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Author Topic: Power Consumption  (Read 4504 times)
Lee Bradley
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« Reply #30 on: March 07, 2007, 09:36:46 AM »

Nick,
I have been wondering the same thing for sometime. Super efficient DC motors have been around for some years now; why aren't they showing up in these applications?  Maybe too much money invested in current designs to throw it out.  Hope you can find some answers. 
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DrivingMissLazy
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« Reply #31 on: March 07, 2007, 02:39:38 PM »

Nick, what about using a Variable Frequency Drive (VFD)?
Several years ago I put one on the blower motor for my home A/C and increased the frequency up to about 70 hertz. definitely improved the amount of air flowing thru the system. I do not see why you could not only slow down the compressor as well as the blower fan to reduce energy consumption.
Richard

Thought,

All theese RV A/C manufactors have not jumped on the band wagon yet with the new DC compressors for Air conditioners.

I wonder why.?

I think I should test one in a roof top. Hummmm?? ??

The equipment now exists in residential systems we sell. The compressors are DC and are able to be ramped down [variable speed]

at night time for high efficency. The speeds very from 900 rpm to 3600 rpm.  I will have to do some research because the compressors

are made in japan and are still the "scroll rotary" type. So they can be mounted Horrizonal in our units.

This could be the answer we need for our conversions to be able to boon dock over night without the gen running and still have A/C.

Nick-
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
Nick Badame Refrig/ACC
1989, MCI 102C3, 8V92T, HT740, 06' conversion FMCA# F-27317-S "Wife- 1969 Italian/German Style"
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« Reply #32 on: March 07, 2007, 03:25:11 PM »

I found a company who handels a compressor that fits our needs.

I wish I had more time right now to study this, but I'm jammed up with my customers.

I'll supply the link and the co.  Maybe one of you can do some reading on theese variable comps.

Then I can easily come up with a prototype.. It looks like theese compressors can run from 9 to 30v's DC. Thats great!

It looks like a 9400 comp will put out 14,000 btu's. and of course needs a controller.

http://www.masterflux.com/   I'm gona start a new thread with this post..Don't want to steal other topics...

Nick-
« Last Edit: March 07, 2007, 03:29:44 PM by Nick Badame Refrig. Co. » Logged

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« Reply #33 on: March 07, 2007, 04:00:51 PM »

Here's the one D.C. air conditioner company that's been around a while...

http://www.dcairco.com/

Thought you would be interested....
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« Reply #34 on: March 07, 2007, 07:28:32 PM »

Two roof mounts on high cooling  6.1 amps

Bill, keep in mind that your compressors were surely not running when you tested the rooftop units' draw under cooling. Must have been fans only. When the compressors are on, they'll pull almost 20a each. It's probably not hot enough where you are to cycle the compressors on.

A/C loads are even higher than those of electric heat. Brian

FWIW, one of my Dometic heat pumps (15K AC, 12K heat) pulls 11A to 12A on cool with the compressor running, and 15A when the compressor's running in heat cycle.  Now I don't understand this factoid, but I've got watts, amps, cycles, etc monitor and that's what it is.   There are no heat strips in these rooftops.  What I expected to be a large start surge doesn't seem to exist...it cycles on and off without problem.   I'm acutely aware of such power use due to my 30A service.  Obviously, the two heat pumps in heat mode use the entire power availability.   Cooling leaves a litte headroom...T's hairdryer will suck that right up.  Terri hasn't quite figured the "power management" gig out yet.   
Some day I'm gonna add an additional panel in order to utilize 50A service when available.  Split the ACs, use only the rear AC on one leg.  Rest of coach on existing 30A system.   Use an adaptor if only 30A.  No different from what I'm doing now.  I frequent a lot of older campgrounds that don't have 50A service.  That's the rationale for the 30A system.  LP makes up the difference.
And, it made the generator install much easier.  But the capacity to use 50A is going to happen soon...maybe next year.  After my little window awnings that I just received today are installed.  Wink
I ordered a tube of various moulding for myself and another busnut, and FedEx managed to drive a forklift over the tube.  Driver stands there and sez he'll make a claim and that I owe him $91 bucks for freight.  Reckon that happened?  Not!  Angry    Some of the moulding was gutter/awning track which was damaged.  Found that the A&E window awnings came with awning track in the tubes.  Cool. 
Sorry for hijacking the thread.... Wink

JR

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JR Lynch , Charlotte, NC
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« Reply #35 on: July 30, 2007, 01:38:47 PM »

Guys and Girls,

Thought I would bring this subject back to the foreground.  When I started this, I was in Little Rock and cold.  Now, I'm in Phoenix and HOT.

Richard, AKA  DrivingMissLazy ask, why would I run the genarator 24 hours a day?   When it 90 degees at sunrise, 100 by 10am, then it really gets hot, you have to run the gen 24 hours so the air can keep up with the heat.  Inside the coach would reach 110 by four.  Turning both A/C on will not cool down the coach.

This is why to run the gen 24 hours.   I believe my gen is using more than a gallon an hour.  Since I've moved to the "pole", it's cheaper, I have power 24/7 and it's cheaper.

Bill
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Cary and Don
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« Reply #36 on: July 30, 2007, 08:09:56 PM »

We have found that if it is hot or cold and we have to use the generator to keep us bearable, it's cheaper to find a place with utilities. When we boondocked with the generator running 16 hours a day, 7.5 Onan, we used at least the $26 a day most places charge with hook ups. 

The Oil space heater does the best job of keeping us warm and using the least amount of electricity.

Don and Cary
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« Reply #37 on: July 31, 2007, 01:02:20 PM »

Bill - If you don't have awnings, they can be a great help in hot weather.  It is amazing what the difference is when you an keep the sun off the glass.  We have Low-E, dual pane, reflective windows in our bus; supposed to cut the heat gain a lot.  Pulling out the awning makes a HUGE difference in how much and how fast the bus heats and what it takes to cool it.  I need to order up the rest of the window awnings; I am behind on this summers bus improvements.

HTH,
Craig - MC7 Oregon
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Craig MC7 - Oregon USA
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« Reply #38 on: July 31, 2007, 01:08:56 PM »

I can confirm Craig's comments.  I too have dual pane, reflective glass windows, and the awnings make a huge difference in heat coming in to the coach.  I have front to back awnings on both sides, and mostly I don't need them, but when I do, Very happy to have them.
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Jim Stewart
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« Reply #39 on: July 31, 2007, 01:20:38 PM »

Do any of you guys know a good (and possibly cheap) supplier of window and big awnings? Makes/ models to consider/ avoid??

Thanks!
Brian B.
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Brian Brown
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« Reply #40 on: July 31, 2007, 01:26:03 PM »

Zip Dee  800-338-2378
Girard   Don Mollers (west coast) cell phone      949-279-1069   


not cheap

The lateral arm type are the cadilac of awnings, very nice, electric motors, no side arm supports to run your face into. but very very pricey.
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Jim Stewart
El Cajon, Ca.  (San Diego area)

Travel is more than the seeing of sights, it is a change that goes on, deep  and permanent, in the ideas of living.
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