MVHR Valve Locations in Open-Plan Kitchen.

[JCB400]

Hello,

 

We are installing a small, basic ground-floor MVHR (Blauberg D-105A) as part of a side-return open-plan kitchen extension to our 1910s terraced house. A full-blown MVHR is beyond the scope of the project.

 

I'd really appreciate any comments on the attached design. A few notes:

 

• North is at the top of the page. There is a steel beam running north-south as shown. We can just get some 125mm duct underneath where it meets the column to the south as shown, boxed off above the kitchen units. The beam is otherwise impassable (within the scope of the project).

 

• East of the beam, the south third of the kitchen has a pitched roof with Velux windows (usual London side-return extension). This also limits valve placement options to the area of the bench seating as shown (hence the proposed directional supply valve to avoid draughts).

 

• Valves can otherwise be placed anywhere in the kitchen ceiling west of the beam. It is not possible to place valves east of the beam other than close to the south wall as shown.

 

• The extension is being constructed with best efforts on the insulation and airtightness front but not to a certifiable standard. My main ventilation priority is the utility room, which will have a condenser tumble drier and be used to dry clothes on hanging rails. I have a CO2 meter and CO2 levels in the house are already poor in occupied rooms. The house does not "officially" need an MVHR, but I would like to ventilate in an energy efficient manner and improve air quality.

 

• The kitchen will have a conventional extractor hood over the hob, vented to outside. Given this, I am questioning the need for an MVHR extract valve in the large open-plan kitchen space and wondering whether having an extract valve solely in the utility room would ensure it is well-ventilated without providing excessive airflow to the 2 supply valves. Would the supply valve location in the south east of the dining area, coupled with the utility room extract valve, set up a drift of fresh air towards the kitchen door to ventilate the kitchen, with the conventional extractor hood used for cooking as required? Such that an extract valve in the kitchen is not needed?

 

• If a kitchen extract valve is needed, where is the best location for it? I thought next to the door so as to be diagonally opposite the supply valve, although I'm concerned this might work against the utility room extract valve.

 

Thanks.

 

JC MVHR GBF.pdf

[MortarThePoint]

On 14/05/2021 at 14:51, JCB400 said:

I have a CO2 meter

 

I'm interested in getting one of these, what model do you have and do you recommend it?

 

Don't know much about MVHR unfortunately so can't really help with your main question

[Bitpipe]

I see your challenge.

 

Given your constraints I don't think you have many other options.

 

If you were to forgo the kitchen extract you'd need to double up the ducting for the utility to make the system easier to balance.

[JCB400]

9 hours ago, MortarThePoint said:

 

I'm interested in getting one of these, what model do you have and do you recommend it?

 

Don't know much about MVHR unfortunately so can't really help with your main question

 

I got this one: http://www.cem-instruments.com/en/Product/detail/id/926. It was £69 on Amazon and has been decent (no longer available on there though). Having owned one for a while, I wish I'd spent more and got one with a battery power option so I could use it more easily and in other places (e.g. the car).

 

I get quite high CO2 levels in the rooms in my house if they are occupied with the doors closed - this is in an unrenovated, supposedly leaky Victorian end of terrace. We reached over 4000 ppm overnight in the bedroom - we now leave the door open as a result, until we renovate. 2500ppm in the living room. One of the problems is that curtains etc. occlude trickle vents.

 

There's a good article about it here: https://www.cibsejournal.com/technical/build-tight-ventilate-right/

 

The research paper the article was based on is here: https://www.researchgate.net/publication/273588438_Building_tight_-_Ventilating_right_How_are_new_air_tightness_standards_affecting_indoor_air_quality_in_dwellings

(it's free to download - just click on the blue "Download full-text PDF" in the top right)

 

My experience has been consistent with the above articles. I gather CO2 can be an issue in cars, which isn't great if it results in drowsiness etc. - hence it would be interesting to measure in your car if you get a battery operated version.

[JCB400]

5 hours ago, Bitpipe said:

I see your challenge.

 

Given your constraints I don't think you have many other options.

 

If you were to forgo the kitchen extract you'd need to double up the ducting for the utility to make the system easier to balance.

 

Yes, thanks for the reply.

[MortarThePoint]

30 minutes ago, JCB400 said:

I get quite high CO2 levels in the rooms in my house if they are occupied with the doors closed - this is in an unrenovated, supposedly leaky Victorian end of terrace. We reached over 4000 ppm overnight in the bedroom - we now leave the door open as a result, until we renovate. 2500ppm in the living room. One of the problems is that curtains etc. occlude trickle vents.

 

Gosh those values are very high. MVHR will help with those greatly. I'm looking to go a different way myself but similar principle

[Jilly]

That's interesting. How about getting some house plants? They will absorb CO2 in the day and increase oxygen levels in the daytime (opposite at night, so not in bedrooms) There are some plants which scavenge toxins like formaldehyde too. 

[MortarThePoint]

1 hour ago, JCB400 said:

There's a good article about it here: https://www.cibsejournal.com/technical/build-tight-ventilate-right/

 

It's a very interesting read. I've wondered about how to improve air circulation between rooms, even thinking about incorporating small fans into the bedroom walls to move air to/ from the hall. Children like to have their bedroom doors open at night and from an AQ perspective that's really good.