Jerry-rig an MVHR unit - how?

[Dreadnaught]

I would like to jerry-rig the MVHR unit to have it running over the winter months before I finally install it properly next spring. But how to mount it?

 

I have about 6-weeks of cladding to finish off before I can turn to first fix. And then it will take me quite a while to get around to installing the MVHR unit properly. So realistically that won't be until next spring. I am very slow.

 

I often camp on site as I work, treating my build as a (very well insulated) tent. The timber frame is insulated, weathertight, with windows and a temporary front door. Its also airtight (blower-door test of 0.47 ACH (n50) recently).

 

The MVHR unit (Brink Flair 325) is sitting in its box waiting for me. And most of the ducting is already installed (with their valves). 

Hence, I'd like to temporarily set-up the unit and have it running over the winter months.

 

- How to mount it? - The MVHR unit itself weighs 37 kg.

    - The walls are 240mm I-beam cassettes, filled with Warmcel and I know where the I-beams are located. 

    - The external wall are currently bare 12.5 mm Smartly but will eventually be covered in 50mm insulated plasterboard.

 

- I could power it from a 240V extension lead.

- I could run the condensate drain to local external drain.

 

Any pointers on how to do this would be gratefully received?

[ProDave]

I would not bother.  With just one of you in the house, just crack 2 windows on opposite sides open on their ventilation gap and that will give you all the fresh air you need.  If time is limited, to it once and do it right when you get the time, rather than waste time bodging something temporary.

[joe90]

How long would it take to mount it properly in the first place? Is it really worth a temp job to have to do it again? I hung mine from the roof I beams in the loft, so that any noise generated did not transmit to the ceilings and that works very well.

Edited September 16, 2022 by joe90

[JohnMo]

They don't even start MVHR units until you are painted - Passivhaus MVHR guidelines.

 

You could easily mess up the heat exchanger and ducts for little or no gain. Get on with finishing the house, instead of jobs that shouldn't be done and certainly not started up until much later in the building process.

[SteamyTea]

2 hours ago, Dreadnaught said:

blower-door test of 0.47 ACH (n50) recently

Well done.

 

Needs a new topic on how you managed that.

[Iceverge]

You could just put it on the floor and use some flexible connectors to the manifolds. Make sure nobody kicks it however. We put ours in just after I'd painted the skin coat. It really dried out the house. 

 

I would beware of dust getting into your ducting however. All cutting should be done outside, especially MDF. The bloody dust gets everywhere.  We went through 2 sets of filters sharpish.

 

I love the sound of your I beam walls. Any pics?  

 

 

 

 

 

 

[Dreadnaught]

Thanks all.

 

I am the sole builder on my project (with occasional hired help) so I can chaperone the MVHR though any dusty phases. And turn it off. 

 

My main wish in having the MVHR operational during the winter is for its benefits in retaining heat. I don't currently have any space heating.

 

The dwelling is very well insulated. For example the roof has 200mm of PIR above the deck and 100mm of woodfibre insulation between the posi-joists beneath. I am hopeful that I can sail through the winter with a toasty house and just a tiny bit of supplemental heating from a Dimplex. It will be a good experiment on how the house will perform even before I add yet more insulation to the walls with a layer of insulated plasterboard.

 

For mounting the MVHR, I am currently debating whether to mount it to the wall or to the concrete floor (220mm concrete raft foundation on screw piles).

 

The Brink installation manual says (my emphasis): 
 

"The Flair 325 … appliance can be mounted onto the wall with the supplied mounting bracket. For a vibration- free installation, the appliance must be mounted to a solid wall with a minimum mass of 200 kg/m2. A gypsum block or metal stud wall does not suffice! Additional measures such as double panelling or extra studs are required in that case. On request, a mounting support for floor mounting (with the same minimal mass) is available."
 

It now strikes me that bolting the MVHR to the concrete floor, and so without it touching the wall, is probably the way to a vibration-free and quiet life. This is despite the adamant advice from a friend, who has installed quite a few Brink units, saying that wall-installation would be fine in my circumstances.

 

Brink can supply a handsome floor stand but its only 400mm tall. And I was planning to install it at the height of a kitchen counter so that my water softener would fit beneath.

 

So I found myself on Google looking at ways to build a sturdy stand. And stumbled across steel slotted-angle … and then UniStrut. UniStrut looks like it could support the Forth Bridge but it looks rather nicer than slotted angle. Both seem quite inexpensive but only available from online stockists, not from the usual local hardware shops.

