MVHR Installation Issues

[Nickw1982]

Hi,

 

I have joined this forum for help and advice on a recent MVHR system installation in my family home. I am not in a related trade\profession and until recently my knowledge about MVHR systems was non existent. I live in a relatively new home that for some unknown reason was built air tight and the upstairs living was very uncomfortable during periods of hot weather. After some research, I decided to retro-fit a MVHR system into the upstairs living area only and mount the system in the loft space. Due to my lack of free time and missing knowledge, I thought I would have it professionally fitted using a reputable MVHR design and installation company. I knew this would increase my costs but i thought that I would have piece of mind knowing the system was installed correctly.

 

The system was installed last week, it took the company approximately 2.5 days in total at a cost to me of around £816 per day (£2,040 total). Over the weekend, i have had chance to check the work and unfortunately I am not happy with 3 particular areas and i would like the forums support to understand if my system has been installed correctly. My 3 issues are the following:

 

1. Supply\Exhaust Vent boxes - The installers have damaged my Gable wall brick work whilst stitch drilling the stone for the vent boxes. Please refer to the "Issues 1" pictures below, you can see that above one vent too much has been taken off the stone and it is now holding water. The silicone seal has collapsed on both vent boxes.
2. Ceiling plenum Installation - The ceiling plenums have not been fixed at both sides in the loft space, loose bits of wood have been wedged underneath adding weight on top of the boards. Please refer to "Issue 2" pictures below - the added weight has popped a screw and damaged my decorating in my bedroom.
3. MVHR System Unit Mounting - The MVHR unit itself has been mounted on my trusses. Please refer to "Issue 3" pictures below. The wood used seems to be too short with only one screw in each. I would of thought that high duty plywood board should be used and screwed multiple times to each trusses to reduce resonance. 

 

I have not yet paid for the installation and I would just like to seek help and advice from the experts to understand if my highlighted issues have substance and how they would compare to other professional installations. Since this is my first MVHR experience, I have no other situation to compare to nor do I have a view of the professional standards for a MVHR installation.

 

Happy to answer any questions, thanks in advance

 

Nick

Edited October 25, 2021 by Nickw1982

[MJNewton]

The installation issues look like fairly typical 'poor attention to detail' that go with many a tradesman that don't take pride in their work. It's the sort of thing that'd disappoint me but also the sort of thing that doesn't surprise me anymore (and what pushes me towards DIY). 

 

Something to note is that if you fitted MVHR to help in the summer then I fear you'll be disappointed. That's not what it's for, and the low capacity of air coupled with relatively flow rates mean that it won't have much of a cooling effect. It can help with stuffiness though, and can help psychologically if you imagine it pumping in fresh air on hot still nights! 

Edited October 25, 2021 by MJNewton

[Roundtuit]

Poor job. As above, its the sort of job that makes you wish you'd had a crack at it yourself.  I'd have a chat with them and discuss your concerns; they're all valid.  I'd also want more separation between the vents - can't remember what the recommendation is, but worth checking before you part with any money. (And the plenum should be covered in insulation when they've finished).

[IanR]

Hi Nick, and welcome.

 

All the points you have made are valid. The only one they could argue is the 3rd. While the fixings do not look substantial enough, it hasn't failed (yet). But I wouldn't be happy with it.

 

As per @MJNewton, I'm more concerned that MVHR will not fix your issue, and is not required in your house.

 

20 minutes ago, Nickw1982 said:

I live in a relatively new home that for some unknown reason was built air tight and the upstairs living was very uncomfortable during periods of hot weather.

 

Why do you think it is "air tight", have you had an air infiltration test done? Do you know the air tightness figure for the house?

 

When you say uncomfortable, are you referring to excessive heat? Are you a full 2 storey, or do you have rooms/dormers in the roof?

 

If the MVHR was installed to get rid of the excess heat, unfortunately it will have negligible effect during the day when it is hot, and only start to help overnight when the ambient temperature outside drops.

[Nickw1982]

Hi All,

 

Thanks for your quick reactions and comments. I have never had an air tightness test done, there are no trickle vents in my windows, the way the house holds residual heat is remarkable, even on a night when the temperature outside is much cooler. My rational behind the MVHR was that it would bring in this cooler air on a night and take out the stale heated air. I am not expecting air conditioning, i just want fresher air

[ProDave]

1 minute ago, Nickw1982 said:

Hi All,

 

Thanks for your quick reactions and comments. I have never had an air tightness test done, there are no trickle vents in my windows, the way the house holds residual heat is remarkable, even on a night when the temperature outside is much cooler. My rational behind the MVHR was that it would bring in this cooler air on a night and take out the stale heated air. I am not expecting air conditioning, i just want fresher air

If there are no trickle vents, are you sure there is no mechanical ventilation already?

