MVHR self install - tips and experience

[flinn]

Hi, I am at the first fix stage of my 250sqm self build. I am planning to install and comission the MVHR system myself. I plan to use a Zehnder ComfoAir Q 350 unit with rigid Lindab Safe ductwork. The duct sizing and flow rates have been designed by an experienced M&E friend.

 

Does anyone have any installation or commissioning tips what might help me avoid any outfalls along the way please?

 

Thanks in advance, John.

[Nickfromwales]

Hi John. 
It’s relatively easy to do, just have a second pair of hands when you uncoil the ductwork as it needs to be completely laid out and untwisted. Then it’ll need at least one extra pair of hands to feed it into the house.

Install the soil and waste pipes first, as they take presidency over the MVHR. 
Have you doubled up runs to the furthest bedrooms? Have you allowed for attenuation? 

[Marvin]

Hi @flinn

 

Not directly about the MVHR but related:

 

If your intending to stay in your self build....

 

Some people have commented that parts of a building can become very warm whilst at the same time other parts can be quite cool. This can be due to solar gain or heat travelling upwards. I would suggest you might consider this dilemma with your M&E friend to see if an additional bit of system can be utilised to relocate the heat within the building. Three story buildings, tall open hallways and large windows all seem to cause this imbalance.  

 

In the spring and autumn, on sunny days, I wish we could take the heat from the East facing windowed rooms in the morning and distribute it to the west end rooms and vice versa in the evening. As it is, using the MVHR, we can only expel the heat or recirculate the heat to the whole building. As we have AIM, that is to say good Airtightness, Insulation and Mechanical Ventilation with Heat Recovery, once the house is warm it stays warm or once cold it stays cold for a long time.

 

Good luck.

 

Marvin.

 

 

[mike2016]

Make sure you keep the ducts dust free / seal them until the build is finished. Have you a plan for the external penetrations & keeping insects & water out? Ideally they should be on the same side of the building and / or 2.5 meters apart. Consider handiest location for the controls and isolation switch in case your neighbour starts burning their tyre collection! Take your time running the ducting, strap well & insulate if running through a cold area (cold roof). 

[Oz07]

On 27/06/2023 at 06:44, flinn said:

Hi, I am at the first fix stage of my 250sqm self build. I am planning to install and comission the MVHR system myself. I plan to use a Zehnder ComfoAir Q 350 unit with rigid Lindab Safe ductwork. The duct sizing and flow rates have been designed by an experienced M&E friend.

 

Does anyone have any installation or commissioning tips what might help me avoid any outfalls along the way please?

 

Thanks in advance, John.

Find someone decent with the right kit to commission!

[Jenki]

12 minutes ago, Oz07 said:

Find someone decent with the right kit to commission!

😞Not really the answer needed on a self build (DIY)forum. If it was the admin could put that in a banner on the landing page and be done with it.

[flinn]

On 27/06/2023 at 08:52, mike2016 said:

Make sure you keep the ducts dust free / seal them until the build is finished. Have you a plan for the external penetrations & keeping insects & water out? Ideally they should be on the same side of the building and / or 2.5 meters apart. Consider handiest location for the controls and isolation switch in case your neighbour starts burning their tyre collection! Take your time running the ducting, strap well & insulate if running through a cold area (cold roof). 

Hi Mike

 

Thanks for your reply - just getting down to this. I've been wondering about strapping - do you need to strap well because there is movement in the system when it is operational?

 

Thanks

[flinn]

On 01/07/2023 at 17:44, Jenki said:

😞Not really the answer needed on a self build (DIY)forum. If it was the admin could put that in a banner on the landing page and be done with it.

Haha, exactly! I have read about people commissioning their own systems. How hard can it be with the right kit?

[Alex Fossa]

I'm planning to do the same using a Zehnder ComfoAir Q 350. Are you going to use attenuators before the supply / return manifolds.

 

What made you decide on rigid Lindab Safe ductwork over flexible plastics?

 

Thx

Alex

[mike2016]

9 hours ago, flinn said:

Hi Mike

 

Thanks for your reply - just getting down to this. I've been wondering about strapping - do you need to strap well because there is movement in the system when it is operational?

 

Thanks

No movement due to the air but you may have other cables or pipes in close proximity and in my attic I often kick the ducts as they are under the insulation as I am moving about. I just like knowing they stay where I left them!

[JohnMo]

15 hours ago, flinn said:

Haha, exactly! I have read about people commissioning their own systems. How hard can it be with the right kit?

It's easy enough if you are methodical and have half a day to spare. You also need the calibration certificate for the flow meter you are using, for building control.

 

I set it all up, with equipment without a calibration cert, then got a man in, with the right kit to certify everything.

 

15 hours ago, flinn said:

Hi Mike

 

Thanks for your reply - just getting down to this. I've been wondering about strapping - do you need to strap well because there is movement in the system when it is operational?

 

Thanks

The duct just has a slow gentle flow of air going through it, I just used metal strapping to stop it moving from A to B over time.

[flinn]

@mike2016 @JohnMo Thanks for your replies!