Workshop Ventilation.

[MWParticipant @mw27036]

Hi,

As we all know it's a scorching summer and we brits don't take readily to too much heat.

So my workshop is a 5mx5m Building, double glazed windows, 50cm thick walls and 19mm thick roof, with tar shingle tiles. I was thinking, "is it hot in here or is it just me?" so I wanted to establish whether it really was just me. So I put a cheap thermometer on the wall after a morning of perusing the local D.I.Y store. And I regularly get temperatures of 35C on a sunny afternoon. I recon the outside is more like 27C.

So something clearly is going on here. The question mark is over how it's fixed, and in order to fix we have to spend pennies, and we want to make sure we get it right, so that we don't have a "2 steps forward, 1 step back" scenario on our hands.

So I started looking at how proper ventilation with a wall fan, rather than a cheap small static 2×2" hole with guards on both sides of the walls which i'm almost certain isn't good enough.

So I probably went overkill when I started to begin with, looking at fans from machine-mart which topped £200, I'm not questioning their top notch quality and airflow rate but it's probably intended for more like a factory scenario rather than a medium sized outbuilding and I'm a little unsettled by the price tag ​.

So I found these £35 ones on ebay, to which I could probably fit a louvre type, wall grille to the exterior, with a bug net attached of course.

Fan:

**LINK**

Outer Wall grille:

**LINK**

Reversing Switch:

**LINK** perhaps there is some way I could perminently reverse the polarity of the motor myself?

So the theory goes, I attach one to the back wall to draw air out, and one at the front to draw air in, now it would have to change the direction of spin in order to do this, so I would need some way of changing it, i'm quite open minded about how that can be done.

simply turning it around and mounting it the other way around, would look pretty odd but I suppose it's doable and removes the associated risk of tricky electrical installation.

So would this help enormously or have I just created some "hot air" idea?

The only other thing I can think of doing would be adding a layer of foam roof insulation and sandwiched between the original planks and some new ones. This would slow the time it takes for it to heat up.

But I haven't had this idea approved by the powers that be and might take some convincing, insulating the walls now is out of the question i'm afraid, I should've done it on construction and now my space is totally filled up and removing it all would be too much bother.

Thank you for listening, I expect with most of us using an outer space for this we have a lot of experience to hear on here!

Michael W

[MWParticipant @mw27036]

Describing ideas on how to cool a workshop in summer and remove moisture in the winter.

[Andy HoldawayParticipant @andyholdaway]

Michael, Reversing a fan motor will give you some air movement, but nowhere near as much as when it is spinning in the correct direction. You will have to change the impeller over as well.

Far better to turn the whole fan around if possible.

Andy

[Mark P.Participant @markp]

As my workshop is my garage I open the front doors,the side door and the window thereby creating a through draft.
Mark P.

[MWParticipant @mw27036]

Posted by Andrew Holdaway on 24/06/2017 19:07:11:

Michael, Reversing a fan motor will give you some air movement, but nowhere near as much as when it is spinning in the correct direction. You will have to change the impeller over as well.

Far better to turn the whole fan around if possible.

Andy

Yeah I just realized that and when picturing the impellor moving in my mind, saw that it wouldn't get much air through, so I'll scrap that idea.

and mounting on the front of the building looks like a possibility, perhaps with an extra guard over the top of it to stop a build up of flies? 

Michael W

Edited By Michael-w on 24/06/2017 19:13:40

[MWParticipant @mw27036]

Posted by Mark P. on 24/06/2017 19:07:59:
As my workshop is my garage I open the front doors,the side door and the window thereby creating a through draft.
Mark P.

One of the biggest downsides I have is the lack of a through draft, all my windows are at the front, and my original idea was to put another one at the back,(I even have two spare windows!!!) but I got that idea thoroughly rejected for security reasons. So this fan business is the only shot I've got going at the moment!

Michael W

Edited By Michael-w on 24/06/2017 19:12:46

[clogsParticipant @clogs]

Michael W,

had a similar problem when I lived in Africa……but the house……found a large Louvered 24"x24"glass window (operated with a cord) in a recl yard so fitted it as high up as poss in the gable end-hall way and in the back door lower panel fitted an Air-con dust filter 12"x14", to keep out the bugs and dust under burgler bars !!!!!!!!!!!

worked a treat, no electric and kept my 3 bed bungalow just a nice temp and secure……..the window closed for the winter and the door panel, just made a small door…….very simple…for the shed I'm sure u can find a v/small UVPC toilet window in a skip somwhere… clogs

[Bob Brown 1Participant @bobbrown1]

You may need to look at the size of the fan needed in terms of m3/h with regards to the building volume, you need to aim for a min of 20 changes/hour so if your workshop is 5 x 5 x 3 metres then you would need a fan of 1500 m3/h.