 

Opening windows at both sides of the house at night would cool things down a lot quicker than mvhr would.  You would want to run the mvhr at boost speed in bypass mode to stand any chance of that doing much overnight cooling and in boost mode the fan may be noisy.

[IanR]

Without an air tightness test there is no knowing even if an MVHR will be effective at heat recovery. Opening a window is likely a better option.

 

Today's Building Regs in England require an air tightness in a new build of better than 10m³/m².h @50Pa. MVHRs are ineffective (for the heat recovery portion) at more than 5m³/m².h @50Pa . At less than 3m³/m².h @50Pa building regs wants centralised mechanical ventilation to ensure sufficient fresh air. It's unlikely a 2012 house, built by a volume builder has achieved better than 3m³/m².h @50Pa, unless a subsequent owner has done lots of work to improve air tightness.

 

If you are feeling it is hot a stuffy up stairs, there could be plenty of air flow, but the fabric of your building has heated up and is rewarming the fresh air as it comes in, giving you the impression there is no air flow. Dormers and rooms in roof are especially prone to this.

 

[Nickw1982]

Thanks again. I would like to add that the house is built against a hill, the upstairs back of the house is at ground level. I don’t like the thought of opening windows through the night with my young family in the house.

 

There is no ventilation or fans in any of the rooms and the windows do not have trickle vents. It would be interesting to get a test done. However the MVHR system is in now, even if it’s to a poor standard. I now have the joy of speaking to the company about these issues. I am still waiting for their invoice. It will not be cheap to replace the stone for issue 1.

[Iceverge]

@Nickw1982

 

How are the noise levels? 

 

 

[riboid]

I have my exhaust and air inlet protruding out and not flush with the wall in my mvhr system.  Firstly, because of external wall insulation I have fitted and secondly, to ensure a proper seal against the brickwork.

Also, as mentioned up above, there is meant to be a minimum spacing between air in and exhaust out (1.5m) and also, I have mine at different elevations too.  You may have that spacing as its difficult to gauge on the photograph.

 

On the whole, it looks pretty shoddy to me and in particular that damage to the stonework.  If it was me - get them to extend it out further and then you would have had no stone damage.  The mvhr unit internally looks poorly installed too.  UK is getting worse for tradesman, so it is.

[Nickw1982]

The system itself is quiet even on boast mode (60%), it is not near any of the bedrooms.

 

Is there any official documentation available on the 1.5 m rule between exhaust and intake vents?

 

@riboid - not quite sure what you mean by extending? If you could elaborate it would be highly appreciated. Thanks.

[joth]

Just to add to what the others say, I can confirm in my experience an MVHR is no use at all for cooling upstairs rooms. More details in the link below.

We have this issue all year round - even when downstairs is getting cold enough to require the UFH to come on, upstairs bedroom is uncomfortably warm all night.  In fact it's worse in winter, as the MVHR will not enter bypass mode.

If we slept with the bedroom door open it is just about bearable, and leaving the window open is generally pleasant, but this is not an option for various reasons (pets, trains). So I'm planning a forced-air retrofit to solve it (basically moving a much larger volume of air between the bedroom and the vaulted hallway void, via a FCU which can have active cooling in summer)

 

 

 

[Iceverge]

5 minutes ago, Nickw1982 said:

The system itself is quiet even on boast mode (60%), it is not near any of the bedrooms.

 

That's good. 

 

I would contact the company at the highest level you can (in writing) and give them an opportunity to fix it. It may only have been a rogue operator and they may be terribly embarrassed about it all. 

 

If they fight you or don't offer a prompt and satisfactory resolution certainly don't pay them.  If you are confident to undertake the works yourself I'd remedy it and deduct your labour from any final settlement payments. 

 

If not, engage a tradesman who you trust to fix it and likewise withhold the difference of any payments from the installers. It doesn't need to be a ventilation specialist but someone who is willing to take on the recommendations of the forum and is well handed. 

 

It's important to give the installers the benefit of the doubt to begin with though. 

 

 

[IanR]

26 minutes ago, Nickw1982 said:

Is there any official documentation available on the 1.5 m rule between exhaust and intake vents?

 

 

Ref. https://www.vent-axia.com/file/792933/download?token=6vlpcIyG

 

 

It also states:

 

[Nickw1982]

@IanR - thanks for the information, really useful. I have just measured the distance between the exhaust and intake vents and it is 0.9m, also the straight length ducting connected to the machine is 0.2m (see picture below). 

