MVHR Loft install in fully renovated property

[I N]

Hi all,

I am looking to install MVHR in a house for a specific purpose not directly related to heat efficiency. We have a 1930s house fully renovated and finished, the area we live in unfortunately has out of control landfill very close by. This means we can't open doors or windows without getting smell of gas (and dust) coming into the house. So looking at installing MVHR as a way of letting clean air into the house. 

Based on the advice I had on here, I am planning to go with Brink Flair 400 unit. I worked out the area (145m2), volume (349m3) and planned out the ducting layout bearing in mind its a finished property with no previous provision for MVHR. I am still learning how to do the calcs as well as optimal layouts and understand I may have to compromise on ducting layout. I am also looking to pay someone for the design (or incorporate design into supply price). What I wanted to check is if my plan is generally doable or am I missing any critical points (and to estimate costs).

What I am planning is follows:
- Brink Flair 400 unit placed in cold loft attached to the rafters, plumbed with condensate drain 
- External inlet and outlets connected into loft eaves via 220x90 vents, 180mm insulated duct
- Brink Pure Induct air filter connected to internal Flair supply via 180mm insulated duct

- one 8-port Ubbink distribution box for supply side and separate 8-port Ubbink distribution box for extract side. 
- Ubbink 75mm flexible ducts on supply single run to each of 4 bedrooms, double run to 3 living spaces
- Ubbink 75mm flexible ducts on extract, single to 2 bathrooms, double to landing, kitchen and basement
- single Ubbink plenum in each area (11 rooms in total)
- Lindab Airy Valves or similar in each room

Questions:
- Does above sound reasonable - have I missed anything obvious?
- Does Flair 400 require any separate controlers or accessories not included into the unit price?
- I know cold loft is not ideal, this was never planned. I planned all ducts as either insulated or on the warm side of the loft. Only exception is Pure Induct - its uninsulated and exposed. How likely is that to matter? (I could build insulated box for it).
- Cost - I priced above based on ventilationland prices for Brink and it comes above 5.5k! I am still waiting for CVC to provide a quote for design & supply. I am a bit worried here, cost is already at high end of my expectation. I understand CVC are likely to be even higher, are there any obvious places I could cut back on costs (e.g. plenums or valves)? 
- one bathroom area is only accessible from below for the final part of run , I can push ducting into location from above but i can't fix plenum from above (its walled off).  Are there any options for securing acessible ducting to the vent from below the ceiling level? 

[Roundtuit]

I may be wrong, but I don't think that's going to help the smell issue is it?  Might actually make it worse if you're ducting smell in to more rooms?

[Conor]

A few notes, hard to be specific without drawings etc.

 

1. The MVHR will do nothing to prevent smells entering the house. In fact it'll be worse than currently. You'd need an activated carbon filtration system as well.

2. The 75mm ducts may need to be doubled up for some rooms - say anything over 7m or so. Definitely over 10m.

3. How many stories does your house have? The duct runs take up more space than you think. 

4. Each plenum should be at the far corner of each room - have you planned duct runs that take in to account joist direction? Are these routes clear to push a duct through? If not, it will get messy and expensive.

[JohnMo]

Have you looked into PIV ventilation systems, with an activated carbon filter. One less fan to drive.  MVHR great in an air tight house, but an additional cost to run in a non airtight house.

[MJNewton]

@Ultima357 did a great write-up of a DIY actrive carbon filter with seemingly really positive results...

 

 

[I N]

4 minutes ago, Conor said:

A few notes, hard to be specific without drawings etc.

 

1. The MVHR will do nothing to prevent smells entering the house. In fact it'll be worse than currently. You'd need an activated carbon filtration system as well.

2. The 75mm ducts may need to be doubled up for some rooms - say anything over 7m or so. Definitely over 10m.

3. How many stories does your house have? The duct runs take up more space than you think. 

4. Each plenum should be at the far corner of each room - have you planned duct runs that take in to account joist direction? Are these routes clear to push a duct through? If not, it will get messy and expensive.

Thanks for the response. I appreciate I am taking the risk here that it may not fix the issue, but its either this or move. If I was renting, we would be packing the bags right now :-). Some people locally have fitted various filtering units to varying degrees of success, so hoping to do the same. 

 

1. On smells issue, that is the purpose of Pure Induct - it has both carbon and particulate filter - supposedly to clean room standard. I spoke to Brink about it and their tech guy uses it in his house to stop the log burner smoke coming in - swears by it (he would obviously).  If anyone on here has one, would love to hear independent view.

2. Yes I doubled all the 75mm ducts to all downstairs areas for this reason (plus they are bigger rooms and more used)

3. Living areas are ground and 1st Floor, there is also a small basement area which gets quite damp..

4. Thanks, I read the recommendations and worked out the runs to maximise air flow through the room. I have also accounted for the joists.

[I N]

11 minutes ago, JohnMo said:

Have you looked into PIV ventilation systems, with an activated carbon filter. One less fan to drive.  MVHR great in an air tight house, but an additional cost to run in a non airtight house.

I have but other than going to specialist industrial suppliers, the standard domestic PIV units filtration is very poor. I guess I could pair up Brink Air Induct with a PIV of some sort, it may be another option but I would be on my own with support and figuring it out. 

In terms of airtightness, I have tried to make building airtight during renovation - its rebuilt from scratch internally - wet plastered, triple glazed glass units, insulation. I've not really worried about airtightness as such, but I imagine it would be pretty good. It certainly gets very very stuffy quickly with 6 people + dog and a cat. 

[jayc89]

We're in a similar position (minus the smells). What's the current building fabric like? Trickle vents? Letter boxes? Wet plaster/dot&dab PB? Unless the house is already reasonably airtight, it's likely the smells will make their way in one way or another.