I have no connection with them whatsoever but why not ask Brendon at https://heacol.co.uk for advice & replacement? You’re in Cumbria and he’s well respected in the industry.

I’m glad to read your system has run for 15years since that was the age of our gas boiler when we replaced it. On going parts replaced in life us normal.

Thank you Judith. I have contacted them.

@bgf @heacol is an active member on our forums too.

Thank you @editor and @judith \we have made contact.

Posted by: @bgf

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Thank you Judith. I have contacted them.

You’re in safe hands with @heacol.

Thank you to all who made suggestion.

An update - we are heating with one working 16kW heat pump and DHW from an immersion heater.

Heat Loss

I had initially used the NRG calculator and it suggested 27kW heat loss.

I downloaded and used the Freedom calc from this forum and it was 20 kW

I paid for an external heat loss calculation at its was just under 20 kW.

Brendon at Heacol ran calculations and it was  just under 20kW

Aira said it was 20 kW but was just based on a total floor area.

Mastertherm said it was 16 kW

N.B. we are in Cumbria and at 150m elevation.

We had Aira visit. 

They put the house floor area into their tablet and said we needed a 20 kW system. 

Aira heat pumps do not work in cascade and max single unit is 12 kW.

They could only offer  2 x 10kW Vaillant Heat pumps.

They then offered to replace all 14 radiators in the house with ones that they specify so that they could offer a 5 year comfort warranty.  The  inclusive price was 27k. Hence I was paying for  two heat pumps and for replacing all the radiators so that they could offer a 5 year comfort warranty.

The Vaillant warranty was 2 years but they would extend to 5. They initially did not think that they could make the back boiler work but called back next day to arrange a call with an engineer. I concluded that there was No further Action.

I have spoken with my local Daikin Engineer and they can offer two 10 kW systems but they would be splits and as underground pipework is 15 year old likely have to repalce and dig a new channel to house. (Will have to do this for a monobloc anyway).  Then have the internal unit noise as well as maintenance costs on two units.  

I asked Mastertherm in Wales to see if they could specify anything They offer Master Therm Czech made Units. They said they could supply a monobloc 7-22 kW system but I would need a local installer. Installer checked and says it is 22 kw at warmer temperatures and  for houses with heat loss up to 16kW.

Brendon from Heacol has visited and we are finalising the details on a monobloc system that can be installed in January.

Before and after pictures. Old Daikin System ( 2 x 16 kw) split with 700l Buffer.

New Panasonic system 25 kw mono bloc with volumiser and thermo syphon system for log stove back boiler.

Really appreciate the lack of noise from the split units in the house. Two new radiators in the far side of the house

Brendon and Jordan from Heacol have done a great job designing and installing the system.

Upstairs now  at 17 to 18 C and downstairs at 20 to 21C when outside at 0C. NB in all rooms unlike before.

Installed from mid January  but commissioning delayed as storm Eowyn knocked out electricity to area.

Some tweaking heat curves to get to the ideal.

This was one of the first of the new large M series Panasonic units in the country and it is a beast of a unit.

 s

Awesome!

Its good to read you’ve got the performance you want and sad that this wasn’t the case previously and it needed 2 new radiators to achieve that.

Please update us when you have enough data to compare the costs. But if you’re warmer than previously then it’s not a direct comparison.

Great to read it’s been successful!

Thank you Judith - COP on the heating is showing as 2.7  (slightly lower on DHW).

To take an example

Electricity usage is shown on ASHP for Sunday as 69.5 kWh for heating and 9.0 for DHW. Total 78.5 kWh.

Smart meter shows total energy usage on Sunday for the house was 101 kWh so calculation says we used 22 kWh for domestic purposes - Ofgem suggest it should be 11 for a modern house.  Needs investigating...

Smart meter is dumb and resets in the early afternoon around 2 pm rather than at midnight.

Did not charge the car on Sunday and it rose to a sunny 5C outside.