Continuous Ventilation Fan for damp/humidity issues

Buddyboy

Registered User
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Just thought I'd post a recommendation, if it is of use to people,
If you have ventilation/damp/humidity issues, then this may help.

I have just replaced the extractor fans in the wet rooms with continuous extraction ones and closed the trickle vents in the bedroom windows. This pulls heat from the living quarters and paradoxically keeps the house warmer (no cold draughts coming in from outside through bedroom windows). It also means the house is ventilated more evenly and mold/moisture is not a problem, which it was in unused rooms.

These are the ones, continuous mode, light mode, and humidity stat. Also, Bluetooth enabled. And about 5% of the price of retrofitting MVHR.

(and they look gorgeous)

Lo-Carbon Svara | Vent-Axia

Fully flexible installation and control
www.vent-axia.com
www.vent-axia.com
Practically silent in trickle operation.

Screwfix.ie sell them, free delivery.

I haven't seen any others like them, especially the range of features. There are other continious extractor fans around, but not as adjustable and with so many features.

I've now installed 4 of them, and the difference is noticeable, both in humidity and heat.

No connection to Vent-Axia or Screwfix.
 
Did you install them yourself? Was it straight-forward as per the manual \ instructions?
 
I installed them myself. Two were straight swap-outs for existing separately wired fans.
One had to be rewired as the existing one was on the light switch circuit. I had to run a new circuit to it, but I live in a bungalow so it was possible. One was to replace an existing one that had too long a duct run (max length is 1.5 M.) but I was able to reuse the existing wiring and ducting by relocating the new fan closer to the soffit outlet.

Unless you are comfortable with this type of work, I'd strongly advise getting an electrician, as there are specific rules around electricity and bathroom zones. Fitting one, even the relocation, only took an hour.

Like everything in life, it depends.
If the existing fan is wired independently of the light switch, then yes, you can just swap it out (it needs a permanent live for continuous operation).
You do not need a switched live as the fan has a light sensor that can be used to boost the fan.
If you need to run wires to it, then you need to know what you're doing (or get an electrician).
If your fans are in zone 1 areas in a bathroom then you need an SELV (12V) installation, again depending on your level of knowledge, maybe an electrician).
I you are replacing a long ducting run (which should have a Centrifugal fan installed) then these won't work, being axial fans (max duct length is 1.5 M).
If it's a straight hole-in-wall installation, then you're fine.

Once the fan is on, it runs on continuous mode, 10ltrs/sec. It boosts for light,19 ltrs/sec. And if it detects humidity it goes to 25 ltrs/sec. Max is 30 ltrs/sec. The App is in google play (free download), which has a lot more settings, and is well worth it. For example, setting times that it does not boost, (e.g. nighttime in an ensuite, delays on activation, and for rooms that aren't used, it can run boost twice a day for a user-selectable duration in order to vent the room.

The manuals are downloadable from vent-axia.
 
Good idea except for closing the vents, you still need to allow fresh air into the property
 
and paradoxically keeps the house warmer
Great result.
What is likely happening here is because you are now ventilating more efficiently (i.e removing more moisture from your home) your house structure (thermal fabric) is also dryer than what it was previously. This dryer structure also means dryer insulation and therefore your insulation is performing better than before. Thus less heat loss and improved internal temperatures allowing your ventilation to work better due to greater temperature differential between indoors & outdoors etc etc.
This is why appropriate ventilation is critical but unfortunately often misunderstood.
 
Good idea except for closing the vents, you still need to allow fresh air into the property
I closed the vents in the bedrooms, but have left the vents in the habitable rooms open, so the warm air moves from these to the bedrooms, and the en-suites. Prior to this the outside air was coming directly into the bedrooms.
the fans you were replacing were they ceiling fans?
Yes, three were ceiling fans, one was through a wall.

Wife, who is more sensitive to these things, agrees the bedrooms/bathrooms smell fresher.

