whole house has been used to define the required size of the heat-pump itself (in kWh),
and the heat loss for each room is used to define the UFH pipe runs within that room.

The installer calculates for each room:

• the length(s) of pipe required to meet the heat demand
• the distance between each each pipe within the floor

... based on the known temperature of the water leaving the heat pump, which should be around 50°C.

That might not be what actually happened for your particular house, but that's how it's meant to be.

The obvious situation when things won't be right is when a house which has existing UFH changes from using a boiler to a heat-pump.
But we'd need to know more about the history of your installation in order to advise further if that's the case.

Let me stop there and give you a chance to contemplate your next question...

@transparent Thanks!  This is my 2nd heat pump and 4th UFH so I agree and understand the largely always on concept hence looking to move to a different system of control than I currently have.  I'm not concerned about the cost of these thermostats as I bought the house with them already installed and knew I'd be needing to remove.

The design I think is a bit of both, it was put in when the house was extended, but obviously by someone who went the thermostat route - which I've also had in the previous house.  Seems like that is the prevailing design for most of them.  I'll have a look and see if I have any of the design documents for the heat, but its got plenty of loops so presume that was all done correctly.

So as I understand it for removing the downstairs element of the system:

1. Disconnect the heatmeister controls of the valve actuators.  They do have wires going back to the "heating controls" box in the main unit but that shouldn't matter as it'll be manual going forwards.
2. replace the valves with manual knobs

3. balance those knobs so the numbers in the clear part all match? currently they look all full/red but presumably pick a number and make sure they're all the same but adjusting the knobs up and down until that's the case

Q. Do I have that right so far?

Q. Then how do it make sure the valve (not sure where this is or if there is one for the downstairs system) and the pump are "open", as assume they're also in that heating control box.

Q. How do I then set the actual temperature? Assume its controlling the flow temp at source and some trial and error until thats correct?
One of the things I thought might be easier with Homely and I assume we'll circle back to if the Homely makes sense v using the grant controls themselves, as appreciate we're on the bigger point here.  If its all removed down to the grant system then the homely install into the modbus is pretty straightforward.

Q. That'd count for the Neo's but then obviously there is the Nest to consider.

I'll probably need to get someone in to do this but helpful to know what I'm asking for.

Posted by: @vanq

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Q. How do I then set the actual temperature? Assume its controlling the flow temp at source and some trial and error until thats correct?

In a nutshell, yes- set weather compensation curve and tweak it until generally comfortable IAT in all weathers (does not take as much tweaking as it sounds).

I'm trialling our midea using native controls, versus homely which I removed in the summer. I actually think I am on track to making a small saving without homely tbh. Either way it is going to be close, and homely isn't cheap....

Posted by: @vanq

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balance those knobs so the numbers in the clear part all match? currently they look all full/red

Well I can get all my UFH flow monitors to show "all at max flow" simply by having the circulating pump on full!

But that's not efficient of course.
The shorter loops would be returning water which still retains lots of energy.

In your case there's also the issue of the upstairs radiators.
Somehow they need to be balanced with whatever the ground-floor manifold is taking.

Have a look at this article about a flow-regulating valve for radiators.
It's similar to those on your UFH manifold but allows you to see the water speed for each radiator.
If you read to the bottom of the text, you'll find a discount for Forum Members. 😊 

Posted by: @vanq

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Q. Then how do it make sure the valve (not sure where this is or if there is one for the downstairs system) and the pump are "open", as assume they're also in that heating control box.

You've got manual butterfly valves at the end of the UFH manifold, which don't have to full open. Mine aren't on my upstairs manifold.

But I assume you're referring to a motorised valve and a speed control for the pump.

The only motorised valve I'd expect to find is the 3-port (2-way) unit which shuts off the space-hating circuit when the DHW cylinder calls for heat.
That should continue to operate as normal because the control system is dictated by a temperature sensor on that cylinder.

If you think we need to know more about "the" pump then post a photo.
But do you actually have one?
The entire system might just be using the pump inbuilt to the ASHP.

Posted by: @vanq

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Q. How do I then set the actual temperature? Assume its controlling the flow temp at source and some trial and error until thats correct?

You should have an Outside Air Temperature (OAT) sensor, which connects back to the ASHP control unit.

And there's a system called Weather Compensation (WC) which allows the installer to select an appropriate WC curve for your house.

Those two mechanisms 'instruct' the heat-pump how to choose the required flow temperature and speed.
Setting up the WC curve is one of most often discussion points on this forum.
Type WC curve into the search box (spyglass at top right of this screen) and you'll find scores of results!

Posted by: @vanq

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Q. That'd count for the Neo's but then obviously there is the Nest to consider.

That's beyond my knowledge-set I'm afraid.

But wait an hour or two and someone else will jump in with some Nest insights.

Posted by: @transparent

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But wait an hour or two and someone else will jump in with some Nest insights.

Absolutely.  Dont use it!

Seriously Nest, like other smart thermostats (other than Homeley, Havenwise, Adia), are wholly unsuitable for heat pump control.  You should be able effectively to disable it by turning the target temperature up to max and setting it to be on 24x7, so that its constantly calling for heat.  Then  use your heat pump native controller to adjust WC so you are comfortable.

Once thats done settings can be finessed if necessary (eg by using zone valves/TRVs as limiters in case of solar gain) but until the basics are right then any temperature sensors/thermostats should all be set to max so the heat pump can do its thing without interferance.

• Have you got a buffer/low loss header?
• Where is your Grant controller/temperature sensor located?
• Does UFH cover the whole house or have you got radiators in part?

@jamespa Hey, apologies for the delay, new job role so not been at home much.

• Have you got a buffer/low loss header?
  I dont think so no
• Where is your Grant controller/temperature sensor located?
  Controller is internal, it has an outside temperature on the display
• Does UFH cover the whole house or have you got radiators in part?
  UFH is full downstairs - controlled by the Heatmeister.  Then the nest controls the upstairs radiators and the hot water.

Would I essentially be able to do the same for the Heatmeister as a first step, set all to max then control on the grant?  Does that also work for hot water?

Thanks

@transparent

Here’s the pictures  

doesnt look to have a normal value to control the heating downstairs only for hot water and upstairs to me but does seem to have a pump for both 

there are 2 separate manifolds for the UFH

As a followup, I have the Aerona Remote controller, and don't seem to be able to edit and control the device from there.  Each time I go to press any of the main buttons just get 3 beeps.  Can get into installer mode but can't see any parameters in either the Chofu/Grant manuals to turn this off.

Posted by: @vanq

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Would I essentially be able to do the same for the Heatmeister as a first step, set all to max then control on the grant?  Does that also work for hot water

yes to both, probably.  External controls for ashps (and many modern boilers) are largely superfluous and frequently counterproductive.

The possible problem is if ufh and radiators are set up to run at different temperatures which they might be.  You need to check this and might need to maintain the mixing function of the manifold.  Many heat pumps can control this as well don't know if the Grant can or not.  

@vanq

If it is this controller press the plus and minus buttons and the snowflake button together at the same time for a few seconds this should get you into the installer menu.

@grantmethestrength thanks, yes I did that. But couldn’t get it so I could use the normal buttons (heating schedule, dhw etc) they all still then had an annoying 3 beeps. What did you use?

@vanq my set up which is a pretty standard kit for the Aerona3 R32 has a timer for the immersion (top most box) a timer for DHW (second box down) and the heat pump controller (third box down) and the EPH remote thermostat controller (bottom box). Because why have one controller when you can have four? Cheers Grant!