Bikersmurf
Expedition Leader
Add a radiator fan or similar and it’ll be better. The warmer it is the less efficient it’ll be.
SpecE450 - Red Cross ERV turned Racecar Tow Rig
- Thread starter 19Spec3
- Start date
PlethoraOfGuns
Adventurer
Sweet spot for the a/c! Also, where does all the condensation drip go?
19Spec3
Member
Yea, I suspect this is just phase 1. I'd prefer not to add a fan if at all possible but we'll see how it does. I'm always plugged into shore power so I'm not worried about power draw so long as the A/C unit is functional.
For now it just drips on top of the cab. Rain gets in there through a 2" gap all the way around so I'm not too worried about the condensation but it's definitely something to keep an eye on.
Oh, weird. I thought those fairings were sealed to the box. I think I saw a build where someone added storage space in that area, since it was sealed to the box? Looking at your pics I see the gap on the sides. Hey, that’ll help with the ventilation. Nice find on those louvered panels. Great to find that random ready made thing that also works for your application.
Rebuilder
Builder of Things That Interest Me
I turned mine into a storage area but I had to fill and seal up the gap. I like the storage area in mine but the A/C idea is great and I may have done it if I had thought of it.
19Spec3
Member
The A/C experiment failed. The weather was about 80F and sunny, fairly low humidity. I turned on the A/C and it started with nice cool air. Then I left for a race and returned in about an hour. When I got back, the interior of the box was warmer than outside air and the A/C unit was blowing ambient or warm air. I surmise that there is insufficient airflow behind the air dam -- no huge surprise there.
I think my next step is to add a fan to vent the air dam. I intend to place it on the small horizontal triangle just above the passenger door and just below the louvered vent I installed. It'll suck cool air in from below and blow it into the air dam in pretty close proximity to the A/C unit's heat exchanger. The best fan I have found thus far is made by Orion Fans and rated at 400CFM, 115v AC power, IP68, 65dB. If needed, I could also install a second fan on the driver's side.
Anybody have any thoughts about whether a single 400 CFM fan would be sufficient ventilation for my 6,000 BTU A/C unit??
I think my next step is to add a fan to vent the air dam. I intend to place it on the small horizontal triangle just above the passenger door and just below the louvered vent I installed. It'll suck cool air in from below and blow it into the air dam in pretty close proximity to the A/C unit's heat exchanger. The best fan I have found thus far is made by Orion Fans and rated at 400CFM, 115v AC power, IP68, 65dB. If needed, I could also install a second fan on the driver's side.
Anybody have any thoughts about whether a single 400 CFM fan would be sufficient ventilation for my 6,000 BTU A/C unit??
PlethoraOfGuns
Adventurer
Oh man, what a bummer! We're hopping whatever you do fixes the issue.
Something like the design of those in-room ac/cassette/mini split unit designs come to mind. Cool air intake from one side, and then the hot exhaust is ducted/pulled out of the other side of the dam. Maybe you can try the two fans first, with one pushing and one pulling, then if needed add some ducting to try and help direct the hot exhaust?
Bikersmurf
Expedition Leader
19Spec3
Member
That's the basic plan. Fabricating the ducting will be a PITA so I figure I'll throw some fan(s) at it first.
I certainly considered a 12v DC fan intended for automotive radiators and the like but, because I'm on shore power all the time with the A/C unit, I intend to use 115v AC fan(s). Also, the intended fan placement will accommodate a max of 7" diameter. So far as I can tell, about 400CFM is about the max I can out of a fan with those restrictions.
Bikersmurf
Expedition Leader
Figure out how many cubic feet there is, and crunch some numbers to determine how frequently the air is exchanged. 800 cfm keeps my ambulance box cool. 400 cfm would likely exchange the air in that area in 1/2 the time.
Fredricksen
Member
I have a 5000 btu window unit in one of the side compartments of my ambulance..
with the exhaust vented to the outside through vents in the door.
I found separating the area by the fan helps A LOT
That part of the a/c that usually hangs out of the window uses the fan to draw air over the condenser..
I just make sure cool air is drawn in.
