Two A/C questions

[2bits]

I have two questions about A/C window units, I am doing the indoor version that is like this one below: (Thanks to the original builder )





Firstly, I *think* I understand the concept of recirculating in air from the cabin to trick the unit into thinking it hasn't done all it's job yet so it will continue to run so it fully dehumidifies the air. I am just wanting a little clarification on the front area on the interior of the unit where the filter is. Isn't this an air intake? It seems pretty obvious that is would be, but then it appears that there are two air intakes, one on the front, and the ones "outside" on the side. Is this correct? I'm just a little cloudy on the details there. My design is moving the interior vent from the floor mount as in the pic, to two small vents on either side of the wall on each side of the unit.

Secondly, does anyone have a source (local boat shop??) for those chrome boat vents? They look good and I want to use those for the outside air inlet on the side of the tear so I will only have to cut the exhaust hole in the floor.

Thanks! !

[asianflava]

There are 2 heat exhancers on an a/c unit. Put simpily: one makes room air cold (evaporator) the other makes outsite air hotter (condenser).

Yes, there are 2 intakes (inside front and outside sides) and 2 exhausts (a/c vent and rear of unit).

From the pics you posted, it looks like the condenser exhausts out the back and enters from the bottom. Probably has an added benefit of allowing condensation to drip to the ground.

As for the vents, you can check Boater's World or West Marine. They have brick and mortar stores as well as a online store.

[Mark Freedom]

Looks to me that the one pictured will overheat and cause it to fail prematurely.[/img]

[Mark Freedom]

Let me clarify, I meant the one in the install picture not the pic I provided

On the sides it vents in to cool the coils, and on the back vents out the hot air.

What you want to look for in an AC unit is one that is thermostatically controlled so you can set it to a temp that will allow it to cycle properly, unlike manual units that you basically set fan speeds instead of an actual temperature.

[asianflava]

Looks to me that the one pictured will overheat and cause it to fail prematurely.

Not really, the bottom of the unit is open to the outside. The consdenser intake is drawn from underneath, the sides of the unit appear to be a few inches from the walls of it's cubby hole. The condenser is exausted out the back.

There should be some kind of separator to prevent the hot exhaust from being drawn back into the condenser intake IMHO.

On the other hand, how many days a year does the unit get used? In my case, it probably gets used a dozen days a year. Even at a quarter of it's expected life expectancy, it should still last several years. The problem is, it will probably die at the worst possible time.

[aggie79]

I'm looking to use a vent one made by Attwood in my build. I think this is the same one Sonetpro used. Here is a link:
http://www.boatbandit.com/louvered-vent--stainless-steel-5612.aspx

[2bits]

I was going to put the side intake vents on the side of the tear which keeps the intake away from the exhaust, inside around the unit will be five inches open on the top and both sides. Also, there would be two vents coming from the cabin that would enter into this same space. There would be a separator just as shown in the first pic so as to isolate the exhaust and I will install a bathroom vent to aid in the exit of the exhaust, as well as a drain pan and tube going out that same hole My setup will basically be the same as his (Woody? Please forgive me I downloaded the pics but did not note who's they were), except the outside air will come in from the side, and the cabin vent will be relocated to the bulkhead as the mattress will meet the A/C (The A/C will not be below the mattress line though).

That pic you posted is awesome thank you so much for that Mark! I already have a 5000btu unit purchased too. I like that the vents point UP. Here's some pics, I am not going to do the upper cold air vent in the cabin like the plans show, I decided I'm just gonna let it go naturally out of the unit because I didn't like how it was going to look with the attachment, but here ya go:

[Mark Freedom]

Looks like you have the plan Thomas, that's very similar to the way I have my install planned.
I have to get my house sold before I can begin my build, I'm going to move from Idaho to Georgia and there's no way I could haul it if I built now.
I have a 26 foot Travel trailer at the moment, but want something more gas friendly to drag around.

I see on the box your AC has a thermostat, so I'm betting you'll be in hog heaven once it all said and done.

