Correctly sizing A2AHP

ispookie666

I do have 3 units. Two daikins for the bedrooms - 2.5kW and a 7.1kW mitsi in the lounge. I could have got away with a 5 or 6 kw unit in the lounge but went with the bigger unit. 
We use the 7.1 unit as the main heating for the whole house during the winter. It did need defrosting every 50ish min when the temp was below 0. 
Bigger units have lower COP or they are not as efficient as the smaller ones. I have not noticed the unit short cycling - even looking at the chart of power draw. 

 The smaller ones have been wired into the rings but the larger unit had a dedicated line from the fuse board(thankfully we had this already).  I suspect the higher peak power draw from the multi splits would need a dedicated circuit. 

If I was doing this again- I would dump the Daikin for Mitsi, you get much better temperature control and better Home Assistant integration. 

Also, multi split would have been an absolute disaster for us (as I have mentioned before). At times our bedroom units are running in the cooling mode when the lounge is on heating. 

The installation cost was just over 2k for the two daikins and similar amount for the Mitsi. But I also spent around 1.5k on Planning permission (yes, you need it). 
Finally, most installer provide 5 yr warranty if you get it annually serviced by them. 

Spies

You don't need PP for one unit, its classed a permitted development as long a the unit can be fit on the side or back of the house and is at least 1 meter away from a neighbours boundary

ispookie666

Spies said:

You don't need PP for one unit, its classed a permitted development as long a the unit can be fit on the side or back of the house and is at least 1 meter away from a neighbours boundary

There is no permitted development rights for any ASHP which is not used solely for heating. This is what the Planning portal says, you can interpret it which ever way you like and the council's interpretation is varied. 

Screwdriva

ispookie666 said:

I do have 3 units. Two daikins for the bedrooms - 2.5kW and a 7.1kW mitsi in the lounge. I could have got away with a 5 or 6 kw unit in the lounge but went with the bigger unit. 

Our options are below. I wonder if this will be sufficient to heat/ cool 5 bedrooms? Efficiency (SEER) is really impressive though and I'm told they come with a 7 year warranty. 

ispookie666

No idea @Screwdriva how big is the outdoor unit?  I'm a bit on the fence when it comes to multi splits. Someone that I know had to scrap the whole system, when the outdoor unit had  died as they could not get it replaced 

Screwdriva

ispookie666 said:

No idea @Screwdriva how big is the outdoor unit? 

https://www.toshiba-aircon.co.uk/product/r32-ras-haori-high-wall/

Not terribly large at all. I'd say around 25% smaller than a AroTherm+ A2W ASHP. 

JSHarris

ispookie666 said:

Spies said:

You don't need PP for one unit, its classed a permitted development as long a the unit can be fit on the side or back of the house and is at least 1 meter away from a neighbours boundary

There is no permitted development rights for any ASHP which is not used solely for heating. This is what the Planning portal says, you can interpret it which ever way you like and the council's interpretation is varied. 

We already had an ASHP (at the rear of the house and included in the PP for the house when built).  I couldn't find any mention of aircon in the Permitted Development rules so asked our local council planning department (cost me over £50 to just ask this simple question, believe it or not).  They wrote back saying that air conditioning systems mounted to the rear of a house didn't need planning consent as they fell within Permitted Development Rights (despite there being no mention of this in the Permitted Development Technical Guide on the government website).

ecraig

Following this thread with interest.
Makes the £1600 ballpark figure I received look quite good for 2 indoor units and 1 outdoor unit.
That was on a Samsung or Mitsubishi setup.
Would be keen to hear price points from others who had a recent installation or quote received.

ispookie666

@Screwdriva, the outdoor units for five rooms have a sound pressure level of 52dB which is pretty significant, maybe look at two splits?  

Spies

ecraig said:

Following this thread with interest.
Makes the £1600 ballpark figure I received look quite good for 2 indoor units and 1 outdoor unit.
That was on a Samsung or Mitsubishi setup.
Would be keen to hear price points from others who had a recent installation or quote received.

Which firm quoted that?