Thread: Is a mobile evaporative cooler in a tin shed a bad idea?

Originally Posted by 419

Nothing significant.

Shading for first few hours of daylight, then full sun.

No lining.

Thin and largely useless foil insulation under roof.

Installing better insulation under roof is on my list of things to do. Also serious extractor fan on wall under roof peak. Both have been on my list for about ten years, so I must be getting closer to doing it.

Any chiller or aircon will have to work really hard, perhaps too hard, until you attend to the insulation.

Originally Posted by mic-d

You'll need to insulate walls too.

Bit of a problem there as, although my 7.5 x 5.8 mt shed isn't lined, most of the walls are covered with base cabinets, hanging boards and shelves. A major and time consuming PITA to empty, remove and replace after insulating, which is probably badly disproportionate to the fairly minor benefit from insulating the walls.


The walls aren’t a major source of transferred heat. The east wall is partially shaded by a tree during the morning. The south wall doesn’t get any sun. The north wall is windows on the top half and below a retaining wall for most of the tin bottom half. The west wall is the main source of non-roof heat, because it gets full sun from early afternoon to sunset. I can’t do much about that as it’s mostly a roller door which can’t be insulated. So the roof is where I’ll get the most bang for my buck.

Originally Posted by mic-d

I've installed the 20mm foilboard from Bunnings for clients and it is easy to do though not cheap. Don't discount the foil insulation, the foilboard has it too, and it acts as a radiant barrier, the heat that you would feel radiating from the ceiling and wall is blocked by the shiny foil because of its low emissivity (this is not only a relfection of the radiant heat, but an inability to radiate the heat much even if it gets very hot, so the shiny side can face inward with the same effect.) It's better if it does not get very hot though because it can still conduct heat to the air.

Thanks for that. Good to know.

Originally Posted by mic-d

So next to the tin it's good to have an air gap, even better if this can be sealed off from the inside and vented through the roof, then you need a bulk insulation and a foil radiant barrier under that (the foilboard gets you to that). Then a solar powered exraction fan in the roof gets an airflow through the shed, you can't do any better than ambient temperature ...

I was working along similar lines with the intention of installing a ceiling with foil on top of insulation batts under the shallow gable roof, with a serious 240V extractor fan at one end close to the roof gable and a suitably sized louvre inlet at the other end so that I can have air moving the heat from the roof away before it gets into the shed. I’ll look into foilboards as they might be easier to install as a one step ceiling and insulation.

Originally Posted by GraemeCook

Any chiller or aircon will have to work really hard, perhaps too hard, until you attend to the insulation.

I was thinking of a smallish mobile cooler that I could move around and direct at me where I'm working, rather than trying to cool the whole shed. Cooling the whole shed with endlessly rising energy prices isn't an option. We'll soon be getting to the same point with cooling and heating the house, especially after today's announcement that we'll be forced by our Victorian government to get rid of our gas hot water, gas heating and gas cooking and replace them with electrical appliances in the coming years.

Originally Posted by 419

...We'll soon be getting to the same point with cooling and heating the house, especially after today's announcement that we'll be forced by our Victorian government to get rid of our gas hot water, gas heating and gas cooking and replace them with electrical appliances in the coming years.

Yup. If we think electricity costs a lot now, wait until it's the only option

Originally Posted by r3nov8or

Yup. If we think electricity costs a lot now, wait until it's the only option

Yeah, off topic, but particularly as every year for the past few years the energy market regulator warns us that there mightn't be enough electricity to meet all needs for the coming summer and winter.

So how is this magically going to be better when everyone currently on gas adds massively to the drain on electricity with coal fired electricity generators being shut down years earlier than expected?

Not to mention the new drain as government moves us to electric vehicles.

But I'm sure that our state government knows what it's doing and it will all turn out okay, because there's a long history of governments knowing what they're doing and it turning out okay. Like ditching the SEC and privatising electricity, and now they're supposedly starting a new SEC that will magically cure electricity shortages and overpricing caused by ditching the old SEC.

Expanding on the wet T-shirts mentioned earlier.

Search for cooling vests. The come in several types. Evapourative cooling vests are soaked in water for a few minutes and after dripping a few more are put on. They will cool you for about 4 hours, give or take. They cost under a hundred and are very effective if there is air movement to evaporate the water. I used them along with a big fan when I worked in the plant when was 30ºC to 40ºC range in the summer. The downside to one in a woodshed is the dust will stick to the wet fabric. A better (at a cost) solution is a phase change vest. Ice packs are chilled in a refrigerator or freezer and placed in pockets in the vest. Good thing about them is you can wear coveralls or shop coats over and they still work the same.

