Fitted Air conditioning

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MattyD803

1,690 posts

64 months

Thursday 24th June 2021
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Fentalogue chic said:
That's some potentially huge solar gain. Might be worth getting someone with Hevacomp or IES VE to do some calcs for you with roof/wall makeup etc. Wouldn't take too long to get a rough idea, or even to establish where you want your indoor unit - cooling the whole room or blowing cool air towards a particular area.
HEVACOMP and or IES VE would certainly be the way to go....but in reality, he's unlikely to find someone willing to spend the time to do that properly as a freebie (once you build it, set up the orientation, construct U-Values etc etc)

From my experience (CEng Klanky), having spent a good few years thermally modelling), as an estimate for the cooling requirement for a 30m.sq 'fairly' leaky shed, with poor-ish U-values, people coming in and out, loads of sun being dumped on the roof, blinds up, blah blah, I would allow a minimum of 250 W/m.sq for cooling.

Therefore, you'll want 7.5kW, minimum. That is, if you want to be able to hold 21/22 deg. internally when its 32/33 deg. outside.

If you want to just deal with warm British weather 'most' of the time (say up to 25/26 deg. outside), and are happy for the internal temp to drift up to say 25degress when it gets hotter outside, 3kW will just about keep your knackers from sweating too much, but you'll want to be keeping the doors closed, blinds shut etc.

You's pay your money, you's take your choice.....but if you want it to double up for heating and cooling all year round, you'll want more than 3kW.



Edited by MattyD803 on Thursday 24th June 12:21

matt666

445 posts

203 months

Thursday 24th June 2021
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I'm trying to get a ballpark on running costs. I'm having a 2.5kW unit fitted, it apparently has a SEER of 7.3. Does that mean a consumption of 2,500 / 7.3 = 342W at full chat? Obviously the inverter will ramp up and down so would average less than that.

Have I got that right?

fastbikes76

2,450 posts

121 months

Thursday 24th June 2021
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matt666 said:
I'm trying to get a ballpark on running costs. I'm having a 2.5kW unit fitted, it apparently has a SEER of 7.3. Does that mean a consumption of 2,500 / 7.3 = 342W at full chat? Obviously the inverter will ramp up and down so would average less than that.

Have I got that right?
My 7.5kw (27k btu) multi split pulls around 1kw leccy with all 3 units on flat out on turbo mode. I have a smart meter fitted and it averages out to £1 a day for all three bedrooms running 10 hours a day.

mfmman

2,362 posts

182 months

Thursday 24th June 2021
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No, SEER will be the average, the S is for seasonal. Full load will probably be just under 1kW

mfmman

2,362 posts

182 months

Thursday 24th June 2021
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fastbikes76 said:
My 7.5kw (27k btu) multi split pulls around 1kw leccy with all 3 units on flat out on turbo mode. I have a smart meter fitted and it averages out to £1 a day for all three bedrooms running 10 hours a day.
I'm not disputing the consumption you are seeing but think that your figures are lower as the heat load is more based on building fabric and external gains rather than internal load (like people, IT and lighting). Once you have the room temperature and fabric temperature pulled down closer to your set point then the systems will ramp down pretty quickly and just idle along at low speed. If the system was running flat out (as in inverter at full speed) for an extended period then the consumption would be higher, possibly above 2kW

fastbikes76

2,450 posts

121 months

Thursday 24th June 2021
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Just reset the smart plug, and ran all three indoor units flat out for an hour on lowest temp and turbo setting. The AC hadn’t been on today as I’ve been in the garden enjoying the sun. House is quite toasty with downstairs thermostat reading 23.5 with doors open.

Regardless of what power it does pull, at 15p per kw/h I use almost exactly a £1 a day on the hottest days when all three units are run flat out to cool the whole house for 10-12 hours. Smart meter readings pre resetting earlier where showing £15.73 leccy over the last 22 days.


MattyD803

1,690 posts

64 months

Thursday 24th June 2021
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fastbikes76 said:
Just reset the smart plug, and ran all three indoor units flat out for an hour on lowest temp and turbo setting. The AC hadn’t been on today as I’ve been in the garden enjoying the sun. House is quite toasty with downstairs thermostat reading 23.5 with doors open.

Regardless of what power it does pull, at 15p per kw/h I use almost exactly a £1 a day on the hottest days when all three units are run flat out to cool the whole house for 10-12 hours. Smart meter readings pre resetting earlier where showing £15.73 leccy over the last 22 days.

I mean, can't really argue with that, but it does seem like a very high CoP. What make of splits are they?

In terms of what you are measuring, is that 7.5kW of multi split air conditioning plugged in through a single 13A socket on your meter, or am I confused?

fastbikes76

2,450 posts

121 months

Thursday 24th June 2021
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MattyD803 said:
I mean, can't really argue with that, but it does seem like a very high CoP. What make of splits are they?

In terms of what you are measuring, is that 7.5kW of multi split air conditioning plugged in through a single 13A socket on your meter, or am I confused?
Yup, the only reason I check constantly is because I find it hard to believe myself how cheap it is too run.

It’s an ElectriX (sp?) 27 000 btu multi split which is 3 x 9000btu indoor units and a single outdoor unit with a Toshiba inverter compressor I’m lead to believe. Everything is powered via the outdoor unit which is plugged into a single 13amp socket in the garage. It’s never pulled anywhere near 13amp by a country mile though.

On heating mode it pulled just shy of 2kw load but I can’t remember if that was 1 or more units on at once. I won’t be using them for heating anyways.

