Weather Comp + independent zone valve

[JohnMo]

20 minutes ago, Mr Blobby said:

We have approx 200 litres, so I take it the manual is correct and an extra expansion vessel is required?

That sounds a lot, are you sure? But if correct, you will need an additional expansion vessel. Too much expansion room is better than not enough.

[Mr Blobby]

13 minutes ago, JohnMo said:

That sounds a lot, are you sure?

 

Ha, you're right, I used 16mm diameter for the UFH pipes, but the internal diameter is of course less.  😆

 

At 12mm ID the volume is just 118.  That's more like it 🙄

[SimonD]

28 minutes ago, Mr Blobby said:

The plumber (and hence the builder) are adamant that I need to mount it on rubber feet, despite advice from Panasonic to bolt the unit to the slab.  We'll see.

You don't need rubber feet on the Panasonics and you don't need to go to the expense of flexi connections to the heat pump either. You can buy and fit rubber feet if you want to and there is also a mounting frame available (with adjustable feet for uneven ground) if you need to install at greater height but this is usually only used for snow clearance. Yep, add another expansion vessel - shame it's not like the Viessmann boilers where there's a specified test procedure you can follow to determine if the built in vessel is sufficient, but it's quick and easy to add another.. 

 

36 minutes ago, Mr Blobby said:

A commissioning service is offered but no detail on pricing etc so I'm going to try to get this up and running myself. 

 

Given your UFH installation, a full commissioning service to balance your UFH will likely take days to do properly given the lag in a slab and also is best done when it's cold out. Just buy yourself a few pipe thermostats and stock up on patience.

 

On 27/05/2026 at 13:05, JohnMo said:

We have relaxed (simplified )that control and just use a room sensor to control everything,

Wow, I'm glad I was sitting down when I read this. @JohnMo has joined the dark side and gone room influence. I never thought I'd ever see the day given how adamant you used to be that it was akin to the devil 😉 What changed? Or is this another experiment?

[Mr Blobby]

We have a concrete pad already poured for the unit to sit on. Its a few inches above ground level.

 

Just seen this in my whatsapp from plumber/builder 🤷‍♂️

 

Edited 4 hours ago by Mr Blobby

[JohnMo]

38 minutes ago, SimonD said:

Wow, I'm glad I was sitting down when I read this. @JohnMo has joined the dark side and gone room influence. I never thought I'd ever see the day given how adamant you used to be that it was akin to the devil 😉 What changed? Or is this another experiment

No not room influence - whole house, one room sensor/thermostat for whole house. Hiaer doesn't have a thermostat built into the controller. It is connected to outside temperature sensor so also allows oat switching the whole heat pump off in heating mode when outside is an average (over 6 hrs) above 10 degs.

 

No need to get excited, still single single zone, WC, no actuators, just an on off permission, mostly because running heat pump at 9 degs OAT on full WC at about 22 degs doesn't work, which is about the temperature it needs at that temperature. So heat pump uses a simple permission to run at 26 degs, runs for a couple of hours and then shuts off for about 18 hrs. The colder it gets the longer the run time.

 

No setbacks just single room temperature 24/7. But really needed for cooling as I run a set flow temp with humidity over ride. So makes sense to flick a single switch that takes thermostat from heat cool and same switch moves ASHP between heat cool also.

[JohnMo]

32 minutes ago, Mr Blobby said:

 

Just seen this in my whatsapp from plumber/builder

I used these to get the snow clearance needed to comply with OEM requirements for snow.

https://www.wolseley.co.uk/product/pump-house-1000mm-condensing-unit-mounting-block/?pid=P667987

[SimonD]

24 minutes ago, JohnMo said:

No not room influence - whole house, one room sensor/thermostat for whole house. Hiaer doesn't have a thermostat built into the controller. It is connected to outside temperature sensor so also allows oat switching the whole heat pump off in heating mode when outside is an average (over 6 hrs) above 10 degs.

 

No need to get excited, still single single zone, WC, no actuators, just an on off permission, mostly because running heat pump at 9 degs OAT on full WC at about 22 degs doesn't work, which is about the temperature it needs at that temperature. So heat pump uses a simple permission to run at 26 degs, runs for a couple of hours and then shuts off for about 18 hrs. The colder it gets the longer the run time.

 

No setbacks just single room temperature 24/7. But really needed for cooling as I run a set flow temp with humidity over ride. So makes sense to flick a single switch that takes thermostat from heat cool and same switch moves ASHP between heat cool also.

 

Hehe, what you've described is room influence, although the best room influence simply sends an additional signal to the heat pump to reduce the flow temps essentially modifying the WC curve. But if you have control from the room, that's room influence as it calls to the heat pump - nothing to do with actuators/open loop in an of themselves. Room influence is just about adding additional system control which uses the room conditions as input. 😁