I have an inflatable hot tub but also a heat pump water heater which is extremely efficient to heat water. As such, I’d like to fill the hot tub with pre-heated water instead of relying on its highly inefficient resistive heating element.

Of course I need to make sure that mixing with cold water is right such that the water is not too hot.

I do not want to use buckets for this. What is the easiest way to connect a hose for this (temporarily)?

Here is a picture of the water heater:

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Here is a picture of the sink:

enter image description here

Ideally I could connect to a normal sink faucet directly because I could mix with cold water directly.

The picture above looks like the most normal faucet, the others (kitchen, shower) have very non-standard outlets

  • Do you have a clothes washer, or a hookup for one that you don't use - that's the easiest way to get garden-hose-threaded hot water, unless you have a utility sink that has a garden hose thread faucet, standard. Of course, after the first 30-50 gallons or so, your heat pump water heater will turn on its backup resistive heating elements and be no more efficient than the hot tub heater.
    – Ecnerwal
    Jul 21, 2023 at 0:55
  • 1
    See: diy.stackexchange.com/a/225493/18078
    – Ecnerwal
    Jul 21, 2023 at 0:58
  • Nice! Is the thing in the faucet of my picture an aerator that I can screw off? I want to confirm before applying force (with a plumbing wrench?)
    – divB
    Jul 21, 2023 at 2:22
  • 1
    A pipe wrench will scar it up, most likely. Padding some pliers with rubber, or putting several wraps of tape around the aerator before trying to unscrew it with any tool more than your hands is typical to attempt to avoid damaging the surface. If you happened to have a tiny strap wrench that might be ideal, but I don't know that I've ever seen one that small.
    – Ecnerwal
    Jul 21, 2023 at 2:35
  • 2
    If you have rubber gloves, that might give you enough grip to get the aerator off by hand.
    – Huesmann
    Jul 21, 2023 at 11:53


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