Trailer and Power Generator

Yes, but they also dry out the food quicker. Then fan blows cold dry air over the food whenever it runs. Maintenance on a chest freezer? About the time it goes bad it's time to get a new one. Also if the walkin goes bad, where do I put $20,000 worth of seafood, NOW! Plus it is over three tons, 65 lbs at a time. If one freezer goes bad, we always have one empty one to move product into. I have a 1 wire system that runs to my computer. Several time a day when I'm on the computer. I monitor the temperature of each freezer. Here's a screen shot;

Well, let's do a little math based on actual data. I've logged all the power consumptions of all the appliances in my house and in my restaurant.

Initial cost.

An 8' square walk-in costs about $5,000 installed. A large chest freezer is around $300 at Sam's Club. 12 freezers is $3600. The win on initial cost goes to the chest freezer.

Capacity: No contest - 12 large chest freezers hold far more than a walk-in because, well, one must leave room to walk around in the walk-in.

Operating cost.

The large chest freezer that I have in my home consumes $4.41 a month in electricity. Multiply that by 12 and $52.92. My approx 10' X 6' walk-in freezer consumed $94.92/month measured during the summer months. Again, the win goes to the chest freezers. All measurements were done with calibrated revenue meters.

The walk-in has several single point failure vunerabilities. The condensing unit. The liquid solenoid valve. The defrost timer. The defrost heater. Etc. All failed during the 12 year life of that walk-in. Unfortunately the compressor failed during our vacation closing and all was lost. Insurance paid out about $8000 for that one. If a chest freezer fails, he might lose those contents but the other 11 are still running. Win goes to the chest freezers.

The one major area where the walk-in wins is cool-down. The chest freezers are so economical to operate because their refrigeration systems are just barely large enough to keep already-cold contents cold. Cool-down is very slow. The walk-in, OTOH, with its 3HP compressor and high velocity evaporator fans would freeze a steam table pan of boiling hot stew in about an hour.

So based on the numbers, the correct advice is "keep the chest freezers, dude!"

"amdx" (clip) there is some thought about

^^^^^^^^^^^^^^^^^^^ Before I installed a proper transfer switch, I used a kludge that worked well, and didn't cost much. I inserted a 4 connector twistlock connector pair into the line from my meter to the house. I then ran a line from my generator to the spot where this twistlock pair is located. The line from the generator was wired with a female connector that matches the male connector running to my house. In a power outage, I go out into the garage and unplug from the utility, and plug into my generator. This is simple, completely eliminates any possibility of hooking the generator to the incoming power line, and costs a lot less that a heavy double-throw switch.

I asked the electrical inspector about that, but with an RV type plug wired to only a single receptacle inside and no connection to the house wiring, and he threw a snit fit. Is that legal and if so how can I prove it?

jsw

"Jim Wilkins" wrote: I asked the electrical inspector about that, but with an RV type plug wired to only a single receptacle inside and no connection to the house wiring, and he threw a snit fit. Is that legal and if so how can I prove it? ^^^^^^^^^^^^^^^^^^^^^^ I don't know what the code says, but he may be a knee-jerk inspector who automatically condemns anything that "isn't the way it's done."

If you plug one of your freezers into your generator, that's certainly legal. If you transfer them one at a time to the generator, that would still have to be legal. Now unplug one of your floor lamps and transfer it to the generator. Then, a piece at a time, put the rest of your household to the generator. At what point would he start objecting? If you are legal so far, then the only remaining step is unplugging from the utility. Could that put you in violation? Trouble is, the inspector may not be smart enough to follow simple logic.

As long as you don't have a fire, it's legal.

If you have a fire, after a power outage, then it's over.

good luck

hamilton

Not fair. The walk-in takes 64 sq feet of floor area, the twelve chests take over twice that. What's the cost of a building nowadays, $30 per square foot?

Again, unfair. Choose the right size of walk-in and redo that argument.

This sounds odd to me; firstly, a freezer indoors costs you twice, once in freezer electricity and (in summer) again in airconditioning cost. Secondly, walk-in freezers ought to have the same efficiency as a chest freezer, and should need less cooling because they have similar insulation but lower external surface area.

Your 'spare' for the walk-in is gonna be a phone call to get a refrigerated container delivered. Any trucking company can do this for you. I'm dubious that you plan to lose all of the contents of a chest if/when one fails, either. And with twelve chest freezers, they're gonna fail twelve times as often. Either way, your contingency plans should cover faults.

I would want to insert something after a main breaker, not before it. Something about plasma.

greg

I have 25 cu ft freezers, 12 x 25 = 300 cu ft of storage. A 8 x 8 x 7 walkin is 448 cu ft but room to walk 2 x 8 x 7 = is 112 cu ft so 448 - 112 = 336 cu ft. Take out another 20cu ft for the evaporator and we are down to 316 cu ft. So very comparable cubic feet. Cost, I think last 6 were $450 each. $5,400 again comparable.

greg

The power grid isn't involved. I want to temporarily run a washing machine or air conditioner from a generator when we lose power after a storm. This is one step above passing a cord through an opened window, without its heat loss and carbon monoxide risk.

jsw

Actually, the situation is not nearly so simple. In terms of the BTU's of heat that are pumped out of the freezer into the room, they are the *very same* heat BTUs that leaked from the room into the freezer. So that turns out to be a wash. Further, the freezers would operate a bit more efficiently in the cooled space because 1) There would be less delta-T across the insulation, so less heat loss + less compressor operation, and 2) the condenser would operate a bit more efficiently in the cooled room because it would see a larger delta-T. On the other side of the equation, all of the waste heat (I squared R loss + core loss) from the compressor motors and (if any) fan motors would appear as heat load to the AC.

Vaughn

With surround coils imbedded under the sheetmetal, the differential is more constant. How thick the insulation is more important.

greg

Put a nice well made minimum 3/8" chain though the top lifting loop and secure it with an Abus lock, around something very hard to cut.

Nice rigs like this..tend to disappear to Mexico/etc etc

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

Check the _actual_ draw on the heater assembly at 120 V (with proper air or water running through it). It may turn out to be anywhere from 2 kW to 10 kW.

Oohhh. Good point, if this is going to be used for backup power for an all metal boat there are special requirements that need to be met.