Why aren't A2A ASHP more popular

[RomyD]

Having realised that RHI will not assist financially with our bungalow renovation due to timelines, we have been looking at alternatives. We considered storage heaters which I expect are much better these days compared to when many of us experienced them years ago, but then Iceverge on here suggested A2A either single or multi split units. 

 

To use A2W we would need rads or UFH neither of which are currently installed so additional expense there. A2A avoids all this.

 

A2A multi split seems like an ideal solution but why is it not a more popular choice considering how cost effective it appears to be?

[J1mbo]

1. Continual fan noise inside
2. The puffing around of hot air

[SteamyTea]

2 minutes ago, J1mbo said:

The puffing around of hot air

That is an advantage of them.

[J1mbo]

That would be personal preference. Typically delivered as high-wall splits, the draft can we quite uncomfortable e.g. for contact lens wearers. I think it's fair to say that most prefer not to have a stream of warm air on their face, which is why cars deliver heating at foot level when set on auto.

[Mr Punter]

The fan noise on many of these systems have a sound pressure of between 20 and 50 dBA depending on the setting they are running at.

 

In heating mode, the warm air is directed downwards to avoid any discomfort.

 

I find that hot radiators, especially with the fins, can set up currents of hot dry air that swirly around the room.

[Iceverge]

Gas was too cheap. 

 

Tradition of wet heating systems. 

 

No contribution to DHW. 

 

Costs start to stack up if you want to out one in every room ( in a well insulated house you don't BTW) 

 

COPs weren't always as good as now. 

 

People didn't know about them in a residential setting. 

 

If you look outside our fair isles they are extremely popular. 

 

[ValleyBoy1958]

A2A was never eligible for RHI payments, so I think that would be the main reason. I looked into it and it worked out much cheaper than an A2W system but our place, being a dormer bungalow, was not suitable due to the tortuous and quite lengthy pathways that the pipework would have had to make.

[saveasteading]

7 hours ago, RomyD said:

We considered storage heaters which I expect are much better these days

That is what the manufacturers say. But physics has not changed and energy in = energy out.

What has improved is the control system for temperature and time. 

 

But it is still using electricity to heat a brick in the night while the price is lower: not really sophisticated at all.

[SteamyTea]

2 hours ago, saveasteading said:

What has improved is the control system for temperature and time. 

Marginal improvements in the insulation, and the brick material, which can make them a little lighter.

Some have fans built in as well.

But basically, they are just heated bricks and a controllable flap to manage the airflow though them.

[TonyT]

You can duct them too, and have a large unit in the loft space with insulated ducts to rooms, so doesn’t need to be the traditional mini wall mounted split system.

 

 

[RomyD]

Maybe other countries that didn't benefit from huge gas reserves needed something else and gas is indeed too cheap. I suppose coal was once the enemy and now it's gas. They will need to migrate the green surcharge away from electricity and on to gas.

 

Anyway UFH would be nice but we can only fit 70mm floor insulation (upgrading from 20mm EPS). Is 70mm enough for UFH?

 

The other thing that puzzles me is that swimming pool A2W heat pumps are also not covered by RHI and appear much cheaper but don't work when it's really cold. Is RHI code for Really Highly Inflated pricing?

 

 

 

[RomyD]

10 minutes ago, TonyT said:

You can duct them too, and have a large unit in the loft space with insulated ducts to rooms, so doesn’t need to be the traditional mini wall mounted split system.

 

 

I quite like the idea of a split system with a pair of internal units. The layout of the bungalow is a large lounge/ kitchen/ diner open plan area of about 55sqm and a hall with the bedrooms hanging off it. One unit in the hall and one in the kitchen/diner area might just do it. We don't like overly warm bedrooms, just a zillion tog duvet does just fine. Most of the glass, windows and bifolds is south facing too. 

[SteamyTea]

10 hours ago, RomyD said:

Is 70mm enough for UFH?

Not really.

[Gone West]

11 hours ago, RomyD said:

Anyway UFH would be nice but we can only fit 70mm floor insulation (upgrading from 20mm EPS). Is 70mm enough for UFH?

I don't understand why people go to the effort of insulating and draughtproofing their houses and then put in a heating system that directly sends a certain proportion of that heat into the ground. IIRC Jeremy calculated that he lost 8% to the ground through his 300mm EPS underfloor insulation. Using radiators is more efficient but even then, heating water to heat a concrete slab or metal radiators to then heat the air seems daft. Why not just heat the air directly, A2A. Over the years I've read on GBF about contributors who use A2A successfully.

