Quick question regarding ASHP

[MrTrevithick]

I’ve noticed these things seem very popular these days and, when you think about it, there’s quite a clever idea hatching there.

One of my customers (a large holiday site) has several new “eco” lodges which are fitted with Mitsubishi units which are supplying the under floor heating and the hot water. The lodges are all built to the modern building specs and when the sun comes out through the large windows are lovely and warm. I can also say the ASHP system does a fantastic job of heating them up.

But a couple of issues.

1. They do like a fair amount of power for an “eco” system, is this normal? They have compared with the older Scandinavian lodges on site (heated with electric heaters and an unvented cylinder with immersion) and they seem to use as much power if not a bit more.

2. The older ones are coming of age and they are starting to break down quite often, control cards, compressors, you know all the expensive stuff. One of the bean counters on site worked out due to these problems and the install / repair costs that they are more expensive to run. Is this normal and people are fitting them because they have a green reputation? 
The reliability issues maybe due to the proximity to the sea perhaps? They don’t look that corroded but salt can get in everywhere.

I’m genuinely interested on peoples views as my customer is starting to get suspicious of these things as being a gimmick and I would like to give him a balanced view.

cheers

[Onoff]

15 minutes ago, MrTrevithick said:

They do like a fair amount of power for an “eco” system, is this normal?

 

How much power they consume is related to just how "eco" these lodges are.

 

Modern building specs are tbh woeful when you compare the lengths people on here go to to achieve fantastic air tightness and insulation levels. Mass builders (probably including eco lodge builders) just generally don't take the time or pay the same attention to detail as individuals with a true understanding of the two concepts. Those that do see massive rewards in terms of lower or even negative fuel bills often when coupled with decent sized PV. 

 

So "eco" might be very misleading in this case. 

Edited December 11, 2020 by Onoff

[joe90]

You say these units “are coming of age”, modern ones are  inverter driven which makes them less power hungry  which make them more efficient. Normally a well designed and installed ASHP gets a COP of about 3 ( 3kW of heat fir 1kWof electricity) but as said above it all depends on the heat required which means the level of insulation, attention to air tightness and a good design.I doubt they have access to mains gas so you can only compare them to oil or bottled gas (excluding direct electricity which has a COP of 1).

 

edit as corrected by @SteamyTea below 

Edited December 11, 2020 by joe90

[SteamyTea]

Can I come and have a look next time you are visiting, I think there is more to this than meets the eye.

 

Two related things spring to mind.

They are undersized and the majority of the use will be for DHW.

[SteamyTea]

28 minutes ago, joe90 said:

3kW of heat fir 3kW of electricity

Or 9kW (Edit, put right above)

 

Not really about kW though, it is about kWh as that takes a time period into account.

 

During a typical week, the CoP may range from just under 1 (legionella cycle), to over 6 (very mild, dry weather and at the point of maximum power transfer).

It also matters where it is measured.  What comes out of the hot tap will be lower than what comes out of the hot pipe from the ASHP.

Edited December 11, 2020 by SteamyTea

[joth]

3 hours ago, Onoff said:

Modern building specs are tbh woeful when you compare the lengths people on here go to to achieve fantastic air tightness and insulation levels. Mass builders (probably including eco lodge builders)

 

Exactly this. I'd imagine that you just need to build a lodge out of sustainably sourced timber to claim the eco badge. In extremis,  I can imagine yurt style eco lodging claim eco as it's like a tent and anticipated no-one would put a heater in it, but then  glamping happened and you can't claim luxury without a 20°C+ sleeping temperature so they get jammed full of cheap heaters. 

 

 

[MrTrevithick]

Interesting points, thank you.

The coming of age seems to be between 3-5 years (or a couple of weeks after the guarantee runs out), as for the build quality of the lodges (which they sell for well over £300k) is getting better but the early ones was terrible but, as pointed out, these are mass production units.

To be honest I’m just in the process of getting rid of the customer but it’ll be nice to present some facts about the shortcomings to the owner,I’ll find out more about the sizing.

I know what you mean about people will always care more when it’s their own project, I suspect this maybe a prime example.