I picked up a Dream 8kW pool / spa heat pump which came without any fittings for the water in/out. The unit looks like this:

enter image description here

The previous owner used a rubber coupling like this for his pond.

example photo of a 2" rubber coupling

I'm looking to connect this pump to 2" piping for a hot tub, and I'm concerned at the longevity and use case for a part with higher pressure pumps and hot tub chemicals.

The pump has male threaded connections that measure 65mm OD, with a 57mm ID. There's a lip that takes the OD down further but I was unable to measure the ID of that.

photo of heat pump outlet along with measurement tool measuring outer diameter

photo of heat pump outlet along with measurement tool measuring inner diameter

The ID makes it between a 1.5" pipe and a 2" pipe so I'm not sure I'll get a snug fit there by inserting a pipe. There may be some sort of 'tailpiece' that comes with the fitting too that I'm not considering.

I have contacted a few spa, pool and pvc pipe specialists who have not heard of this type of fixing before.

Could someone advise if I'm missing any connection combinations here? I could try 3D printing a part but I would have the same concerns with perishing over time.

  • The stock photo appears to be some type of compression fitting (blue nut squeezes a black ring that squeezes the pipe) with an OD of the pipe in the 50mm/2" range (OD, not pipe size) judging by your measurements. Which would be 1-1/2" pipe size.
    – Ecnerwal
    Commented Dec 1, 2023 at 20:17
  • 1
    Presumably you find a dealer who sells these and has or can order parts, or parts on ebay..
    – Ecnerwal
    Commented Dec 1, 2023 at 20:28
  • @Ecnerwal They sell 'direct' and seem unresponsive from my attempts. I have also tried finding spares on the usual places including eBay
    – MrNorm
    Commented Dec 1, 2023 at 20:37

2 Answers 2


According to the manufacturer spec sheet, those are 1 1/2" fittings on the unit. These look like standard 1 1/2 inch hot tub pump connectors. The mating connector is below.

Pump Union - 1.5"FBT x 1.5"SS

The one above is 1 1/2" Female Buttress Thread x 1 1/2" slip joint, ready to be glued to 1 1/2" PVC pipe or flex hose. You'll need reducers to go to 2". The GPM rate is low enough though that the smaller pipe is likely the right application. You should be able to source these from your local spa store or one of the national spa vendors.

Your unit is ten years old, so it's possible the fittings are 2" and don't match the current spec sheet. They do look the correct style though. Remember gaskets.

  • Thanks for your reply. I'm afraid I have already purchased this pump coupling only to find that 1.5" is too small and 2" is too big to screw onto the threads. I have also phoned several hot tub places who could not find stock for the 65mm thread
    – MrNorm
    Commented Dec 1, 2023 at 20:39
  • Sounds like the older unit uses a different size then, since the current spec sheet is 1.5". I suspect you're going to have to call them and buy fittings, or pull the housing off and replace the existing fittings with standard ones.
    – KMJ
    Commented Dec 2, 2023 at 0:51

This looks like a generic Chinese pool heat pump, which can be found all over Alibaba/Aliexpress.

Checking up the spec for that unit says the fitting is 50/48.3mm.

It's possible to buy both 48.3mm and 50mm unions for 'pool heat exchanger' which look like they match.

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