 

I am continuing to think. Insights would be most welcome.

 

Edited September 18, 2022 by Dreadnaught

[SteamyTea]

3 minutes ago, Dreadnaught said:

I can sail through the winter with a toasty house and just a tiny bit of supplemental heating from a Dimplex.

Put an energy meter, with a temperature logger on it.  Will give you really useful information.

[Gone West]

24 minutes ago, Dreadnaught said:

Insights would be most welcome.

In the winter we worked in the house with a 2kW fan heater which kept the whole house comfortable. We didn't have the MVHR connected but found we didn't need windows open for ventilation. I think as there were only two of us working in the house and no other source of moisture and with the large total air volume, we didn't need a ventilation system.

[joe90]

4 hours ago, Dreadnaught said:

So I found myself on Google looking at ways to build a sturdy stand.

 

4 hours ago, Dreadnaught said:

Insights would be most welcome.

Wood? I built a stand from 2”x2” timber to mount my buffer tank on at about 800mm and that weighs far more than an MVHR. any slight “give” in timber will also absorb vibration 🤔

[Nickfromwales]

A couple of strips of self-adhesive neoprene on the reverse of the unit, and use the supplied wall bracket.

Of the units I've fitted to date ( same unit as you've bought, funnily enough ) I've not had any noise issues with floor mounting to posi-joisted floors on 1st floors, or from mounting to TF walls either. Reports from clients to date stated complete inaudibility in the adjacent rooms, from the unit itself, and same in rooms from airflow / functionality.

I always mitigate against noise / sound in my MVHR designs, so the results come from design / engineering vs luck, but easily doable for any DIY'er as long as they know what to do and where.

 

Another reason for doing plenty of reading up here on Buildhub!!

 

@Dreadnaught

Have you bought attenuators to go between your manifolds and the Flair?

[Dreadnaught]

5 hours ago, Nickfromwales said:

Have you bought attenuators to go between your manifolds and the Flair?

 

Yes, 1m-length flexible Ubbink-supplied attenuators on both the supply to and extract from the dwelling 👍

[Dreadnaught]

On 18/09/2022 at 12:44, joe90 said:

Wood? I built a stand from 2”x2” timber to mount my buffer tank on at about 800mm and that weighs far more than an MVHR. any slight “give” in timber will also absorb vibration

 

You make a good point. Yes. Thanks @joe90.

[MarkyG82]

On the subject of mounting, what about a hanging platform? Nothing fancy and maybe on 3 cords (chords?) to allow for self leveling. Should offer a good level of isolation. Horizontal supports could be used to counter any rotation offered by the unit boosting.

[joe90]

31 minutes ago, MarkyG82 said:

what about a hanging platform?

Exactly what I did, hung from roof I beams and on rubber feet. This was done to stop any noise and vibration through the bedroom ceilings and it works very well, no noise at all apart from a little air noise from terminals when on boost.

[Simplysimon]

On 16/09/2022 at 12:44, SteamyTea said:

Needs a new topic on how you managed that.

i beams with smartply glued and fixed to the face with every joint glued? then a good foam (illbruck fm330) and seal everywhere (illbruck sp925) just in case?

[Nickfromwales]

On 19/09/2022 at 06:48, Dreadnaught said:

 

Yes, 1m-length flexible Ubbink-supplied attenuators on both the supply to and extract from the dwelling 👍

Ah, ok. I’m not a fan of those tbh.

I use ( sometimes multiples of ) the 500mm long rigid box attenuators religiously, after not getting very good results from those flexi attenuators ( which EsaveP recommended ). Since dealing with Nick Vaisey and the team at CVC Systems, who introduced me to these a few years back, things have become markedly improved!! Client feedback on top results / inaudibility is irrefutable.

Client on the aforementioned lesser-performing  job wanted cheap, and she got cheap. Rumour has it that they’re filing on her land, a sequel to Silence of the lambs……”Silence of the fans”.

 

Not done one that way since, but I am fortunate enough to be working for more discerning clientele these days ( very fortunate, touch wood ). I did one install with the 1000mm long box attenuators, that was fun getting those into a 1.2m wide plant room  

 

Consider a change to the box attenuators @Dreadnaught, as the flexis are very difficult to keep in the ‘round’ state, eg if you need to clamp or support them they just collapse under their own weight.

