Heating / Cooling What is considerd to be the ESPAR of Air Conditioning systems?

layoutshooter · Feb 23, 2013

I have the new Comfort Pro stand alone. It is not plumbed into the truck. It has a 6000W generator. It is hooked up to the battery boxes and charges all batteries.

It works OK. NOT enough heat or A/C capacity for my truck but it works for the most part. Had some problems when I first got it but they fixed it.

Rocketman · Feb 23, 2013

I never had an APU on my straight, but from everything I have read and heard, the ThermoKing Tripac is by far the best and most dependable. The tripac actually uses an Espar heater for heat and then the APU does the a/c. It is a pretty neat system.

For my money though, I wouldn't use any of the standard APU's if I had a place to mount a rooftop. If I had a place for it, I would go with a rooftop, an Espar and a good quality generator. Onan Quiet Diesel is what most use and they are very nice generators. There other generators though. This setup is by far the most reliable from everything I've heard over the years.

LDB · Feb 23, 2013

What are the details on the 12v system mentioned in the earlier post? Links?

layoutshooter · Feb 23, 2013

Rocketman said:
I never had an APU on my straight, but from everything I have read and heard, the ThermoKing Tripac is by far the best and most dependable. The tripac actually uses an Espar heater for heat and then the APU does the a/c. It is a pretty neat system.

For my money though, I wouldn't use any of the standard APU's if I had a place to mount a rooftop. If I had a place for it, I would go with a rooftop, an Espar and a good quality generator. Onan Quiet Diesel is what most use and they are very nice generators. There other generators though. This setup is by far the most reliable from everything I've heard over the years.

The Onan set up is the way to go. Not a fan of the Tripac, no generator. I wanted a unit with a generator.

Rocketman · Feb 23, 2013

LDB said:
What are the details on the 12v system mentioned in the earlier post? Links?

Pretty sure I've read about it in a thread here on EO. You might find it in a search.

xiggi · Feb 23, 2013

LDB said:
What are the details on the 12v system mentioned in the earlier post? Links?

Its still on espar of mi site but they no longer sell it. Its only 4700 BTU just not really big enough.

Scroll down the page you see info.

http://www.esparofmichigan.com/index.php?content=products

Sent from my Fisher Price - ABC 123

Turtle · Feb 23, 2013

LDB said:
What are the details on the 12v system mentioned in the earlier post? Links?

DC Airco is one.
DC Air Conditioners 12v 24v 48v 74v 110-750 Vdc
Like I said, they're expensive. I think the 9000 BTU is about $3500 and the 13000 BTU unit is about $5500.

Rocketman · Feb 23, 2013

Turtle said:
DC Airco is one.
DC Air Conditioners 12v 24v 48v 74v 110-750 Vdc
Like I said, they're expensive. I think the 9000 BTU is about $3500 and the 13000 BTU unit is about $5500.

Is there any power requirements listed. I know I could look, but then I would ask you to explain it anyway..lol. How many batteries required to run the 13k for 10 hours?

Turtle · Feb 23, 2013

Rocketman said:
Is there any power requirements listed. I know I could look, but then I would ask you to explain it anyway..lol. How many batteries required to run the 13k for 10 hours?

Well, if you look at the wattage draws for the various cooling conditions, you can figure it out. The outside temps (like 111° F in sunny Laredo versus 80° F in overcast Indianapolis), relative humidity, and whether you're trying to cool the entire van or you have a bulkhead or put up a curtain (which is what RLENT does) makes a difference on which duty cycle the air conditioner is running. Basically, it's a 100% or a 50% duty cycle, and the more time spent at 100% output the more battery amps it'll take.

DC Airco's truck-cab and cargo van unit, the DC 9000 (9000 BTU), draws 600 Watts at 100% duty cycle and 300 Watts at the 50% duty cycle. Presumably, you're well insulated and have a curtain or a bulkhead so you're only trying to cool down part of the van. If you use the van's AC unit in concert with the rooftop unit to get the initial temp down to a suitable level, then the rooftop will spend most of it's time in the 50% duty cycle and will draw only 300 Watts.

Watts divided by volts = amps. So, 600 Watts / 12 volts = 50 amps, and at the 50% duty cycle it's 30 amps.