You might want to stick you hand on the roof/ceiling (carefully) when the sun is shining on it as you may be surprised as hot it gets

My workshop/garage is 7 x 4.5 x 4 meters cavity wall with 60mm Celotex, Celcon block inner and roof has 120mm of Celotex insulation, max/min thermometer this week shows a max of 27.5 and min 18. I could open the big door and a couple of windows but it's not really needed.

Bob

[MuzzerParticipant @muzzer]

I'd agree – the flow rate of those fans is pitiful. May be OK for getting rid of the pong after laying an industrial sized cable in the karzi but won't do much to cool a workshop with a large external surface area.

Can't you just open the windows on each side of the building? Leave them cracked open when you are out. Modern windows are designed to be secure with the window slightly ajar and this gives enough turnover of air to moderate the temperature. I have several Velux-style skylights that also assist the process. They aren't expensive and give the added benefit of great lighting.

If you get in there and it's filthy hot, you can open the windows and windows wide and blast some cool air in there. Something like this.

Murray

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Bob Brown 1 on 24/06/2017 19:57:34:

You might want to stick you hand on the roof/ceiling (carefully) when the sun is shining on it as you may be surprised as hot it gets

Solar radiation amounts to about 1 kW/m² so, depending on the design and orientation of your roof you could be getting up to 25 kW of solar heating. More likely about half that but still a lot to get rid of.

How about some form of shading? Louvred panels on the roof?

Russell

[vintagengineerParticipant @vintagengineer]

In my workshop I had a air to air heat pump fitted. This an aircon unit that produces warm air in the winter and cold air in the summer. Cost was about £1000.

[BazyleParticipant @bazyle]

Roof insulation should be your first thought not an extra as it will also do a good job in the winter. A few days lost in summer heat when the insulation is not sufficient will be more than made up by extra working days in the winter when it used to be too cold.
Adding a reverse fan is pointless. Add a second normal fan and open the door. Paint the roof with a mix of garden lime and water to whiten it. Direct the gutter into a rain butt so when the lime is washed off it is available again to use on the garden and not wasted.
Fit a mist sprayer to spray water on the roof.
Grow hops over the roof. If you have seen hop fields you will know they grow fast enough in a year to cover it by summer.

[Nick_GParticipant @nick_g]

.

I may be wrong but I 'think' I have a recollection of the OP asking or being involved in the same question this time last year.??

Nick

[Paul LousickParticipant @paullousick59116]

Hi Michael,

I live in Australia and the first thing we do to reduce the heat (and warm in winter) in our homes is to insulate the ceiling. Roof mounted vents are added to take the away from the heat in the ceiling space. These can be static vents or be fitted with fans.

Wall mounted fans are cheap and will exhaust the hot air in your workshop (also available with auto opening lourvres to seal when turned off). A simple vent may be all that is required to bring air into your workshop. Air will be sucked in when air is exhausted by the fan and the problem of reversing the fan direction eliminated.

Reversing the direction of an A/C fan motor could be a problem, it is not as simple as switching the input wires.

Paul

Edited By Paul Lousick on 25/06/2017 00:16:09

[Steven VineParticipant @stevenvine79904]

Posted by Nick_G on 24/06/2017 23:56:34:

.

I may be wrong but I 'think' I have a recollection of the OP asking or being involved in the same question this time last year.??

Nick

You are right.

Link to Hot Workshop topic. **LINK**

Steve

 

Edited By Steven Vine on 25/06/2017 00:23:47

Edited By Steven Vine on 25/06/2017 00:25:04

[Nick_GParticipant @nick_g]

Posted by Steven Vine on 25/06/2017 00:22:38:

You are right.

Link to Hot Workshop topic. **LINK**

Steve

Edited By Steven Vine on 25/06/2017 00:23:47

Edited By Steven Vine on 25/06/2017 00:25:04

.

Oh.!

Nick

[Ian S CParticipant @iansc]

With fans it is difficult to reverse them as they use shaded pole induction motors I have done it on one motor by stripping it down and reversing the armature.

Ian S C

[Clive HartlandParticipant @clivehartland94829]

One point to consider is the colour of the roof and exterior, a dark surface will absorb heat whereas a light coloured surface will reflect the heat. A dark garage door facing the Sun will heat the inside, paint the door with a light colour and the inside temperature will drop considerably.even without insulation. The roof could be covered by a light metal to reflect the Sun. It goes without saying that opening windows are also useful, fumes and cooling.

