Alternative cooling

[Zephod]

As many of you know, I'm not keen on loads of solar panels nor generators.

For the past year my bus has been ventilated very successfully with a pair of CPU fans. The other day I was working at the front of the bus using heat shrink sleeving which lets off an odor when it's heated.

I noticed the odor moved slowly down the length of the bus over a couple of hours before it was gone. That tells you immediately that my CPU fan based ventilation works.

I'm in the midst of an upgrade. I bought a marine bilge blower on eBay a few days ago. Oh boy... it's powerful. By my calculations in just 7 minutes it should evacuate all the air from the bus.

I've been trying various things with it. First I tried pumping air in via a 15 foot bilge hose. I put the intake complete with my trust Honda lawnmower engine air filter. It blew air in at a fair lick. Then I whipped the filter off and had a raging gale coming in.

Eventually, I put the fan on one of my two exhaust vents. That probably worked the best though the duct tape I was using kept coming off. That makes me suspect it was putting too much air through so it might be a case of having to use one fan to feed two vents. Still, at 130CFM in a bus with 25 feet by 7 by 6 of living space, it will take 7 minutes to replace all the air.

My goal for tomorrow is to find two bushes at Lowes that will convert my vent piping from 4 inch ID to take a 3 inch pipe (max 3.25 OD) then a max 3.25OD T adaptor. I can cut my bilge hose to connect the T adaptor to the two vents and to the fan. Clearly I'll need to put a mesh filter on the fan to stop debris getting sucked in. And I'll need some clips to hold the hose to the fan.

Interestingly, I was looking at my blog entry today detailing my experiments when up came an advert for some kind of whole house cooling fan. They were advising against AC on the basis of cost. I knew I wasn't the only one to be working with fans instead of AC.

AC has sex appeal but honestly, being cool is more about moving air than having cold air. I lived for years with just a fan and no AC. Not because I didn't have AC. I just never saw the point when I could have a fan, drink fluids and take my clothes off!

Anyway, today's experiments are here. http://schoolbushome.blogspot.com/2017/07/its-mystery.html

I did have somewhat of a mystery with humidity and temperature changes that didn't seem to relate too well to what I was doing. I'm suspecting the changeable weather was mostly to blame. I might get myself a thermometer with an external sensor so I can compare internal versus external temperature and humidity.


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[J_E]

Zephod, I've missed where you are located.  I am guessing somewhere in the norther parts of the US or in Canada.  In those areas, keeping the inside of your bus close to the outside air temp will work on most summer days.  Further south, where the ambient gets to be a bit warmer than comfort dictates, you want a little more.  That being said, I'd happily settle for some shade and a cool ocean breeze.

Sounds like your ventilation ideas work very similar to the whole house ventilation fans you described.  They are also designed for those areas, or times when the ambient air temp is cooler than the indoor temps.  Open some windows, run the fan and sooner than you know it your house has cooled down.  Would have loved to have one when I lived near Seattle.

Rather than try to pull air the length of the bus, have you tried placing the fan and/or exhaust at a high point near the center of your buss and pulling in air from both ends?  You will end up exhausting from the hottest area of the bus (near the roof) and your intake air will have a shorter distance to travel.  If you allow the blower to exhaust directly and use doors, windows, or a damper to intake air, you should be able to save valuable real estate that any ducting would take up.

Take a look at some of those portable electric coolers.  That claim to be able to cool 15-20 degrees below ambient without using a compressor.  Maybe a copy or modification of that design would allow you to further temper, and maybe even cool, your intake air.

[Zephod]

Zephod, I've missed where you are located.  I am guessing somewhere in the norther parts of the US or in Canada.  In those areas, keeping the inside of your bus close to the outside air temp will work on most summer days.  Further south, where the ambient gets to be a bit warmer than comfort dictates, you want a little more.  That being said, I'd happily settle for some shade and a cool ocean breeze.