So, figuring a 50% duty cycle, 30 amps per hour will be 300 amps over 10 hours. However, the Peukert Effect needs to be taken into account for such high amp draws, and you don't want to draw your batteries down below 50% DoD (Depth of Discharge). If you have a 500 Ah battery bank and draw at rate of of 30 amps, the Peukert Corrected amp draw is actually 31.17 amps, and you can draw that for 16 hours to empty, or 8 hours to 50% DoD. Obviously, a 500 Ah battery bank isn't gonna cut it.

With a 600 Ah battery bank at 30 amp draw, the Peukert Effect, coincidentally, actually works out the same as simple math does, where the Puekert Corrected amp draw is exactly 30 amps, and you can draw that for 20 hours to empty, or 10 hours to 50% DoD.

Bump up the battery bank to 700 Ah, and the Peukert Corrected amp draw becomes 29.04 with the 30 amp draw of the AC. You can run that for 24 hours until empty or 12 to 50% DoD.

Of course, these numbers assume no other draws from the battery bank of any kind, the AC always at 50% duty cycle, you always, always, always properly recharge the batteries after every discharge (like with the Sterling Power charging system), and, most importantly, you are using Miracle Batteries which never degrade and lose capacity over time.

A pair of Trojan L 16E-AC 6-volt batteries, each weighing 100 pounds, will give you 370 Ah. Two pair will give you 740 Ah. For the 12-volt air conditioner, that's the minimum I'd go with (and I'm not positive, but I think that's what RLENT has).

Even better would be four of the L 16P-AC batteries ("P" instead of the "E") that each weigh 125 pounds (500 pounds total) and give you 870 Ah. That will plenty of juice for other 12-volt and inverter loads, and will still provide plenty of power as the battery ages and loses capacity over time. And running it for 10 hours will only get you down to 75% DoD, which will prolong the life of the batteries considerably.

Rocketman · Feb 23, 2013

So...the 9000 BTU @ $3,500 + 4 batteries @ app. $300 each + a good professional installation with charging system and wiring @ $1000? = $5,700-$6,000 out the door possibly?

Yeah, thats expensive, but cheaper than an APU, uses no fuel and if installed correctly would likely be pretty trouble free. The only problem I see would be in case of longer layovers. In that case, you could always have a small generator to run just for charging the batteries when needed.

Turtle · Feb 23, 2013

Yeah, that's probably a good ballpark figure, maybe even a little on the high end, depending on the type of batteries you get (AGM might be more, Trojans might be less, depending on where you get them).

I think in such a case as extended layovers and no ability to idle (like with the new Sprinters), it would be good to have a small generator to charge the batteries. The Sterling Power system is incredible efficient, so idling with that installed will charge up the batteries in a fraction of the time it does when using the alternator itself, but you'd still be better off with a generator. Cheaper in the long run than idling, as well.

RLENT can give you all the gory details. He had a few problems early on with his AC unit, but they got those worked out and far as I know he's happy with it.

guido4475 · Feb 23, 2013

So at around $2,700 for a Front frame mount receiver hitch,(50#), an aluminum hitch basket(30#), a Honda generator, EU3000, (140#), and a Rooftop A/C unit, (89#) And even add an Espar At what, 50#, and another $1,800,00, (Second battery included) I would still think this setup is so much more better in the long run, lighter, and somewhat cheaper, not to mention no need to worry about how long of a charge batteries have before they need to be re-charged.I mean, where's the benefit, besides being quieter?

Rocketman · Feb 23, 2013

Turtle said:
Yeah, that's probably a good ballpark figure, maybe even a little on the high end, depending on the type of batteries you get (AGM might be more, Trojans might be less, depending on where you get them).

I think in such a case as extended layovers and no ability to idle (like with the new Sprinters), it would be good to have a small generator to charge the batteries. The Sterling Power system is incredible efficient, so idling with that installed will charge up the batteries in a fraction of the time it does when using the alternator itself, but you'd still be better off with a generator. Cheaper in the long run than idling, as well.

RLENT can give you all the gory details. He had a few problems early on with his AC unit, but they got those worked out and far as I know he's happy with it.

I'm not looking at this time...but given my complete dislike and distrust of anything APU, I would be more inclined to go this route than an APU.

