Positive Input ventilation system, any good?

sl_jones

Hi all,

I live in a 1st floor flat and every time it's gets cold outside we experience alot of damp on all of the windows in our flat apart from the kitchen. I have a clock in my living room that states that the humidity is around 50-60 and it's like that all year round (I have also tried an official device to check the humidity and that states the same). This causes us to have mould grow all around the windows and the french doors, it's also very hot in the summer.

It's actually so hot that we don't put our heating on in the winter because its so hot inside the flat so we don't need it. The downside to this is that we have to have a fan on almost all the time up til about November.

But i was wondering whether or not a Positive input ventilation system would help, with both the condensation and the the heat. We are lucky enough to have a loft with our flat because we are top floor. So i think we have quite a few opinion available to us as tp what we may be able to put.

So does anyone have any recommendation? I've heard that the envirovent are good but very expensive and that the Nuaire vents are around 300-400 and you can fit them yourself?

coffeehound

The air in the loft will be warmer than the flat in summer so piv wont cool the flat then.

Since presumably opening windows doesnt solve it, youd need to either reduce the sources of humidity and/or employ a dehumidifier to control humidity.

A compact air conditioner would cool you in summer as well as reducing humidity somewhat.

Fire_Fox

How are the windows constructed? Frame material, single or double glazed, trickle vents etc. Some types are such an effective 'thermal bridge' that water will always settle in cold weather, even when the humidity is not excessive.

Preventing mould growth around such windows and glazed external doors requires a morning commitment to wiping up (discard the kitchen roll or dry the cloth outside) and ventilating the immediate area to remove water that has started to penetrate. Trust me, I know how boring this daily ritual is, but also how effective.

Whatever ventilation system you opt for, you may need written consent of the freeholder, consider Building Regs, especially fire safety. PIV may not need you to make a hole through the walls or roof, but you will be encouraging air flow and taking electrics into the loft/ outside the habitable rooms (flammable materials/ no fire alarm etc).

The freeholder may be more willing to give consent if you have a professional (BPEC 'Domestic Ventilation Systems' qualification) on board, you may even need one if Building Regs come into play.

SuzieSue

Do a search on this forum. There have been several recent threads covering this.

sl_jones

Fire_Fox wrote: »

How are the windows constructed? Frame material, single or double glazed, trickle vents etc. Some types are such an effective 'thermal bridge' that water will always settle in cold weather, even when the humidity is not excessive.

All the windows are double glazed PVC and they all have vents added to them. The french door is aluminium, which is where we get it worst, however i don't want to paid 1500 to have new french doors put in because i don't think it will stop the condensation.

Whatever ventilation system you opt for, you may need written consent of the freeholder, consider Building Regs, especially fire safety. PIV may not need you to make a hole through the walls or roof, but you will be encouraging air flow and taking electrics into the loft/ outside the habitable rooms (flammable materials/ no fire alarm etc).

The freeholder may be more willing to give consent if you have a professional (BPEC 'Domestic Ventilation Systems' qualification) on board, you may even need one if Building Regs come into play.

We own the freehold, the only issue would be installing something myself however there is a shop near me that sells the nuaire sytem so he might install it as well.

Fire_Fox

sl_jones wrote: »

All the windows are double glazed PVC and they all have vents added to them. The french door is aluminium, which is where we get it worst, however i don't want to paid 1500 to have new french doors put in because i don't think it will stop the condensation.

No single action is likely to stop the condensation and mould.

My city centre flat has double glazed metal framed windows (no thermal break or inbuilt vents). Replacing would be eye-wateringly expensive, and consent would be almost impossible. I'd literally have to stop traffic! :rotfl:

My research to date suggests our options are limited: most sources recommend replacement. Alternatively some combination of: reducing humidity to much lower than 'normal', ventilating the area adjacent to the window (or door), reducing the frame's ability to lose heat (= be a less effective thermal bridge).

There is some relevant scientific research by Historic England "Improving the Thermal Performance of Traditional Windows: Metal-framed windows " (2016) Lengthy and rather dry, but thorough with the options available, and free to download.

Fire_Fox

We own the freehold, the only issue would be installing something myself however there is a shop near me that sells the nuaire sytem so he might install it as well.

If you might get your chosen product installed, consider also taking advice on your overall ventilation strategy with a home visit before you make the final decision. Apparently the reason for introducing the 'Domestic Ventilation Installer' (BPEC qualified) was how many products were so poorly selected or systems were so badly designed and installed that they were ineffective.

That seems to be the case here: I strongly suspect the ductwork for my (cheap domestic) cooker hood and bathroom fan takes a rather tortuous route before it finally vents outside. But the products are intended to have a short, ideally straight, run of ducting.

coffeehound

Something worth trying is to leave the bathroom extractor fan running full time with trickle vents open and/or windows on ventilation setting in other rooms (bathroom window shut).

Humidity at 60% is high so this should help reduce it without further expenditure, and since the flat is too warm, presumbly the cooling effect wont be a problem.

If the bathroom extractor is ineffective then it would be worth fitting a good one as a first step.