Ram Promaster Forum banner

Window AC Unit Recommendation

78K views 169 replies 39 participants last post by  travelvanvan 
#1 ·
I have a small 5000 BTU window unit that I believe will run off my Yamaha 2000W inverter generator or shore power when available.... I just measured it at 16" in width. My original plan for quick-relief of a hot summer night was to make a plywood insert for driver or passenger front window and plop this baby in --- however, now that my ProMaster finally arrived from the dealership -- I measured the window opening and it's just over 15".

I did some quick internet shopping and haven't located a window unit that is under 16" width and am wondering if any of you folks have any leads for me.

Thank you.
 
#3 ·
#4 ·
Agree with RD. My experiment with single hose was a disaster. Portable units take up a lot of floor space. The hoses are big & have to be stored then attached to external vents so set up time is significant. The exhaust hose gets HOT and radiates all that heat inside.
 
#5 ·
I've seen videos of guys installing a window unit through a van's front window or other door window and it wasn't particularly fast or easy either. They have to rig all kinds of supports and seals to make it work. I'm not saying a hose or two are easy, but how can they be harder than a 40~50 pound A/C? I'd also be concerned about accidentally dropping it and/or scratching the interior or paint. Personally, I wouldn't want either.

Just glad my window unit is mounted permanently. :)
 
#6 ·
I installed a 5kbtu window air below one of the rear twin beds. 4" plumbing elbows provide the intake and exhaust air and the intake has a 150 cfm computer box fan to boost airflow. Seems to work quite well but that would depend on number of windows and insulation level. It is a Frigidaire FFRA0522R1 with remote. Open box at Best Buy was about $120.
 

Attachments

#7 ·
That's similar to my installation which has worked without a single issue for over 10 years now. Even if I had to replace it now it would cost very little.

Anyway, just noticed specs on your A/C show it only pulls 450 watts, and Frigidaire also lists an energy star unit that pulls 410 watts (presumably at rated conditions). At night I'd expect even lower power consumption.

With a small energy-efficient A/C like these I'm confident I could cool overnight from batteries -- would need only 4 kWh at most for 8 hours assuming 80% inverter and wiring efficiency. I figure 4 large or 8 medium batteries should about do it. Granted that's a lot of lead weight.
 
#8 ·
Looks great Wbullivant!!

Can I ask a few questions...

What is the small closed compartment in the box, to the left of the A/C used for ?

Do the plumbing elbows just exit through the floor?

And finally... did you have install a drain for the A/C for the condensation?

Thanks,
Tom
 
#9 ·
I would love to do this. Can you post more diagrams and photos so we all can get a better idea of what is going with the intake and exhaust including vehicle exits, etc.

Any draw backs to installing a setup like yours up near the ceiling vs floor?
 
#10 ·
I would love to do this. Can you post more diagrams and photos so we all can get a better idea of what is going with the intake and exhaust including vehicle exits, etc.

Any draw backs to installing a setup like yours up near the ceiling vs floor?
There shouldn't be as long as you meet the A/C's primary need that you get enough cool air flow over the condenser. My A/C has been on floor also but on new van I would install it higher for better placement.

It's hard to tell dimensions from pictures but I would allow more room around A/C for better cooling, particularly off the back. I did a lot of testing with different arrangements in garage prior to finalizing design, and ended up with 2 ports 4" in diameter and short as possible venting through floor.

And the most important thing of all is that you don't let warm exhaust off the back circulate back to the condenser's intake side. That will lead to overheating, poor performance, and failure.
 
#12 ·
#13 ·
wbullivant, This is an interesting and important alternative to roof air. Posting the pics on this site could insure they are always available. I can see how this could be modified for a side wall also. Do you have any performance experience to share? My intuition wonders if the single 4" in/out vents are adequate. Looks like doubling that to both sides would only add a few extra inches. Thanks for sharing.
 
#14 ·
Roblee
Subjectively I would say that the unit cools effectively but I'll get come temperature drop data (delta air return to output) when I have the opportunity to operate it for a longer period of time. It was somewhat challenging to find appropriate locations for having the 4" elbows go through the floor in the rear location I used. A side installation would give greater freedom but I ruled it out from an aesthetics standpoint. I think the most important issue is adequate airflow through the condenser and my Sythe DFS123812H-3000 case fan booster is quite effective yet uses about 8 watts. Even more powerful 120mm fans are available but noise db increase rapidly. The fan is barely audible in my installation.

With my 654 watt PV panels the 450 watt AC will run on a sunny day without taking energy from the battery pack (four 230 amp GCB's). At night I calculate about four hours of AC without going below 50% of pack capacity and allowing for my compressor frig and other minor draws. My guess is that a 5kbtu unit is not going to be adequate for most Promaster conversions. I have only rear windows and 3" of Polyiso foam in the walls, 1" in the floor, and 1.5" in the ceiling. Solar panels shade much of my roof. It may be feasible to build in a compact 8kbtu unit in a similar fashion.

