mvhr Bearing replacement of Nuaire MRXBOX95AB-LP1 MVHR

[wei]

Dear all, 

 

I am sharing my experience of replacing a worn bearing of a Nuaire MRXBOX95AB-LP1 MVHR fan/motor. Hope this will help someone someday.

Note that this particular motor model is Torin-Sifan MIB190-045 EC . The manufacture really went out of its way to make repair difficult!!

You will require soldering to access the bearing, so if you can source one on ebay, maybe just buy one (costs ~£200). Also, pole star told me their bpi-ec-190-44 motor is a compatible replacement that costs £120.

 

Back story

A few months back my NVHR is getting noisy and noisier. After contacting a third party (HRV-group) engineer to have a look, they said the bearing is worn (not surprising) and told me the motor needs replacement. While I was waiting for a quote I contacted Nuaire for the model of the motor to see if I can source one. 

They are not at all helpful and quoted me ~£1500 to replace the entire unit! 

Quote

Your unit is now obsolete and we no longer carry any spares for it.  The whole unit would need to be replaced I have attached some information about the replacement unit and the cost is shown below.

 

The cost for the required part is shown below.  This is not a formal quote and the costs could change at any time.

 

A few days later HRV contacted me to say basically the same thing, as they also contacted Nuaire. 

I am of course not going to spend that amount of money just because one or two bearings are worn!!!!

So after reading a few helpful posts here and Youtube videos. I decided to take things into my own hands.

 

Step1 - Exposing the motor

Since neither Nuaire or HRV-group can or willing to tell me the motor model, first step is to dissemble the the outer casing of the MVHR, this is the easiest part, just beware for this exact MVHR it is celling mount, so be careful unscrewing, don't let the casing fall down. After this the fan can visible:

 

There are two fans, I turn on the power to determine which one is noisy.

Continue to unscrew all 8 screws to fully expose the motor. 

 

Step2 - Taking the motor off

It is not easy to disconnect the motor. The wires are soldered into the PCB board at the motor end (unlike some other models where it disconnects when you unscrew the motor backplate). While the other end can be disconnected from the main unite PCB, it is impossible to take the wire out or insert back in as the cables are tuck deep behind the MVHR metal casing, probably require to take the entire MVHR unit down. My solution? simple, I cut the cables near the motor. And re-connect them back in when I am done.

 

 

Step3 - Disconnect the motor PCB board/Exposing bearing

With the motor isolated. unscrew the backplate to expose the PCB board, you can see how the wires are all soldered in! First disconnect the earthing connecting the PCB to the backplate. now the PCB board is fully visible.

 

Now the PCB board is loose, however you won't be able to take it off, as there are two wires from the motor is soldered (again) to the PCB board (as highlighted in the picture). You'd need to desolder these two contacts to disconnect the two wires in order to take the PCB off.

IMPORTANT: Make sure you remember/mark which wire goes to which contact. I bet you will forgot as they look the same. If you re-connect them the wrong way I'd bet the motor will spin the wrong way.

 

 

Now the NSK 608Z bearing is fully accessible.

 

Step 4 - replacing the bearing

There are two bearings, one at each end. For me it is the front one (under the PCB) that's rusty and needs replacement. 

First you'd need to take the clip off and make sure you don't lose it.

 

For me I need a bearing puller to take the motor core out first. You need one whose grab is very thin as the motor gap is very thin!

I used this one: https://www.amazon.co.uk/dp/B07WFYXHJQ?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 

 

With the core in your hand, it is now easy to hammer to take them out. I bought the same NSK 608ZZ bearings from https://bearing-king.co.uk/

 

Step 5 - put everything back

The hard part is done! now you just need to put everything back. Some tips:

looping the two motor core wires back to the PCB board front will be difficult as the two holes are small. I used two threads to tighten each of the wires first and through the two small holes to guide them out back to the soldering position. 

 

Since I have cut the wires, I ordered some wire connector so that I have an easy time connecting the fan back into the MVHR unit.

 

 

After thoughts

While I am happy that I managed to save the motor at the end, it really is a tough job. Nuaire/Torin really make sure nothing is easy. But recommending your customer to replace the entire unit just because of a nosy bearing is absurd and extremely wasteful! 

 

 

 

Edited April 5 by wei

[arbennett]

This is useful should I ever need to repair ours! We had a fan failure on ours and Nuaire replaced both fans and pcb under warranty due to no longer being able to supply to same fan.