Bus Conversions dot Com Bulletin Board
December 21, 2014, 06:19:30 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If your computer is lost, damaged, or stolen, your Online mags will be safe.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: [1] 2  All   Go Down
  Print  
Author Topic: Rooftop AC  (Read 3324 times)
Tikvah
Hero Member
*****
Offline Offline

Posts: 591



WWW

Ignore
« on: May 18, 2011, 09:40:18 AM »

I realize this could open a can of worms.  But, easy answers often are never easy.

One of the first things I want to do in my new conversion project is get the rooftops installed.  One, so I know where the wires need to run, and secondly, it will be hot working in there without them.
I don't plan to spend my summers in Arizona or Florida.  But, I don't like heat either.  So, here's my questions:

Do I need two or three rooftop units?  My current plan is to install three; one over the driver, one about mid-way, in the kitchen area, and the third in the rear bedroom.
What size should they be?  Maybe this depends on insulation.  I am not raising the roof, so I'll have about 3" of insulation in the roof, including both dow foam board, and some bubble-reflective.
Also, I'm a firm believer that air conditioners are better slightly undersized than oversized, especially in the humid areas. 
Does anyone use the heat strip that is an option with these?
Do you have any brands that are preferred or brands that I should stay away from?

Logged

I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
Jriddle
Hero Member
*****
Offline Offline

Posts: 679





Ignore
« Reply #1 on: May 18, 2011, 09:49:46 AM »

Three should be plenty.
I have heat strips in mine but can't see what good they are. Kind Of like P$$!NG in the wind if you know what I mean.

John
Logged

If It Can't Be Grown Then It Has To Be Mined
John Riddle
Wells NV
1984 MC9
happycamperbrat
Hero Member
*****
Offline Offline

Posts: 1813





Ignore
« Reply #2 on: May 18, 2011, 10:20:58 AM »

I gotta tell you I was really surprised when I had my driveway dwellers from Alaska recently. They had a 35' coach and said the insulation in it was just a layer of that foil bubble wrap. While they were here it was 105 one day. Their bus was parked with the windshield facing west and no shade. They hung a heavy blanket in the windshield and only had one roof top air. It was very comfortable inside their coach! I dont know what brand or whatever the roof top was, but it was older and it worked very very well even here in the  HOT
Logged

The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post
Tikvah
Hero Member
*****
Offline Offline

Posts: 591



WWW

Ignore
« Reply #3 on: May 18, 2011, 10:29:07 AM »

I have to tell you... one of my companies sells that bubble foil.  I've come to realize that the benifits of this stuff is huge.  The "R-value" isn't great, but it is hard to argue that it reflects an incredible amount of energy.  It is amazing in steel pole barns that gain heat.  I've never seen it used in a bus, but I certainly plan to use it, both in the roof and the walls.  Reflecting the sun's heat out in the hot summer sun is the biggest part of this game. 
I did a work shop recently for my previous home.   It had 4" walls.  I simply stapled this bubble/foil/bubble to the walls with a 3-1/2" fiberglass inside the studs.  It turned out that the shop could be heated with very little energy.
Enough of my sales pitch Smiley
Logged

I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
eddiepotts
Sr. Member
****
Offline Offline

Posts: 446





Ignore
« Reply #4 on: May 18, 2011, 10:29:54 AM »

I like having 3. I do not think undersize is better than oversized. In your house it is important because it runs off a thermostat. If you bring the temp down faster than you remove the humidity yes it will always feel damp and sticky eventhough it is 75*. In your coach it is a bit differant. They will need to run all the time removing humidity. At least here it does. It takes about 5 min for people start to complain about the heat if the genny gets hot and shuts down. The only way I can keep it going in 95* weather is to close the front lounge door and turn the back two off. Get what you can afford. You don't want to be buying six of them to fix the heat. You can always turn one off.
Logged
belfert
Hero Member
*****
Offline Offline

Posts: 5475




Ignore
« Reply #5 on: May 18, 2011, 10:42:03 AM »

I would put more A/C capacity towards the front as that is where all the windows usually are.  My front living area has lots of glass and my one 15K BTU unit up front can't handle the heat load especially when in the 90s.  I am going to be installing another A/C unit up front.

Logged

Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
happycamperbrat
Hero Member
*****
Offline Offline

Posts: 1813





Ignore
« Reply #6 on: May 18, 2011, 10:42:44 AM »

I have to tell you... one of my companies sells that bubble foil.  I've come to realize that the benifits of this stuff is huge.  The "R-value" isn't great, but it is hard to argue that it reflects an incredible amount of energy.  It is amazing in steel pole barns that gain heat.  I've never seen it used in a bus, but I certainly plan to use it, both in the roof and the walls.  Reflecting the sun's heat out in the hot summer sun is the biggest part of this game. 
I did a work shop recently for my previous home.   It had 4" walls.  I simply stapled this bubble/foil/bubble to the walls with a 3-1/2" fiberglass inside the studs.  It turned out that the shop could be heated with very little energy.
Enough of my sales pitch Smiley


Good to know! I have a lot of "dimples" inside the RTS and plan on filling them with cut to size foam board, then a complete layer of foam board over that, then another layer of that foil bubble stuff. I will only be using the foil bubble stuff in the back where the engine is.... maybe 2 layers of it there, not sure. But Im sooo impressed with this stuff for both fire prevention, fumes, and now the actual insulation value too! Time and time again in here I read the most important thing to keeping a coach comfortable is the insulation...
Logged

The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post
Seville
Jr. Member
**
Offline Offline

Posts: 65




Ignore
« Reply #7 on: May 18, 2011, 01:55:37 PM »

I went overboard with the AC's but I dont regret it. I have 5 Coleman Mach 15s with the heat strips.
Plus I have the original bus AC in case the generator breaks down.
I think they are a God send!

