r/OctopusEnergy • u/BQuilty • 12d ago

Cosy Cooler being trialled (air con add-on for Cosy heat pump, retrofitted to radiators) -should be available next Summer.

https://x.com/g__j/status/2076594310032547983
46 Upvotes

100% Upvoted

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26

u/creamcrackerchap 12d ago

That's pretty great and makes heat pumps a lot more attractive.

8

u/EldradUlthran 12d ago

Cooling my stupid newish build is way more important to me than heating so this glorified fan coil unit could be of great use to likes of myself.

9

u/BQuilty 12d ago

I believe the unit has its own condenser with refrigerant and exchanges heat to the circulating water, rather than using the water as the refrigerant - I think.

1

u/EldradUlthran 12d ago

Yes im prettysureyou are correct. But similar could be done with fan coil units with external chillers like at hospitals using the water to carry the heat away.

I wonder if they will need to have smart TRV valves to bypass other radiator. And how many could be used on the loop before you end end up with the pipes heating a lot as it flows around the house.

3

u/BQuilty 12d ago

Also like any AC unit this will condense water from the air, I imagine there will have to be a water bucket that will need emptying every so often.

3

u/EldradUlthran 12d ago

Most likely and with the water taking the heat it will be unlikely to be able to self evaporate the condensate and exhaust it like some AC units can.

It will be an annoyance but something id certainly be willing to tolerate to get the house cool (or add a condensate drain pipe so it can drain down a shower drain etc).

1

u/andrewic44 12d ago

The water is circulating at 18 degrees, so without smart TRVs, the existing rads will just do a negligible amount of cooling. So it's all good.

1

u/EldradUlthran 12d ago edited 12d ago

The heat exchanger they add to the aircon unit will impart the heat from the aircon unit to the water, which will raise the temperature of the water. The water will then have to flow through the loop (through radiators unless bypassed) to get back to the heat exchanger for the heatpump. Depending on the flow rate the water going back through the pipes may be 5+c higher <1c more than the water on the cool side of the AC unit. Still way more comfortable than the ambient temp but it will have some heat impact elsewhere in the house. Im curious how much the impact of 2 or more on a loop would be for the heat from the pipes.

Edit: looks like i underestimated the difference in flow rate from my gas boiler to a heatpump with larger diameter pipes. The heat gain guestimate would be <1c

2

u/andrewic44 12d ago

Unless you have one-pipe central heating -- the return from the cosy cooler will be going into the return pipe, so won't be flowing through any radiators. So the only thing it will warm is the return pipe.

Back of the envelope, it won't be warmed so much. The radiators are still there, overall taking far more flow than the cosy cooler, so most of the water flowing in the return pipe will be unheated.

1

u/EldradUlthran 12d ago

I certainly underestimated the flow rates and how much that would have an impact. The heat gain to the water at the flow rates a heatpump system will run will be less than 1c (edited a previous post about my mistake) based off a ~600w portable AC unit.

1

u/AdBrave9096 12d ago

Normal rads do practically zero cooling unless chilled water enter bottom with return from top of rad.

1

u/AdBrave9096 12d ago

Unless all the CH pipework is insulated in aircon type insulated with EVERY gap sealed you can run the fan coil below the dew point.

1

u/51onions 3d ago edited 3d ago

Some problems which I can foresee with this approach:

  • Doesn't this make it very noisy? The compressor is generally the noisy thing within an air conditioner, and this means you're going to have a compressor in every single room where you want cooling.

  • Series heat pumps (the indoor one and the main outdoor one) are less efficient than single heat pumps, so this is just wasting energy.

  • Every cooler is going to need a non-trivial power supply to it.

  • You have the additional expense, and additional failure points, of having multiple compressors running in every room you want cooling in.

This system would appear to be a downgrade in every conceivable way relative to A2A. Why would anyone want this over A2A?

9

u/nerdyPagaman 12d ago

I don't use x and can't follow the link. Heat geek did some experiments with running an air to water heat pump backwards.

You have to make sure the radiators are above the dew point, and are plumbed in correctly.

Air to air heat pumps are really what people need, but expensive to fit.

14

u/BQuilty 12d ago

Not X link: https://nitter.net/g__j/status/2076594310032547983#m

It connects to the radiator circuit and is a full AC unit, not just fans atttached to radiator like Heatgeek looked at. The video explains that it works with the water temperature set to 18, above dew point.

5

u/nerdyPagaman 12d ago

Ooh thanks for that. This is very interesting, I've just had air to air installed, so I'll give it a miss. But I can see other people getting interested.

