Adding ventilation to 90s build with none

[seanblee]

Hi folks, looking for some advice on ventilation strategy please. I live in a small-ish 90s 3bed detached house with 2 bathrooms upstairs and a toilet and utility downstairs. It has 15yo Everest double glazing with no trickle vents and intermittent extractor fans in the two bathrooms.

 

Now that the weather has turned cooler overnight, as with every year, we're having big issues with condensation on the bedroom windows overnight, in addition to damp on the window reveals at the bottom corners. I have a Netatmo climate monitor and I'm finding that the bedroom CO2 level is getting up to 2500ppm overnight too, so it's clear there isn't sufficient ventilation. I installed a Nuaire PIV a few years ago, pushing air into the upstairs landing, but it hasn't really helped, presumably as there's no circulation through the bedrooms.

 

In an ideal world, I'd like to retrofit MVHR, but it's not practical to get ducting downstairs so it would only cover upstairs and I'm not sure it's worth the cost. I'm therefore considering alternatives. My current thinking is to ditch the PIV, add dMEV fans in the bathrooms and add humidity controlled vents in the bedrooms, either as window trickle vents or wall vents. Is this my best option or is there something else that I should be considering?

 

Any advice gratefully received, many thanks!

 

Sean

[Mr Punter]

Trickle vents in the bedroom windows.

[JohnMo]

21 minutes ago, seanblee said:

My current thinking is to ditch the PIV, add dMEV fans in the bathrooms and add humidity controlled vents in the bedrooms, either as window trickle vents or wall vents. Is this my best option or is there something else that I should be considering

You saved me some writing as that is exactly what I would recommend. Greenwood dMEV is very quite in operation and generally available on eBay at good prices. @HughF has just installed some humidity controlled trickle vents.

 

For ventilation to be effective it needs to purge the whole space, so cross ventilation is really important.

 

So if you have a bedroom at the front and bathroom at the back of the house that is idea. Trickle vents in the bedrooms but not in the bathroom, so the air has to go through the whole space. The doors need to have a gap (10mm) so the air has a passage way to move through when doors are closed.

[HughF]

I used the Higroster humidity activated vents, they’re very nice and so far no complaints from my wife about noise or drafts. 
 

They are much better than the glidevale ones from bpc ventilation. 
 

We are going to ditch the dMVHR plan for the extension and fit three of these to the doors instead, saving the fused spur position for a future air-air

[seanblee]

Thanks! @JohnMo bathrooms are back to back in the rear right corner of the house, with the main bedroom front right and the other bedrooms rear left and front left - landing is rear central. Hoping that means dMEV in the ensuite will purge the main bedroom if there's a trickle vent in the window at the front, then I'm relying on the main bathroom to clear the other two bedrooms, which may be a bigger ask...

 

@HughF thanks, I've had a quick look but struggled to find a UK supplier online - I saw yours came from Brookvent, don't suppose you have a contact you could share please?

[JohnMo]

The Greenwood dMEV units are easy to adjust for flow rate and have a built-in humidity sensor. If you have a utility put in there and the kitchen.

 

What will happen in practice is the bedroom trickle vents will open at night with breathing etc, any downstairs will close. But the dMEV fans keep running, those downstairs will drag the air from the bedrooms downstairs and out the house. The opposite will be true when everyone is downstairs.

[HughF]

1 hour ago, seanblee said:

Thanks! @JohnMo bathrooms are back to back in the rear right corner of the house, with the main bedroom front right and the other bedrooms rear left and front left - landing is rear central. Hoping that means dMEV in the ensuite will purge the main bedroom if there's a trickle vent in the window at the front, then I'm relying on the main bathroom to clear the other two bedrooms, which may be a bigger ask...

 

@HughF thanks, I've had a quick look but struggled to find a UK supplier online - I saw yours came from Brookvent, don't suppose you have a contact you could share please?

I do have a contact at Brookvent but they are so utterly useless at getting back to you, I asked the manufacturer in Poland if they would sell direct and they will. sklep@brevis.com.pl And ask for Oliwia.

[seanblee]

Thanks both, I now have a couple of Greenwood CV2GIP on order from eBay and I've dropped an email to Brevis about the vents. I'll update once everything's been installed!

[seanblee]

First two CV2 dMEV are now installed in the bathrooms. Sadly I discovered the underside of the roof felt was covered in condensation when fitting the second extractor today - I've already had ridge ventilation fitted to try and resolve this, so now I'm hoping reducing the general humidity in the house might also solve my loft issues. Brevis refused to sell me the vents so I've had to go through Brookvent, I'm currently waiting on a pro forma...

[seanblee]

First night with the dMEV in the en suite last night and, even without the trickle vents, the CO2 in the bedroom didn't go above 1000ppm all night. By comparison, the previous night it hit 2500ppm at peak. I'd say that means it's working! Looking forward to getting the vents and getting rid of the PIV now...

[seanblee]

The Higroster vents finally arrived from Brookvent last week (delays at the Brevis end apparently), so I spent a few hours over the last couple of days fitting them. As I mentioned, the windows didn't have trickle vents before, so I ended up making a couple of templates from MDF, one for inside and one for outside, then removing each opener in turn and routing a slot into it. All went well and they're now fitted to all bedrooms and the lounge and playroom downstairs. I also removed the PIV yesterday and stuck it on eBay. I'll be keeping an eye on things over the next few weeks but initial signs are good - much less moisture inside the bedroom windows last night and the reveals stayed dry, which is better than the night before. Thanks again for the advice!

[seanblee]

Oh, couple of photos from the inside of the vents, and the damp reveals that are still drying out - you can see the mould on the caulk around the trim that I need to clean once again, fingers crossed for the last time this time!

[JohnMo]

Glad to hear it seems working.

[Tom_]

 I am thinking about the same vent and dMEV combination, just wondering how it has been a few weeks later?