My 2013 Tacoma Access Cab Chinook build in progress

There will be a 4" duct on the fan that will run parallel to the drain tube so the cool intake air and hot exhaust air can not mix..the hot air exits at the bottom of the chase..... the units internal coil cooling fan draws in the fresh air from the vent or the open botyomed chase so no intake restriction is possible and cools the coils... my duct exhaust fan will insure that there is no heat build up as it pulls air from the hot coils at the same time. A fan pushing and a fan pulling at the same time...
As a bonus Scott, even though I positioned the louver below the unit in the Chase (so driving rain could drain to the ground instead of sit in the sealed intake air chamber) I can reach the drain from outside. And yes the foiled area is a chase with a removable insulated panel that is the back wall of my tiny closet. I need to be able to remove it to service the fan, drain tube and tail light. It will all get finished with glue on grey felt. The floor below is removable to service the generator. ...
Are you a HVAC guy Scott? Look at this link. I would love your thoughts ... I think I am covered on air flow..

http://www.buildagreenrv.com/window-air-conditioner-to-cool-an-rv/

 

I figured that 4" just wasnt finished yet. Sorry, not hvac but enough construction experience to recognize what I'm looking at and decent math proficiency. There are some differences in his test, mainly the size of the fan and the fact that his is on the inlet and yours is on the exhaust. In his second test using a fan it was a 9" model to get 800+ cfm and up to 4- 4" vent holes. will your 4" fan in 1-4" vent equal 1/2 that to be comparable on your 5000 btu unit? Probably need a 6" fan/duct combo to have similar reasults. Just going by crosss sectional area of a 9" circle vs 6". A 9" circle is 63+ sq in, a 6" circle 28+ sq in, and a 4" only 12+ sq in. I can't really tell from the pics how the intake air reaches the unit but regardless of vent size the smallest cross section in the chase or where it reaches the unit will be the pinch point on the intake. Any way you can steal 2" more from the closet to cram a 6-7" fan/duct in there? It seems the exhaust is the bigger issue.

 

Thanks for your thoughts Scott!.. l will report on how my set up works out..,space planning in such a tiny space has been difficult to say the least.... my thinking are that medium volume air flow is all that is needed on my tiny unit. The internal fan is very low volume. The test using the high CFM fan used by the guy in the link is a bit moot because he has no restriction on the exhaust side. Open back. My theory allows for air to flow in while sucking the hot air out. My auxiliary fan pulls more volumn than the internal fan pushes therfore, in an unrestricted sealed system, the volume of cool fresh air passing over the hot coils and then being removed from the unit can not be less than a unit installed as intended (in theory! )....

 

I enjoy the process of brainstorming so the invitation to "share my thoughts" was irresistable. My reccomendation is based on what i inferred from comparing his testing to your 1/2 size unit. I hope it works to your expectation and delight. One thing I recall from the few duct installs I have done is that fan flow rates go down with duct length and even more so with any elbows. 3-4' will be a little but a single 90 elbow can act like 20-30'. Also, use smooth pipe instead of corrigated or flex and duct tape instead of screws. It's great seeing you do all this creative work to bring this classic back to life.

 

Just wow... This is pretty awesome OP.

 

Thanks Tom!

 

Thank you Scott! It is sure nice having you think this through with me... I ran the AC in place today with some temporary foam partitions separating the intake and exhaust. Granted it was not a perfectly sealed test, but I think I need more airflow. I am going to see if a HVAC friend will look at it with me as well... I want to get it right and not fool with it down the road.

 

I got a bunch of stuff done today despite my lack of confidence in my AC venting... I will get some advise and look into higher volume fans..l to be continued...
I dressed out my closet floor/removable generator hatch with pergo flooring and made some of the transition trim pieces that needed to happen before I button up the wall coverings.
The electric is getting ready to happen... I have thought it all through pretty well. My friend Paul gave me some sexy slim line little flat brushed aluminum puck lights with a dimmer that were left over from a cruise ship installation. I also have a pair of 12 volt fans. A boat captain old friend is helping me with the wiring and has contributed a bunch of wiring and electrical odds and ends...

 

I love using marine wiring for campers. marine 12/2 (looks like 2-wire romex, but with red/black insulation and tinned stranded wire) is my defacto stuff for most DC circuits up to around 20 amps (or even 30 amps if its a short run). of course, battery main cables to the power converter/center need to be heavier gauge. and marine 12/3 is what I use for the AC circuit side (again looks like romex, but has black/white/green insulated tinned stranded wires).

