Bad condensation in bedrooms - MEV or DCV?

robbe

Hi there,

Been reading a few recent posts about black mould with interest as we have a problem mainly in the upstairs bathroom/bedroom with excessive condensation and in some cases mould on blinds/window frames. House is a 1970s semi-detached property located in Dublin which has had the bedrooms, and bathroom, internally insulated. Windows are generally open during the day but there are no trickle vents on windows (double glazed installed around 15 years ago) and the previous owner blocked up the vents, presumably as there was a gale blowing through them. The bathroom has an extractor fan but this struggles to deal with 2 or 3 teenagers having long showers.

In winter months there's excessive condensation particularly in the smaller rooms (incl 2 bedrooms) at the back of the house. We'd been thinking maybe of small dehumidifiers or more recently I'd read some posts about MEV and DCV as a solution. I'd discounted DCV as the house is very draughty and unsuitable for the benefits of DCV. I emailed a few companies I could find who do this based on a google search and have only had one response which recommended a DCV system, albeit it would require a survey (ballpark cost of a full house DCV system was €4k). Can I ask if anyone has had an MEV system installed and if so if they could share their experience? I'd welcome any installer recommendations by PM as well as my google searching so far hasn't yielded loads of options.

Thanks in advance

Clo-Clo

I have similar issues, tried small dehumidifiers and a total waste of time. In the end I bought one of these for part of the house:

https://www.meaco.ie/meaco-dd8l-dehumidifier/

It runs at night using night rate and takes an incredible amount of water out of the house, especially for the first week. Now a lot of night it will turn itself off because the humidity is down far enough. I wasn't even sure if it was working right and I got a monitor and it works perfect

The house is a bungalow and in two sections so I bought one of these for the other section:

https://www.amazon.co.uk/dp/B0839LY6LG?psc=1&ref=ppx_yo2ov_dt_b_product_details

I got it on special in amazon sale, a lot cheaper than the Meaco but smaller area, again took huge amount of water out but very noisy, contacted support and have a new one so need to test tonight if problem resolved.

It's not as advantage as the meaco

Extra benefit with the Meaco, leave clothes beside it over night and they are dry next morning.

Would love a MHRV system but they are 5-10k so this was next best option

robbe

Thanks for the response - I've looked to get some trickle vents installed in the windows of the worst rooms (at the back of the house) so hopefully that may make some difference. As they're mostly bedrooms I'm not sure the dehumidifier would be a solution (as they'd want to keep their doors closed or as close as would makie it hard for the dehumidifier to perform adequately (unless you have had a different experience). I can't justify/afford the cost of the DCV solution but hopefully the window vents will help and I'll take a look at the dehumidifier option too.

Cheers

10-10-20

https://www.boards.ie/discussion/comment/121617663#Comment_121617663

The trick with the dehumidifier is that if it's left running in a central location (landing, etc) then it will have a positive effect on the rooms during the day, meaning that at night that the RH level doesn't climb up so high to cause as much condensation. You'll still get condensation as there will still be perspiration and respiration within the rooms at night, but the air will have more capacity to hold that moisture and the condensation will be less. I'd try getting a desiccant dehumidifier first before installing trickle-vents, and set it to run around 50 to 60% RH. It will take some days to draw out the existing humidity load from the building and fabric and then you should begin to see improvements.

robbe

https://www.boards.ie/discussion/comment/121618071#Comment_121618071

Cheers - I had a look at the Meaco site, would you go for dessicant or standard model? Area where it will be used is a landing and it shouldn't get too cold (or cold enough to require heating which is what I understood the main difference between the dessicant unit and the ordinary one)?

10-10-20

https://www.boards.ie/discussion/comment/121618167#Comment_121618167

I have one of each. The desiccant one is more effective for a larger area. It heats up the air slightly more too, but I think it's a better all-rounder.

Clo-Clo

https://www.boards.ie/discussion/comment/121618167#Comment_121618167

I would go for the dessicant....

Some more advice on this thread which is why I went Meaco

https://www.boards.ie/discussion/2058317849/dehumidifier-recommendations

SharkMX

My sister moved into a 1970s bungalow a few years ago. She started to get mould the exact same way you describe.

When she asked an engineer friend of the family he left some temperature and humidity sensors in the house for a couple of weeks.

He looked at the data and his solution was that she was letting parts of the house get too cold. He told her to turn up the heating and have it on all day. If that didnt work then get a dehumidifier too. But the heating worked and she ended up never getting the dehumidifier.

I can remember the exact explanation but something along the lines the moisture makes it way to condense in the coldest rooms in the house. Heat the house higher and more evenly.

My sister was always a cheapskate with the heat, so im not surprised tbh

AndrewJRenko

https://www.boards.ie/discussion/comment/121619185#Comment_121619185

You couldn't be keeping the heating on at night though, could you?

SharkMX

https://www.boards.ie/discussion/comment/121619490#Comment_121619490

Obviously not, but if the fabric of the house is warm the temp doesnt drop that much at night.

You can read up about thermal mass and cooldown etc. Google is your friend.

Clo-Clo

https://www.boards.ie/discussion/comment/121619185#Comment_121619185

Heating the house constantly will reduce condensation, I seen that as I have a large stove which I only use the odd time. Once it was up and running for 2 days non stop the moisture levels was tiny

But the price of keeping the heating running non stop compared to the price of a dehumidifier?

listermint

https://www.boards.ie/discussion/comment/121619554#Comment_121619554

By absolute multitudes

Also it's easier to heat less humid air..

robbe

Thanks for the all advice everyone. Have ordered the desiccant Meaco dehumidifier which I'll use on the landing and see how I get on with it. Have someone taking a look at trickle vents on the windows which tbh would be no bad thing as the bedrooms are stuffy.

Cheers!

Clo-Clo

https://www.boards.ie/discussion/comment/121619596#Comment_121619596

Had them in previous house, honestly I didn't think it was great and was always looking at dehumidifier or heat recovery.

but that could be just me. Seems to be a source of cold more than anything