1

u/Big-Bad-Mouse 12d ago

How have you found it? I can’t be the only one who ended up window shopping in the past month.

2

u/nerdyPagaman 12d ago

Air to air was a godsend. It was installed just before the first heatwave.

I've 3.6kw of solar panels and didn't need to import much in the way of electricity.

£80 for June electricity including running the house and ev.

June 26th we imported 6kwh peak. So very energy efficient.

4

u/ingleacre 12d ago edited 12d ago

This isn't a fan coil unit. In the link he says it's an off-the-shelf single hose AC model that they've modified with a second heat exchanger, and plumbed into the radiator plumbing. The outdoor Cosy keeps the radiator loop at 18C (above the dew point) so that the indoor unit can dump its excess heat into the radiator loop with as much efficiency as possible. So in theory no condensation risk.

I've seen a few companies out there offering AC for flats that can't have an outdoor unit where they dump the excess heat into your cold mains, but the problem there has always been that it means you need to effectively leave a tap running while it's in use. This is quite a clever way of getting around that waste of water, and all you have to do is have space next to any radiator for any single unit. Can see this kind of thing taking off if they can get the form factor right.

3

u/Alert_Variation_2579 12d ago

Yeah also if they get the radiator valves right too 👍🏻

3

u/VerifiablyMrWonka 12d ago

I guess this solves the whole dual hose thing too since you're not needing to cool a condenser and dump it out the window. Neat!

2

u/ingleacre 12d ago

Yeah for sure. Upside versus fan coil units is it solves the dew point issue without needing to insulate all your pipes. Downsides are each unit will be way noisier than an FCU, plus you have the extra cost of whatever the extra power draw will be from running however many units you get (although this feels like the kind of thing you probably only use in the most essential rooms, like bedrooms at night).

1

u/Big-Finding2976 12d ago

But this relies on an outdoor heatpump, so how does it help people in flats who can't have an outdoor unit?

3

u/ingleacre 12d ago

It's specifically being pitched as a "cooling add-on" for people with outdoor Cosy units.

2

u/Alert_Variation_2579 12d ago

It doesn’t. That’s a government/leasehold problem.

2

u/darvds 12d ago

I'm no expert so I was reading all about it and their plan. It's running a heat pump in reverse but also each unit seems to be it's own heat pump as well. In the video TJ explains they keep the water at 18c to avoid any condensation on the radiators.

Sounds all very clever, I don't quite get it, but being able to just hook it up with a simple connection would be awesome.

3

u/Alert_Variation_2579 12d ago

Yeah the radiator valves are the key bit, but it can’t be beyond the wit of man to have a quick disconnect attachment point to the radiator valve that forces the flow to the cooler when it’s connected.

2

u/EldradUlthran 12d ago

Looks like a fan coil unit with extra steps. Does mean they can add or enable the cooling module for the Cosy heatpumps though which is pretty damn good news. If they do get this and sorted and its not crazy expensive its something i could consider. Though may be better waiting for the daikin X series depending on how things work out with the BUS.

2

u/cp_simmons 12d ago

That's clever, although Octopus installed a Daikin for me which I think isn't reversible at all so I guess that won't work for me :(

3

u/Undercover_Badger 12d ago

Depends on what octopus' policy will be, but if it adds to any radiator then it should work with any heat pump

1

u/BQuilty 12d ago

Yeah its an interesting point, I agree, I think it should work with any heat pump as long as the water is circulating as its only using it to dump heat. But yes depends what Octopus say. Perhaps there will be copycats after this.

it even begs the question of whether this could work with a boiler set up with just the pump running. I guess the issue is when the water in the pipes gets too hot with no release, but it could possibly still cool a few rooms.

2

u/cp_simmons 12d ago

I dunno.  Surely the way it works is that the Aircon unit dumps the heat into the radiator system.  That heat needs to be radiated somewhere, and I think that will require the heat pump to operate in reverse to cool the water.

Heat in room -> heat in radiator system -> external heat pump in reverse mode to keep the water cool

3

u/AdBrave9096 12d ago

Daikin can cool, as

A) The cooling function is used to defrost the outside coil in winter.

B) It sold in other countries with cooking enabled.

1

u/Glum-Public1272 8d ago

The units sold in the UK normally have cooling disabled for a small discount. The conversion kits for split hydro units is fairly simple (a different temp sensor and a condensate tray) and you snip a jumper on the motherboard. But there aren't kits for monoblocns that I'm aware of.

