Garage temperature and humidity control

[Pondrew]

One thing that may help; which I have done before (not in a garage, in a home recording studio; basically a sound insulated shed) is to cut an extract fan into an external wall, controlled by a humidistat. If you are heating, cut it in at low level, as heat rises! If you were to go this route, a fan able to 'change' the air a minimum of once an hour would be ideal. Always base calcs on m3, not m2; volume is the key. There are mainstream fans available with 'built-in' humidistats (a large bathroom extract fan). The air will then be made up by natural infiltration at a lower %RH (relative humidity).
If your space is 6x8x(average)3.5m = 168m, a fan capable of 168m3 per hour would definitely help. HTH

[B21]

B21, thanks for your input - yes, sometimes cars have to go in and out in the wet or at any time. I suspect heat and air circulation will help a lot, but a dehumidifier might still be useful for when things get really wet such as when a wet car has to come in or if I'm washing cars in cold weather.

I hadn't considered driving the cars over heaters. That's interesting.

Just brainstorming but if you could get these lined up these are a safe -ish way of heating under a car ?

https://www.amazon.co.uk/Tubular-Heater ... ljaz10cnVl

People seem to have had good experiences with de-humidifiers so why not ?

If the door is insulated that’s a major step..

[Pondrew]

If the door is insulated that’s a major step..

starting to think that the garage may be 'over insulated', as it stands. With a B&B raised floor, cavity wall insulation and an insulated roller, there is possibly nowhere for the moisture to go, except condensing out when it hits 'dew point'. If this is the issue, getting rid of the humid air is the best way to solve it.

[PerryGunn]

If the door is insulated that’s a major step..

starting to think that the garage may be 'over insulated', as it stands. With a B&B raised floor, cavity wall insulation and an insulated roller, there is possibly nowhere for the moisture to go, except condensing out when it hits 'dew point'. If this is the issue, getting rid of the humid air is the best way to solve it.

+1 on this

Anyone who is looking at dehumidifying/heating a detached garage should look at ventilation first - it might well save them a few £££

My garage is concrete base, brick walls, detached, uninsulated and my workshop is attached to the rear - air can get around/under the garage doors and the workshop has vents in the walls. As a consequence there is continuous gentle airflow through both the garage and the workshop. The only time I use any heat is a quick blast with a small fan heater in the workshop to take the chill off if I'm working in there on a cold day.

I have never had any condensation issues in either the garage or the workshop and no issues with surface rust on tools.

Unless you live somewhere with extremely cold winters, cars don't need a heated garage, just one that doesn't leak and is well ventilated.

[M1k3yC]

Thanks for the additional suggestions and input, much appreciated.

Yes, the automatic roller door is insulated - I've checked. Pondrew, moisture becoming trapped is likely, I agree. A humidity controlled extraction fan is an interesting idea. However, I spoke to a friend last night that has done some work controlling humidity and temperature on an industrial scale. He pointed out that the extracted air has to be replaced and at this time of year the outside air is likely to be a very high humidity so it won't work very well.

A dehumidifier looks like the best first step, but I'm still researching them. I think that a good desiccant dehumidifier would be the right choice because of the potential for low temperatures in the garage and the fact it will generate some heat when in use as well.

[pvr]

What do you think of this?

https://www.tlc-direct.co.uk/Products/V ... sYQAvD_BwE


It looks like it would do the job

[Pondrew]

FYI. If anyone wants any Vent-Axia products, let me know, as I have a trade account with them, so may be able to save a few quid.

[pvr]

Thanks Pondrew, might take you up on that. Their headquarter s are only a couple of miles away.

What do you think of that product for the purpose of a garage?

[earthdweller]

Thanks for the additional suggestions and input, much appreciated.

Yes, the automatic roller door is insulated - I've checked. Pondrew, moisture becoming trapped is likely, I agree. A humidity controlled extraction fan is an interesting idea. However, I spoke to a friend last night that has done some work controlling humidity and temperature on an industrial scale. He pointed out that the extracted air has to be replaced and at this time of year the outside air is likely to be a very high humidity so it won't work very well.

A dehumidifier looks like the best first step, but I'm still researching them. I think that a good desiccant dehumidifier would be the right choice because of the potential for low temperatures in the garage and the fact it will generate some heat when in use as well.

I did that research and really the only option is a desiccant one to deal with the low temps

Mine has a vent that blows air in various directions on the top which puts out some heat and moves dry air around the garage

Where I am today we have torrential horizontal rain and 60 mph winds

I do think what you need to do depends very much on the location. I think if I lived on the south coast it would be a very different proposition but the damp, wet and very humid weather here needs a different approach I think

[Pondrew]

What do you think of that product for the purpose of a garage?

Not seen that before TBH. I don't really get involved with domestic stuff and certainly not garages! I did design and install a 'whole house' heat recovery ventilation system (using a V-A system) for my last house which worked fantastically well and saved ££££s on heating as well as zero condensation in all the bathrooms. I would recommend these to anyone (if it's feasible)
Vent-Axia are a good brand (although not the cheapest) and the current demand for 'eco-friendly' ventilation and the Covid vent push is making all of these people market some weird and wonderful devices ATM. Ultimately you can't change the laws of physics, or chemistry, it's how you apply them that is important.

[pvr]

Uh, what is a heat recovery system … I am on oil so anything that I can put in the loft and reduces that would be good (think £500 a month on oil in the winter)

[M1k3yC]

earthdweller, thanks - that's where I think that I'm at. Currently favouring a Meaco DD8L Zambezi Dehumidifier. I found it sold elsewhere online at c. £230.

[Pondrew]

I am on oil so anything that I can put in the loft

I was on oil too. My oil usage for the last complete year (2019) was c.£450. House was 260m2, the only other heat was a woodburner in the main living room (4kw max) used only occasionally.
They are known as MVHRs (Mechanical Ventilation with Heat Recovery). Only problem is they are extremely difficult to retro-fit into an existing house, as you need lots of ducting everywhere.
It's basically a fan unit with two fans. One is intake, the other is extract. There is then a 'heat recovery cell' which all air passes through. The cell retains the heat of the extracted air and releases it into the fresh ambient intake air. So you save the heat but change the air. Brilliant (and very simple) idea and work extremely well if installed correctly and balanced correctly.
Put it this way, if I ever build another house, this will be top of my list for 'essentials'.
They are not very popular because a). builders know nothing about them and b) they can be a pain to install in 'standard' construction methods.
LABCs have tried to push them for a good few years, but developers have pushed back for the reasons above.