Dual A/C's - Trying to Keep Cool In Texas

[smiller]

Originally Posted by allentx1

We had the custom made solar screens that snap on the outside put on.

Can you let us know where you got those? I hate fussing with the inside stuff.

[Bob Landry]

The 20 degree temperature difference often referenced is the difference between the return air inside the trailer and the discharge air from the registers, also refered to by people in the A/C business as the "split across the coil". it has nothing to do with ambient(outside) temperature. The outside temp does have some effect in the sense that you are absorbing heat through the skin of the trailer, but it is not used for any type of quantitative measurement or equipment performance calculations. If the trailer is 100 degrees when you turn your AC on, you are going to get 80 degree air at startup. That's not encouraging, but it is what it is. As the trailer cools, you will also see a reduction in discharge air temp, but at any rate, the best you are going to see is a 18-20 degree split if all is working as it should.
You will get maximum efficiency from your units by keeping the filters and coils cleaned, and taping leaks where the ducting is leaking cold air into the roof where it does you no good at all.

[Petlover]

I have a 3750fl with slide toppers and it still gets very hot in the front room. I am considering tinting the windows in the entire camper. The choices are the dark gray for autos or the bronze used in homes (which reflects 75% of the sunlight and heat.)

Has anyone tinted their windows to reduce the heat?

Petlover

[Me.Bikes.Dogs]

I got tint a week ago but haven't installed it yet. I'll let you know how it goes.

[Petlover]

Thanks, I would appreciate it.

Petlover

Having a mostly black 3750fl Big Sky edition in the 100+ temps of California with both AC's running I too managed low 80's. The owners manual says at best the units will exchange 20 degrees. Finding shade helps the most, but in my opinion slide toppers help some because the sun is not hitting directly on the top. I have em. I'm not ambitious enough to put foil in already tinted privacy windows with shades although I know that too works real well.

[Brebre]

We recently bought a 2013 Dodge 3500. When we went to get our windows tinted at the same place that we have, he asked us if we knew about ceramic tint. He had a homemade box with a sunlamps to show us the difference. I mean the way it cut the heat was unreal. After having it our truck for about a month in August (Louisiana) I decided to see about outin it on my Fuzion 395 toy hauler on all windows except the garage. I don't have to keep my night shades down anymore. It's keeping our unit about 10 degrees cooler too.

[Bob Landry]

The comments about the difference between outside and inside temps are irrelevant. There is no quantitative measurement that will tell you what the inside temperature should be based on outside temperature.The 20 degree difference that people like to reference is the temperature difference between the discharge and return air, also referred to as Delta T. An 18-20 degree split indicates the unit is properly charged and properly sized fpr the space you want to cool. A technician can easily determine proper charge by measuring the current draw of the compressor, but that's a topic for another thread. For the purpose of this one, there are some things you can do to improve cooling. First drop the lower cover and make sure the plenum feeding the ducts is properly taped. That is the biggest shortfall with Keystone air conditioner installations. Put your hand up in the return air chamber. You should not feel cold air being sucked in from the evaporator blower. If you do, retape it. Pull the ceiling registers off and make sure the ducts are sealed where the holes were cut for the registers. If they are not properly taped, you are losing cold air into the ceiling where it is doing you no good.

Finally, the more heat you can reject, the less you have to remove. There are many widow treatments such as tint film, foil faced insulation. heat blinds and probably many that I have not heard of. all of these try to stop the heat radiation after it has already entered the camper. IMHO, Thats a little like the cart before the horse. The window tints are only going to reject 65% of the heat.
Solar/heat reflecting screens is a much better way to go. There are two companies, Phifer and E-Z Snap that makes solar screen that I would consider. They claim 95% heat rejection which may seem a little aggressive, but it's still better than 65% and after comparing samples that both companies sent me, I could not tell any difference between Phiffer and EZ Snap, which was twice as expensive. EZ Snap does have a superior mounting system and that's the one I opted for. There are websites that will sell Phifer by the ft and in several widths. . I measured my windows, cut scaled down patterns and arranged them to allow me to order the width I needed to minimize waste.The EZ Snap studs either attach by drilling into the wall of the RV(No Thanks) or they attach with a super-duper 3M adhesive. I haven't installed my screens yet, but that's a project to keep me busy while I'm at Lake Catherine State Park next week.

Hopefully some of this information will help you cool down the trailer and save you some $$$ in the process, and with Fall and cooler weather upon us, you'll have time to do the research and make a sensible purchase.