Solar and battery vs ASHP

1961Nick

Northern_Line said:

I've had one guy come to check our requirements who said he would only bother with Daikin or Mitsubishi as they're the best and there's not loads between costs, so that promising! Do you know if the 0% is also applicable to air-air?

If you're talking about VAT then the answer no. That's probably because air/air gives you the option of cooling which is counter-productive because it potentially increases energy consumption.

1961Nick

Northern_Line said:

1961Nick said:

Northern_Line said:

Thank you all.


I would love a GSHP, but our house is somewhat unique. It’s why we bought it!  Due to its different elevations, we don’t have a garden per se, instead we have a raised decking area of approximately 30m2, so the GSHP is not viable.

How much room is there under the decking because that would be a perfect location for ashp outdoor units?

About 30 m2? I must admit I hadn’t though about that. I will look into and see if they’re viable. I’ve heard very good things about them!

I was thinking more about height... you'd need about 60cm?

ispookie666

@1961Nick Unfortunately that is not correct.  A2A ASHP are eligible for 0% VAT and previously was 5%, I have had them installed at these rates.  

@Northern_Line You can look into having it installed under decking or raised as long as there is adequate airflow, if not this will be problematic 

• Height of winter, especially when temperature drops below 0C, as the whole thing can turn into a fridge/freezer 
• Height of summer 

The efficiency/COP can drop off significantly.  

1961Nick

ispookie666 said:

@1961Nick Unfortunately that is not correct.  A2A ASHP are eligible for 0% VAT and previously was 5%, I have had them installed at these rates.  

@Northern_Line You can look into having it installed under decking or raised as long as there is adequate airflow, if not this will be problematic 

• Height of winter, especially when temperature drops below 0C, as the whole thing can turn into a fridge/freezer 
• Height of summer 

The efficiency/COP can drop off significantly.  

I'd missed the reduction to 0% vat for dual use air conditioners in the spring budget so thanks for the update.

shinytop

ispookie666 said:

Any ASHP which can do cooling is not included in permitted development. Some councils have no clue about this, resulting in the common misconception about the first ASHP.
It is a silly rule hopefully will be superseded. The environmental planning officers are very cautious about the noise effect of the outdoor units. 

My Aircons were installed by an Aircon installer, you do need to be Fgas certified and was provided with 5 yr warranty, if purchased and serviced with him. 

The only incentive is 0% VAT as this is considered a low carbon tech. 

I'd suggest getting a reputable brand - someone once said, it's either Daikin or Mitsubishi ☺️

Actually the guidelines say "The air source heat pump must be: Used solely for heating purposes" So as long as you don't use it for cooling, the fact that it can do it shouldn't matter. Who knows with planning though. 

I think the reason cooling isn't allowed is the combination of a lot of open windows in summer and people running ACs at night. 

Some people also say that ACs in a UK summer are an expensive and environmentally irresponsible luxury.  A bit like hot tubs.   

Screwdriva

Both These options would set us back about £10,000. I’m inclined to believe the ASHP might kill two birds with one stone, deliver a long-term uplift in the EPC and in our case pay for itself relatively quickly. However, I wanted to test these options with the forum to see if my thinking is sound.

Thanks 

Here's a slight tweak on some of the above suggestions for you:

1) Max # of solar panels with SolarEdge optimizers/ inverter or Enphase micro inverters, but no battery (save the £8K)

2) Use those funds to invest in an Air to Air Source Heat Pump to provide heating/ cooling at a higher SCOP than Air to Water. Daikin, Panasonic or Mitsubishi are all excellent.

3) For Hot Water, invest in an Air Source Heat Pump Hot water cylinder like the Valiant AroStore OR invest in the upcoming Daikin Air to Air system (see #2 above) with a separate port for hot water (one A-A multi-split unit to heat the home and hot water). 

4) SD3 Micro Turbine to make up for those low solar days. Sounds like you may not need planning permission to install one. 

Excess PV generation can be sold back to the grid via Outgoing Agile Octopus. 

If twice as much funds were available (~ £15K), a Ground Source Heat Pump would have another more efficient than ASHP option in sub zero temperatures (albeit one that would not provide cooling if ever needed).

Reed_Richards

Screwdriva said:

If more funds were available, a Ground Source Heat Pump would have another more efficient than ASHP option (albeit one that would not provide cooling if ever needed).

Why not cooling?  In principle any heat pump can be run in "reverse" to provide cooling and in practice may commercially available heat pumps can do this.  Cooling air is liable to give rise to condensation and this can be a problem in any system designed primarily for heating - but that's not the fault of the heat pump.    

Screwdriva

Reed_Richards said:

Why not cooling?  In principle any heat pump can be run in "reverse" to provide cooling and in practice may commercially available heat pumps can do this.  Cooling air is liable to give rise to condensation and this can be a problem in any system designed primarily for heating - but that's not the fault of the heat pump.    

https://www.youtube.com/watch?v=GKDucs4zl7Y

Been tried. In practice, doesn't work with radiators or UFH, even with a boatload of radiator fans. Besides, who doesn't like a nice cool breeze (that only an A-A heat pump can deliver)?

Solarchaser

If you are pulling up the floor anyway, then ufh sounds a good shout to me.

Low valley and poor aspect would suggest a poor return on solar, though I wonder if you could ground mount in front of your decking area?

Solar and heating are not necessarily great bed fellows, however solar can reduce your heating bill in the shoulder months where you may use heating but it's still quite sunny, March, April, September,  October. 
And as you will use hot water all year round, it can be helpful there too.

An overly large water tank that runs heating and hot water may be a solution,  and heating provided either by a heat pump, or by immersion ran off peak (as I am... trialling).

There are multiple options.

I'd suggest you explore all your solar options before diving in to anything, as regardless of what system you go for, solar will definitely help reduce the bills.

Northern_Line

Hi all,

Happy new year and apologies for not getting back to you all. We decided in the end to go with air-water heat pump system. 

My preference was actually air-air but finding someone to come and quote, or even get those who came to quote to actually provide a quote, has proved unsuccessful.

As with all these things when you’re spending money, the quality of the company is everything. Our preferred contractor has been responsive, is well reviewed, competitive for the quote and has decades of experience as well as being locally based. So overall, we’re happy with choosing them.

The one delay has been a result of us haggling with the developer. We’re arguing it’s a disgrace we’re having to change the heating system after buying this place only 4 months ago. Then again, a new build developer is only obliged to provide you with a heating system, not a cost effective or heat effective one.  We knew these heaters would be rubbish when we agreed to buy the property so we got a good deal on the price. At the end of the day we might be on a hiding to nothing but it feels like it’s worth a try.

I’ve not ruled out solar, but the priority for this winter is to sort the heating so we’re not freezing next year or spending absurd amounts on energy. We might upgrade our car in the summer and if we go with an EV, we will review whether we want solar then.