MVHR critique for bungalow & recommended suppliers

[Stu789]

We are hoping to push the button on the timber frame order shortly and I'm keen to avoid MVHR ducting issues.

Please chip in with any suggestions and also recommended companies for design/supply/commissioning (unless I can satisfy BC by self-commissioning) - I'll very likely do install.

 

This is a self-build bungalow - 170m2 floor area excluding the garage, MVHR unit and manifolds to go up in the attic and use radial ducts to 7 inlets/ 7 outlets.

Warm roof, posijoists/attic trusses/2.4m ceiling throughout except the vaulted dining room.

Outside air inlet/exhaust on North facing wall with an extra pre-filter box on inlet connected via Aerfoam ducting.

Ducting to/from rooms using Ubbink semi-rigid ducting.

Thanks for suggestions

[JohnMo]

Inlet/outlet seem a long way from MVHR unit.

 

You only really need 1 extract from kitchen. I would locate the extract between the island and the dining area towards the wall units and have no supply in there at all. Air will travel from lounge and sweep area any way.

 

No need for supply or extract in cupboard areas.

 

Pantry supply or extract?

 

Look at airflow paths from a supply terminal and see the shortest travel path to an extract and make sure you sweep all floor areas that are normally used (not cupboard etc)

[Indy]

BPC Ventilation will do a design for you and also supply - they're generally one of the cheaper suppliers if you're planning a self install and commissioning. 

[G and J]

We used heat, space & light. Very pleased with outcome. They designed, supplied, we fitted, and they commissioned (also did our air test).

 

Other tip we got very early on was to allow for holes for ducting in our steels/size of webbed joists from outset, but this may not apply to your installation being a bungalow.

[Post and beam]

Kitchen extracts too close together.

Why are there supply ducts to Kitchen? and they are too close to the extracts.

Are the external vents 2 metres apart?

What physical size MVHR unit do you want, will it fit through the loft hatch? A brink 400 will not fit through a standard hatch. Ask me how i know.

On the face of it this installation looks like it will be easy from the loft , just string the ducting along the joists and drop 90 degrees into your ceiling outlets. No need for anyone else to do it if you are handy with a screwdriver. 

What ceiling vents have you chosen and how will you handle the 90 degree turn? I ask because the Ubbink ones need to be mounted on some kind of standoff in the loft to get the correct location at the plasterboard interface. Did that make sense?

[Indy]

BTW - we did use Heat Space and Light as well, for the whole package and quite pleased overall (apart from the cost!)

[Stu789]

Thanks John/Post and beam/others - this is very helpful.

4 hours ago, JohnMo said:

Inlet/outlet seem a long way from MVHR unit.

You only really need 1 extract from kitchen. I would locate the extract between the island and the dining area towards the wall units and have no supply in there at all. Air will travel from lounge and sweep area any way.

No need for supply or extract in cupboard areas.

Pantry supply or extract?

- MVHR moved shortening outside connections

- Reduced kitchen to 1 extract

- Does the dining room (south facing lots of glass) not need some airflow as air drawn from lounge won't cover it?  

- Larger alcove will have be wheelchair and golf club storage - could be wet hence thinking an extract would be helpful, deleted extract in coat alcove

- Pantry was a supply and plant room an extract - generous door undercut or vent between the two

1 hour ago, Post and beam said:

Kitchen extracts too close together.

Why are there supply ducts to Kitchen? and they are too close to the extracts.

Are the external vents 2 metres apart?

What physical size MVHR unit do you want, will it fit through the loft hatch? A brink 400 will not fit through a standard hatch. Ask me how i know.

On the face of it this installation looks like it will be easy from the loft , just string the ducting along the joists and drop 90 degrees into your ceiling outlets. No need for anyone else to do it if you are handy with a screwdriver. 

What ceiling vents have you chosen and how will you handle the 90 degree turn? I ask because the Ubbink ones need to be mounted on some kind of standoff in the loft to get the correct location at the plasterboard interface. Did that make sense?

- Yes - External vents were 2m apart - a little more on the revised plan

- Will keep an eye on MVHR unit size & hatch - obviously not an issue when building but if it needed a whole unit replacement...

- Yet to look at vents - will check their requirements - would be nice that they don't sit proud of the loft floor!

 

Updated version:

 

[JohnMo]

Move kitchen extract further along the wall to the gap between kitchen units and the other unit in dining. You don't need the supply by the lounge door. Just supply more into the lounge, around 60m3/h, it will spill 45 into kitchen and balance will flow into utility sweep the whole kitchen diner.

 

Air supplies to bed 2 and physio room will spill down corridor, under doors to bathroom and ensuite. The extract in the hall messes this flow8 path so is not needed.

 

I would do a combi supply extract outside wall unit and the the ducts can run together from MVHR unit to external wall.

 

I would follow passivhaus flow rates for bedrooms, maybe slightly higher for your physio room if in regular/daily use. I would also be tempted to change description to bedroom on your plan.

 

[Stu789]

Thanks @JohnMo - the kitchen extract makes sense now & those other changes simplify the design further.

 

[JohnMo]

Looking again now it's simplified the pantry supply isn't really adding to anything. The plant room extract is drawing air through that room anyway. Having the supply causes a short cut from pantry to plant room.

 

Do double 90mm duct to lounge, everything else should be fine in single 90mm ducts. If in loft you will need insulation on ducts. Or build a PIR tunnel for the ducts. Build the MVHR into an accessible insulated box to stop heat gain in summer and cold in winter.

 

Loft hatch will really need to incorporate a ladder for access. Floor loft for access to allow filter and general maintenance to MVHR. 

 

MVHR will need a dry trap for condensation drainage.

 

Since you have moved the MVHR is there any reason not to move back to where it was and take the inlet outlet out the other end of the building by diner. Then all the possible noise is well away from bedrooms.

 

Observation pantry seems to take up a lot of space for effectively a corner cupboard and what is the appliance garage? I would look to simplify the pantry, appliance garage and coat store. You have 4 doors in that area which is very busy.

 

Do you need a plant room? Cylinder is making space too much of premium, you have loads of dead space in the loft, your MVHR is there already. Assume you have a heat pump UFH manifold could go in the utility where the cylinder is shown. Then have a more usable utility.

[Stu789]

Makes sense to drop the pantry supply and add 2nd outlet in lounge.

Its a warm roof & the room extract/supply ductwork should be under the loft boarding but good point on avoiding summer heat gain.

I had put the extract/supply on the north facing wall - south facing is all glazed (with decent overhang, triple glazing etc) - could put it through the east facing roof as alternative.

I agree its busy round the coat/pantry area - I'm for dropping the coat door but some negotiation with SWMBO needed...

Will look at headroom and DHW cylinders as agree it would free up a chunk of space.

 

All very helpful thanks

[JohnMo]

46 minutes ago, Stu789 said:

2nd outlet in lounge

No need to add a second outlet, if it's a pain - just do two ducts to a single outlet 2x90mm to 125mm plenum.

[JohnMo]

50 minutes ago, Stu789 said:

Will look at headroom and DHW cylinders

Horizontal cylinder?