And Micks'r while you are correct, these were only fitted last week, so it is too soon for the fabric etc. to dry out. Any change now is due to increased/improved ventilation (as you said).
 
You would be surprised. Fabric / structure can dry out very quickly especially when it is cold outside.
 
Unless you are comfortable with this type of work, I'd strongly advise getting an electrician, as there are specific rules around electricity and bathroom zones.
Agreed, unless there is wiring in place already, or you can get away with extending an existing circuit, by law you will need an electrician.
 
I closed the vents in the bedrooms, but have left the vents in the habitable rooms open, so the warm air moves from these to the bedrooms, and the en-suites. Prior to this the outside air was coming directly into the bedrooms.

Yes, three were ceiling fans, one was through a wall.

Wife, who is more sensitive to these things, agrees the bedrooms/bathrooms smell fresher.

And Micks'r while you are correct, these were only fitted last week, so it is too soon for the fabric etc. to dry out. Any change now is due to increased/improved ventilation (as you said).
I thought you'd closed all your vents. I'm not sure the layout of your house but you still need ffresh air supply to bedrooms when you're sleeping. Aereco (and I'm sure others) do humidity controllred vents including trickle vents for windows, which are closed most of the time but open when the humidity in the room increases to allow fresh air in.
 
No problem alkers86. I leave the bedroom doors open and the layout of the house is long with a central hall. The Living area is at the top, open plan with underfloor heating and no doors. So the warm air moves down the corridor and into the bedrooms either side, drawn in by the ensuites off the bedrooms.

I understand where you're coming from, but the layout of my house suits this flow of air.

And it certainly has made a difference, even after a week. I might even save money :)
 
Just coming back to this with an update, as it was a work in progress.
Also to note, we have underfloor heating in the living room 65Sqm, and kitchen - off living room with no door in between. This is on, set to 20 degrees all day.
The bedrooms/en-suites/hall have radiator heating, turned on 1/2 an hour in the morning and 1/2 an hour at night, before going to bed. Bedrooms 2 & 3 (with en-suites) aren't used and the heat is lower with the use of TRVs.
So only used rooms in the house are living room, kitchen, and one bedroom/en-suite

I have changed my mind about leaving the unused bedroom window vents closed and the bedroom doors open, as what was happening was the moisture laden warm air was being pulled into these rooms by the trickle fans and being deposited on the bedroom windows. I have changed to leaving the trickle vents on the bedroom windows open, and closing the bedroom doors. the rooms/en-suites are a closed vent loop as such. Air coming in to the bedroom and leaving via the continuous extract fan in the en-suite. This appears to be working well. The fans are designed to ramp up to 100% for 90 minutes each 24 hour period, if they haven't been boosted. So far, no condensation on the unused rooms windows whenever I check.

I leave the main bedroom window vents open, and in the morning, when the en-suite is used, I leave the en-suite door closed, and open the en-suite window. The fan obviously ramps up due to the humidity. At the end of the shower, I wipe down the shower walls and the en-suite window, which also makes a big difference to the resultant humidity. I close the en-suite window and leave the bedroom window trickle vent open for the rest of the day.

I also have put the dehumidifier onto the hall as it is a bit of a cul-de-sac for ventilation.

To be honest, my main logical error was thinking that the outside air, and >80% humidity, was wetter than the inside air, at around 55~65%. Further investigation shows that it is the relative humidity, so the air outside is so much colder, it can't hold much moisture. (Hence dry skin and chapped lips in winter).

My last thing is to get a few himidistats to check things.

As Micks'r said, ventilation (and moisture) is often misunderstood. And with so many variables (including bungalow/2 story, house layout, room use, etc) it is a journey to get what works. Also the fact that it is only one of the variables, heat and insulation being others that are all interdependent.

Hopefully I've cracked it.
 
