Garage dehumidifier

[Bob-iylho]

Hi,
Can anyone recommend a dehumidifier for a 6x 9m wooden garage with loft space, the triple garage is split into a double and single, the single has all the house heating system and is quite warm. The double has my S2 JPS esprit in and not so warm.
Ideally I want one where it kicks in as and when and drains externally so I never have to do anything with it.
Thanks.

[_Sorted_]

PIV! Totally superb. Cheap to run. No draining required.

For example. https://www.google.com/search?q=nuaire&client=...

[arguti]

I use a few of these in various garages - dessicant works down to freezing level and zero maintenance..have always bought from this company - usually next day delivery and excellent service.

https://www.dry-it-out.com/dry/garage-workshop/dd3...

[tapkaJohnD]

I've argued this before, and I'll try again - ventilation is more effective than dehumidifying. Certainly cheaper.

Warm weather allows the air to absorb moisture, and when it cools that water will condense out. Any colder surface will attract it. But colder air is drier air and carries less water. Rather than try to remove the water from the vast volume of air in your garage, ventilate the garage and allow the weather to waft the water away.

I live in the North West of the UK, with the highest rainfall of any. My garage has a sound roof, but ill fitting doors. The wind whistles through it! But with only reasonable care, my cars and tools do not suffer from rust. Good ventilation is superior, IMHO, to expensive attempts to dry out the garage. Only things like a Carcoon can be better, because they work on the much smaller volume of air confined around the vehicle.

John

[_Sorted_]

tapkaJohnD said:

I've argued this before, and I'll try again - ventilation is more effective than dehumidifying. Certainly cheaper.

Warm weather allows the air to absorb moisture, and when it cools that water will condense out. Any colder surface will attract it. But colder air is drier air and carries less water. Rather than try to remove the water from the vast volume of air in your garage, ventilate the garage and allow the weather to waft the water away.

I live in the North West of the UK, with the highest rainfall of any. My garage has a sound roof, but ill fitting doors. The wind whistles through it! But with only reasonable care, my cars and tools do not suffer from rust. Good ventilation is superior, IMHO, to expensive attempts to dry out the garage. Only things like a Carcoon can be better, because they work on the much smaller volume of air confined around the vehicle.

John

This^^^^ Used a really good dehumidifier for a year or so, Meaco DD8L-Zambezi 8L, but have retired it since having a Positive Input Ventilation (PIV) system fitted. It is difficult to explain, but the constant airflow makes the garage a much better place to be in. Air filtered also. Cost fitted about £80 more than the dehumidifier, but ongoing costs lower. Am a convert. No sign of any damp.

[anonymous-user]

A dehumidifier will have very limited effect at lower temperatures, so if the garage gets cold (from the OP's post that seems to be the case) then some of the other solutions available are likely to perform better.

[The Dangerous Elk]

Andy-IM said:

A dehumidifier will have very limited effect at lower temperatures, so if the garage gets cold (from the OP's post that seems to be the case) then some of the other solutions available are likely to perform better.

Will the humidity level be lower at cold temps ?

[200Plus Club]

Andy-IM said:

A dehumidifier will have very limited effect at lower temperatures, so if the garage gets cold (from the OP's post that seems to be the case) then some of the other solutions available are likely to perform better.

Absorption type (rotary dessicant) are adequate in the UK in winter whereas the refrigerant type dehumidifier do struggle in cold.

[Squadrone Rosso]

arguti said:

I use a few of these in various garages - dessicant works down to freezing level and zero maintenance..have always bought from this company - usually next day delivery and excellent service.

https://www.dry-it-out.com/dry/garage-workshop/dd3...

Me too. I’m running the same as this. An excellent company to deal with.

[tapkaJohnD]

The Dangerous Elk said:

Will the humidity level be lower at cold temps ?

The maximum amount of water that can exist as vapour in air falls as the temperature falls. The actual amount in relation to that value is the humidity.
As a mass of air with water vapour cools, its humidity will increase, as the amount of water vapour is constant and the vapour capacity of the air is falling.
When the two coincide, at the "Dew point", water vapour condenses, into mist, fog, cloud, dew or if cold enough, frost.

A garaged car will be colder than the air around it, so the dew will form on the car, rather than as mist. It's liquid water that promotes rust.

So, as that warm air in your garage, laden with water vapour, starts to cool as the weather changes, the new cold air has less water vapour and is further from its dew point than the previously warm air. Better to let the colder air blow it away, than let the water condense. or else go to the expence of condensing it out in a machine.
JOhn

[Bob-iylho]

Thanks chaps, will look at all the links but tempted to go PIV.

[AW10]

_Sorted_ said:

This^^^^ Used a really good dehumidifier for a year or so, Meaco DD8L-Zambezi 8L, but have retired it since having a Positive Input Ventilation (PIV) system fitted. It is difficult to explain, but the constant airflow makes the garage a much better place to be in. Air filtered also. Cost fitted about £80 more than the dehumidifier, but ongoing costs lower. Am a convert. No sign of any damp.