Not nessecarily a long term solution but one that will get you by until you can upgrade your shed. Also useful when you have to work outside and don't like melting.

Pete

I didn’t think about what might be on the walls in a work shop 🤭. You can find various ways to shade the walls as an alternative too, such as some type of rollaway blind over the rolladoor end…. Although an evap system isn’t ideal and a big one still needs you to overcome the lack of ventilation or it will become inefficient as the relative humidity increases, a little one for personal cooling could work. We have a Ryobi one + fan that can mount over a bucket of water and works as an evaporative cooler very well, but you probably want to direct it toward the open door or window.

I have a roof mounted evap in my shed, the only real issue is I need another one as it’s not big enough. I’ve seen no noticeable issues regards rust. As a bonus it’s great for helping to shift dust and fumes out of the shed with a continual replenishing with fresh air from outside.

I wouldn’t be without it, but your location is going to be a big factor in how useful one is.

Cheers Andrew

Originally Posted by AJ.

I have a roof mounted evap in my shed, the only real issue is I need another one as it’s not big enough. I’ve seen no noticeable issues regards rust. As a bonus it’s great for helping to shift dust and fumes out of the shed with a continual replenishing with fresh air from outside.

I wouldn’t be without it, but your location is going to be a big factor in how useful one is.

Cheers Andrew

Don’t the roof mounted units use a heat exchanger?

Originally Posted by 419

Bit of a problem there as, although my 7.5 x 5.8 mt shed isn't lined, most of the walls are covered with base cabinets, hanging boards and shelves.

That might actually be a bonus. There could be a little bit of insulating value in those cabinets and shelves. That leaves the roof.

It is only about 44 m2 so the costs of batts to cover that space would not be exorbitant. Worth thinking about. And it would also be practice if you later want to review the insulation in your house.

Originally Posted by mic-d

Don’t the roof mounted units use a heat exchanger?

mine has honeycomb pads that water runs through, air cools as it’s sucked through. That’s the only style I have ever seen.

cheers Andrew

Originally Posted by QC Inspector

Expanding on the wet T-shirts mentioned earlier.

Search for cooling vests. The come in several types. Evapourative cooling vests are soaked in water for a few minutes and after dripping a few more are put on. They will cool you for about 4 hours, give or take. They cost under a hundred and are very effective if there is air movement to evaporate the water. I used them along with a big fan when I worked in the plant when was 30ºC to 40ºC range in the summer. The downside to one in a woodshed is the dust will stick to the wet fabric. A better (at a cost) solution is a phase change vest. Ice packs are chilled in a refrigerator or freezer and placed in pockets in the vest. Good thing about them is you can wear coveralls or shop coats over and they still work the same.

Not nessecarily a long term solution but one that will get you by until you can upgrade your shed. Also useful when you have to work outside and don't like melting.

Pete

Thank you! Never heard of these. Googled them and they're readily available. Even better, they're made for dogs, which my old dog will probably like as he's finding hot weather harder.

Originally Posted by mic-d

We have a Ryobi one + fan that can mount over a bucket of water and works as an evaporative cooler very well, but you probably want to direct it toward the open door or window.

Thanks. That encourages me to carry out an experiment with ice blocks - the type sealed in plastic bottles - in front of my monster fan. Shouldn't be much of a humidity problem with that, apart from minor condensation on the blocks.

Originally Posted by GraemeCook

That might actually be a bonus. There could be a little bit of insulating value in those cabinets and shelves. That leaves the roof.

Probably not. There is a bit of insulating value from direct heat on the walls as the horizontal steel channels supporting the cladding allow about 50mm behind the cabinets and hanging boards, but the trapped heat will still rise to under the roof.

Originally Posted by GraemeCook

It is only about 44 m2 so the costs of batts to cover that space would not be exorbitant. Worth thinking about. And it would also be practice if you later want to review the insulation in your house.

I've had enough practice installing batts in standard existing house roofs and I don't want any more. The shed is much easier as I can work from below installing a ceiling and pushing batts in rather than being in the roof space and getting overheated and itchy with insulation fibres.

My house insulation is pretty good. It's the energy costs that are the problem. I dread to think what they'd be like in any uninsulated house built more than about 20 - 25 years ago, let alone a 1960s and earlier weatherboard.