Non-AC Cooling

[CaptSquid]

The thought came through my coconut -- yeah, I know, it's dangerous to think.

Anyway, why not mount a radiator cooling fan in the roof vent? I found some 16" push-pull fans like one would install on your vehicle radiator. You could install a rheostat in line to control the speed and/or direction.

Thoughts?

[jazty]

That's what I've been using in the warmer months. I grabbed a rad fan from a Subaru Outback. It can really move air! I then connected it to a PWM motor controller for speed control. While it can turn either way, it does best in one direction, which suits me fine because the fan is behind a bug screen. Fans do best sucking through bug screens instead of blowing against them.

[CaptSquid]

Pix of your mount? They'd help considerably. I already have a 12 VDC line run down one side of the bus.

[jazty]

I don't have it installed right now, but I can assure you that it ain't anything sexy. Just a square chunk of 3/8" plywood with a hole cut out in the center and the fan screwed to the plywood. I'll be making something more permanent and pretty some time soon. It's near the top of the multi page to-do list

[EastCoastCB]

Couple of these would be great. I've got a few myself. Two for the 40' bus and one for the shorty.
They DO take up a bit of clearance, but if you haven't lifted the roof you should have plenty of room. I know you probably don't wanna go this route, just throwing it out there for those out there following along, lurking, or googling.

[CaptSquid]

ECB, I'm talking about venting when sitting still. Those do-dads you have would be great when moving, but I'm not moving.

[EastCoastCB]

Originally Posted by CaptSquid

ECB, I'm talking about venting when sitting still. Those do-dads you have would be great when moving, but I'm not moving.

They have low-amp motors driving fans in them. They're specifically made to cool the inside of an RV while its stopped, even in the rain.
But they CAN be used while moving, as well.

[warewolff]

Originally Posted by jazty

I don't have it installed right now, but I can assure you that it ain't anything sexy. Just a square chunk of 3/8" plywood with a hole cut out in the center and the fan screwed to the plywood. I'll be making something more permanent and pretty some time soon. It's near the top of the multi page to-do list

I'd like to see this too. Sounds very efficient.

[cadillackid]

radiator fans are highly inefficient and noisy... power consumption isnt part of their equation whemn designed... moving high volume of air at high static pressure is...

radiator fins (esp with an A/C comndensor in front) require a lot of static Push or ability to pull against a vacuum...

theres much better blade shape and motor type to use for moving volume of air at low pressure as is the case when ventilating..

-Christopher

[EastCoastCB]

https://www.youtube.com/watch?v=s8T0XOD2pHE

https://www.youtube.com/watch?v=m26tIbgy6TY

[jazty]

Man.. From $130 up to $360 for the fan.. The lower end of the price range isn't all that bad for having trim pieces and all. Best I can tell they pull 3 amps on high, which is also nice. It's a shame that the "Technical Information" section on the Fantastic Vents website doesn't actually have any technical information..

[EastCoastCB]

Originally Posted by jazty

Man.. From $130 up to $360 for the fan.. The lower end of the price range isn't all that bad for having trim pieces and all. Best I can tell they pull 3 amps on high, which is also nice. It's a shame that the "Technical Information" section on the Fantastic Vents website doesn't actually have any technical information..

The fantastic brand uses the least amps, by a good bit.
I got mine NIB for $50 each. Just watch ebay. Seller didn't know what they had!
I scored three of them.
On my folks' RV, the roof vent is one of the MOST used features.

[cadillackid]

im even thinking about changing my hatch to a fantastic roof vent... i could have a hhoiuse battery and on those hot days leave the fantastic turned on to pull the heat out.. so when I get in to drive my A/C has an easier time of it.. thats assuming that you can completely seal closed a fantastic when you are driving.

theres a ton of times when RVing that the roof vent would be of beneficial use..
-Christtopher

[Tango]

Somewhere I recall a description of what sounded like a clever venting installation. One pair of small computer fans drawing air in low...and another pair exhausting the roof. Low power usage and apparently a quicker exchange as the lower pair somewhat pressurized the space.

[jazty]

Originally Posted by EastCoastCB

I got mine NIB for $50 each. Just watch ebay. Seller didn't know what they had!

Holy schnitzel.. If I could score them for that price I would definitely jump on it. However, it's already hot enough to warrant running a fan and I'm not currently in a position to spend that chunk of change. The rad fan worked like a champ and with the PWM controller can be run very quietly. I'll be popping that son of a gun in soon.

I've been thinking about utilizing an unused Arduino to turn on and control the fan speed depending on the indoor and outdoor air temperature.

I see it working like this:
- Set a desired indoor temperature
- IF the interior air temp is higher than the desired temp AND the interior air temp is hotter or equal to the exterior air temp THEN turn on the fan.

That should work well for spring and fall.
It would also be nice to set an upper temperature threshold where the fan ignores the temperature delta and runs the fan on high to create a breeze, which would be nice for the summer.

Similar to what the $300+ Fantastic fans do...

[EastCoastCB]

Originally Posted by jazty

Holy schnitzel.. If I could score them for that price I would definitely jump on it. However, it's already hot enough to warrant running a fan and I'm not currently in a position to spend that chunk of change. The rad fan worked like a champ and with the PWM controller can be run very quietly. I'll be popping that son of a gun in soon.

I've been thinking about utilizing an unused Arduino to turn on and control the fan speed depending on the indoor and outdoor air temperature.

I see it working like this:
- Set a desired indoor temperature
- IF the interior air temp is higher than the desired temp AND the interior air temp is hotter or equal to the exterior air temp THEN turn on the fan.

That should work well for spring and fall.
It would also be nice to set an upper temperature threshold where the fan ignores the temperature delta and runs the fan on high to create a breeze, which would be nice for the summer.

Similar to what the $300+ Fantastic fans do...

FWIW the seller had more, so I posted a link on here for others. Another member snatched up the last one they had.
But they pop up from time to time like that.
The basic $120 model is pretty nice, and the trim ring coming with it is pretty cool.
I'm either going with a rooftop ac and one vent on my shorty, or two roof vents and a window unit in the rear. Probably the latter.
Fantastic sell the same vent without a fan or motor, just a static vent, for around $40. could add a small, efficient fan and probably save some money, just a thought.

[cadillackid]

can the vents be closed off and sealed when you want t osay run Air-COnditioning.. or like me in the great north in winter..
-Christopher

[dredman]

I will put in my plug for the fantastic fan - best $250 I have spent - but I got the DElux model - push a button for close/open, has a thermostat, and a rain sensor that closes the top (good thing too, now that it is mounted over my bed) push/pull directional, 3 speeds can pull all the heat out in a couple minutes.

[EastCoastCB]

Originally Posted by cadillackid

can the vents be closed off and sealed when you want t osay run Air-COnditioning.. or like me in the great north in winter..
-Christopher

Yeah they even have an easily replaceable gasket. they seal up well, especially when coupled with a rain cover.

[CaptSquid]

Originally Posted by cadillackid

can the vents be closed off and sealed when you want t osay run Air-COnditioning.. or like me in the great north in winter..
-Christopher

Winter? Ohio? Yeah, right! Son, you don't KNOW winter until you've survived the Great Plains winters.