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Ventilation - AC vs powered vent fans vs ??


KGordon

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My new to me '87 Mini-Cruiser "Mosey", does not have any powered ventilation or a generator.   The folks I bought it from kept the roof vent clear and mounted a portable AC unit on one of the seats (it vents out the window and drains to the outside through the bottom of the rig).  That's not a long-term solution for us, so I am researching alternatives.  We live in northern New Jersey and our house is not air conditioned, I keep the house cool with fans and light control, and I'm not a fan of sleeping in AC.  On the other hand, we don't want to fry, and we'd like to be able to safely leave our terrier mutt in the rig if we have to run into a store or some such.  I'm wondering if solar powered vent fans would make more sense than a heavy AC that needs shore power or a generator to run.  Thoughts and recommendations will be much appreciated. 

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What you have will make a bubble of cold air in the vicinity, but it is drawing in ambient air from the outside that is equal to the hot air going out the vent so its not really efficient. A couple  or three choices.

1.Use what you have.  2. Same idea but get a newer 2 hose roll around, it will use less power and make more cold air in the rv. 3. Linda the moderator here made her own version of the 2 hose. The unit sits between the seats when running. A window cut out with the vent hose attached that goes in a cab door window AND (important) she has a curtain that hangs down from the overhead bunk that seals the hot side of the ac from the cold. The needed air is drawn in from the other window. The result is a hot cab and a cold rv. Cheap you have most of the pieces already,  it works, and in moderate weather leave the AC home.

A vent fan can NEVER lower the inside temp any cooler than the outside temp. In most cases not even that as there is a lot of solar heat gain from the sun in an RV. If you drive with out AC and your critter is OK with just the breeze, then a good roof vent fan and a table fan should work.  

Using Reflectix  on the windows will greatly reduce the heat gain from the windows. https://www.reflectixinc.com/products/double-reflective-insulation/   Get it at your local big box lumber store.

Most of the "solar" power vent fans are lame and don't really move enough air. But some thing like a Fan-Tastic Fan will do nicely. Add a 100w solar panel set up and a good house battery and it will run all day.  http://www.fantasticvent.com/index.html There are other mfgs to look at but you get the idea compare amps, CFM and $$$. Get one that is reverse able.

 

 

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Thanks for that!  Actually I was wondering about relocating the current unit from the dinette to the area between the cab seats.  I would need to make a stand for it that contains some kind of catch basin for the condensation, but that shouldn't be too difficult!   The rig already has Reflectix on the front cab over windows and a gray tinting film on all of the coach windows.  Both probably need cleaning and refreshing, but that's fairly straightforward.   And I like the idea of a solar panel to run a Fantasticvent and otherwise trickle charge the battery.  But relocating the AC, which apparently does a good job of cooling the coach in its present location would be simple and effective.  Can't wait for my mechanic to finish replacing the tires and doing the other necessary maintenance jobs so I can start to play!

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1 hour ago, KGordon said:

Can't wait for my mechanic to finish replacing the tires and doing the other necessary maintenance jobs so I can start to play!

It might be worth giving your mechanic a quick call and warn him that there's a good chance that the lug nuts on the left rear rims are 'Left hand thread'. If he doesn't know what that means, you might want to find another mechanic. :)

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Thanks for the tip....and I'm sure he'll know what that means.  His specialty is restoring quirky old cars and trucks.

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A roof mount in the vent hole is the best AC. I think $500 or so though. Most likely there is 120v power hidden in the vent edge. For ventilation vent fans my preference is a variable speed one. I find the three speed fans too noisy on low and it is always nice to pull in some quiet cool air in the evening. If there is no 12dc power in the vent hole you might be able to pull some power from a nearby light fixture.

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The main vent is wired for a 120v air conditioner, so if I were to use that opening for a 12v fan I'd have to run wires from a nearby light or some such.  In an idea world, I'd love both.  AC for stinky hot weather and a fan for nice cool evenings. 

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If your going to keep your roll around AC and use it up front, then put the 12v vent fan in the main vent. Use the 110c ac wires to carry the 12v for the fan. The 110v wires should go to a junction box in one of the overhead cabinets. Just disconnect the wires there and a short jumper to one of the cabinet lights and poof :sorcerer: you have 12v to the main vent.

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3 hours ago, WME said:

If your going to keep your roll around AC and use it up front, then put the 12v vent fan in the main vent. Use the 110c ac wires to carry the 12v for the fan. The 110v wires should go to a junction box in one of the overhead cabinets. Just disconnect the wires there and a short jumper to one of the cabinet lights and poof :sorcerer: you have 12v to the main vent.

I don't have any junction boxes in my Sunrader. All wires go right to power center. Hmm. My 12 volt overhead fan is connected to ceiling  light fixture only 18 inches away. Wire is not noticeable at all. Oh and I don't know how heavy that AC unit is but I only put mine in the camper when needed. Not always hot and nice to have more room. Mine weighs about 50lbs

Linda S

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OK no junction box, still got to get the wire from the vent to the power panel. Is it glassed into the wall or is it exposed and hid in a cabinet. You could always unhook it it from the CB in the power panel and jumper it over to the 12v side of things.  

JUST MAKE SURE YOUR NOT PLUGGED INTO SHORE POWER when you go messing around

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2 hours ago, WME said:

OK no junction box, still got to get the wire from the vent to the power panel. Is it glassed into the wall or is it exposed and hid in a cabinet. You could always unhook it it from the CB in the power panel and jumper it over to the 12v side of things.  