I "split" the area in front of, and behind the condenser into a two parts (where the fan is)
with a piece foil faced polyiso (to partition the entire cabinet) so the hot air doesn't get recycled back through.
The exhaust fan pulls in cool air into one side of the ac , and the hot exhaust goes out the other..
Using my ugly art skills.. the purple is the inside wall
the red lines are the barrier wall made from the poly iso.
The space between the purple and red is the 'cool air intake' area
and the area to the rear of the a/c is the hot exhaust
As long as I put cool, fresh air into the middle space, the a/c works great
hope that makes a little bit of sense..
with the exhaust vented to the outside through vents in the door.
I found separating the area by the fan helps A LOT
That part of the a/c that usually hangs out of the window uses the fan to draw air over the condenser..
I just make sure cool air is drawn in.
I "split" the area in front of, and behind the condenser into a two parts (where the fan is)
with a piece foil faced polyiso (to partition the entire cabinet) so the hot air doesn't get recycled back through.
The exhaust fan pulls in cool air into one side of the ac , and the hot exhaust goes out the other..
Using my ugly art skills.. the purple is the inside wall
the red lines are the barrier wall made from the poly iso.
The space between the purple and red is the 'cool air intake' area
and the area to the rear of the a/c is the hot exhaust
As long as I put cool, fresh air into the middle space, the a/c works great
hope that makes a little bit of sense..
qcdstick
Member
Looking like a nice setup!
I, like Federiksen here, also went with a window unit in an exterior cabinet, and found the performance to be sub-par. Even with this amount of open air around the unit, it tends to re-breathe a lot of its own exhaust and performance suffers. Works fine at first, or on moderately warm days, but gets less effective as it really has to work hard. The issue is obviously compounded 10 fold with the setup you have. I think it's going to take a lot of fan to exchange air in there enough to keep it cool enough to work well, baffling would help a ton if you can isolate the hot and cold sides to different vents.
My AC unit can intake air from above, or from the sides (just one side now as installed), and exhausts straight out the back through the condenser. I'm planning to add some baffles to direct the hot exhaust out of the compartment, which I hope will mean mostly "fresh" cool air makes it into the unit vs recycling the same air within the compartment. Next time we have a hot day, I plan to do some experimenting with folded cardboard just to try some ideas. Will report back.
Note: I have the compartment door open when the AC is on
I, like Federiksen here, also went with a window unit in an exterior cabinet, and found the performance to be sub-par. Even with this amount of open air around the unit, it tends to re-breathe a lot of its own exhaust and performance suffers. Works fine at first, or on moderately warm days, but gets less effective as it really has to work hard. The issue is obviously compounded 10 fold with the setup you have. I think it's going to take a lot of fan to exchange air in there enough to keep it cool enough to work well, baffling would help a ton if you can isolate the hot and cold sides to different vents.
My AC unit can intake air from above, or from the sides (just one side now as installed), and exhausts straight out the back through the condenser. I'm planning to add some baffles to direct the hot exhaust out of the compartment, which I hope will mean mostly "fresh" cool air makes it into the unit vs recycling the same air within the compartment. Next time we have a hot day, I plan to do some experimenting with folded cardboard just to try some ideas. Will report back.
Note: I have the compartment door open when the AC is on
Fredricksen
Member
@qcdstick you could do pretty much the same thing I did.. (except my unit is rotated 90* )
Put a partition on the that left side of the a/c, (separating the intake & exhaust) so it can draw air from the area below.. where that blue flashlight is.. and maybe extend a partition where that wooden shelf is it doesn't re-breath hot air.
The difference is notable.
Once the box gets to a comfortable temperature..
I can set the fan down to low, and put it in 'eco' mode, and it stays cool.
Put a partition on the that left side of the a/c, (separating the intake & exhaust) so it can draw air from the area below.. where that blue flashlight is.. and maybe extend a partition where that wooden shelf is it doesn't re-breath hot air.
The difference is notable.
Once the box gets to a comfortable temperature..
I can set the fan down to low, and put it in 'eco' mode, and it stays cool.