Did you fit one of the flatmaster systems? They seem better suited for a garage than the loft mount units. And did you fit any exhaust vents or does the system just rely on the various leakage points to allow air to flow through the garage?

[_Sorted_]

AW10 said:

_Sorted_ said:

This^^^^ Used a really good dehumidifier for a year or so, Meaco DD8L-Zambezi 8L, but have retired it since having a Positive Input Ventilation (PIV) system fitted. It is difficult to explain, but the constant airflow makes the garage a much better place to be in. Air filtered also. Cost fitted about £80 more than the dehumidifier, but ongoing costs lower. Am a convert. No sign of any damp.

Did you fit one of the flatmaster systems? They seem better suited for a garage than the loft mount units. And did you fit any exhaust vents or does the system just rely on the various leakage points to allow air to flow through the garage?

Confession. Did not look at Flatmaster system. Went for Nuaire Drimaster-Eco link and hall control. Hall control puts controls on room side of machine for convenience. Was really unconvinced PIV would work, but after retiring dehumidifier have dialled down fan to a low setting. Much quieter than dehumidifier. Almost silent. Was a bit harsh on price. Looked up invoice and cost was £233 plus £40 fitting.

Edit: No exhaust vents required and the garage is really well sealed/insulated.

Pictures of unit fitted below:






The slightly dodgy looking spacer between ceiling and ring closest to ceiling is being removed once garage redecorated this month. The plastic ring will then sit flush against ceiling.

Edited by _Sorted_ on Tuesday 8th January 11:11

[AW10]

Thanks for the info and photos. My garage is detached, single skin brick and an open trussed roof space so it looks like the wall mount flat system is the better fit, pulling air from the outside and releasing it into the garage.

[Paul Drawmer]

tapkaJohnD said:

The maximum amount of water that can exist as vapour in air falls as the temperature falls. The actual amount in relation to that value is the humidity.
As a mass of air with water vapour cools, its humidity will increase, as the amount of water vapour is constant and the vapour capacity of the air is falling.
When the two coincide, at the "Dew point", water vapour condenses, into mist, fog, cloud, dew or if cold enough, frost.

A garaged car will be colder than the air around it, so the dew will form on the car, rather than as mist. It's liquid water that promotes rust.

So, as that warm air in your garage, laden with water vapour, starts to cool as the weather changes, the new cold air has less water vapour and is further from its dew point than the previously warm air. Better to let the colder air blow it away, than let the water condense. or else go to the expence of condensing it out in a machine.
JOhn

^^^ This is right but...

The reverse can happen as well.
Garage is cool and dry and well ventilated; until a load of warm, wet air blows in; the water vapour will condense on all the cold stuff in the garage.

If the garage isn't insulated and open to draughts, you will get condensation as a result of temperature and humidity changes. There's nothing you can do about it without running a dehumidifier all the time. If you're going to do that, seal it up to stop the air changing so fast and add insulation to slow down the temperature changes.

[wilksy61]

Got this little fella in my garage, permanent drain to outside, my garage is a fully insulated single (small) modern thing. I also have a small heater set at 10°C to provide additional background warmth when needed.




I have a Netamo Coach which allows me to monitor the humidity and temperature, I have the humidity set at 55 - 60% which seems to work without any of my tools or car rusting.

[Evoquative]

Looking like two clear schools of thought here, ventilate thoroughly or seal up, insulate and dehumidify.

I think I am favouring the latter as I need to work in the garage on an almost daily basis, therefore I will be adding a lot of moisture to the air myself and lots of air changing will mean it gets rather cold...

The great advice I got on doors will be acted on to put in a much more draft resistant doors with insulation, so that will be followed up with some insulation on the walls, a vapour barrier and some OSB, boarding in the ceiling and insulating, plus a dehumidifier. Definitely a more expensive route, but more comfortable for working in and more reliable against changes in the weather perhaps. Decisions to make!

[The Dangerous Elk]

How many nights does the inside of a garage get down to 3-2 degrees ?......down my way not often.

Not often, I got a refrigerant one (2.5ltr) for £35.....happy with the "costing" of that and the cost of the odd night of heat top-up.

[singlecoil]

This is a good subject for me, I have several times converted unsuitable buildings into workshops either car related or for wood working (which is more demanding). I prefer the good insulation and dehumidifier (and fan heater for when I'm in there) approach.

One of the things that made a surprising and worthwhile difference was to install T&G 22mm 8x2 moisture proof chipboard flooring, with a damp-proof membrane beneath. It will easily take the weight of a car and is much more pleasant to kneel or lie on than rough damp concrete. The tongue and groove aspect means there are no raised edges between the sheets even if the floor is uneven.

[The Dangerous Elk]

Wooden floors in a "Garage" ? , a bit impracticable/dangerous for me.