 

[Roundtuit]

11 minutes ago, Nickw1982 said:

@IanR - thanks for the information, really useful. I have just measured the distance between the exhaust and intake vents and it is 0.9m, also the straight length ducting connected to the machine is 0.2m (see picture below). 

 

Sorry you've got these problems, but it looks like they need to start again really, as the warranty won't be valid if its not installed correctly.  Have they used that silver flexi duct throughout? Rigid or semi-rigid would be more usual.

[Nickw1982]

@Roundtuit - there is a mixture of ducting to be honest, all fully insulated. Let me share the design that the company did below; that being said it has not been followed to a tee.

 

Edited October 25, 2021 by Nickw1982

[Nickw1982]

I would like thank everybody for your help and supporting comments. Based on your feedback, I sent the MVHR company the below email and attachments on the 25th October 2021. Today, 17 days later, I received their response and I will post a sanitised version below this post and would appreciate once again your valuable feedback  ..... I don't think its much to ask for things to be done correctly by the professionals 

 

---------- Email Start-----------

I would like to make you aware of my disappointment and dissatisfaction regarding the installation of a MVHR system at my property by XXXXXX which took place over the 19th & 20th of October 2021. Due to the long lead time on materials and prior site visits, I would have expected that there was enough time to thoroughly plan my installation to ensure a high quality installation. However, there are multiple major issues and I have now had the time to seek independent advice to which I would request your written response on the points raised below. I have attached a copy of the Vent-Axia Sentinal Kinetic Advance Installation and commissioning manual for your reference.

1.      Supply\Exhaust External Grille boxes (see attached pictures with prefix 1)

                             i.           The installers have damaged my gable wall work whilst stitch drilling and chiselling the stone. The stone has been over chiselled above one box exposing the inner and creating an area that will hold water. This will accelerate weathering and the wall area will weaken over time. My builder has advised that this stone needs replacing as soon as possible. There is also cracking around both grille box areas and the silicone used to seal both grilles has collapsed allowing water to penetrate.

                            ii.           The grille boxes are not installed as per the manufacturer’s installation and commissioning manual which clearly stipulates on page 3, point 9 that the external grille boxes should be a minimum of 1500mm apart. I have measured mine and they are 900mm apart.

2.      MVHR System Unit Mounting (see attached pictures with prefix 2)

                             i.           The MVHR unit has not been mounted as per the manufacturer’s installation and commissioning manual which clearly stipulates page 16, point 2 that there should be a minimum of at least 0.7m of straight pipe in line with the spigots. I have measured mine and there is 0.2m of straight pipe connected to the unit. There is also 0.6m space underneath the unit.

                            ii.           The unit has not been mounted as per our agreement using the plywood board. It still exists on the short wood with single screws.

3.      Ceiling plenum Installation (see attached pictures with prefix 3)

                             i.           Most ceiling plenums have not been fixed at both sides in the loft space, loose bits of wood have been wedged underneath them adding weight on top my ceiling boards. The added weight has popped a screw and damaged my decorating in a bedroom.

I only have to look on your website to understand that XXXXXXXXX puts the customer at the heart of its business by providing a professional service. I therefore would like to give you this opportunity to turn these issues around and I look forward to your response.

---------- Email Finish-----------

Sentinel Kinetic Advance MVHR - Installation & Commissioning.pdf

[Nickw1982]

Here is the MVHR installers response with link  (rather than attachment) to my email sent  (See my previous post for original email). I would really appreciate your help and supporting comments. Thank you.

 

---------- Email Start-----------

With reference to the communication, you sent to me on the 25^th October and the communication you sent to XXXX earlier this week.

 

We have every intention of answering your queries and issues raised correctly and accurately based on the information you attached and forward to me. However, despite the length of time that has passed there are some questions you have raised that XXXXXX can only answer correctly once we have received the clarification from the manufacturer of the unit we have provided and installed in your property.

 

The Technical Director of VA has been handling your queries on the installation guide detail you have referenced to us. VA have done their best to get these answers sent to us by today and may yet arrive later this afternoon.

 

I will attend to the response you have requested once that information is in my possession along with all installer issues raised. This may not arrive with you until tomorrow morning but as XXXXX requested a small extension was to give VA more time to respond to ourselves.

 

Please find attached the compliance guide (domestic_ventilation_compliance_guide_2010.pdf (publishing.service.gov.uk) that all systems should be installed by as a minimum standard. You may find conflicting points within it that answer some points you have raised. You may even find more questions to raise against your previous email.

