Full house renovation with MVHR

[Pappa]

Hi guys

 

I want to retrofit MVHR in an old Victorian Terrace that I'm currently gutting out and taking back to the brick.

I intend to cover all ventilation holes for granular control using MVHR.

Any advice or tips?

Any recommendations on systems, manufacturers, or fitters?

 

Thanks in advance

 

P

[Sparrowhawk]

Hi @Pappa and welcome.

 

First question, are you planning, designing and installing the system yourself? Do you want to pay someone to plan and design the system and then you installed it yourself? Or are you looking for everything to be taken care of for you?

 

This forum is full of tips and advice. It's interesting to see how much people's practices have evolved over the last five years if you dig back into the older archives in the forum. People's ideas of what ducting should be like and machines they use have changed a lot. One big decision to make is how much you want to spend. A lot of people use cheaper MVHR units like the Ventaxia Kinetic Sentinel. While others use passivhaus quality machines like those from Zender or Brink.

 

I'm in the middle of doing calculations for my retrofit (see https://forum.buildhub.org.uk/topic/38091-critique-my-mvhr-plans-round-2/ and other threads). For me getting the ducts from ground floor to first floor is taking most of the brainwork. I'm leaning towards using one of the more expensive passive house quality machines. But honestly just having the ventilation will probably make the most difference rather than the machine used.

 

[JohnMo]

8 hours ago, Pappa said:

retrofit MVHR

To make it beneficial (running costs and heat losses) you need good airtightness, do you have a plan to tackle this?

 

8 hours ago, Pappa said:

granular control using MVHR

What do you mean by granular control? MVHR is pretty much switch on, commission, then forget (except filter clean/replace). Ours almost never goes into boost and is set at about 0.3 ACH.

 

8 hours ago, Pappa said:

manufacturers

Titon, UK company, UK support, you actually get support from the designers not a call centre. For retrofit look at coander effect supply nozzles to simplify duct routing, also look at cascade MVHR.

[Pappa]

Thanks for the comments

 

2 hours ago, Sparrowhawk said:

First question, are you planning, designing and installing the system yourself?

Yes, I wan to design and install myself.

I'll probably need the most amount of help on the design as I'll need to drill through brick walls (mostly structural) to get the ducting through.

I'm also going to have wet underfloor heating (UFH) in the whole house so I need to figure out how the ducting will share underfloor space with UFH.

Tbh, I'm happy to instruct a company if they can back up their price with service and quality.

 

2 hours ago, JohnMo said:

To make it beneficial (running costs and heat losses) you need good airtightness, do you have a plan to tackle this?

 

-I'm carrying out a loft dormer conversion and also a 2 storey extension to the rear of the property. I'm going to ask the architect to specify airtightness in these plans.

-With respect to the rest of the house, I've got vent bricks dotted around. I'm going to seal these tight.

-Its an old Victorian era property with Lyme based mortar between the bricks and Lyme based plaster. This is breathable, and I don't have a solution to make it airtight.

-The best I could probably do is to paint the internal walls in a non breathable paint to ensure there is no diffusion of air (and heat) through the walls.

-My wife is the weakest link. I've got no control over her opening the windows I'm afraid . That being said, This system will really shine through on very cold or wet days (which is most of the year) when she won't open the windows.

 

Thanks again

 

P

[JohnMo]

30 minutes ago, Pappa said:

I'll need to drill through brick walls

Cascade system design should limit this to a large degree.

 

32 minutes ago, Pappa said:

wife is the weakest link. I've got no control over her opening the windows I'm afraid

Nothing wrong with opening windows with MVHR.

 

33 minutes ago, Pappa said:

Lyme based plaster. This is breathable

There is a difference between breathable and airtight. Breathable normal means vapour open, so can be airtight also. How are you planning to line the internal walls?

[Mike]

An interesting project, and also ideally suited to upgrading the thermal insulation throughout too. Indeed the work you're doing requires that to comply with Building Regulations, but I guess you know that if you've been talking to an architect.

 

12 hours ago, Pappa said:

-Its an old Victorian era property with Lyme based mortar between the bricks and Lyme based plaster. This is breathable, and I don't have a solution to make it airtight.

 

Lime plaster is breathable and airtight, provided it is sound, without cracks, and has been stripped of vinyl paints and papers. However you'll also need to seal all the junctions with other materials using specialist airtightness products - there are other threads on here about those.

 

 

12 hours ago, Pappa said:

The best I could probably do is to paint the internal walls in a non breathable paint to ensure there is no diffusion of air (and heat) through the walls.

You want breathable paint, to allow moisture vapour to escape.

 

15 hours ago, Sparrowhawk said:

A lot of people use cheaper MVHR units like the Ventaxia Kinetic Sentinel. While others use passivhaus quality machines like those from Zender or Brink.

This is a key decision. If you can afford to, stick to those independently tested for the Passivhaus Institute: https://database.passivehouse.com/en/components/list/ventilation_small (the 'efficiency ratio' is the overall measure, taking into account heat recovery + electricity consumption). Passivhaus certified units come with a more realistic measure of their performance compared to non-certified units (Paul have a short explanation). But any properly specified MVHR unit is better than none.

 

12 hours ago, Pappa said:

I need to figure out how the ducting will share underfloor space with UFH.

Generally the ducting is run in the ceilings, or sometimes the partitions, so unlikely to be a problem.