ASHP, Just an outdoor fridge ?

[Post and beam]

So, i have been investigating the potential of an ASHP instead of a gas boiler in my Potton design.

The technology looks very close to a refrigerator, in fairness one that is expected to last for 20 years but still... a fridge all the same.

Can anyone educate me why they are so fxxxng expensive.

 

I get suspicious when the sales blurb tried to justify a higher wattage model 16kw instaed of 9kw for example would cost more to install because its physically a bit bigger and heavier. Why ?

 

Up to £8k - £10k to install.   I cannot see this at all.

 

Please enlighten me wise people.

 

Thanks

keith

[ReedRichards]

Those large "American style" fridge freezers are pretty expensive and their volume is not huge compared to the volume of a typical dwelling.  Scale up a fridge freezer by volume and an ASHP looks pretty cheap.  The installation cost must depend largely on how much of the necessary infrastructure you have.  If you are starting from scratch then central heating with a ASHP should cost much the same as central heating with a gas boiler except for the difference in cost between the boiler and the heat pump.  You'll need a hot water cylinder with the heat pump whereas you might have a combi gas boiler and the radiators, if you have them, need to be larger surface area so a bit more expensive.    

[joe90]

I get told off when I refer to an ASHP being a fridge in reverse, but the techknowledgy is the same, dead east to fit DIY, (I did mine), I guess it’s economy of scale, when they become mainstream like gas boilers their price will come down (psss look on EBay Like I did).

[Iceverge]

I too couldn't see the ridiculous price for install making sense. You can buy an ASHP for 2.5k yet the install seemed to add 12.5k to the build.

 

Direct electric here. 

 

We insulated our way out of the conundrum. 

[ProDave]

You can easily buy an ASHP for about £5K and it just needs a plumber and an electrician capable of reading an instruction manual to install it.

 

Or you can pay a "specialist" company a lot more to install it.

 

 

[JohnMo]

There a rip off because the government will chuck £5k towards installers.  The installers hike up the price and say 'but we are now giving you £5k off because of the grant.

 

Technically not any different from an A2A heat pump, slightly different heat exchanger and no fan coil unit inside the house.  So actually simpler, but generally cost more.

 

You can get them at a reasonable price, you need to shop around and DIY install as mentioned above, rather than going for a grant.

 

You really don't want to over size them.

[Radian]

9 hours ago, joe90 said:

I get told off when I refer to an ASHP being a fridge in reverse

 

I wonder why?

 

If you took an ordinary fridge and peeled it apart so you could shove the internal cooling panels outside your wall and kept the bit at the back (that gets hot) inside your hose - then set it to try and cool the contents of the fridge (now the entire world outside) you'd be almost there. Add a fan to the outside bit to keep more air passing over it for efficiency and you've got the majority of the components of an ASHP. (Oh and swap the fridge thermostat for a central heating type)

[SteamyTea]

59 minutes ago, Radian said:

wonder why?

I don't, they work just the same as a fridge.

A fridge in reverse would produce electricity from a temperature difference.

[Radian]

2 minutes ago, SteamyTea said:

I don't, they work just the same as a fridge.

A fridge in reverse would produce electricity from a temperature difference.

Yes, we're into the semantics of "reverse". Of course the configuration of a Stirling engine actually gets this job done using the same physics.

[HughF]

Buy it and diy install it, there is zero justification for paying an installer, unless you’re the sort of person who doesn’t understand plumbing. But then you probably wouldn’t be on a self build forum.

When I’m in front of the laptop I’ll upload the freedom heat pumps sizing/design toolkit spreadsheet. It’s pretty decent (but has a few flaws)

[George]

Now the RHI has gone, buying direct is more appealing. The £5k grant can easily just be gobbled up in the overheads of a specialist company.

 

I paid £11.5 for a 16kW system with all the internal tank and install. But that's all coming back as RHI payments (£2.5k back already) so just paying for the inflation.  

[SimonD]

On 11/07/2022 at 23:03, joe90 said:

I get told off when I refer to an ASHP being a fridge in reverse, but the techknowledgy is the same, dead east to fit DIY, (I did mine), I guess it’s economy of scale, when they become mainstream like gas boilers their price will come down (psss look on EBay Like I did).

 

On 12/07/2022 at 10:03, SteamyTea said:

I don't, they work just the same as a fridge.

A fridge in reverse would produce electricity from a temperature difference.

 

On 12/07/2022 at 10:12, Radian said:

Yes, we're into the semantics of "reverse"

 

Funnily I've just been watching this series on heatpump design on the Institute of Refrigeration website: https://ior.org.uk/heat-pump-design-course

 

The guy running the training says in the introduction.

 

AND NO..a heat pump is NOT a reversed refrigerator.
• IT IS a refrigerator.

I suppose that clarifies things except a lot of people might think it's going to make their house cold......

[joe90]

Perhaps the word “opposite” rather than “reverse” then, a heat pump that produces the opposite result, heat rather than cold 🤷‍♂️

[SteamyTea]

9 minutes ago, joe90 said:

Perhaps the word “opposite” rather than “reverse” then

That would be a cooker.

[joe90]

59 minutes ago, SteamyTea said:

That would be a cooker.

No, that’s not a heat pump 🤷‍♂️

[SimonD]

9 hours ago, joe90 said:

Perhaps the word “opposite” rather than “reverse” then, a heat pump that produces the opposite result, heat rather than cold 🤷‍♂️

 

8 hours ago, joe90 said:

No, that’s not a heat pump 🤷‍♂️

 

Well, to matters even more clear to the unitiated, the guy running the heatpump training moved on to explain that a heatpump pump makes heat 'run up hill' compared to the normal process of heat rolling down a hill from hot to cold. That's definitely the reverse cycle, but I can't help but imagine a scenario explaining to a customer that it's a refrigerator that chases heat up the hill using what's in effect a powerful water gun. I wonder how many customers would sign you up then 😁

[SteamyTea]

38 minutes ago, SimonD said:

moved on to explain that a heatpump pump makes heat 'run up hill' compared to the normal process of heat rolling down a hill from hot to cold

"All models are wrong, some models are useful".

 

Time for this, again.

 

 

[JohnMo]

It is the same. A fridge removes heat from the air (inside a fridge) and moves the heat the to room. 

 

A heat pump removes heat from the air in its location and puts into the room.

[Radian]

11 hours ago, SimonD said:

AND NO..a heat pump is NOT a reversed refrigerator.
• IT IS a refrigerator.

I suppose that clarifies things except a lot of people might think it's going to make their house cold......

 

Therefore the introduction could say "IT IS a refrigerator that tries to cool the outdoor world" to clarify things.

[SteamyTea]

6 minutes ago, Radian said:

 

Therefore the introduction could say "IT IS a refrigerator that tries to cool the outdoor world" to clarify things.

Or

 

PV/T = C

 

Where:

P = Pressure

V = Volume

T = Temperature

C = Is Constant

 

Or, a picture

 

[Marvin]

My one is a reverse reverse refrigerator as it is producing heat on the outside and cool on the inside at the moment. 

Edited July 29, 2022 by Marvin

[SteamyTea]

How do PV sales people describe how they work.

Do they say they create a black hole.

[JohnMo]

And back to the question - why do cost so much?

[SteamyTea]

1 minute ago, JohnMo said:

And back to the question - why do cost so much?

There was a question?

[jack]

32 minutes ago, Radian said:

 

Therefore the introduction could say "IT IS a refrigerator that tries to cool the outdoor world" to clarify things.

What about when my ASHP is in cooling mode?