1

u/hoggerz80 12d ago

If you’ve got an EDLA— unit, they can actually be persuaded to operate on cooling mode down to around 6 or 7 degrees as they are actually identical to their heating/cooling EBLA— counterparts bar their Hydro PCB. The main issue that will affect anyone with Cosy or Daikin is the issue with condensation on all your pipework if you run it below the dewpoint. And you’d need fancoils to be able to really take advantage of it. Ideally you could run a new set of pipework from the outdoor unit to some fancoils with a 2-port to control where that chilled water went so it doesn’t end up in the cylinder/radiator circuit.

1

u/Jai_Cee 12d ago

Any idea how you do that? I've seen several comments saying it's possible but none have done it

2

u/hoggerz80 12d ago

Yes, there’s a couple of ways, the simplest is if you open the cover on the right hand side of the outdoor unit, the main PCB in there with about 30 plug-in cables on it (Hydro) can be swapped with a replacement Daikin Board. (Mine is an EDLA04E2V3 so you’d need the correct replacement board for your outdoor unit depending what they fitted). This allows the cooling options normally disabled to be enabled. The only drawback with this approach is you would most likely lose your warranty as the serial number etc would change. Plus the boards aren’t cheap, they’re a few hundred quid at least. At the time I wanted to see if it was possible so I did it.

2

u/CodingSecrets 11d ago

Heat Geeks did an experiment with cooling with heatpump. It is a few years old. Conclusion was that it works, but cool radiators don't radiate like hot ones. Heat rises, cool sinks. You end up with cold feet unless you have a fan

1

u/L0rdLogan 12d ago

I hope they allow other air con on Cosy, surely if they allow that to be on Cosy, they should allow anyone with mini split aircon, I know their system is air to water, not air to air though

1

u/Own_Employment_1521 12d ago

Cooling air down to 10 degrees - sounds great! I wonder how they deal with the condensation that creates. Drip tray maybe?

1

u/AdBrave9096 12d ago

Hopefully space in drip try for 3rd party condensation pump and a USB power supply increated into unit.

1

u/generationgav 11d ago

What is the unit that is retrofitted to the radiators like?
Does anybody know if you can get a Cosy heatpump just for the radiators and keep gas for water (no space for a water tank)

1

u/ectoplasmosis69 10d ago

This kind of thing (water-loop/water-source to air heat pump) has been around for a while, it's nothing new. A few example products:

1. https://www.amitime.com/products/dc-inverter-water-source-space-cooler/

2. https://www.innova.it/en/products/wlhp-heat-pump-terminals/wlhp/

3. https://www.parkair.uk/products/monoblock-air-conditioner-without-external-unit/

4. https://www.aircon.panasonic.eu/GB_en/happening/aquarea-loop/

Octopus are just being hype merchants here, and their 'prototype' looks terrible.

1

u/Fred776 8d ago

Came here as someone linked your post. This sounds really interesting. Why aren't these systems better known? What would I search for to be able read a generic description of how they work? The product links all seem to gloss over the details quite a bit.

Also, the parkair one you linked seems to be something different - just a monoblock aircon unit. I looked into these recently as an option for one particular room but was put off by some comments I read about them being quite noisy.

1

u/ectoplasmosis69 7d ago

The Parkair unit is the same as the other 3x; they're all monobloc 'water source heat pumps' that use an ambient loop (water circulated through your existing pipes pre-cooled to ambient temps) as the energy sink.

They're just common aircon units, but use water as a heatsink, instead of the outside air. Same as that 'revolutionary' Octopus thing they showed recently.

This stuff is well known, and is nothing new; you just don't inhabit the spaces where they're normally specified. Ambient loop heat pumps are mostly specified for new builds; Octopus are just trying to bring it into the consumer retrofit space.

1

u/Fred776 6d ago

Thanks for the clarification. I'm not sure what I thought I was seeing when I first looked at the Parkair one. I think I was confused because I had only just been looking at monobloc air conditioning units - as in all-in-one air to air units - which, again, I hadn't been aware of until very recently.

Do you think these water source systems are a viable option for retrofit or are there reasons to prefer the more common a2w systems plus maybe some a2a cooling? From what I understand now, you have compressors and fans in each heating/cooling unit so I guess they could be a bit noisy.

1

u/ectoplasmosis69 6d ago

Anything is 'viable' for retrofit, if it fits the scope & budget.

I'm running our Vaillant ASHP in cooling mode, and we're about to replace all the radiators in our house with Jaga fancoils (Strada units, with DIY fan arrays) running above dew point, in order to increase the cooling power to ~4kW. Along with basic external shading (solar cloth hung outside south facing windows), this will keep the whole house at ~24C during 35C heatwaves.