[2bits]

I just picked up a chrome louvered vent exactly like what I was looking for from Keith a member here. Here is his teardrop and a pic of a vent like what I got:



Another big bonus was to get to see my first homebuilt teardrop today! I was very excited about that and it was good to meet you too Keith, we live very close to each other so that is cool too. It was good to see that project because it is so similar to the one I am doing.

[john]

The pics are of my build. I had a couple of goals. One was to fully hide my AC for aesthetic reasons. Secondly I wanted to avoid cutting a hole in my roof for a vent to better keep water out.

The floor vent in front if the AC on the raised floor was an attempt to draw fresh air into the tear. The vent can be opened or closed. Under that vent is the area where the AC sucks in exterior air from under the trailer to blow across it's condenser. As such it is a low pressure area. My goal was to use this low pressure to vent the tear. I could turn the compressor part of the AC off but leave the fan part on to draw air out of the trailer through the floor vent and eventually out the back of the AC and cool air in through the windows.

Also when the AC was totally on (compressor pumping) the vent could be opened to draw a little fresh air in while the AC blows cold. At the time I was concerned that we (we sleep five in the thing) would use up the oxygen in the cabin while asleep.

Lastly, it could be used to trick the AC into not cycling as much. By drawing in a little fresh air.

Results:
It works as a vent (compressor off) if I have only two people in the tear. The flow out of the floor vent is too low to cool the tear if there are more than two people inside. I have a trick to fix this problem.

It also draws a O2 in when I have the compressor running on the AC but I am not sure O2 depletion is a problem.



For the AC to work best as a simple vent I would have to be able to cut the flow of air in from under the trailer so that the only way for the air to get to the AC would be through the floor vent. I plan to add a flap at the air intake under the trailer to do this. This would make using the AC as a simple vent more efficient.

As for overheating I have had no problems. The intake and exhaust are separated. What is not shown in the pics is that the hot air exiting the AC is directed away from the intake and toward my wife's feet as she cooks. This has the effect of drawing in cool air from elsewhere under the trailer to be pulled in by the AC.





Edit: I just took a closer look at 2bits' sketches above. I wasn't brave enough to use interior air for cooling the condenser. I see no reason not to, though, and it may help with premature cycling. My one floor vent was a baby step toward 2bit's two vents on either side of the AC.

[2bits]

Hi John,

Thanks for replying, I thank you very much for posting your build pics as they have really helped me come up with a solution to my own issues and it also led me to the issue of the A/C cycling off too soon, which I would hate to have to experience after the thing is built! I am impressed that something you you designed would be considered a baby step of my working off that idea! Great minds eh!

[Mark Freedom]

When I made my comment above about it overheating, I didn't realize it could get air to the side intakes.
I thought it would probably strain the compressor to the point of meltdown, much like one does when they get clogged up with dirt.

[2bits]

Yeah Mark, sorry about that, I just posted a couple of John's pics and you didn't get to see these other ones with the hole in the floor he had built for air intake on his, so your thinking was right on without them. Gotta make sure that air can get in, and air can get out, and most importantly that it isn't the same air! I noticed that was a big topic when I want to the A-Z index in General Discussion. I use that sticky as my guidelines of knowledge. Can't wait to see how mine turns out haha

[Mark Freedom]

Your design is the closest that I've seen to my plan.
I plan my intakes to vent up to the side right below where the hatch is just back from and below the hinge on the side, so it pulls in clean fresh air, and then the out vent will be in the floor run into a box and out through a floor register.
I was going to use a round 4 or 5 inch stainless vent on each side like
this one that west carries, and then just a regular house type floor vent on the exhaust.

[2bits]

Yup, that's pretty much the same as what I plan to do! On the cabin vent, I am going to use a vent that will close, as that would create a nice little draft in the winter.

Those vent covers you found are quite a deal at $3.99! Good find! I got this one from Keith for $5. It needs some cleaning up and one ding taken out, but it is the exact one I wanted and just my price!



Looking forward to seeing your build come to shape!