Turtle · Feb 24, 2013

guido4475 said:
So at around $2,700 for a Front frame mount receiver hitch,(50#), an aluminum hitch basket(30#), a Honda generator, EU3000, (140#), and a Rooftop A/C unit, (89#) And even add an Espar At what, 50#, and another $1,800,00, (Second battery included) I would still think this setup is so much more better in the long run, lighter, and somewhat cheaper, not to mention no need to worry about how long of a charge batteries have before they need to be re-charged.I mean, where's the benefit, besides being quieter?

It's largely a personal choice on how you want to deal with things, but there are several benefits, as well as disadvantages, to both systems. A 12-volt AC is far more energy efficient, but far more expensive. The more you use it, the more beneficial a 12-volt unit would be. If you only use it 60-90 days a year, then the 110V system would be more cost effective. The generator system is definitely lighter, as you need enough batteries to keep from discharging them down below 50% between charged, and that means lots and lots of lead. If weight is a significant factor, then a large battery bank can be quickly eliminated as a viable option. But if weight isn't a factor, then batteries make more sense, because you can charge them while running down the road, and the gasoline required to power the charging alternator is a miniscule fraction of that required by a dedicated generator, even one as efficient as a Honda or Yamaha inverter-generator. For extended summer layovers where AC usage will be high, or even on the cooler days for extended periods, you will have to recharge the batteries somehow, either shore power, generator power, or idling. That's where a small generator would come in handy.

But the most obvious benefits of the 12-volt system is you don't have to change the oil every 100 hours in the batteries like you do the generator, and batteries don't require gasoline. Removing the guesswork about how long of a charge the batteries have is as simple as using a battery monitor which keeps track of all amps in and all amps out and tells you how many amps you have left.

A large 12-volt battery system requires a certain amount of education and knowledge to not only make the proper connections for safety, but also in how to treat and care for the batteries. Things like proper monitoring, charging, discharging. And knowing the difference between cranking, deepc-cycle and hybrid batteries, and how they should be treated differently. Too many people think batteries are batteries and they are all the same. But once you know how to treat your batteries, and have the proper systems set up to deal with them, it's all pretty much automatic and requires very little time and effort to maintain them.

I wouldn't recommend a generator to someone who doesn't want to mess with annoying details of how to properly store gasoline or how to change the oil on a schedule, anymore than I'd recommend a 12-volt battery system to someone who doesn't want to educate themselves about the proper cabling, fuses, connections, monitoring and charging procedures. If the bulk of your battery experience is that of a cranking battery, maybe a small aux battery, and Maglite D-cells, then a generator is probably going to be better for you.

One option, and it's a good one, is to use a generator to power a 110V AC in the summer, and to keep a decent sized battery bank charged up year around. You use the generator to run the AC and to charge the batteries at all times when the batteries aren't being charged while running down the road. In this case the generator doesn't replace the batteries, but rather becomes your primary method of keeping the batteries charged when the engine isn't running.

Rocketman · Feb 24, 2013

guido4475 said:
So at around $2,700 for a Front frame mount receiver hitch,(50#), an aluminum hitch basket(30#), a Honda generator, EU3000, (140#), and a Rooftop A/C unit, (89#) And even add an Espar At what, 50#, and another $1,800,00, (Second battery included) I would still think this setup is so much more better in the long run, lighter, and somewhat cheaper, not to mention no need to worry about how long of a charge batteries have before they need to be re-charged.I mean, where's the benefit, besides being quieter?

The benefit is no moving parts...at least not on the power supply end. If set up right, the batteries would be a lot less trouble. That's the problem I have with the APU's. They seem to be a lot of trouble to keep operational.

RLENT · Feb 24, 2013

xiggi said:
Espar of mi no longer sells them.

Perhaps that explains why I received no reply whatsoever to the last email I sent to Espar of Michigan this past December 11th, regarding what I noted as problems with the units performance and/or design.

Something that I can assure you was highly disappointing after spending roughly $5K on the unit ... and then an additional $1K within the last year or so on good quality batteries to power the unit ...

xiggi said:
He says they were not very good for our application. I believe they were only 4500 BTU.

4700 BTU actually IIRC ...

xiggi said:
I think rl has a bulkhead which would increase the units efficiency.

As Turtle mentioned, I have a curtain (quilted moving blanket) hanging just behind my bunk - which reduces the area to be cooled ... but doesn't make the unit any more "efficient" ...

xiggi said:
Its still on espar of mi site but they no longer sell it. Its only 4700 BTU just not really big enough.

