Replace MVHR every 10 years?

[TheMitchells]

Just going through this months 'BuildIt' magazine and read the following about ventilation systems - its an article about designing a home with a long lifespan and minimal maintenance.

 

"There are two main ways that this (condensation and damp issues) can be stopped.  One is to install a relatively complex system of mechanical extract ducts and fans to remove the moist air before it gets into the structure, but this will need constant maintenance and the kit will have to be replaced every decade or so."

 

The article was writen by Julian Owen, an architect and writer of several books on self build and ezxtensions.  If he's talking about MVHR, I always thought they were fairly low maintenance with the filters checked every couple of months.  And why would they need replacing?  Is he correct?

 

Edited February 23, 2017 by TheMitchells

[jamiehamy]

Hmm, interesting! Anything mechanical needs replacing eventually - but when is another question. Of course in ten years there will be better, more efficient models with new features - I can't see these units needing much in the way of proactive maintenance other than what you suggest. The ducting is unlikely to ever need replaced - maybe the unit eventually however I don't think they are the most complesx of devices so if a motor burns out or PCB goes it should be straightforward to replace. 

 

[Jeremy Harris]

Maintenance on ours is a 6 monthly filter check/clean/replace, with a reminder on the control unit display when this is due, plus an annual clean out of the filter boxes with a vacuum cleaner, really just the fresh air in side to remove the build up of dead flies etc that get sucked in but stopped by the filter.  Every two years there is an advisory to inspect the heat exchanger and if it's dirty give it a wash.

 

The fan motors are usually brushless, so the only likely failure is the bearings, but they are so lightly loaded most of the time that I would be surprised if they only lasted 10 years; they are probably good for 20 years plus I think.

 

The electronic controls, in particular the motor drives, are probably the shortest life component, and they may well need replacing at around the 10 year mark, just because their capacitors will be right at their end of life around then.  This might well mean replacing the whole control board, but I've had a look at ours and reckon that it should be easy enough to just remove it, do a precautionary replacement of the commutation capacitors on the motor drives and replace it.  with luck that should extend it's life for a long time.

 

I strongly suspect that MVHR prices will decrease as they become more popular, so even replacing the whole unit isn't likely to be too big a deal.  As it has to be easy to get at, to comply with building regs, and as the ducts should last decades, it's not a big job to just replace the unit. 

[Gone West]

2 hours ago, TheMitchells said:

The article was writen by Julian Owen, an architect and writer of several books on self build and ezxtensions.

 

The problem with this is that a lot of people will think he is an 'expert' and will be put off from using MHRV. They may also think because it's not worth installing MHRV it's not worth building airtight.

[Jeremy Harris]

3 minutes ago, PeterStarck said:

The problem with this is that a lot of people will think he is an 'expert' and will be put off from using MHRV. They may also think because it's not worth installing MHRV it's not worth building airtight.

 

You're right, and the real problem is that few architects are fully aware of how an MVHR unit is constructed, or even how it works, other than at a basic level.  How many architects are also heating and ventilation engineers?  Probably very few, I suspect. 

 

Some of the simpler MVHR units really are so simple internally that there's no reason they couldn't last for decades, and all MVHR systems, even ours with it's built in air-to-air heat pump, are less complex, and have fewer moving parts, than something like a boiler. 

 

What's the life of a modern boiler, I wonder?  Our old gas boiler was still working perfectly well when we replaced it, yet it was about 30 years old.  We only replaced it in order to fit a more efficient combi, and that combi is now around 7 or 8 years old and probably still has 10 years or more of life left.

 

 

[Bitpipe]

It's quite remarkable how little there is inside a MVHR unit really. Agree that they should last much longer than 10 years.

 

To make the obligatory thread diversion, our local garage reckons they'll be out of business before too long as cars from the last 10 years are becoming increasingly uneconomical to repair due to ECUs failing and now they have s/w issues that ca only be addressed by the dealers.

 

 

[jamiehamy]

8 minutes ago, Bitpipe said:

It's quite remarkable how little there is inside a MVHR unit really. Agree that they should last much longer than 10 years.

 

To make the obligatory thread diversion, our local garage reckons they'll be out of business before too long as cars from the last 10 years are becoming increasingly uneconomical to repair due to ECUs failing and now they have s/w issues that ca only be addressed by the dealers.

 

 

They've been saying that since I was a boy - it won't happen! Despite all the electrical gubbins, car technology is pretty much the same as it was 50 years ago!  Allthey do is take anything remotely mechanicaly and add something electric on top - windows, sunroof, mirrors, shock absorbers, lights, brakes, door handles, locks, steering pumps. All the underlying elements are still the same. 

[Bitpipe]

59 minutes ago, jamiehamy said:

They've been saying that since I was a boy - it won't happen! Despite all the electrical gubbins, car technology is pretty much the same as it was 50 years ago!  Allthey do is take anything remotely mechanicaly and add something electric on top - windows, sunroof, mirrors, shock absorbers, lights, brakes, door handles, locks, steering pumps. All the underlying elements are still the same. 