 

https://www.aircon247.com/p/9324538/lg-mu5r30u40-88kw-multi-split-outdoor-unit-r32---202122.html

 

Rant over.

 

[TW9]

It does seem that in the UK we're largely in a one solution fits all mindset. Need heating? Fit a gas boiler. While the govt is trying to move us away from gas they aren't doing anything to break the mindset. Instead of the only solution being gas they're trying to make the only solution A2W heat pumps.

 

A2A could work really well for some properties so why isn't it being promoted alongside A2W?

[smart51]

The parents of a friend of mine lives in a house from the 60s where the whole estate was built with warm air heating.  There were vents in the floors and walls and ceilings.  They really liked it but all their neighbours had the systems replaced in the 80s with gas central heating.  Not for any good reason, parents of friends said.

 

Brits have a very rigid way of thinking at times.  "There is only one acceptable way to do things".  It used to be coal.  And then it was gas.  You'd be labeled a weirdo for having anything else.

 

20 years from now most houses will have heat pumps.  20 years after that we'll have a generation of people who have known nothing else.  Except for their weird granddad who still burns dinosaur fart.

[SteamyTea]

29 minutes ago, Gone West said:

Using radiators is more efficient but even then, heating water to heat a concrete slab or metal radiators to then heat the air seems daft. Why not just heat the air directly, A2A

Basically comes down to the thermal properties of materials.

You can physically move a lot of energy, quickly, with water, not so easy with air.

 

[SteamyTea]

Just now, smart51 said:

Except for their weird granddad who still burns dinosaur fart.

There are people in the village I work in that still burn coal.  Quite a few of them.

They were offered bore hole GSHP, for free, a few years back, not many took them up on the offer.

[ProDave]

16 hours ago, saveasteading said:

That is what the manufacturers say. But physics has not changed and energy in = energy out.

What has improved is the control system for temperature and time. 

 

But it is still using electricity to heat a brick in the night while the price is lower: not really sophisticated at all.

It is almost impossible to buy an old style storage heater now.  All you can get now are LOT20 compliant types that have electronic controls.  That of course means they need a permanent supply as well as the off peak supply.  They also incorporate a convector heater.  No doubt they achieve better room temperature control but that will to some extent be by using peak rate heating to supliment stored heat.

 

I was asked to repair one once where the fancy controller had failed and the cost of a replacement for that made a gas boiler control PCB look like good value.

 

There is nothing I have seen about these expensive posh versions of storage heaters that would make me want one.

[SteamyTea]

2 minutes ago, ProDave said:

All you can get now are LOT20 compliant types that have electronic controls. 

I looked into replacing mine a while back.  I was not impressed with the cost.

I did think of making a plinth, with a couple of fans around the base of mine.

Then just control the fan when I wanted more convection.

Trouble is my heat load is too small to worry about it.

[Iceverge]

1 hour ago, TW9 said:

A2A could work really well for some properties so why isn't it being promoted alongside A2W?

 

It's too cheap and  too easy. 

 

Couldn't possibly work . 

[Iceverge]

1 hour ago, SteamyTea said:

There are people in the village I work in that still burn coal.  Quite a few of them.

They were offered bore hole GSHP, for free, a few years back, not many took them up on the offer.

 

They're  waiting to see how gas works out. Its probably still too early to tell. 

[SteamyTea]

6 minutes ago, Iceverge said:

 

They're  waiting to see how gas works out. Its probably still too early to tell. 

Yes, especially as they know they are not going to get any piped in.

 

[joe90]

3 hours ago, Gone West said:

I don't understand why people go to the effort of insulating and draughtproofing their houses and then put in a heating system that directly sends a certain proportion of that heat into the ground. IIRC Jeremy calculated that he lost 8% to the ground through his 300mm EPS underfloor insulation. Using radiators is more efficient but even then, heating water to heat a concrete slab or metal radiators to then heat the air seems daft. Why not just heat the air directly, A2A. Over the years I've read on GBF about contributors who use A2A successfully.

 

https://www.aircon247.com/p/9324538/lg-mu5r30u40-88kw-multi-split-outdoor-unit-r32---202122.html

 

Rant over.

 

However, I think 8% losses through the floor is minimal and in my case (as I have UFH) worth the small cost to not have (what I consider) ugly radiators or “indoor units”. My heating costs are so low that 8% of very little is very very little ?‍♂️. My heating is yet to come on yet this year. I do however have a new well insulated house and existing housing stock is not this fortunate so I think there is a market fir the A2A units.

[SteamyTea]

42 minutes ago, joe90 said:

I do however have a new well insulated house and existing housing stock is not this fortunate

Mine isn't on either, it is a very mild November in the SW this year.