looking for house-wide ventilation solution

[johnhenstock83]

hi,

 

we're lucky to have a house that's damp free, but there are some ventilation issues. the house is well built (1950s ex council) and the original mortar is lime based, breathes really well. the issue is that the house has been properly insulated with double glazing, cavity insulation (beads) and loft insulation (270mm + 30mm air + tongue & grove boarding). house is extremely warm and heats up in no time, holds temperature really well too, it's a blessing in the current circumstances.

 

as you can imagine, though, it doesn't breathe properly. we cook a lot, shower daily, bathe the children, boil the kettle etc. and that creates a lot of moisture. needles to say, the house corners, for example, are quite cold and I can feel moisture on the walls (outside is bone dry, so no leak/damp etc.).

 

I found the vent axia pureair home system, which seems to be what I need. I did have a few questions though:

https://www.tlc-direct.co.uk/Products/VAPAHH.html

 

1. my understanding is that this will be installed in the loft and the vent will be upstairs, in the hallway. is this usually enough to ventilate the entire house? I don't want to disturb the recently renovated bedrooms/walls to route ducting all the way downstairs from the loft.

 

2. is this system enough for a medium sized 3 bed terrace? it's around 100sqm.

 

3. I can see the original ventilation bricks on the external walls, but they've clearly been plugged on the inside, as it's just plasterboard. is it worth opening these up? if so, what do I install? I like the idea of direct ventilation, but without losing heat in the process.

 

any thoughts on the above would be much appreciated, thank you all!

[JohnMo]

Without heat recovery you will loose heat no matter how you ventilate.

 

So basically you have two options without major upheaval

 

PIV, as linked too above.  Seems to do what you want, basically it takes fresh filtered air and it blows through the house out open window vents and through any gaps in the building fabric. It has a suitable settings for a 3 bed house.

 

The Other way

dMEV, this pulls air out of the building via fans in wet rooms and kitchen.  So you need a fan in each of these rooms instead of intermittent fans.  You need vents in all other rooms.  Fresh air is pulled in the vents and across the rooms to the wet rooms and out of the fan.

 

You can add humidity controlled vents for a low cost, these will limit the ventilation when it's not needed.

 

The link has the brochure and user manual, with the flow rates required etc.

[johnhenstock83]

thanks for that.

 

I guess I'd be happy with the system linked above, I just need to find out if it's enough to have one single vent in the landing upstairs. that would be easy to install, downstairs vents not so much.

 

but from what you said and the issues we're having (house doesn't breathe that much due to insulation, no trickle vents in windows, high humidity due to lifestyle etc.), I don't really need a PIV system (as in getting the air in), but an extraction system with heat recovery. is that correct?

 

I basically want the humid air out, not new fresh air in. or I want fresh air in, but how does the "old", stale, humid air leave the house if I don't have trickle vents?

[JohnMo]

No issue with a single supply terminal.

 

But you need vents to direct the flow through the rooms.

 

You could retrofit something like these

https://www.bpdstore.co.uk/glidevale-energy-saver-humidity-sensitive-trickle-ventilator/p/182

 

You can't get old air out without getting new air in. If you want heat recovery two options

 

MVHR, rip house apart to install.

 

dMVHR, fan unit required in each room, hole in each room through outside wall.  Will need power run to each fan. A single unit not that expensive, but several starts to get expensive.

 

Without heat recovery PIV, will replace old with new air, humidity controlled vents will help mitigate heat loss by closing when ventilation is not needed.

 

[larry]

Have you ruled out MVHR? Depends a bit on the layout of your house as to how much you need to rip it out. Easiest probably to get top floor done as you could site unit in loft (probably) and then get access to rooms via ceilings for vents. If you use the radial ducting system it is only 75mm ducting so can also be boxed in eg. Backs of wardrobes. 

I did mine DIY (I have no doubt a pro would look at it and tell me 30 things I've done wrong) but we are super happy and I daresay my house will be a lot more sieve like than yours. Cost approx £2k total for the unit and relevant vents ducts plenums etc.