Nomad Joatman is a DIYer and motorhead who is HVAC and air conditioning certified.  He lives on a rolling lab of sorts. Folks looking to buy back up power should understand the importance of load management before they buy a generator, less is usually more if you do it right.

Here’s an email sent to me by the Nomad:

George,

Think of it this way: A 3 ton A/C is 36,000 BTU and requires a compressor motor that puts out 4.5hp to 5.5hp.  That’s going to eat up a 6/1’s hp to start it, but it will start it.  The biggest hog at the trough is the big central air systems.  They cool an entire house, regardless of whether someone is in the room.  We need to change our thinking a little here.  Let’s step back to the days before central air.  Window units were the rage.  You had one where you lived, whichever room that was.  The bedroom got one, you spent 1/3 of your life there and you slept comfortably.  If you had one in the parlor/living room, you were up-town!  We sold people in the late 1960s on the idea of going to central air for the convenience.  Yeah, we did the numbers game….totaled up the LRA & RLA on all their window units compared that to the central unit we were selling and “showed” them how inefficient their window units were, never mind that they were never all on at the same time trying to cool areas were they weren’t living.  That was my first experience with “numbers can mean whatever you want them too.”  I digress….

My “house” is a 40′ Motorcoach conversion.  I cool it with a 2 ton or 24,000 BTU 2 stage heat pump that is powered by a 7.25KW Chinese diesel.  My generator has NEVER loaded down!  The key here is that the unit is two stage, having two small compressors.  The thermostat demands cooling, the first compressor and fans kick on, if after two minutes the temperature hasn’t dropped, the second compressor kicks in to lend support. Each compressor is 115VAC and I run them on each leg of the 220VAC, balancing the load on the system.

Now, the cost initially for the system is usually higher.  Let’s face it, there’s more hardware involved.  Two compressors and some added controls, but the advantages are clear.  Instead of taking one big bite, you take two smaller ones.  A couple of the big A/C manufactures started experimenting with variable speed compressors a few years ago.  They we’re a turbine type of compressor rather than a piston driven.  The advantage was a spin-up start rather a big jolt to get the thing going.  They were called “Scroll Compressors” and their start up was a lot more gentle.  The downside was the same as a jet turbine…Noise.  Carrier actually came out with a “blanket” to wrap them to deaden the noise.  They may still make them, I know they sure promoted the heck out of them.

There are some of the big A/C companies that are working on variable speed compressors.  There may be some out now.  Same principle, start slower and increase speed and output as demanded.

Now as for your “customers” that say they need 15KW to push a 36,000 BTU or 3 ton system….Bullshit!  I’m reminded of a CD I bought from a so called “Guru of bus conversion.”

When sizing a generator for your bus conversion he told people to add up the wattage of everything in their rig, add 20 percent and buy accordingly.  Now I ask you, are you going to run everything in your house at once?!?!  I actually saw a rig that a guy (using the CD) had done a conversion on an MCI bus.  He had a 20KW diesel genset that weighed 1100 lbs mounted in one of the storage bays!  It took up half of a 6′ x 7′ bay and was so loud even with sound deadening and a custom muffler, that you couldn’t have a conversation near his rig……I digress again.

My belt drive compressor system will utilize three automotive compressors.  I will use time delays (variable voltage & time) to sequence them on at 1 minute intervals.  All of it is over the counter (OTC) stuff, if you know what you need.

I need to correct something or rather clarify:

(1) Locked Rotor Amps or LRA is not a measure of starting requirements on a compressor.  It is how much amperage a compressor will pull if the rotor locked in failure before the compressors internal circuit breaker will trip.  It’s valuable in sizing the line wiring and breaker requirements, but is not how much amperage a unit will pull at startup!

(2) A “soft start” kit is not the same as a hard start kit.  A soft start kit actually reduces the amount of “kick” a compressor receives to start.  They are usually used in situations where there is a loud compressor start-up to quiet a noisy compressor.  They are hard on the start windings and will kill a compressor quicker.

(3) The start capacitor can be increased safely by 20 percent in both VAC and MFD.  But only the start capacitor, not the run capacitor!  The spike on the start will be so quick and short that some recording devices won’t even register it.

In summary:

Let’s not air condition places we aren’t living.  Short of wearing space suits, the next best thing is window units.  They condition the areas where we are, not where we may go. They are a simple method of sequencing, taking little bites, instead of one big one.

Use time delays on A/C’s.  When a compressor runs the pressure on the “high side” is running about 270-325PSI and the “low side” is 70-100PSI.  When the system shuts down it takes time for the pressures to equalize.  The longer a compressor is off the better.  That’s why the owners manual on any refrigeration product recommends a 3 minute delay before re-starting.  If you don’t wait, the system is starting against a load.  Use a delay on break and set it for 5 minutes or more to reduce start-up load.  The delay on break will keep kids and the relatives from short cycling the system.

That’s all for now George,

Oh I almost forgot…..

