Workshop heat recycling and suitable fan

[RogerS]

My workshop has very high eaves and any hot air is going to rise. So I was thinking of installing one (maybe two) long lengths of soil pipe vertically with a fan at the bottom to suck the hot air down to floor level on a continuous (continual?) basis.

Reason for putting the fan at the bottom is to be able to blow out the dust from time to time. So..type of fan? Are there fans designed to suck and those designed to push? Original thought was a small bathroom extractor type but certainly the ones from Screwfix die after a while and I'm not sure they are designed for constant running. Don't really want to go up much in size either - more faffing about and something else to bang my head on. I have enough excuses for that (banging my head, that is).

Anyone done this? Is it a daft idea?

 

[MickCheese]

Do you have a fan driven dust filter in your workshop? Like the jet ones.

If so why not try that high up to keep the air circulating and catch the dust at the same time.

I am not sure how effective a 4" pipe would be at moving sufficient air to be worth while.

It seems your standard bathroom fan moves approx 85 cubic metres per hour, that about 1.5 a minute, and that is at its maximum. Then you have to add in the restricted pipe length.

Just my thoughts.

Mick

 

[MikeG.]

If nothing else, Roger, this proposal will help prevent condensation, and associated rust, within your workshop. The downside is that you may not feel much warmer, because moving air (even if it is warm) makes you feel cool (think breeze on a hot summers day).

The simplest solution would be a bathroom extractor mounted inside a ply box (so that it is extracting from the box), with your plastic duct attached to the box. there won't be any great losses over a small distance of straight round pipe.......it is done all the time in rooves over bathrooms and kitchens.

Why not kill 2 birds with one stone, and build another box at the top end of the pipe with a filter in it? That way the fine dust particles will also be removed rather than just stirred up by the fan.

Mike

 

[Doug B]

Anyone done this? Is it a daft idea?

Not at all Roger, i used to fit out showrooms for a builders merchant, they had open roofed buildings & they had the very same arrangement but on a much larger scale.
What you need is to be able to control the speed of the fan, if you move air quickly, as Mike has said you get a breeze. So in the winter the fans blew down, but very slowly & in the summer the fans were on maximum speed so giving a cool breeze.

 

[DaveL]

Roger,

My home made cyclone dust collector vents via two large filters in the roof space of the shop. In the winter when the wood burner is going, running the dust collector, IMHO does make it feel warmer in the shop. If I am not making dust that needs collecting I run it for a few minutes every half hour.

 

[MikeG.]

PS

Roger,

I would be cautious of trying two of these. You might find they actually cancel each other out. What you are trying to achieve is a circulation , and in a small space like a workshop you really will be fine with just one fan stirring things around. Thats a good idea of Dougs, too.......wire in a dimmer switch.

Mike

 

[RogerS]

Thanks chaps..some good ideas there.

Good point about the velocity creating draughts but I also like the idea of a fast throughput in summer as it does get very warm so some form of speed control is needed.

Eaves are high (15ft from ground level) and so mounting anything up at that height from a cleaning perspective is out of the question.

So no such thing as fans that are designed to suck and those designed to blow?

Condensation not an issue. It was very well insulated when built - OK perhaps not to modern standards but not bad. Pretty well sealed (plus points as well as minus points) and the entire south facing wall has double glazed K glass wall to ceiling so quite a bit of heat gain from the sun.

God, I wish it was this empty now. These were taken in 2006

 

[MikeG.]

Roger,

time to edit your thread name to include "Gloat alert"

What a lovely workshop! I reckon you have the height there to insert a raised storage floor above your joists........

Mike

 

[MickCheese]

What a fantastic workspace.

Do you not find yourself gazing out of the window instead of working?

Mick

 

[RogerS]

That's very kind of you to say so. Sadly the open spaces didn't last long and the view got kind of overgrown!

 

[MickCheese]

I prefer the other view

At least you can now work without the distracting scenery.

Mick

 

[j]

Might be an idea to reverse the fan in the winter.
Don't ceiling fans have a reverse switch so in the winter they circulate warm air? I'm sure mine had a switch, but TBH I never tried it.

 

[head clansman]

hi rogerS


Thermostate control ( auotmatic on /off then ) with a reversable cieling fan summer winter thingy .hc :wink: :lol:

 

[big soft moose]

My workshop has very high eaves and any hot air is going to rise. So I was thinking of installing one (maybe two) long lengths of soil pipe vertically with a fan at the bottom to suck the hot air down to floor level on a continuous (continual?) basis.

you could also look at installing an insulated drop ceiling at beam height to try and keep the heat lower down to start with - though the down side of that is that it might make handling long stock problematic.