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Rooftop a.c. vs apu

ChanceMaster

ChanceMaster

Expert Expediter
Hello,
Currently driving a freightliner Columbia with an apu that provides barely tolerable a/c to the bottom bunk and only with the sleeper curtain closed. I was told a few months ago while getting the apu serviced that our model was the first one produced by thermoking.

Doing some very early research for owner considering new truck purchase.

My questions are :

Are the newer apu's better at providing a/c comfort to whole truck ?

Advantage of rooftop over apu ?

Experience with rooftop vent fans ?

It's hot out here ! Thanks for any help.
Posted with my Droid EO Forum App
 
P

purgoose10

Veteran Expediter
ChanceMaster said:
Hello,
Currently driving a freightliner Columbia with an apu that provides barely tolerable a/c to the bottom bunk and only with the sleeper curtain closed. I was told a few months ago while getting the apu serviced that our model was the first one produced by thermoking.

Doing some very early research for owner considering new truck purchase.

My questions are :

Are the newer apu's better at providing a/c comfort to whole truck ?

Advantage of rooftop over apu ?

Experience with rooftop vent fans ?

It's hot out here ! Thanks for any help.
Posted with my Droid EO Forum App
Click to expand...


I have many friends who use APU systems and they all love them. Yes the old units will not cool like they did new. When they get 5 yrs or older they loose their punch. 5 yrs of pounding on our smooth American hwys will kill about anything.
I know one guy R/R the condensor and compressor and his worked great, but he's a pretty good mechanic.
 
TeamCaffee

TeamCaffee

Administrator
Staff member
Owner/Operator
We had a Rig Master for six years and in the really bad heat the Rig Master would maintain the sleeper was about it. It was not often we were in that severe of heat and I thought the Rig Master was fine. In the winter time I did not think anything could beat the Rig Master for heat but I am thinking this little Espar Heater just might do the job.

We now have a ONAN generator and a Dometic Roof Top Air Condition and so far we have not been anyplace that it could not cool the sleeper down. When in Texas over the 4th of July the air conditioner ran all day and was able at night to reach temperature and shut down. We run a table top fan as well when it is that hot to keep air conditioner circulating. It has sure impressed the heck out of us with it cooling abilities.
 
fatboy1

fatboy1

Veteran Expediter
i would do the roof a/c and good genset than just having an apu, depends on how big your sleeper is also. have used rig aster before in a small sleeper and worked super, larger sleepers not so good.
 
ChanceMaster

ChanceMaster

Expert Expediter
TeamCaffee said:
We had a Rig Master for six years and in the really bad heat the Rig Master would maintain the sleeper was about it. It was not often we were in that severe of heat and I thought the Rig Master was fine. In the winter time I did not think anything could beat the Rig Master for heat but I am thinking this little Espar Heater just might do the job.

We now have a ONAN generator and a Dometic Roof Top Air Condition and so far we have not been anyplace that it could not cool the sleeper down. When in Texas over the 4th of July the air conditioner ran all day and was able at night to reach temperature and shut down. We run a table top fan as well when it is that hot to keep air conditioner circulating. It has sure impressed the heck out of us with it cooling abilities.
Click to expand...

Thanks for the detailed reply,

This leads to another question..Does your rooftop keep the entire cab cool , or just the sleeper ? I have a good quality fan but find that it does not do very good at moving the cool air where I want it.

Not very familiar with the term "genset" either. I will assume that the generator is the "gen set" Does the generator keep the truck batteries charged like the apu ? where is the generator mounted ? is there a cab mounted switch or is it automatic ?

So many questions ! Thanks for all the replys and comments..it remains Hot out here !
 
E

Eastex

Seasoned Expediter
ONAN is probably the major manufacturer of generators for the RV industry and they are owned by Cummins. ONAN has an excellent reputation for making good reliable Generators (a.k.a. Gensets) and they manufacture models that operate off of gasoline, diesel and propane.
So far as roof air conditioners are concerned, you can get them anywhere from 8,000 b.t.u. up to 15,000 b.t.u. I believe that the most commonly used ratings are 13,500 b.t.u. and 15,000 b.t.u., either of which should most certainly be able to keep the entire cab including sleeper as cool as you want. Hope this helps you make a decision.
 
TeamCaffee

TeamCaffee

Administrator
Staff member
Owner/Operator
When the weather is super hot we keep the cab window curtain closed as well as the sleeper curtains closed to help the generator.

Our fan is pretty old and how we picked it out was standing in Walmart with all of the fans blowing and picking one out and standing away from the fan. The best fan for us was one the was not the highest cost or the lowest. Our fan is about 5 years old now and still working like a charm.