So far we are quite happy with the performance of the AC installation. In our two previous RV's the roof AC was so loud we often used ear plugs. This installation is a significant improvement.
 
#16 ·
wbullivant,
If you hadn’t said it works I would never ever believed it would. This opens a huge opportunity for a really cheap AC under the bed. I have to get over the idea of drilling the holes but since I have several huge ones now for the windows and vent- why not? Thanks!
zwarte
I am sorry to hear this as I have been thinking of getting a small one to put in the van for camping in the hot of the south or summer.
 
#18 ·
Nice job making those fit tightly. Will you share more info? Like size of your van, number of windows, type of insulation, A/C capacity, where you store it while traveling, how it's powered (generator or campground?), etc. Mostly I'd love to hear how well it cools during the day if parked in sun.
 
#19 ·
Hi,
Don't mean to get off topic, but just wondering if this solution would work for some? Or, if anyone has tried it?

http://www.turbokool.com/

Its an evaporative cooler, so dry climates only -- not likely to work in Florida. But, in dry climates it provides a lot of cooling for very little power. It runs on 5 amps and 12 volts, so it would work fine with solar and batteries -- no shore power or generators needed.

RD posted a really "cool" DIY version of an evaporative cooler a little while back.

Gary
 
#20 ·
.....cut.... Or, if anyone has tried it? ....cut....
Not a small RV unit, but I installed a large evaporative cooling project in California at a manufacturing plant, and it definitely has its limits (which we knew going in). Normal air conditioning would have been way too expensive because of all the heat being generated in building so we compromised.

Like you say, it would work in dry desert-like conditions very well. In Florida, or along Gulf Coast, or even East Coast, I would personally not try it. The wet bulb temperature in these areas is often too high, and I'd also be concerned that the swamp cooler would make humidity too high in van to the point of supporting mold, mildew, etc.

My daughter lived in a small town near Death Valley and I recall seeing swamp coolers sold at hardware store. In that environment they would have been great -- in large part because they help humidify the air which was way too dry for me.
 
#21 ·
I have a Master-Cool evaporative unit on my home in AZ. It can make that 1600 sq ft house so cold you cannot stand it. We have it on a thermostat because if it runs on low all the time (which is normal for them) we have to put on a sweater even at near 100 outside. Dry is the secret. 4% humidity is not unusual there. If you want to try evaporative cooling in your van expect 10º delta and it does work well at even 50% humidity. See:
http://www.promasterforum.com/forum/showthread.php?t=50722
 
#26 ·
It does not mean that to me at all. That's not the way refrigeration works. I designed and installed a few custom 300- to 500-ton blast freezers so I know a thing or two about this subject.

Anyway, I apologize if I was critical of your design, but I was just trying to help you by pointing out weak areas in the design. More importantly, I was pointing these out so someone else without experience doesn't copy it too closely and create themselves a serious problem.

I get you and others may not want or appreciate my help so I'll stay out of your design entirely. Sometimes it appears there is no way to critique a design without hurting people's feelings because they take it personal.

Good luck. :)
 
#30 ·
Chance
I assure you no offense was intended. I related my experience my experience in operating the unit and gave my conclusions about use of the booster fan. I would appreciate hearing your conclusions and the logic behind them. Bill
 
#29 ·
A quick thought

It appears that to use a hose - equipped stand alone unit you need a good place to route the heat output hose so that the system works best.

Has anyone tried a square adapter plate over the Fantastic/Maxxair vent unit to suck the hot air out of the AC unit. Seems to me that if the fan speed was "synced" to the AC output fan speed, you wouldn't need to vent out a window, but could use the vent to remove the hot air.

Just wondering if it would work or if it's been tried...:nerd:
 
#31 · (Edited)
Any more on this sort of an instal is good to get here and since you two are doing it in a similar way by venting through the floor I would appreciate whatever more you know or have learned. I looked for conflict in rereading and I thought you both presented respectful details and no criticism. That is great in my mind. I tend to think the forced ventilation is a good thing and both cheap and low energy so it might be preferred.

proeddie,
Interesting. Moving the cooler air around the van is one issue and exhausting the hot air off the condenser is another. which are you thinking.
 
#33 ·
This is a fascinating thread, but somehow, wandering the boonies of Alaska . . . we're having a hard time warming-up to this discussion.
 
#34 ·
Dumb question: why draw outside air for the A/C intake? Wouldn't it be more efficient to draw air from in the cabin, like putting your car A/C on recycle (recirculate)? It seems counterintuitive to draw hot, humid air, but I bet you have a darn good reason, don't you?
 
#35 ·
Hi,
This has been a really interesting thread to me because I'm trying to decide on some sort of AC for the van. But, I don't want to get into needing shore power whenever I need the AC.

