That would've been easily invalidated by prior art from nearly a century ago; as I mentioned in a sibling comment, this was a common arrangement in the early days of domestic refrigeration.

Here's a video from someone who managed to salvage some of the components of such a system: https://www.youtube.com/watch?v=h1tXIYl20jA

That is an interesting thought, but I assume that the working ranges of the different appliances are different so there would be some complexities and inefficiencies getting them all connected to a common circulation loop. If there was a thermal equivalent of a transformer used for alternating current, that would be amazing.

There's some commercial options for this, but it's not common. Usually, these devices just have their own compressors, because they all pale in comparison to the heat pump(s) used for climate control. For example, I have a HP water heater, and its heat pump is about 1/3 of a ton, whereas most homes need 3+ tons for climate control. Fridges are a fraction of that.

For HP clothes dryers, there's no efficiency to steal from somewhere else, because they use both the hot and cold coils - similar to (the same, really) dehumidifiers.

The tradeoff would also be running high-pressure refrigerant lines everywhere. That would require EPA certification (in the US, anyway) to connect/disconnect an appliance, and it would probably be less reliable. These sealed-system units are generally pretty reliable, because the refrigerant is installed at the factory under ideal conditions, and there's no connections that are made later that may be done poorly.

A few years ago I was planning to build a velomobile that I would live out of for a year while circumnavigating Australia, and potentially indefinitely. (My plans changed.) I was disappointed at how hard refrigeration information was to come by (maybe I should have sought a traditional paper book), but I was kinda looking forward to figuring out if I could use one compressor to cool a small fridge, cool and perhaps heat the cabin, heat water, and heat a slow cooker (target 80°C). The bits I could work out suggested you might want a different refrigerant for the cooling and heating applications, or different back pressures; but I was rather hampered in my reckoning by my lack of domain knowledge—I was definitely going to have to talk to professionals! If so, and combined with the limited power collection available (<1m² usable solar panels on the vehicle, could lay out more while parked), butane was probably going to make more sense for cooking.

I even ran some naive numbers on the amount of water that would condense in expected conditions, concluding it could be handy but I’d probably still need to source more water.

So... A little better than Peltier cooling in every other dimension too.

Likely high speed compressors --- the oldest hermetic systems used an induction motor running at 1800 RPM, then later they went to 3600 RPM, and now they're running on a VFD that possibly goes much faster. By making it pump faster, they can use a smaller compressor and reduce costs, at the expense of longevity and noise.

They use lighter lubricant oils than were historically used, which allows more vibration. It’s also why compressors burn out far more quickly than they used to.

In an "open home" concept I guess it might make sense, but I've never lived in a place like that.

I guess all of the places I've lived the kitchen was always its own room, maybe adjacent to the dining room if anything.

No new appliances (>10y now I think about it, they came with the house.)

I'm not the same person, but I do not (and never have) noticed any noise when my fridge is running. Whether that means we have different fridges or different tolerances for noise, I'm not sure.

oh thanks for the tip! I'll look into it.

There will be greater fluctuations of temperature but that doesn't need to be a problem.

Just today I ordered a 32dB Liebherr; the previous one had 35dB and could be heard all around the studio (I measured the noise using a dedicated sound meter).

Skill issue on the manufacturer's part. I live in a studio and never hear the fridge. This is part of a fitted kitchen, though, but I doubt the panel hiding the fridge makes that big of a difference.

New appliances are far better than old ones here. Especially old ones that (I assume) haven't been maintained and so are working far harder than they used to. I've lived in places with old ones that were fine and old ones that were awful, both. I've had much more consistently good results in places with newer ones.