Steve W

I've used the two pipe Mibec which is very good. The 2 x 25mm data and cable pipes may not be sufficient depending on the heatpump. In the case where the ASHP communicates to a control box in the house with a data cable and the internal control box controls the system then only a single data cable is required plus power for the ASHP. I swapped from an early Daikin to an Altherma 3 which requires multiple cables as there is no control box in the house - all functions are performed at the ASHP. Additionally with the Altherma 3 you are looking at multiple power cables - ASHP + immersion. I opted for a 50mm flexible conduit and a Mibec with 2 pipes.

Just thought I'd post an update. After some to-ing and fro-ing the supplier agreed to swap out the ASHP for an Atherma 3. I have now had the replacement for nearly 12 months and I'm happy to say that the unit has worked flawlessly and does not exhibit the "ice cube" problem of the previous unit.

Bearing swap complete. No problems changing the bearings, getting the case square again was tedious. I have outlined the steps in the attached document. DOMUS HRX2 Bearing Change.docx

Matters have taken a turn for the worse! Previously the noise from the MVHR was merely annoying - yesterday it became louder and I have to switch it off at night. I ordered the bearings from Bolton Bearings so should be here in the next couple of days. I had noticed that the bearing has extra clearance and will report back if the clearance is an issue. It's a surprisingly common bearing and used in lots of application which presumably is why it is so plentiful and cheap. The next generation of fans will probably have bearings that are not removable and are a custom size - after all you want people to buy the expensive fans.

See my other posts as this provides further information on the motor, bearings and suppliers.

I have a DOMUS HRXD installed in 2018 - at least one of the bearings has gone noisy. I contacted the manufacturer with regards to a new fan assembly and was told the fan assembly was no longer available but the fan from the HRX2D was the same apart from the electrical connection. I enquired at two DOMUS suppliers and was quoted £500.00 and £650.00 for a single replacement part. Essentially it is nearly as cheap to buy a brand new Vent Axia MVHR which has cheaper spares than replace the fan assembly. So Yes, there is very little in an MVHR but the fan units which are expensive to replace (if available - HRX2D is nearing the end of its sales life) and are only as good as the bearings in the motor. I am currently exploring replacing the bearings in the motors or buying the naked fan unit - failing that it's a new Vent Axia.

Not Cheap but it is in stock and a lot less than buying one from Domus.

Thanks for the update - that fan looks totally disgusting! I have had a look at the YouTube video (https://youtu.be/QmdSoj7Gr90) and its looks to be a straight forward job using 8 x 22 x 7 bearings (608 series). I have had a look through the various bearing suppliers and I will be buying 4 x SKF E2.608-2Z/C3 given that they have an excellent specification. SKF Energy Efficient Bearings - Optimized to increase service life SKF Energy Efficient (E2) deep groove ball bearings can provide more than twice the service life while reducing energy use and total cost of ownership. Design improvements reduce frictional losses in the bearing by at least 30% when compared to the same size SKF Explorer bearing. This results in energy savings over the life of the application. Benefits Longer Bearing Service Life Longer Grease Life Reduced Operating Temperature Higher Speed Capability Sustained Performance Reduced Energy Use Lower Cost of Ownership Boundary dimensions in accordance with ISO15 - which makes them dimensionally interchangeable with standard deep groove ball bearings Reduce Friction Means Increased grease life and service life Optimized to reduce frictional losses and operating temperature in the bearing, capped SKF Energy Efficient deep groove ball bearings can last at least twice as long as comparable SKF Explorer bearings in many applications. This means that in applications where conventional bearings fail and are replaced, the longer service life of SKF E2 bearings could potentially halve the number of bearings consumed over the machine lifetime or even eliminate the need for replacement altogether. In instances where an application is run-to-failure, SKF E2 bearings could conceivably double the life of the application, consequently reducing the total cost of ownership. It would appear from the YouTube comments that life expectancy of bearings is of the order of 4.5 years.

Not as bad as £1300.00 (2x£650) that I was quoted elsewhere! (plus postage). I will not be buying a Domus replacement should the need arise.

Hi Iain, It may be some time before I will be stripping down the MVHR unit - bogged down in flooring at the moment. The picture is from the instructions I got from Domus on how to the replace the fans. I have attached the guide as it may make it slightly easier. Steve W Domus Ventilation - Changing HRX2D Replacement Motors - SPR425-SPR426 (1).pdf

I've just had another price for the two fan units, £1300.00 inc VAT plus delivery. Hopefully they should be standard bearings which are freely available. I use simply bearings that offer a next day service and have top notch makes. It will be mid to end March before I can strip the unit too many other jobs now im retired. Will document the process to help others.

Domus supplied with a document on how to change the motor which is reasonably straight forward. I have extracted a photo of the fan unit just in case anybody can identify it.

I have a Domus HRX2 MVHR that I installed in 2018. It would appear that one of the fans has started to fail and although it is not noticeable during the day, during the night it is audible and makes getting back to sleep difficult. I have been in touch with Domus and they have told me that the fans for this unit are no longer available however the fans from the HXR2D are mechanically the same - different connector (I'm a retired electrician so this isn't a problem). The parts are SPR425 and SPR426with a price of £409.75 each + VAT and £10.00 delivery. The original unit only cost j£1073.00 inc VAT and delivery so nearly a £1000 pounds for fans seems exorbitant. Has anybody had any dealings with these fans? Is it possible to replace the bearings as I've seen another post where standard bearings from Amazon have been used to remediate a problem? Are there any firms that specialize in reconditioning these units? How long should a fan last that runs continuously? Would a Nuaire MRXBOXAB-ECO2 be a suitable replacement albeit I would need to rework the pipework slightly. Given the cost of two fans I am seriously considering replacing the unit with one from another manufacturer that has more cost effective spares. Any advice would be greatly appreciated. Steve W I have access to bearings pullers and a vast array of tools as well as a mate who has machining facilities if needed

I have a Solar iBoost that connects to the single emersion heater which heats the water to 60C+ on a sunny day. The legionella functions in the ASHP are disabled and there in no connection from the ASHP to the DHW immersion heater.

I don't believe that the engineer turned the freeze prevention off completely but I can't be certain as the weather has been quite mild. He didn't leave a new system config report and he didn't update any existing documentation either.