Our traveling is nearly always in the west, and if we did go down to the gulf or Florida it would be in the winter when no AC is probably needed. So, mostly dry conditions.


I'm still on the fence about using some type of evaporative cooler or something like a 5K BTU/hr window AC adapted to the van.

I've got a roll around evaporative cooler that we use for the house that does a good job for the few days of hot weather we get in Bozeman each summer. We have a couple days of 90F coming up, and I'm going to put it in the van in full sun and see what it does. The plan would be to put this between the driver and passenger seats with the cab windows and back windows all open some (as evap coolers like).

The evap cooler takes up some space and we would only take it along on hot trips, which would not be common for us. Its this one: https://www.amazon.com/Honeywell-CO...&sr=8-7&keywords=honeywell+evaporative+cooler

The one we have in hand runs on 175 watts, and with 95% inverter efic, this would be 16 amps, and adding 4 amps for other stuff would put us at 20 amps with AC running. So, going down to 20% SOC on our 220 AH batteries, we could get 9 hrs of night use. During the day the solar would keep with the load, and normally we would be driving and not even running the evap AC. So, that seems workable?

There are other evap coolers with less capacity that use much less than 175 watts (eg 50 watts), and this would also be a possibility if our large cooler seems like too much capacity. With a 50 watt cooler, we could go forever on batteries and solar.
https://www.sylvane.com/honeywell-cs071ae-evaporative-cooler.html

I'll report on how the test comes out.

Other possibility is to uses a 5 or 6K BTU/hr window AC unit. I've looked at some of the ways people have done this (Wbullvent, Chance, and Sonicsix plus some others on YouTube etc). The ones that actually replace (say) a back window seem likely to give the best performance, but I don't like the idea of the window mount. SonicSix's setup http://rvroadtrip.us/library/van_airconditioner.php seems like the most likely to give the full cooling performance of the window AC as it has a decent condenser cooling air input area, and a large condenser cooling exhaust area?? But he says that is did not cool well enough for him and he went to a larger portable unit -- I think he is in Alabama, so tough area for cooling.

Chance, sounds like yours is working well -- would you say its good or 90 or 95F dry conditions?

My rough calcs say that in the shade, my insulated van with the Reflectex plugs in the windows, and 95F ambient, the heat loss is 1600 BTU/hr plus 1500 BTU/hr gain from two people, dog, ... -- so, about 3000 BTU/hr. So, looks like a 5 or 6K unit would do it, but not with a lot of margin??
With my current battery setup, I'd only be able to get about 5 hrs, but that might be enough, or I could go to 4 golf cart batteries.

I'd appreciate any thoughts, advice, suggestions on which way we should go?

Thanks -- Gary
 
#36 ·
Just my random comments on using a 5k btu window units. I think people are under sizing the condenser air flow requirements. The condenser fan is about 9" and people are trying to get that air flow thru a 3 or 4 inch hole, you will need a leaf blower to get enough air flow. As the air temperature around the condenser increases the efficiency drops. If you measure the condenser intake area and exhaust area they are pretty close in size. It takes 4.25 - 4" holes to equal an 8 inch hole. Putting bug screen on the outlet reduces the "net free area" of the hole and increases back pressure. An a/c mounted on the floor will stratify the air in the van, a fan is needed.

I use a 5k unit spliced into the duct work of 2500 sqft home to avoid running my "about to fail at any moment" 2.5 ton a/c system.

Yes it runs continuously, but it's cheap and only uses 5 amps.
 
#38 ·
And yet mine has worked flawlessly for over 10 years. Go figure. :)


Agree it's not ideal to limit air flow but keep in mind portable units over twice as large in capacity often vent through a single long hose with much more restriction. It's obviously possible to make it work "good enough". Doesn't have to be perfect.
 
#39 ·
Chance,

I agree, i'm trying to narrow down the intake and output sizes.

I know the window unit condenser airflow is designed for the worst case scenario.

You have 25 sqin for the exhaust, what is the intake size?

I'm thinking 2 - 4" holes or a 6" hole maybe all that is necessary for the exhaust. Also pondering if a single 4" intake hole would work, since the cool intake can be less than the heated output.
 
#41 ·
Phil
I really don't have room for more holes through the floor of the van in my current location due to the spare & other stuff. My thought is that if much larger portable AC's get by with 4" ports, then they should be adequate for a 5kbtu unit. The gaps around my condenser intake and exhaust enclosure provide significantly more cross sectional area than the 4" ports so they shouldn't be significantly restricting airflow. I use a 120mm booster fan which has an flow opening greater than the 4" ports.. When I turn on the 130cfm booster I subjectively feel a much greater flow. Bill
 
#65 ·
RoadTrek Popular has a similar mount. Window A/C type unit mounted inside the fiberglas topper with louvers at the rear of the topper for venting.

No external unit to raise roof height or decrease aerodynamics. High mount still raises CG. We'd have to weld in louvers into the tops of our rear doors to do this.
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top