---------- Email Finish-----------

 

[MJNewton]

My heart was a racing a little reading that response... and it's not even my issue! Been in similar situations before though (although not with MVHR) and I suspect it is triggering a Pavlovian response of feeling anxious when going into battles like this! Just remind yourself that they are human too, and whether you've got a case or not I am sure all companies get their fair share of unreasonable customers and complaints so you mustn't be too surprised or offended if they initially think you might be one of them. You didn't sound like one to me in your complaint though, so if you keep that calm and level-headed stance I think it'll work in your favour. You are disappointed that's all, and feel that the installation hasn't lived up to expectations of what you consider acceptable based on your understanding and interpretation of the manufacturer's instructions, which doesn't sound unreasonable to me.

 

Their holding response sounds okay to me - at least you got one! Sure, it'd be nice if they just rolled over and said 'gosh yeah, that's not quite up to scratch is it - let's work out a plan how best to proceed from here' but if they really have got VA involved then that's a reasonable second-place position. If VA back down on their own installation instructions, well, I think you'd have to accept that. VA are basically the expert witness in this case and if they say some of the pertinent bits (i.e. the intake/exhaust separation and straight pipe distance) are actually okay and not of real concern then that'd be good enough for me. I'm not expecting them to though, after all why put stuff like that in their instructions if it doesn't actually matter either way? There's nothing stopping you from speaking with VA directly once you know the individual's name in order to challenge an about-turn, but I wouldn't do that yet - let things run their course and respect the effort the installers are putting in and that it is they that have approached this 3rd party. Or so they say, it might be the ventilation-world equivalent of 'having spoken to my solicitor...' which is actually a euphemism for 'having Googled a bit looking for ways to wriggle out of this...'.

 

Regarding the compliance guide it's difficult to comment about that, mainly because I haven't read it all. If it is to become a relevant document to your case then the installers will need to be more specific with their references, just like you were against the installation instructions. It's a shame they put that line in really - feels a bit passive aggressive - but it sounds like it's going to be referred so get reading!

 

Hang in there, and don't lose perspective. It's a situation that needs resolving, yes, but if you and yours have still got your health then everything is merely a bonus.

Edited November 11, 2021 by MJNewton

[MJNewton]

I couldn't resist reading the compliance guide, and am not really seeing much relevance in it to be honest so it'll be interesting to see what bits they going to be relying on.

 

Indeed, the only relevant bit I did spot was a piece of rope which might end up being used to hang them:

 

Regarding location of exhaust vents, Table 7.0 Section 5c says 'The location of the external discharge terminal should ensure that the potential for recirculation of extract air through the supply air inlet is minimised.' and that is surely exactly why Vent Axia suggest a minimum separation of 1500mm (if not, what is the reason for it?).

[Marvin]

Yes @Nickw1982 the external stone is a great shame and needs sorting but not before altering the distance between the inlet and outlet. 

 

 

 

[Roundtuit]

Got a bit bored reading their response tbh.  Looks like a 'holding' position whilst they decide what to do, with nothing of substance.  They are 

probably just buying some time trying to find a way to get their ass off the line.  The installation problems aren't going to go away on their own and aren't really subjective, so I think you're in a strong position to get it sorted.  It'll be interesting to see what Vent Axia say.

[Nickw1982]

10 hours ago, MJNewton said:

I couldn't resist reading the compliance guide, and am not really seeing much relevance in it to be honest so it'll be interesting to see what bits they going to be relying on.

 

Indeed, the only relevant bit I did spot was a piece of rope which might end up being used to hang them:

 

Regarding location of exhaust vents, Table 7.0 Section 5c says 'The location of the external discharge terminal should ensure that the potential for recirculation of extract air through the supply air inlet is minimised.' and that is surely exactly why Vent Axia suggest a minimum separation of 1500mm (if not, what is the reason for it?).

 

Appreciate your response and reading - I was also drawn to the same table, i believe they have used this document to highlight the associated Supplementary Information in this table 7.0 Section 5c. Where it states that a minimum of 300mm horizontal distance is required.

 

That said, I have requested that they seek a formal response\statement from the Vent Axia business for the points raised. Let's see what they come back with ?

[IanR]

9 minutes ago, Nickw1982 said:

Where it states that a minimum of 300mm horizontal distance is required.

 

I would look at it that the install needs to meet both the 10 year old HM Government guide AND the manufacturer's installation requirements.

 

If one is stating a minimum 300mm separation, and another stating a minimum 1.5m separation, then the install must have 1.5m Min separation to meet all requirements.