JUST MAKE SURE YOUR NOT PLUGGED INTO SHORE POWER when you go messing around

Nope I'm fine with my wire along the ceiling to the light fixture. Been that way almost since I got my camper and never had to do a thing to it

Linda S

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51 minutes ago, linda s said:

Nope I'm fine with my wire along the ceiling to the light fixture. Been that way almost since I got my camper and never had to do a thing to it

Linda S

I agree not the best thing to using 120 wiring for 12 volts tends to confuse things. I put a Fantastic fan in my tow behind and that works OK for me.

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I do have a cabinet mounted junction box labeled AC, but I think I'd like to keep the 12v and 110 clearly differentiated.  A bit of tidy channel on the ceiling sounds like the way to go.  I'll have to weigh the unit when my mechanic's done playing with her.  Since I still work a few days a week, we'll mostly be taking short trips....easy to see whether the weather calls for AC.  

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impretty sure the portable AC unit is exhausting air out that dryer hose, WME not drawing air. While not Ideal, I would also advise a roof unit if you have a dog; otherwise you are basically at risk of violating laws depending on the state you are in. In New Jersey for example it is not only illegal to drive without having your dog seat belted, its also illegal to leave him in the vehicle unattended in non-AC and other "cruel" situations... That and a couple other reasons are why I avoid that state, run a high efficiency roof unit and have a 2500 watt inverter generator strapped to the rear bumper.

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Vent fans work great as long as the humidity is not real high. Camping is what it is, camping. If you can't stand the heat stay out of the woods! I have gotten up on really hot nights and turned on the showers cold water and gone back to bed.  

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4 hours ago, Totem said:

impretty sure the portable AC unit is exhausting air out that dryer hose, WME not drawing air.

Yes the portable AC is exhausting the hot air out the hose. BUT where is all that air coming from? Its coming from inside the coach and because the coach doesn't collapse from the vacuum there is replacement air coming into the coach and that is ambient (hot) from the outside.

That's why the new high effiency roll arounds have 2 hoses going to the window. One hose is hot out and the other is ambient air in, that way the unit works just like a window mount and is just as efficient.

http://www.air-conditioner-home.com/dual-hose-pacs/

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So if I decide to spring for a roof mounted AC in the pre-wired main vent, can I also have a fantasticvent fan on another part of the roof, and if so where?  Replacing the bathroom vent, replacing the useless crank-up antenna?

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The fantastic fan will fit in the bath room anything, else means you saw a 14x14 hole in the roof.

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Great!  Maybe I'll start there, then gradually upgrade.  Big money this year is going for tires, roof reseal, propane/CO alarm and other critical safety stuff.

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I've seen folks add another 14" hole directly over the over cab bed in many rigs to add an additional fantastic but keep roof AC. seemed to be very prevalent on midwest toyota rally dolphin folks rigs if memory serves.

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If you have a Fansastic fan anywhere all you need to do is open one of the side windows in the cabover. Most of the cabover vents I've seen are factory installs

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My mini-cruiser is not so lavishly outfitted.  One 14" vent in the main ceiling just aft of the cab over.  It is wired with 120v for AC.  Another small round vent in the bath, that seems to be powered but I need to take it apart to clean and investigate further.  And that's it.  So at the very least a fantasticvent is in order somewhere!

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Edited by KGordon
Added pic of bathroom vent.
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If upgrading a 12 volt fan I can't suggest a better one than the Maxx fan vent. Mine is still working fine after at least 12 years and the rain guard is incorporated into the design so no thing sticking up on your roof when your not using it. I hate seeing those rain guards. Yes it cost more than a regular fan but add the cost of the rain guard and not that much. In out 4 speeds and quiet

https://www.etrailer.com/RV-Vents-and-Fans/MaxxAir/MA00-06401K.html?feed=npn&gclid=CKKFnuXhr9MCFUGRfgodpoEEwA

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Looks like your going to be putting your new powered vent in the AC hole. Hopefully you can get the bathroom fan going, it doesn't look like anything Ive seen recently, so a replacement is going to a problem. Unless Derek can rummage around the net and find one.

 

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I like the look of that fan with the built in rain protection.  I'm wondering if the place to put it isn't over the dinette, since I still have a crank up antenna that should probably be removed before it causes problems.  Instead of patching the hole, enlarge it and insert a fan.  That would leave the 120 v wired main vent available for an AC.   I was thinking of removing the antenna as part of the roof job anyway.  The historian in me likes things original...but not at the expense of safety and utility.

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Only one 14" vent, wired for AC, but with nothing in it and the little round "mystery" vent in the bath that will require further investigation and cleaning when I bring her home from my mechanic's (she's getting new tires, new rear springs, and lots of new belts, hoses, fluids etc.).  So my thinking is to let the existing 14" vent await an AC, figure out what's up with the bathroom vent, and pull the crank up antenna and install a Maxxair 12v fan in the hole that I can use when 120 v shore power is not available.  That can all be done before I reseal the roof, which is a priority.  AC and 12v solar power would come later.

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I recently purchased the new MaxAir 7000K to install where my old noisy bathroom fan is located. Excellent fan! Has a shroud that raises and lowers automatically. Camping World has it for $450....ridiculous price but I found a RV dealer on eBay that had them for $179 no tax and free shipping! Even comes with a remote. 

Edited by markwilliam1
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Cutting a hole for a vent is not just cutting a hole. The vent holes are framed in with the roof rafters. Look close and see if you can get at least one side of your frame  screwed to a rafter.

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