ASHP Running Cost

[GaryW]

So, Newbie to the heat pump world.

 

Aerona being installed into my new build next Friday.

As a middle aged man, this is as exciting as it gets........

 

Done research - at start, looking to setup with weather compensation on.

Will throw my installer setup in the bin and adapt myself.

 

Looking for tips.

 

Intend to setup:

2x Nest Thermostat for general On/Off control on CH - set to 23 - so only turns off when I want for extended period or significant overheat event.

Flow temp as low as possible on startup and creep up 1Deg until comfy @20Deg.

All pipes are valved, but I intend to only have 2 zones - Up and down.

 

House -

Self Build

250m2

UFH - upstairs and down.

Heat Loss Calc. 7.1kW

Additional stove (6kw) in vaulted exposed living room - hopefully rarely on.

 

Priority DHW - 250L HP tank

Volumizer 30L on return.

No buffer or LLH.

 

What else?

I've several temp probes in the screed, but seems useless in reality - room temp is the master of all.

 

Our schedule is: house empty 08:00-17:30.

 

interested to see how to save energy during this time period.

 

 

 

[JohnMo]

Little confused why you are doing WC and then adding expensive thermostats?  Sort of missing the point of WC.

 

Nighttime and most of daytime you will be on setback, only a couple of degrees though.

 

You may want to read the Chofu manual, that is original manufacturer's and their manual has all the functions not included in the Grant manual.  The controller is the thermostat in an original install etc.

Chofu-Operating-Installation-Manual.pdf

[GaryW]

I already have 2x Nest Thermostats from my last - old, damp and oil fired central heated home.

So its a simple use case - I could always ebay them...

 

On the controller being a thermostat in an original install - still, it doesn't vary the flow temp to room temperature - so what benefit does this have?.

 

I will have a read, for sure.

[Marvin]

Hi @GaryW

 

Yes low and slow is the order of the day. Low temperature water and slowly warming.

 

The smaller the difference between the outside air temperature and the flow temperature from the ASHP the greater the fuel saving.

 

We use adjusted weather compensation. When the day gets warmer the heating water temperature goes down. Our buffer tank is at 35°C and it is 10.8°C outside and over 22°C inside so allowing losses, say a difference of 28 degrees so for every 1kWh used, 4kWh of heat produced.

 

Good luck

 

M

 

 

[HughF]

49 minutes ago, GaryW said:

I already have 2x Nest Thermostats from my last - old, damp and oil fired central heated home.

So its a simple use case - I could always ebay them...

 

On the controller being a thermostat in an original install - still, it doesn't vary the flow temp to room temperature - so what benefit does this have?.

 

I will have a read, for sure.

You’re asking for load compensation, a reduction in flow temperature occurring automatically when the room temperature reaches the target. Not all heat pump controllers offer this. Not sure if the Chofu one does or not.

[Radian]

3 hours ago, GaryW said:

Our schedule is: house empty 08:00-17:30.

 

 

That's something I rarely see being considered here. Maybe the majority of BH contributors are retired 😁

But seriously, given the best way to run UFH is constant room temperature and the response time is in the order of hours, what if anything can be done to minimise heating costs with such an occupation pattern?

[ReedRichards]

6 hours ago, JohnMo said:

Little confused why you are doing WC and then adding expensive thermostats?  Sort of missing the point of WC.

 

 

There is "hard core" weather compensation and "soft" weather compensation.  If you want go "hard core" then you fine-tune your weather compensation settings so that the house holds your desired set temperature without the aid of a thermostat and if you want to adjust the temperature, e.g. for a night time set back, you adjust the weather compensation setting to achieve that.  Or you can do "soft" weather compensation where your weather-compensated water temperature is a bit higher than it would be if fine-tuned but you have more wiggle room, in particular the ability to warm up the house a bit faster. And you don't need to spend however long it takes to get the fine-tuning sorted.  But you need thermostats.