I've used the heat strips when the temps were in the high 30's and they worked very well. It takes about 10 or 15 minutes to warm up but when they do, they get the bus nice and toasty.

I haven't tried them out in freezing temps yet. I guess I'll find out soon enough.
Logged

New York City
1984 MC9 6v92T
mcidave
Newbie
*
Offline Offline

Posts: 42





Ignore
« Reply #8 on: May 18, 2011, 02:05:34 PM »

I have three 15k Colemans installed right in the same locations you originally mentioned and when it's really hot I need the front and middlle units on to cool.  The windows are the issue, but my family likes the view...
I have heat strips in the front and rear, but I went with a heat pump for the middle, if it's really cold I like the heat that my built in propane furnace supplies.  Can't go wrong with at least three units.
Logged
TomC
Hero Member
*****
Offline Offline

Posts: 6974





Ignore
« Reply #9 on: May 18, 2011, 02:26:00 PM »

I too have three units positioned like you said.  Insulation wise-when I stripped the interior, I installed 1x2 fir strips going lengthwise then had insulation sprayed in and ground down to the fir strips.  I have 2.25" of sprayed insulation that works well.  Single pane Peninsula glass with light tinting.  On a over 100 degree day, I can run two out of the three Coleman 13,500btu's and the bus is a comfortable 75 degrees inside.  Run all three, and my wife has to wear a sweater.

As to the heat strips-all three of mine have them.  The trick is to close the vents to slow down the air speed, and they do work-but take about 5 minutes to warm up, so in the meantime have cold air swirling around-which can be irritating.  I rarely use them-usually have two electric space heaters that just about heat the bus completely.  Then also have my 35,000btu ducted propane furnace that does a really good job at heating.

I would suggest in this day and age (and this comes from Camping World) you use the Dometic Penquin.  If you go into a Camping World service bay, you'll see lots of Coleman and Carrier A/C's that are broken.  They said they have the least problems with the Penquins.  Use the 15,000btu since it has a more powerful fan.  And they have a three speed fan, rather then just 2 speeds with the others-so it is quieter at night on low. Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
luvrbus
Hero Member
*****
Online Online

Posts: 13128




Ignore
« Reply #10 on: May 18, 2011, 02:32:03 PM »

The Mexican made Dometic Penquins are having their share of problems now and have ever since moving to Mexico


good luck
Logged

Life is short drink the good wine first
Jriddle
Hero Member
*****
Offline Offline

Posts: 679





Ignore
« Reply #11 on: May 18, 2011, 03:04:36 PM »

As to the heat strips-all three of mine have them.  The trick is to close the vents to slow down the air speed, and they do work-but take about 5 minutes to warm up, so in the meantime have cold air swirling around-which can be irritating.

Tom
I will have to try this. I think I got to the Irritating part very quickly.

Thanks John
Logged

If It Can't Be Grown Then It Has To Be Mined
John Riddle
Wells NV
1984 MC9
belfert
Hero Member
*****
Offline Offline

Posts: 5475




Ignore
« Reply #12 on: May 18, 2011, 05:51:06 PM »

Be aware that the 15K Penguins are only available for use with a wall thermostat or the Dometic Comfort Control Center.  This means they do not have a model with the thermostat on the ceiling unit.

This may or may not be an issue for folks.  I would just as well not have a separate thermostat, but I got my Penguins cheap.
Logged

Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
wal1809
Hero Member
*****
Offline Offline

Posts: 1339




Ignore
« Reply #13 on: May 18, 2011, 06:05:34 PM »

I have 3 unitsa as well and that keeps it arctic cold in here.  My wife likes 62 degrees while sleeping under 2 blankets Huh  The heat strips are about as useful as lipstick on a pig.
Logged

1984 Silver Eagle Model 10 6V92 Allison auto tranny
www.snakebreaker.com
jmblake
Jason & Martha Blake
Sr. Member
****
Offline Offline

Posts: 323



WWW

Ignore
« Reply #14 on: May 18, 2011, 07:20:10 PM »

I used 2 15,000 dometics with the heat strips, The bus is spray foamed and insulated windows and as far as air conditionig the warmest place we have been is Myrtle beech in July and it was hot and they kept the bus a cool 70 and still cycled on and off. The heat strips we also use all the time and keep it toasty down in to the 30s. I used the comfort control that belfert mentioned and it works great you can controll  every thing independent from each other plus it controls the furnace and has a separate temperature sensor in the back for the rear unit. Jason
Logged

Pages: [1] 2  All   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!