My last thing is to get a few himidistats to check things.
I've a few of the https://www.amazon.co.uk/SNZB-02-Temperature-Humidity-Compatible-Including/dp/B08BFW697F/ref=sr_1_4?crid=2O6ND7142039&keywords=humidistat%2Bsonoff&qid=1670861494&sprefix=humidistat%2Bewelink%2Caps%2C1700&sr=8-4&th=1 (Sonoff) ones and they work well enough with the eWeLink app.
 
There's a new book out that I found very good - "The warm dry home" by Peter Ward. He recommends a humidity controlled vent similar to the one you describe but also able to warm the air that it draws in to reduce humidity (https://www.vapourflow.com/). I have no personal experience of these vents but they do seem to make sense and the book goes into exhaustive details about controlling humidity in the home (with particular emphasis on old solid-wall construction).

The book is available here: https://www.heritage-house.org/products/the-warm-dry-home-1.html
 
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Just another update. I've been watching the 4 fans on my phone for a while now, and it is surprising how often they ramp up due to humidity. The one in bedroom #3, which is unused, and at the north end of the house, in an extension, is particularly active, maybe two or three times a day for 15 minutes. This was the one with the worst damp/mould problem. The damp/mould hasn't returned, so it is definitely making a difference.

My guess is that it started when I dramatically increased the loft insulation. And the working from home (including all the related cooking etc.) for the last two years is what increased the humidity so much. (the house was empty all day before that).

Looking positive.
 
Hi @Buddyboy

I'm considering replacing my existing bathroom fans with the Vent-Axia Continuous running fans with humidistats.
Have you had any problems so far with the four extractors you installed?
There are quite a few reviews on Screwfix about faulty Vent Axia fans having to be replaced and I am slightly concerned that I'll end up replacing a working fan with a dud.
I'd be very interested in hearing about your experience one month on.
 
Hi PensionPlans,
absolutely no problems so far, and still happy with them. They seem to be doing the job. The one in our ensuite definitely reacts to humidity. On occasion my wife turns off the fan switch from force of habit. All this does is lose the silent running setting, all other settings remain. All that is needed is to reconnect it via bluetooth to the phone and it resyncs the silent mode times (I assume it does not have an inbuilt clock).

I want to pick up a few humidistats to check the other room. The north facing bedroom which was the original problem definitely has had the humidity problem resolved. No more mould has appeared.
 
Hi PensionPlans,
absolutely no problems so far, and still happy with them. They seem to be doing the job. The one in our ensuite definitely reacts to humidity. On occasion my wife turns off the fan switch from force of habit. All this does is lose the silent running setting, all other settings remain. All that is needed is to reconnect it via bluetooth to the phone and it resyncs the silent mode times (I assume it does not have an inbuilt clock).

I want to pick up a few humidistats to check the other room. The north facing bedroom which was the original problem definitely has had the humidity problem resolved. No more mould has appeared.
Hi @Buddyboy

Thanks for the reassurance as I'm getting work done in the attic this week anyway so it's the perfect time to change around vents and switches.
It seems the perfect solution for my challenge here with people hermetically sealing the bathroom before running the shower for hours on end.

Do you still have it wired to a light switch?
I had assumed it would be rewired with no connection to the light switch.
 
Hi PP,
Three were already on separate switches, so they were already fine (but as I said, my wife sometimes, through muscle memory, turns the fan switch off). No problem just turning it back on. You only have to resync it to the app if you have any timed functions, e.g. silent hours. Otherwise it retains it's settings. The resync is just opening the fan settings in the app. You will know if it has to be done as the fan will have a small red light if the power was interrupted.

The one that was wired to the light switch was rewired to a permanent live. As you are getting work done in the attic, it should be no problem tapping into an existing (socket/RCD) feed, and putting in a dipole isolation switch.

As you want them as continuous trickle, you will need to get a permanent live to it. You can use the light switch as a trigger (it's in the manual), but there is no need as it can automatically trigger via a light sensor.

Just as I'm typing this the fan in the office has just ramped up as it has detected increased humidity. I could set it to not ramp up during working hours, but it's not excessively loud so I didn't bother.
 
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