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Dux Airoheat Heat Pump

This is a guide to the spare parts and servicing of a Dux Airoheat Heat Pump direct from a heat pump hot water specialist with a restricted electrical license. This page discusses some issues that may arise with a Dux Airoheat Heat Pump. For all other issues, I would recommend a refrigeration mechanic to attend. The refrigeration mechanic will be able to assess things further and depending on the age of the unit condemn it “beyond Economical Repair”.

Dux Airoheat Spare parts

Dux Airoheat Fan

Dux Airoheat Fan:
Old style Fan: please phone for pricing
Airoheat New style Fan: please phone for pricing

The Dux Airoheat fan is mounted a little differently to other heat pumps in the market. It is mounted horizontally on top of the heat pump. This positioning unfortunately allows water ingress through to the bearings of the fan. This in turn causes failing of the fan over time and sometimes a swirling noise or metallic clunking sound.

Problems that arise from failing of the fan include causing issues with efficiency and even causing the top of the Airoheat to ice up. I have literally had the whole top of the heat pump turned into a block of ice which needed to be thawed out to allow any works to be done. The top of the heat pump icing up can also cause issues to the hot logic with water ingress. Please check this if this has happened as you are likely to get caught out.

Replacement changes from model to model. The first Airoheat had a separate capacitor for fan that had to be fitted though this was eventually superseded to having a capacitor in built into the hot logic.

This style had 4 wires that were all colour coded connecting to push style connector. Unfortunately when replacing the fan you need to use the existing connector that was on the old fan.

The newer style fan is a much easier replacement. The fan pushes onto a plug on the hot logic box and has a small back nut for tightening.

Airoheat Hot Logic

Airoheat old style hot logic please phone for pricing
Airoheat new style hot logic please phone for pricing

Hot logic rain cover kit please phone for pricing (Note does not include hot logic)

Dux Airoheat hot logic mostly has issues caused by water ingress.

Although there have been many many series of the Airoheat logic there are really 3 different types.

1st style

* Had no built in capacitor for fan

* Has issues with all three sensors entering through one cable gland. Silicon was then placed around the cables for added protection. Unfortunately this silicon didn’t work very well and the logic had major problems with water ingress causing burnouts to the logic.

2nd style

* Had capacitor for fan built into logic

* Main issue was still water though not as bad as the last style. Dux have now fixed the issue of the 3 sensors entering through the 1 cable gland have now been separated. Dux tried to further fix this water ingress by manufacturing a cradle to suspend the logic higher than before. This sits it well above the condensate tray. A plastic cover then sat over the top of the entire logic and this did help quite a lot to solve this issue. This was called a “Hot Logic Rain Cover Kit”

3rd style

* Has completely waterproof electrical connections as well as box. Works very much like a plug and play style controller. I have encountered very few issues with this style of logic.

Thermal overload

Looks very much like a standard thermostat but is missing the temperature disc and therefore only acts as a thermal overload. If this ever fails please be careful that it hasn’t failed for a reason e.g. the tank has overheated.

Airoheat sensors

There are 3 airoheat sensors that connect in the hot logic. In my experience very rarely will you have issues with a sensor.

1. Ambient air temperature sensor.

Ambient Air Temperature sensor please phone for pricing

This is really the only sensor that we can replace as a plumber/electrician

2. Over pressure switch. This is connected to the refrigerator side. A hot water specialist can bypass for testing to confirm it is not an issue with the hot logic. However, if it has failed I usually recommend replacement of the entire unit if over 5 years old.

3. Tank temperature sensor. This is fixed to the tank wall and usually only has issues when it has been damaged during the manufacturing process. If this is failed the tank may simply not heat up or do the opposite and overheat. If this happens the entire tank needs to be replaced.

Over pressure switch

As suggested earlier in Airoheat sensors a hot water specialist can test to confirm there is not an issue with the hot logic. However, if there is an issue you usually need to get a refrigeration mechanic in to repair if economical.

Pressure temperature relief valve

Dux installs aluminum anodes in the Dux Aiorheat Heat Pump Product for all water conditions. Due to this it tended to cause issues with the pressure temperature relief valve leaking prematurely. As a standard, I would only replace that relief valve with a high quality stainless steel seat valve. Sometimes a tank flush and anode replacement would need to be done to. You will see a lot yellow gooey liquid if you do this.


There are very few issues with the capacitor on this or any heat pump. A hot water specialist can test the capacitor using microfarad of the capacitor to work out if it is still good or not. Though it would be unlikely to have an issue with it.

Dux Airoheat Heat Pump

Check this out: Video and Manuals on the Dux Airoheat

How the Dux Airoheat works

Dux Heat Pump old style manual

Dux Airoheat New style owners guide

same day hot water service logo

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