[mechman48Participant @mechman48]

My converted garage/workshop is insulated with Celotex in studding panels on the walls behind OSB, the roof space has space blanket loft insulation, there are Celotex panels glued to the insulated roll panel main door, the entry door also has a Celotex panel glued to it so it is pretty well insulated. When it comes to ventilation I leave the entry door ( SW facing ) open, when I'm in, &, as any prevailing winds are NE or SW the S/westerly creates a nice breeze into the garage. It is rare that I need to open the main door any amount to create a through draught when it gets over hot…?? & then it was only up a couple of inches so really don't have a major problem.

George.

[MWParticipant @mw27036]

Yes it appears I have already talked about this, so I must get myself checked out for early onset dementia. Sorry for that blunder, but it's worth asking twice because I think I've already got some more concrete ideas and suggestions than I had the first time round.

A reversible fan doesn't look like a good prospect so that'll go firmly in the dump.

The type of roof tiles I use are black armourglass ones, and they're quite expensive so I think I'll keep those for now.

Roof insulation sounds like a great idea but trying to get that approved will be something else, if I could quietly do it I would but it's a big area to do and I don't think i'll be able to sneak that many foam panels and planks without someone taking notice.

Would I need some kind of special outdoor vent if I had one facing the outside to draw air in? I take it would need to be better protected from the elements and bugs?

Michael W

 

Edited By Michael-w on 25/06/2017 12:16:26

[MWParticipant @mw27036]

Posted by mechman48 on 25/06/2017 12:13:57:

My converted garage/workshop is insulated with Celotex in studding panels on the walls behind OSB, the roof space has space blanket loft insulation, there are Celotex panels glued to the insulated roll panel main door, the entry door also has a Celotex panel glued to it so it is pretty well insulated.

George.

I know the very ones, I think I have a few pieces in the loft but I know they've got stacks of them at wickes, I got my earlier dimensions wrong, it's 5x4x1.8m in size, so for the roof, i'll probably need around 20m in total, taking a little off for the purlin gaps inbetween.

Michael W

Edited By Michael-w on 25/06/2017 12:28:37

[Clive HartlandParticipant @clivehartland94829]

Consider also that any air fan extracted will be replaced with air from outside at the temperature outside. If it is hot out then you get hot in.

[BazyleParticipant @bazyle]

From the previous thread you have seem to have an opening window. Put a standard desk fan in front of the window sucking air in and blowing it at you and open the door to let it out. It is only a few days a year, now almost over, and this solution is quick. Fan has use in other rooms when not needed in shed.

Re getting insulation past the wife. Find another man with wife and get the wives to be friends. Encourage them to go out together, shopping etc. On an exchange basis the other man will help you move equipment in if you help him move beer barrels into his shed.

[Tim StevensParticipant @timstevens64731]

The question continues '… remove moisture in winter' and I'm sure we all know how effective for this are the de-humidifiers. And a bonus – a liberal supply of de-ionised water for all sorts of useful jobs including steam boilers.

What is not so obvious is the cooling effect of such devices in summer. At least, in UK summers, in which seriously hot days are often humid. All our weather crosses the sea, so it's only natural. In such cases, the cooling effect of sweating is ineffective because it cannot evaporate – but with a decent dehumidifier it can. As long as you keep the doors and windows shut, of course.

I hot dry places like Australia, I suppose that the only answer is to have planted lots of boolabong trees around your workshop about 50 years ago. Ho hum …

Cheers, Tim

[duncan webster 1Participant @duncanwebster1]

Posted by Tim Stevens on 25/06/2017 21:36:14:

The question continues '… remove moisture in winter' and I'm sure we all know how effective for this are the de-humidifiers. And a bonus – a liberal supply of de-ionised water for all sorts of useful jobs including steam boilers.

What is not so obvious is the cooling effect of such devices in summer. At least, in UK summers, in which seriously hot days are often humid. All our weather crosses the sea, so it's only natural. In such cases, the cooling effect of sweating is ineffective because it cannot evaporate – but with a decent dehumidifier it can. As long as you keep the doors and windows shut, of course.

I hot dry places like Australia, I suppose that the only answer is to have planted lots of boolabong trees around your workshop about 50 years ago. Ho hum …

Cheers, Tim

Yes a dehumidifier will make the air drier, but with the doors and windows shut it will make it even hotter, as it is consuming power, and all that power comes out as heat. This is why aircon units are stuck on the outside of buildings, so the heat goes outside.

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