If memory serves, people are using 5K BTU A/C units to cool cargo vans ... so the (lack of) cooling capacity is a bit of a red herring - at least based on my observations of the unit's performance ... although I will allow that the unit certainly doesn't have an excess of capacity.

The problem (IMO) is not the capacity - it is (or may be) certain aspects in the design of the unit - which are apparently programmed or hard-coded into the silicon (chip) of the unit's controller.

I can't really say for sure - since, as I alluded to above, my last email to Espar of Michigan received no response whatsoever ... not even an acknowledgement that it was received.

There were a couple of problems that I noted in that email which were the result of observations I made last summer while in Laredo ... specifically at midnight (with no additional heat load from the sun) when the outside ambient temperature was around 90F degrees. Since the unit was not cooling enough to allow me to sleep, I decided to investigate what was going on.

The first problem I discovered was the placement of the ambient/return air temperature sensor - from my email to Espar of Michigan:

"Location of the temperature probe/sensor:

The stock location inside the housing of the unit is no good - the area it is mounted in apparently either gets cooled, or the coolness of what it is mounted to makes the probe read incorrectly, thinking that it is much cooler in the cab than it actually is. I unmounted the probe and moved it outside of the inner cover (which contains the LED panel and controls) with the outer shroud off and noticed an immediate difference in the temperature output (much cooler) It would be helpful if this probe came with a longer lead wire - so that it could be located further away from the unit."

The second problem relates to how the unit's compressors (there are two) cycle on and off - from the email:

"Compressor "cycling":

This one is the real biggie - with the vehicle off and running solely on the batteries, the refrigerant compressors cycled on and off ... with the vehicle running (and supplying more voltage) this does not occur.

This is huge ... because it results in a 10+ degree swing in the air temperature coming from the outlets of the unit. The outlet air temperature would drop to around 72 degrees F (which was quite comfortable) while the compressors were engaged. Within 30 seconds or so of running at that temp, the compressors would cycle off and the outlet temperature would gradually start to climb ... until it hit around 84 or 86 degrees F .... it would stay there around 30 seconds or so ... and then the whole cycle would repeat ... endlessly ..."

It is my opinion, that the manufacturer (Dirna) of the unit, in seeking to optimize the unit for minimal power consumption, threw the baby out with the bath water - by not providing a way for the end-user to turn off the power-saving feature of compressor cycling, to achieve maximal cooling at the expense of power consumption.

The unit - with no compressor cycling - would have kept me cool that night in Laredo ...

As mentioned by Turtle, my aux battery bank consists of four Trojan L 16E-AC 6-volt batteries ... so "lack of power" wasn't a problem.

A fix for the problem would be relatively easy and cheap for the manufacturer to implement ... if they chose to do so ... a redesigned controller PCB is all it would take.

As many of you have no doubt observed, I can be rather blunt and have a rather acerbic tongue at times. I felt that my email to Espar of Michigan was largely polite overall, in light of the circumstances, and was mostly asking for some help/advice/input in terms of troubleshooting the problems I was experiencing.

I have, up until this point, been on good terms, so far as I know, with the owner and staff of Espar of Michigan.

Probably the most "acerbic" thing I said in the entire email was the following, which followed the text I quoted above:

"It was simply intolerable, in terms of actually trying to sleep.

Like I said previously - this cycling does not occur if the vehicle is running ... it will blow good and cold all day long.

Any thoughts ?"

Needless to say, the complete lack of any response whatsoever was ... disappointing ... to say the very least ...

LDB · Feb 24, 2013

RLENT said:
As Turtle mentioned, I have a curtain (quilted moving blanket) hanging just behind my bunk - which reduces the area to be cooled ... but doesn't make the unit any more "efficient" ...

Just can't ever resist the urge to scold or correct someone.

Turtle · Feb 24, 2013

LDB said:
Just can't ever resist the urge to scold or correct someone.

It's largely a matter of semantics and pedantics. When you reduce the size of the area to be cooled, like by putting up a curtain, the process of cooling the smaller area becomes more efficient than cooling a larger area, a less energy is required to cool the area down to the desired level. True enough, the unit itself doesn't become more efficient, but the entire cooling process becomes more efficient with a smaller area to cool.