Portable split air to air

QrizB

The Washington Post has an article on how European imports of Chinese air conditioners is up 55% on last year.

The article itself is paywalled, but here's a snippet about the Midea Portasplit (the one I didn't buy as it was out of my price bracket):

Midea’s PortaSplit — a particularly popular portable unit designed to circumvent European regulations prohibiting certain building modifications — quickly sold out, leading some desperate consumers to create websites monitoring PortaSplits as they were restocked. Sales of the model reached more than 200,000 units in Europe this year, double the figure from a year earlier, the company’s regional sales director told the Chinese state-run wire service Xinhua.

Here's the German website they refer to, that's monitoring Portasplit stock levels in Germany:

https://braucheklima.de/

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/82063415#Comment_82063415

This is really useful information. So I can assume that while the portasplit runs of full power, it will consume over 1.2KWh of power vs. the Delonghi EX100 which will consume just over half that at 640 Watts at full blast. When the room reaches the desired temperature, the Midea will modulate itself down to 350 odd Watts where the Delonghi will just cut out the compressor entirely, which drops consumption to under 100 Watts.

QrizB

So I can assume that while the portasplit runs of full power, it will consume over 1.2KWh of power vs. the Delonghi EX100 which will consume just over half that at 640 Watts at full blast.

I don't think that's a reasonable assumption. Or, at least, it's not a reasonable comparison.

The power required by the split to deliver 12k BTU will depend on the difference in temperature between indoors and outdoors. When it's hotter outdoors, the pump needs to work harder to compress the refrigerant to a liquid and the returning refrigerant is warmer and so more needs to be pumped around the circuit to get the same amount of refrigeration capacity. On the other hand, when it's cooler outside it'll need less power.

It's the same effect you see with ASHPs used for heating, where the COP is higher in warmer weather and lower in colder weather. If the indoor temperature is the same as the outdoor temperature, the maximum power required should be quite a lot lower.

If I'm awake at midnight (which is when the Met Office next expect it to be 21C here) I'll crank the split up to the max and see how much power it needs then. It should be much less than the 1200 watts I saw when it was 33C outside.

Equal indoor-and-outdoor temperatures is how your Delonghi is rated per Table 2 of Annex VII (since both sides of the heat pump are fed by indoor air). However, if it's cooler indoors than outdoors, your single-hose unit will be drawing hotter air into the house. While the unit itself will still be drawing 640 watts and removing 2500 watts of heat from the room, the effect of drawing hot air back into the house will be to reduce the effective performance.

A very rough energy & mass balance calculation (assuming a 20C room temperature, 60C heat pump exhaust and 30C outdoors, with an air heat capacity of 1.21 J per litre-Kelvin) would suggest such a system would be drawing ~65 litres/second of outdoor air back into the building, which is an energy flow of 785 watts. That's an effective 31% loss of capacity from 2500 watts to 1715 watts, and an effective EER reduction to 2.7.

(60C is the generally-quoted maximum exhaust temperature for hose-equipped heat pumps. A lower temperature would result in more performance loss, a higher one would be better. If you know the actual exhaust temperature for your Delonghi I can repeat the calculation.)

When the room reaches the desired temperature, the Midea will modulate itself down to 350 odd Watts where the Delonghi will just cut out the compressor entirely, which drops consumption to under 100 Watts.

That's also not accurate, as you hadn't asked that question! At ~350 watts the split was still providing cooling. Once the target temperature is achieved, if no more cooling is required my split will stop cooling and justrun the circulation fan pulling 30-40 watts. But it's a tapered approach; it doesn't run flat-out then cut out, it reduces its output to maintain the target temperature until such time as minimum output is still too much, then stops.

When the room temperature rises, it'll re-start at minimum output and ramp up again if needed.

Aside:

Looking online it seems an earlier version of the EX100 used R410A rather than R290. Do you know which version you have? It should be marked on the label on the unit itself.

QrizB

It's not midnight yet, and it's not 21C outside (it's closer to 25C) but I'm off to bed.

I changed the set temperature on the split to 16C and cranked the fan up to "turbo", the highest setting, to try to provoke it into maximum output. Power drawn increased to about 750 watts and stayed there while I left it running for ten minutes.

I then returned it to the previous settings of 21C and medium fan. Power dropped back in stages and, after a few minutes, the unit stopped trying to cool the room. Power demand dropped all the way to 5 watts while it waited for the room to warm up again.

While I was typing the previous paragraphs, it has cycled back on again and is now using 370 watts and providing cooling. (I can't say exactly how much cooling; I'd need instrumentation I don't own for that.)

QrizB

I wasn't awake at midnight but I was at 0440 when it was about 17C outside.

I repeated my experiment. Power consumption topped out at 385 watts.

If it was delivering 12k BTU / 3.5kW that would be an EER of around 9, which seems on the high side but isn't impossible considering it was pumping heat "downhill" from a warm place to a cooler place.

(Immediately before I adjusted the settings for the experiment, the split was providing some cooling and was drawing 230 watts. That's the lowest power-while-cooling I recall seeing.)

Martyn1981

That makes a lot of sense QrizB. I don't really see why a portasplit would pull any more power than a comparable rated 'normal' split unit. They are fundamentally the same thing, I believe(?)

For our 3.5kW unit, it can pull just over a kW sometimes, when switched on, but not for very long, as the compressor gets up to speed. And they will pull about 1kW, for a minute or two each time when de-icing. But for the majority of time, even working hard, it's more like 700W max.

Over a night, when running at high temp to pre-heat our house, and with lower temps outside, it will average around 400W to 500W. For cooling, especially when temps are 30C+, it does appear to be working harder than when heating, and back up towards those 700W figures.

Screwdriva

The EX100 I own is R290.

Based on what you've shared, I'm certain that the portasplit will be quieter, more capable of cooling a large room and slightly more expensive to purchase. I am not convinced that a "porta split" would actually cost less to run at higher temperatures (>29 degrees) but am now convinced it will cost less to run when it's cooler.

As an aside, I established contact with the product manager of Delonghi appliances to ask them to launch the EX105A+++ in the UK next year. The response was surprisingly positive given I have no formal capacity to make sure a request.

Assuming a ~£700 price point off season, I expect that will push the limits of single hose portable aircon appeal.

QrizB

Assuming a ~£700 price point off season, I expect that will push the limits of single hose portable aircon appeal.

I agree a 4.1 EER is impressive, but suspect many people will still choose lower-efficiency but much cheaper units - it's a common trait to minimise CAPEX and under-appreciate OPEX.

QrizB

Talking of CAPEX, air conditioner prices on eBay are bonkers right now. There are people selling new-in-box Tronic (Lidl's own brand) aircons for £600+ when Lidl was retailing then for £150 earlier in the year.

And someone is offering one exactly like my old single-hose unit - which I bought in 2015 secondhand for £10, and gave away to a workmate when I bought the split - for £260. £260 for a noisy, inefficient and decade-old appliance!

Edit: since I posted here an hour ago, the seller has put the price up to £500!

TroubledTarts

https://forums.moneysavingexpert.com/discussion/comment/82066175#Comment_82066175

Crazy, even recently someone looking at the on wall unit we have in the garage gym was £799 before the rush now £1299-1499. We got ours 5+ years ago for £549.…definitely a demand exceeds supply issue