Our ONAN charges the truck batteries as did our Rig Master. If you will look at the pictures in some of my blogs you can see the generator on the drivers side behind the fuel tanks. Has a large white cover. If you are going to the Expo you can see this for yourself.

There are both an inside switch to control the ONAN and we can set the ONAN to perform system checks and start when needed.
 
TeamCozumel

TeamCozumel

Seasoned Expediter
We currently have a rooftop and it's on an older model sleeper built by Bentz (2006). My major issue is the noise. It's too loud but it needs to be on when it's hot.

If I were starting from scratch I would not do roof air. I would go with a thermo-king or carrier apu option. We were in a truck with the carrier apu that had the a/c and it was just as efficient and effective as the rooftop we have now. But the downside of this set-up was the carrier apu noise.

Just my two cents.
 
ChanceMaster

ChanceMaster

Expert Expediter
TeamCozumel said:
We currently have a rooftop and it's on an older model sleeper built by Bentz (2006). My major issue is the noise. It's too loud but it needs to be on when it's hot.

If I were starting from scratch I would not do roof air. I would go with a thermo-king or carrier apu option. We were in a truck with the carrier apu that had the a/c and it was just as efficient and effective as the rooftop we have now. But the downside of this set-up was the carrier apu noise.

Just my two cents.
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Yes noise is a consideration for sure.

Your the first to mention this as a problem with rooftop a/c's Our current apu is noisy as well. Co driver (truck owner) usually stays in hotel, and we have to park considering the apu noise. I usually stay in truck.

I wonder if your rooftop unit is older or a budget model ? I think our next purchase for the truck is going to be a rooftop fan. truck is too old to invest in a rooftop a/c..but the next truck !!
 
TeamCaffee

TeamCaffee

Administrator
Staff member
Owner/Operator
Our air conditioning was running yesterday directly above our table and I was able to be on a conference call using my phone on speaker with no problems.

I have not heard of that issue either.
 
rfields200

rfields200

Seasoned Expediter
I have had a Tri-Pac APU for 3 years and am totally satisfied with it. I have a 84" sleeper and the unit will cool the whole truck down no matter how hot it is outside. Plus the unit is very quiet. The heat comes from an Espar unit and it will turn the truck into a sauna even at below zero temps. I had a different brand prior to the Tri-Pac and am glad I chose this one this time.
 
guido4475

guido4475

Not a Member
A freind and I installed a 13,500 btu rooftop Dometic last week on his Spartan body van he bought.Even with temps in the high 90's, high humidity,un-insulated box,ceiling being a translucent roof,it cooled it down to cold inside, and I mean cold, the 12' box in 20 minutes..he since then insulated it, as I had mine also..Definitely a rooftop model, in my opinion!
 
ChanceMaster

ChanceMaster

Expert Expediter
guido4475 said:
A freind and I installed a 13,500 btu rooftop Dometic last week on his Spartan body van he bought.Even with temps in the high 90's, high humidity,un-insulated box,ceiling being a translucent roof,it cooled it down to cold inside, and I mean cold, the 12' box in 20 minutes..he since then insulated it, as I had mine also..Definitely a rooftop model, in my opinion!
Click to expand...

I was reading Phil Madsens blog regarding his equipment on his truck. I'm pretty sure He has a Dometic as well..and I'm sure He did the research too. Pretty sure I will be steering the truck owner toward a rooftop when the time comes. Im assuming the generator can be fueled by the trucks tanks ?

Lots of good info on this forum thanks everyone.
 
E

EASYTRADER

Expert Expediter
In ACs size does matter. Whether you go APU or rooftop the higher the BTUs the more cooling you will get. A 13000 BTU apu will cool the same as a 13000 rooftop. On exactly the same truck it may feel like the rooftop does a better job because it is blowing down on you, but it is in fact the same.

The most important thing for maintaining truck sleepr temperature is "insulation" if you are specing a new class 8 truck "Get the ARTIC" insulation upgrade I think that's what some companies call it. That will keep out the heat as well as the cold.

I have a AAA sleeper and its insulation is inadaquate, in the summer you can actually feel heat coming through the ceiling. It is adaquate most of the time but on the real hot days it sucks.

Posted with my Droid EO Forum App
 
greg334

greg334

Veteran Expediter
The problem that many may not get is if your apu is putting out 13k btu, there is a serious problem. With the engines they put in these apus, they should be at least 20k btu capacity if not 25k btu.
 
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