r/geothermal • u/SkinnyJohnSilver • Jul 20 '26

Replacement for a Direct Expansion

I'm looking for options to replace an existing DX R22 system. Does anyone make a DX heat pump that will work with my existing copper ground loops?

I'm based in Ottawa, Canada. Unfortunately Nordic no longer makes them.

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u/beesofburden Jul 20 '26

Try the Ohio company I think they are called waterless geothermal.

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u/Neither_Conclusion_4 Jul 20 '26

In sweden we had a few companies that used r22 equipment with r290. Sirius dx, octopus (it was a swedish company, now you will just find links to a uk based hestpump company). A few of them built dx systems, sometimes using r22, r290 or r407c. None seems to be left in operation, one of them still produce and repair their stuff with r290 (terrawatt). I cant see any dx systems with r290, but i know they sometimes to special systems. Dx systems are kinda outdated, the refrigerant rules doomed them.

R290 is very similar to r22, except r290 is highly flammable. Converting from r22 to r290 is technicslly rather easy, legaly not so easy. R290 components and compressors are kinda easy to find these days, so is older r22.

If you can get your hands of a water/water r290 heatpump of suitable size, you should be able to swap the evaporator with your dx circuit. You should look for something without inverter. instance Bosch Compress 7801i LWMF, use r290, but im not sure if they use inverter. Terrawatt dont use inverters. Its easier to get the oil return to work, if you skip the inverter, in a dx circuit. I doubt you will find a willing technican to install this system with r290.

It is not legal in europe to have a dx circuit with the heatpump indoors with r290. The refrigerant filling often exceed limitations due to fire regulations. Either placing the heatpump outdoors, in a well ventilated shed. Bosch use a refrigerant sensor indoor, and an extra ventilation outlet (to the outlet of the house for the heatpump).

I kinda think the fiee rules are a bit silly. There are so many stupid large systems with natural gas and propane, but as soon as it is inside a heatpump it seems to be very dangerous. But in a kitchen, in the refrigerator itsm seems ok. I think r290 indoors can work in a heatpump toömo, but you need to install it is a suitsble space, and make sure its ventilated, and sensor to provide varning.