What I find interesting is put one unit on and it pulls about 500-550w, the second and 3rd unit only adds another 250-300w load as I guess the compressor is already running . So not much more to run all 3 units than it is to run just the one.

MattyD803

1,690 posts

64 months

Thursday 24th June 2021
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fastbikes76 said:
Yup, the only reason I check constantly is because I find it hard to believe myself how cheap it is too run.

It’s an ElectriX (sp?) 27 000 btu multi split which is 3 x 9000btu indoor units and a single outdoor unit with a Toshiba inverter compressor I’m lead to believe. Everything is powered via the outdoor unit which is plugged into a single 13amp socket in the garage. It’s never pulled anywhere near 13amp by a country mile though.

On heating mode it pulled just shy of 2kw load but I can’t remember if that was 1 or more units on at once. I won’t be using them for heating anyways.

What I find interesting is put one unit on and it pulls about 500-550w, the second and 3rd unit only adds another 250-300w load as I guess the compressor is already running . So not much more to run all 3 units than it is to run just the one.
Well blow me down, assuming your meter is accurate, that's an excellent CoP.....food for thought that....

fastbikes76

2,450 posts

121 months

Thursday 24th June 2021
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MattyD803 said:
Well blow me down, assuming your meter is accurate, that's an excellent CoP.....food for thought that....
Meter is accurate enough, wouldn’t want to measure down to decimal points but on face value my 3kw hot tub heater pulled 3kw on the smart plug so near enough for me. As I say, totally blew my mind how cheap it is to run, then again a fridge costs sod all to run all year and this is just three big ones with the doors left open biggrin

Harry Flashman

19,283 posts

241 months

Thursday 24th June 2021
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MattyD803 said:
Well blow me down, assuming your meter is accurate, that's an excellent CoP.....food for thought that....
I have the same brand, and get the same result on a dual split. Really, it shows that sharing one main outdoor unit is a good idea and doesn't seem to compromise cooling power. Difference is I only have one multi split, so if I run separate units to other rooms it goes up.

The multi split does downstairs main common areas, and the separate smaller single split or one box units do bedrooms - logistically I was unable to use a multi split for multiple bedrooms. That said, bedrooms work out relatively cheap at night as we have four hours of cheap electricity due to the Octopus Go tariff we have for the electric car.

They really are not horribly expensive to run.

Flumpo

3,685 posts

72 months

Thursday 24th June 2021
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Sorry to derail a bit, how often are people having their air con serviced? Is that a thing? I have a Panasonic set up but it’s over 2 years old now and not sure if I should get someone to look at it.

Google doesn’t come up with anything apart from commercial servicing locally - Leeds.

Thanks I’m advance

Fentalogue chic

5,245 posts

119 months

Thursday 24th June 2021
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No point - clean the indoor unit filters, make sure there are no leaves built up round the outdoor unit - that's about it. Maybe some slightly bleachy water run through the condensate tray and pipe if you are paranoid.

Flumpo

3,685 posts

72 months

Thursday 24th June 2021
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Fentalogue chic said:
No point - clean the indoor unit filters, make sure there are no leaves built up round the outdoor unit - that's about it. Maybe some slightly bleachy water run through the condensate tray and pipe if you are paranoid.
Thanks I will have a look, it was more i wasn’t sure if various parts needed any maintenance rather than any cleanliness concerns.

Fentalogue chic

5,245 posts

119 months

Thursday 24th June 2021
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Flumpo said:
Thanks I will have a look, it was more i wasn’t sure if various parts needed any maintenance rather than any cleanliness concerns.
No maintenance required other than that mentioned, unless it stops working.

Fentalogue chic

5,245 posts

119 months

Friday 25th June 2021
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ThatGuyWhoDoesStuff said:
I've had a quote from a company for the installation of a split system with a single outdoor unit, and 2 indoor units - powered from being wired into a mains double socket.

The indoor units are specced at 2.5kW and 3.5kW, and the outdoor unit has a cooling capacity of 3.2-7.7kW.

I've had a quote from another company and they've said they can't do the above - as the power draw will be too high for a double socket. They haven't inspected the circuit, so by all accounts it's your bog standard double socket. They said I'd need to run from the mains board (which would be difficult).

So who is right!?
Check the specs of the unit you are looking at - it will give the maximum electrical current draw. Then check with a spark that you can pull that from the wiring you have in place.

surveyor

17,768 posts

183 months

Sunday 4th July 2021
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Just the electrics and gas to sort out.

I’m not going to embarrass name him by name but one particular member of the forum went beyond all expectations by lending a scaffold tower, drill and trailer to transport them all. Remarkable individual.

Edited by surveyor on Sunday 4th July 16:20

4Q

3,347 posts

143 months

Sunday 4th July 2021
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surveyor said:






Just the electrics and gas to sort out.

I’m not going to embarrass name him by name but one particular member of the forum went beyond all expectations by lending a scaffold tower, drill and trailer to transport them all. Remarkable individual.

Edited by surveyor on Sunday 4th July 16:20
thumbup looks good

PF62

3,575 posts

172 months

Sunday 4th July 2021
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surveyor said:
Microwave oven sat on a counter?

look at the thumbsnap automatic tags in the original picture

Fentalogue chic

5,245 posts

119 months

Sunday 4th July 2021
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surveyor said:
The sneaky downpipe install... one of my favourites. I have 3 downpipes going up the gable wall of my house "connecting" to the gutter - only one of them actually carries water. laugh