[Nickfromwales]

On 18/09/2022 at 08:40, Dreadnaught said:

I am continuing to think. Insights would be most welcome.

You can use the uni-strut no probs there, if it bodes better, and can likely still be very rigid with no hindrance to the softener going underneath it. Be mindful that the softener is a PITA with noise created from regeneration,  so do yourself a favour and but one with electronica, eg so you can dictate when it regenerates ( early hours or midday etc ).

Also, note the positions of the overflow and discharge of the softener, as most I’ve fitted have had to be raised slightly off the floor to facilitate the correct ( and effective ) gravity flow away from the unit, particularly where the pipework has to run horizontally away thus lifting the height of where the 2x discharge pipes enter the waste pipework.

[Dreadnaught]

On 28/09/2022 at 21:16, Nickfromwales said:

1000mm long box attenuators

 

Thanks @Nickfromwales. I have been looking online trying to work out what you mean by a box attenuator. Is is this sort of thing?

Or do you mean the round ones, like this?

[Dreadnaught]

On 28/09/2022 at 20:28, Simplysimon said:

i beams with smartply glued and fixed to the face with every joint glued? then a good foam (illbruck fm330) and seal everywhere (illbruck sp925) just in case?

 

Pretty close, yes.

 

My walls are indeed I-beams with Smartyply nailed on. The joints and nail-heads were over-pained with airtightness paint. Windows were foamed and double-sealed with decent tapes by me. Rooflight were upstands painted with airtightness paint. The joint between wall and roof was foamed for insulation and painted with airtightness paint. The joint between wall and concrete raft foundation was painted with airtightness paint. All penetrations were sealed with decent grommets and tapes by me and mostly also overpainted with airtightness paint too. 

 

The OSB flat roof was left un-sealed, with some slightly-worrying gaps between boards were clearly visible but there is a Bauder three-membrane warm roof above. Before the air test, I was ready to spray paint the entire OSB roof deck with airtightness paint (form inside) but fortunately it was not needed and Bauder's claim that their roof build-up was airtight has proven true. 

 

Above all, the building has a simple L-shaped form. And airtightness was managed by me personally, so I kept an eye on all the details.

 

 

[joe90]

On 28/09/2022 at 21:16, Nickfromwales said:

box attenuators

Or make your own that doubles up as a manifold 😇

[Nick Laslett]

I went with these rectangular Lindab attenuators. 
 

https://www.phstore.co.uk/attenuators/lindab-lrca

 

 

*edit System is a very long way from being up and running, so no idea on their effectiveness. 

Edited September 30, 2022 by Nick Laslett

[Nickfromwales]

12 hours ago, Nick Laslett said:

I went with these rectangular Lindab attenuators. 
 

https://www.phstore.co.uk/attenuators/lindab-lrca

 

 

*edit System is a very long way from being up and running, so no idea on their effectiveness. 

 

@Dreadnaught These are the ones I use / specify now.

 

Just had 4 of the 500mm ones fitted on my current clients project, quite a big house so a double-unit install, and the guys from CVC Systems persevered to get them in, in what can be described as a “not large” plant space under the second stairwell. Didn’t help that I also spec’d a Brink Air Comfort for heating / cooling of the open spaces and bedrooms which took up the last few mm’s of space available . I’m sure the installers will forgive me over time……  

[jayc89]

On 30/09/2022 at 20:50, Nickfromwales said:

 

@Dreadnaught These are the ones I use / specify now.

 

Just had 4 of the 500mm ones fitted on my current clients project, quite a big house so a double-unit install, and the guys from CVC Systems persevered to get them in, in what can be described as a “not large” plant space under the second stairwell. Didn’t help that I also spec’d a Brink Air Comfort for heating / cooling of the open spaces and bedrooms which took up the last few mm’s of space available . I’m sure the installers will forgive me over time……  

 

Looking at the 160mm units, these seem to match or beat Lindab's noise reduction figures, and for a fraction of the price - https://www.ductstore.co.uk/acatalog/info-SIL50-600-160.html - what am I missing?

Edited October 15, 2023 by jayc89

[jayc89]

On 19/09/2022 at 01:07, Nickfromwales said:

A couple of strips of self-adhesive neoprene on the reverse of the unit, and use the supplied wall bracket.

 

Isn't that basically the same as compriband?