 

That's the plan John. All marine wiring with soldered connections just like a boat. My electric plan is really simple.
Pretty much lights, fans, charging station and fridge (3 way) on the12 volt side.... shore power to house battery charging, fridge, AC and vent fan, microwave, tv/roku and an outlet or two. I will have a circuit from the 3.5 kw generator that the shore power will plug into to power off the gen set...no switch or possibility of getting current from shore power and generator simultaneously. ... Then I am extending the factory 100/400 120 volt inverter outlet to the galley so I can use a crock pot while rolling.

 

I have the air conditioning cabinet finalised I hope... I installed a pair of 4"x8" grills on the intake side side. It wil, supplement the outside fresh air with some interior air. Then on the exhaust side (hot air from the coil side), I installed a 4"x12" grate to the exterior and sourced a 220 CFM 4" duct fan...i reworked the condensation tray to the back of the enclosure so if any water was to enter the AC enclosure it will be able to drain out the condensate tube...... I think it will have plenty of ventilation on both sides. I won't have the fan until Tuesday to test it though...

I also installed the Tough Country add a leaf kit today. It feels awesome with the airbags at 50 psi!

 

I got the 120 volt electric roughed in today. Painted shallow switch/ outlet boxes grey and got them in position but loose. All the wiring is a stranded 3 wire romex type marine wiring...
I am using the old copper coil power distribution box from Chinool...shore power in, a single 15 amp breaker plus a step down 12 volt transformer... pretty bullet proof. When I am out of the country I will have another voltage converter. 240 volt to 120 as needed...feels good to get this portion started...
And the add a leaf was a HUGE asset! It feels great. I dropped the air bag pressure down to 40 lbs,

 

Continued with the wiring today. I extended the factory 100/400 watt inverter harness and the wiring harness for the generator... soldered and shrink tubed the ran through plastic wiring corrugated tubing...
I also started pulling wires for the 12 volt system... I will have bus bars under the benches on both sides to wire to for lights, fan, fridge, charging station etc...
I have a pair of #12 wires in position that will run from the house battery as a main feed. There will be a switch that I will be able to select 12 volt from the house battery when off grid or I will have12 volts off the inverter if plugged in to shore power or if the generator is running.
I will be charging the house battery off a battery tender that will be powered by the trucks factory 120 volt inverter... I have opted to keep the trucks battery and charging system completely isolated from the house 12 volt system.

 

How much current have you figured for the max on the #12 feed?

 

Hey Scott... very low draw and short runs on the 12 volt side.. maybe 7 Amps with LED lights, fan and fridge..charging station., tiny demand water pump.. i was originally planning on connecting the 2 batteries with a meaty cably and switch. My plan to keep the 2 batteries seperate really simplified my electric job...

 

Sounds like you have it under control. My compressor takes 30A and the run is over 10' each way (grounded to a buss near the battery rather than the frame) so instead of a mix of several different awg's I just run #10 for any power over 3A and #18 for the rest. Overkill but I got a deal on 100' of #10 TXL.

 

I wanted to position bus bars for convenient wiring for my few camper amenities... it will be easy to expand if I have any higher amp needs in the future...either directly to the house battery or the truck battery. I also still have the option to connect the 2 and create a 2 battery system. Starting out simple!

 

I am picking away at the wiring...while it is a pretty simple system (or systems really!) It is a big job. All the 120 volt is roughed in and ready to be secured and to have the outlets and switches installed... I have the power distribution panel for the generator wired. I have added an outlet in the shore power storage compartment. The cord will simply plug in to run the system off of the generator instead of an outside source...
I have rethought keeping the 2 batteries seperate. There are too many advantages to linking them. House battery charging, boost starting etc. I bought a marine add a battery kit that has a battery switch and charging relay isolator. I will probably connect the batteries with a #6 wire. I need to verify the amp draw on the truck starter before I make the call... I have a 12 volt fuse and rocker switch panel that will mount on the front of the passenger side bench with the battery switches.
Also the wiring for the factory inverter has been extended for an outlet in the galley so we can have a crackpot cooking while we are rolling.

 

The longer a project goes, the more times I'll chang my mind. I think that bothers some but not me. Looking good.

 

I can not tell you how many changes I have made. That is the problem with designing on the fly. I go to bed with a design problem and work it out in my sleep... what a luxury it would have been to have an engineered blueprint to work with from the beginning...but I did not know what I was building really! Evolution of a project....