Sounds like your ventilation ideas work very similar to the whole house ventilation fans you described.  They are also designed for those areas, or times when the ambient air temp is cooler than the indoor temps.  Open some windows, run the fan and sooner than you know it your house has cooled down.  Would have loved to have one when I lived near Seattle.

Rather than try to pull air the length of the bus, have you tried placing the fan and/or exhaust at a high point near the center of your buss and pulling in air from both ends?  You will end up exhausting from the hottest area of the bus (near the roof) and your intake air will have a shorter distance to travel.  If you allow the blower to exhaust directly and use doors, windows, or a damper to intake air, you should be able to save valuable real estate that any ducting would take up.

Take a look at some of those portable electric coolers.  That claim to be able to cool 15-20 degrees below ambient without using a compressor.  Maybe a copy or modification of that design would allow you to further temper, and maybe even cool, your intake air.

I'm actually living in Columbia sc at the moment. Sure... it gets hot but it's not too bad after dark nor in the shade.

My plan is to extract air at the back of the bus via my existing exhaust vents (which were originally student lights). I'll pull air from close to the ceiling. This is my test setup...


I do have a Peltier unit. I bought one to play with but though it's interesting, it's not really worthwhile. By stacking Peltier units, you can get really low temperatures - lower than liquid helium. The killer is each unit needs 60 - 100 watts. To make a cooling panel, I'd probably need 20+ which really kills the idea.

I'm pulling air the length of the bus because it makes more sense given the way I've built my bus. I have no roof vents so this works out easier.

I'll just have to see how my current experiment goes. I'm hoping my 5AH battery will run the fan for the needed 10 minutes. I'll have to adjust parameters on my charge controller.

The front panel looks like it's just going to be used to charge my portable battery pack - the one that charges my cell phone etc.
As you can see... I pick and choose my technology lol.


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[buswarrior]

ribbed flex pipe creates resistance to air flow much more than smooth rigid pipe.

The air bounces around inside, and has to change direction unnecessarily. think aerodynamics and turns in a road.

An upgrade to a bit of home galvanized duct piping will give you an incremental improvement.

Interesting experiments.

happy coaching!
buswarrior

[belfert]

When the temperature is high enough all a fan does is blow hot air and doesn't help much.

My body is very sensitive to humidity since I had two incidents of heat exhaustion about 15 years ago.  I use air conditioning all the time in my house for about three months of the year.  The electricity cost is at most $200 a year.  Whole house fans used to be a big thing in Minnesota, but new houses all have central air for at least the past 30 years.  My parent's first house was built in 1972 without A/C and had a whole house fan.  My parent's current house was built in 1979 and had central air from the start.  My father would never go without air conditioning now.

If fans work for you that is great.  It certainly saves a lot of money to not have air conditioners and a generator to run them.

[luvrbus]

Just seems to me like a Fan-Tastic or even the 20 bucks bathroom vent 12v fan would work better for you

[Zephod]

ribbed flex pipe creates resistance to air flow much more than smooth rigid pipe.

The air bounces around inside, and has to change direction unnecessarily. think aerodynamics and turns in a road.

An upgrade to a bit of home galvanized duct piping will give you an incremental improvement.

Interesting experiments.

happy coaching!
buswarrior

What you say is technically probably correct with vortexes etc. in practical terms though, it doesn't make any real difference. My bottleneck on my 4 inch vent is the mosquito mesh. Fortunately I have two vents. I'm thinking of splitting the output from the fan using a T adaptor, putting a 4 to 3 bush into my 4 inch vent tubes then connecting the bush to the T using the flex duct. Then I'll have to make an inlet manifold. That'll probably be rigid 3 inch tube with an end cap and  bets cut in the side with mosquito mesh wrapped around it. It doesn't have to look pretty. It just has to work.