 

Hmm, at the moment I have a fault with my '08 Audi A6 auto gearbox - locks out and I need to press a hidden button under the ash tray with a pen to unlock. Problem is with the gearbox ECU which garage could remove,  send for 3rd party reconditioning, and re-install. They stopped doing this though because there was no guarantee that the ECU would't fail again and they had upset customers who had shelled out £100s on the labour cost.  Only Audi will supply new ones and they need to do all the work - cost £1500+ Apparently I have over 10 such ECUs distributed through the car 

 

[jamiehamy]

12 minutes ago, Bitpipe said:

 

Hmm, at the moment I have a fault with my '08 Audi A6 auto gearbox - locks out and I need to press a hidden button under the ash tray with a pen to unlock. Problem is with the gearbox ECU which garage could remove,  send for 3rd party reconditioning, and re-install. They stopped doing this though because there was no guarantee that the ECU would't fail again and they had upset customers who had shelled out £100s on the labour cost.  Only Audi will supply new ones and they need to do all the work - cost £1500+ Apparently I have over 10 such ECUs distributed through the car 

 

Audi auto gearboxes? They are mince - full stop. Where did you take it to out of interest? Have you tried somewhere like this? http://www.ecutesting.com/audi_a4_a6_multitronic_gearbox.html - 

Edited February 23, 2017 by jamiehamy

[Temp]

Oh dear, we turned our MVHR system on for the first time in February 2007 :-)

 

 

[PeterW]

5 hours ago, PeterStarck said:

The problem with this is that a lot of people will think he is an 'expert'

 

He makes most of his money selling building plots for vastly inflated prices in the East Midlands ...

 

Come across a few of his - usually with a dodgy "standard" design house approved ..!

[Steptoe]

5 hours ago, PeterStarck said:

The problem with this is that a lot of people will think he is an 'expert' and will be put off from using MHRV. They may also think because it's not worth installing MHRV it's not worth building airtight.

 

but that is an inherent problem nowadays with almost everything,

the internet is full of 'experts' that are (at best) misinformed, and some just put across their own opinions as fact

most people simply want to peddle their own version of events for their own gain, either financially, or egotistically.

 

[Bitpipe]

6 hours ago, jamiehamy said:

Audi auto gearboxes? They are mince - full stop. Where did you take it to out of interest? Have you tried somewhere like this? http://www.ecutesting.com/audi_a4_a6_multitronic_gearbox.html - 

Cool, at the moment I drive round with a pen permanently stuck in the over-ride slot, has worked for 8 months

 

Will give them a call, just need a friendly mechanic to extract it for me..

 

[Bitpipe]

On a related note, had my private BC come round for a pre- final inspection. He said 'I'll need the MVHR commissioning cert'  I responded that it was a DIY install (which is common) so what did he need to see exactly?

 

We agreed that I'll send him the spec of the unit to ensure it's adequately sized for the house

 

[Jeremy Harris]

I went through Part F to see what the requirements were in terms of competency to install an MVHR and it turns out that there aren't any!  The problem is a cultural one, I think.  Building inspectors are getting so used to seeing bits of paper from a supposedly competent person that they seem to expect them for everything. 

 

There is a guidance note for providing the evidence that an MVHR has been correctly commissioned, but when I was looking through all the regs its existence was far from obvious, so I just wrote up a report showing compliance with each part of Part F that applied, with some installation photos to show things like the accessibility requirement.  It was only later that I found the compliance guidance note, but if anyone's looking for it, it's here:  https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/456656/domestic_ventilation_compliance_guide_2010.pdf

 

It's a bit easier to find, now that the government website has been tidied up.  Back when we started our build I ended up downloading all the regs and cross referencing the bits that applied to us in a single document, as it was more than a bit frustrating trying to wade through loads of stuff that didn't apply.

Edited February 24, 2017 by JSHarris
typo, spelled "commissioned" incorrectly..............

[TheMitchells]

On 23/02/2017 at 15:55, PeterStarck said:

The problem with this is that a lot of people will think he is an 'expert' and will be put off from using MHRV. They may also think because it's not worth installing MHRV it's not worth building airtight.

That was my thought - most people do not know about MVHR and if they hear they need replacing every 10 years, it will put them off - especially as it 'required constant maintenance.'  I shall be sending an email to the magazine to query the article and comments.

[Jeremy Harris]

49 minutes ago, TheMitchells said:

That was my thought - most people do not know about MVHR and if they hear they need replacing every 10 years, it will put them off - especially as it 'required constant maintenance.'  I shall be sending an email to the magazine to query the article and comments.

 

Worth telling them, but I have a feeling that the magazine may well just ignore your views, I'm afraid to say.

 

There's no logic with these things, especially when you look at all the things in a  house and compare their maintenance requirements.  Most people would spend more time maintaining their vacuum cleaner than they ever will maintaining an MVHR.........................

[daiking]

43 minutes ago, JSHarris said:

 

Worth telling them, but I have a feeling that the magazine may well just ignore your views, I'm afraid to say.

 

There's no logic with these things, especially when you look at all the things in a  house and compare their maintenance requirements.  Most people would spend more time maintaining their vacuum cleaner than they ever will maintaining an MVHR.........................

 

 that you think normal people maintain their hoovers (TM). You give people far too much credit. 

 

face it, the advertorial in question is probably financed by vent people and if it isn't I expect the magazine in question will be full of adverts of associated products.

Edited February 24, 2017 by daiking

[Jeremy Harris]

34 minutes ago, daiking said:

 

 that you think normal people maintain their hoovers (TM). You give people far too much credit. 

 

face it, the advertorial in question is probably financed by vent people and if it isn't I expect the magazine in question will be full of adverts of associated products.

 

 

I seem to end up emptying our vacuum cleaner every couple of weeks, cleaning the filters three or four times a year and giving the internals of the thing a good clean maybe once a year, so I reckon that's more time and effort than I spend on the MVHR! 

 

It takes at the most 2 minutes or so, every 6 months, to change the filters and clean out the chamber on the fresh air in side of the MVHR.  It's quicker than taking the filters out of the vacuum cleaner and cleaning them and probably not much longer than it takes to empty the vacuum cleaner chamber into the bin.

[Steve W]

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.

[Stones]

@Steve W Appreciate this relates to fans in a Vent Axia, bit hopefully give you the push to try bearing replacement.

 

 

[Steve W]

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