My system for using the waste exhaust for air conditioning……well, think about two drip coffee makers; one leading to the other, one’s outlet goes to the reservoir of the other and vice versa.  As one empties the other fills, the full one switches on and the empty off until it’s full again……think about it

Nomad Joatman

I receive many emails from folks with 3 ton air conditioners that are told they need a 15kw or larger generator to run their AC and other stuff. I believe it is important to sell people what they need, and no more. Smaller generators are less expensive to buy, cheaper to maintain, and in many cases the smaller sets get better fuel economy.

I have a friend with a 5hp air compressor.  It will kick out a 30 amp breaker because it attempts to start with pressure against the piston (bad; but easily fixed). Others report starting and running a 5hp air compressor with the lowly 6/1 and a properly set up gen head. A friend in Australia uses his 6/1 for running an ARC welder, and he notes that his Honda gas generator that provides twice the KW rating struggles to run it, we must consider those flywheels and know they are a source of energy and storage.  We might note that the world is full of people that push the truth. It starts when your competitor starts lying about their products, and pretty soon, their sales are up and yours are down.

I first saw it in stereo amplifiers.  A few manufacturers started using peak power figures versus RMS power, and soon other vendors followed suit.  The public was totally confused, and many potential buyers have no clue about peak versus RMS power, and just how big a difference there is, they just buy what they think is the most for the money.

A prime example of this is electric appliances, Hardware store air compressors are advertised at peak Horse Power figures, Vacuum cleaners are advertised in the same way. In fact the Vacuum cleaner saleswoman[1] stoops even lower. I have seen a good many advertisements where the Amperage is used as a power figure, more amps, more suck! It really sucks that they get away with it.

As we know, there’s a lot of design work to get efficient impellers to create that suck, and we also know there are countless other factors. We know we could add a heating element to that vacuum cleaner and pull even more amps, but I doubt it would suck any more dirt off the floor.

Back to that air compressor, is it really a 5hp unit you have? Maybe the one the Lister 6/1 has been running so well is just like 99% of them, it’s called a 5hp, but that’s a peak power figure.. Peak HP is the Horse Power that occurs at the peak, if we look at the AC sine wave, we notice there is a moment when no work is done, (the zero cross over). The recognition of this leads to the RMS figure which is the attempt to give you a more meaningful figure.

I always tell people to put a ‘clamp on amp meter’ on their stuff to find out what it really takes to start a load, remember running takes far less than starting.

Many of my AE Motorhead friends are in the south, and I can tell you they would rather have a cool room in the heat of the day during a power outage than food! We up north have little appreciation for just how hot and miserable it can get. I remember visiting Atlanta Georgia, there was a popular shopping district all set up underground, one could go from building to building underground, just like Prairie dogs, and with darned good reason.

As of this writing, I realize I can no longer ignore Air Conditioning loads, and folk’s pleadings to help size generator sets to allow them to run the stuff. At times, answering all my email is impossible, so putting answers on the CD, and posting at utterpower.com is the more reasonable solution.

I am aware that lots of stuff is designed to sell, and far less things are designed to live with. Small refrigerators drive me crazy, but till I started corresponding with Nomad Joatman, I didn’t have a clue as to what was really going on in some of my observations. For me to attempt to learn what this man already knows, and write about it, would be a little like trying to catch up to Jeff Maier in Electrical Engineering, and use of Biofuels.. I’d have to be smoking rope to think that would happen.

Sharing information is key, those who take the time to inform themselves will do well, I get a good many emails saying.. “I wish I would have read that before I bought. Can’t we all say that?

It is time our community had a little information about load management, it will make all the difference, I know this and have written about it, but I am NOT an AC guy or an HVAC guy either, these certified installers and repair people size and install all kinds of stuff, some feel the smallest detail is a trade secret, and they’re likely to be out of work if they tell you anything helpful, others are disgusted with sales types, that would sell their own father[2] twice what he needs because the commission check is bigger..

The Nomad lives in a land Yacht of his own making, it is a rolling lab of sorts, and on top of being certified in two important disciplines, he has the incentive to come up with efficient designs for himself. It means it works better with less power, and burns less fuel, that’s exactly what we want on the grid or off the gird, energy won’t be getting cheaper anytime soon.

I have the pleasure of having friends and associates from around the world, I learn that Mamad in Iran is busy with his customers teaching load management and providing solutions that allow customers to continue running their existing generators even though their business (and loads) has grown considerably.

We need to spread the word, it’s good to use less energy, and best to run a smaller generator when you can..

Tod Bjorkman is one of the greatest information gatherers I ever met. Give this guy a problem, and the first thing he’d do is gather a pile of reference material on the subject taller than a building, then he’d organize it according to relevance and digest the material. Tod would distill the material and produce answers and solutions as if they came from God!

I need to stay focused on information, there are too many distractions in life, selling is one of them.. As I write this, I am excited about the new generator; it is simple, more efficient, longer living, and starts and runs loads like nothing else I’ve seen. DIYers need access to it, there is only so much you can do in a day, Utterpower must stay on information,  there is a transition underway here. it is all about delivering a higher return on investment.

I’d like to introduce you to Nomad Joatman, certified HVAC and AC technician.

[1] We must not assume it’s a man doing the selling.
[2] Another attempt to degenderize this article, Hillary will appreciate my efforts here.