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[Zephod]

Just seems to me like a Fan-Tastic or even the 20 bucks bathroom vent 12v fan would work better for you

My vents were already existing holes where the student light were. No holes in the roof. My bilge fan pulls 130CFM so 7 minutes sucks all the air out of the bus.

If I'd had a roof hatch, I could have used that but I don't. I'm not keen on the idea of putting a hole in a perfectly good roof either.

The $20 bathroom vent fan is really a $2 CPU fan in disguise.


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[daddysgirl]

This is, of course, your preference. But if you had the need or desire to further aid with cooling, a small de-humidifier would make a big difference...especially in the closet, or anywhere fabrics are stored.
AC itself works in part by dehumidifying the air.

[Zephod]

This is, of course, your preference. But if you had the need or desire to further aid with cooling, a small de-humidifier would make a big difference...especially in the closet, or anywhere fabrics are stored.
AC itself works in part by dehumidifying the air.

Oh, undoubtedly AC would be better. Having said that, this is something I'm building on a stretchy budget. Heaven knows how much I've spent. But I've done everything myself from electrics to plumbing to cabinetry to welding.

I'm trying to avoid as many gizmos as possible. Originally I wasn't even going to have solar panels.


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[Tony LEE]

with no holes in the roof, where does all this air get exhausted to?

[Oonrahnjay]

with no holes in the roof, where does all this air get exhausted to? 

       Tony, on American school buses (almost universally), there are a pair of rearward facing red lamps, which flash when activated to show that the vehicle is stationary and picking up or dropping off students.  These lamps are usually 7" diameter round lights and are fitted to appropriately sized holes in the upper rear bulkhead of the bus.  So his setup is using two existing holes in what is pretty much the uppermost portion of a vertical panel as the exhaust vents.  The only other useful location would be the similarly-sited front warning lamps above the windshield but that would bring issues of weather sealing etc.  For what he wants, he's picked a very good site, indeed.

[Zephod]

       Tony, on American school buses (almost universally), there are a pair of rearward facing red lamps, which flash when activated to show that the vehicle is stationary and picking up or dropping off students.  These lamps are usually 7" diameter round lights and are fitted to appropriately sized holes in the upper rear bulkhead of the bus.  So his setup is using two existing holes in what is pretty much the uppermost portion of a vertical panel as the exhaust vents.  The only other useful location would be the similarly-sited front warning lamps above the windshield but that would bring issues of weather sealing etc.  For what he wants, he's picked a very good site, indeed.

Thank you. Actually there are four lights. Two amber, two red. I'm a school bus driver in my real life. The ambers are activated when I'm getting ready to stop. The book says 100-300 feet before a stop but sometimes it's not possible. The reds come on as soon as the door begins to open and at the same time as the stop arm and crossing barrier deploy.

The lights are the same both front and rear.

And there you can see in the center, backup camera 1 (I have two), two vents, two solar panels powering the vents and two capped over places where there were lights. The holes were 5" approx.


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[Zephod]

By the end of today, this is how V2 of my ventilation system looks. Gone are the two CPU fans that have been ventilating for the past year or so, replaced by a bilge blower that should in theory replace all the air in the cabin in 7 minutes. I'll have to see which battery works best with this monster and whether I need to pool the front and back solar panels.



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[daddysgirl]

Oh, undoubtedly AC would be better. Having said that, this is something I'm building on a stretchy budget. Heaven knows how much I've spent. But I've done everything myself from electrics to plumbing to cabinetry to welding.

I'm trying to avoid as many gizmos as possible. Originally I wasn't even going to have solar panels.


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I'm sorry...I didn't mean to imply A/C system.
I have seen the significant work you have done and totally understand budget issues. My thought of a small dehumidifier was equally considered as another means to lower temperature, as it was to prevent the damage humidity can do. Humidity grows mold, warps wood, etc...as you know.
I use a small one in my house, and it saves me a fortune in electric bills. I got it for $75.00. But it's just a thought. Do whatever works best for you