Power-Save 1200?

PhilS · January 2008

I have started down the long trail to switch my refrigerator(s) to solar and away from propane. I have two 6cf RV fridges flush mounted in the kitchen and they work well.....

.... but the cost of propane is making them expensive to use. I estimate $50/month now and increasing every year forever.

I have an Magnum MS2812 coming now from W-S (c'mon, Mike, when are ya gonna ship that puppy?), to replace a Xantrex MC2512 that currently supplies most of the home power. The Xantrex then will replace an old Heart Interface "ultra-hi efficiency" 2000w inverter that runs the water pump. My Prosine 1.0 will continue to power lights and entertainment.

I am starting to shop for a refrigerator, paying close attention to the energy labels. I see adequate units with energy ratings of under 400KWhY. In doing searches for energy saving refrigerators, the following site came up:

http://www.power-save1200.com/

Would it work with an inverter? Would it actually generate any significant savings? You 'engineering-types' (meant in a good way) have any useful input on these?

Phil

mike95490 · January 2008

Re: Power-Save 1200?

It's a power factor controller, and only contains a few $ worth of capacitors.

Matching a $5 "RUN" capacitor to each motor you have is a better bargin. Of course the grey box likely has a fuse in it, so it costs almost "$30" in parts. And they have the nerve to sell it for $300 Why don't I dream these things up ?

I suspect it only has 1 fixed capacitor, unlike industrial units with circuits to switch in different sizes of capacitors, as the loads change.
http://www.lntebg.com/mps/pfc.html

What can happen, is that if you have too much "Correction" you waste money by not having enough inductive motors running.

PhilS · January 2008

Re: Power-Save 1200?

Thanks, Mike. So maybe ONE run capacitor for the fridge only?

I should add that my original planning was to migrate those two RV fridges to AC power. I started using one on solar last spring, and was preparing to have them both on AC this year.

BUT there is a recall on these units, you can view a 766-post thread about Dometic and this product here: http://www.rv.net/forums/index.cfm/fuseaction/thread/tid/18592867.cfm

The distilled version is this: using these refrigerators on electric causes an inadequate weld to crack on the burner tubes, venting the ammonia to atmosphere. Then it's totally broken. Worse, if there's flame present it can start a fire (who knew ammonia could burn?!?). Dometic's official recall fix is to install a shield around the burner to prevent the fire. Nothing about changing anything to prevent the failure in the first place. Dang. But OTOH those resistance heating elements in those fridges aren't efficient so maybe this will all end up better in the long run.

So because of this manufacturing defect, my previous path to solar powered refrigeration has been closed and I must find another. I have about 1800 watts of panels feeding into an 1300AH 12V bank.

Any suggestions on a refrigerator? I've searched back a couple of years and it seems anything new would be ok, top freezer with the lowest consumption.

Phil

crewzer · January 2008

Re: Power-Save 1200?

Phil,

Here's a link to my HE fridge reports. I'll post the Nov. 1 through Feb. 1 report in a few days. It looks like it's going to come in at 1 kWh/day.

http://forum.solar-electric.com/showthread.php?t=449

HTH,
Jim / crewzer

PhilS · January 2008

Re: Power-Save 1200?

Jim, I re-read your thread a half-dozen times last year. Shooting for one that's less than 1KWh/day and you've given me hope of achieving that goal. Top freezer seems like the way to go, and even a small 18cf fridge would be cavernous after living with 12cf for the last 8 years. And that was still better than the luke-cold Siber (8cf?) that we endured for the decade before that.

I'm pondering the ice-maker option. I'm used to making them manually (bottled water only as I'm a con-a-sewer) but it would be a nice luxury. OTOH that's more power consumption for the heater (the motor and valve I'd deem negligible).

Did you get the ice maker Jim?

Phil

mike95490 · January 2008

Re: Power-Save 1200?

Here's some stuff about motor caps:

http://www.clrwtr.com/Single-Phase-Electric-Motors-Characteristics-Applications.htm
nearly down at the end.

http://www.newarkinone.thinkhost.com/brands/promos/leading_edge/ILL_Cap_Motor_run_capacitors.pdf
Longish article

I don't see much around covering small motor capacitor selection, and new energy star units likely have something in them anyway, to bump up their efficiency.

PhilS · January 2008

Re: Power-Save 1200?

mike90045 wrote: »

and new energy star units likely have something in them anyway, to bump up their efficiency.

That's kinda what I figgered Mike. But I also knew where to ask.

A little off-topic (but I'M the OP)... How toxic is ammonia? I mean, if one of these fridges developed a blowout, would my DW find her animals dead when we got home from work? (assuming no fire... I can't/won't haul them in to a dealer for the retrofit)

Phil

mike95490 · January 2008

Re: Power-Save 1200?

PhilS wrote: »

How toxic is ammonia? I mean, if one of these fridges developed a blowout

1) I'd figure it's close enough to be a topic !

2) It depends on the amount of ammonia in the system, and the size of the room it is in, and the size of the heater vent.

Ammonia is heavier than air, and will sink to floor level. The grocery store stuff you can buy is about 5%, and for cooling systems, it needs to be 90% or better. A cup of it (90%) will really stink up the place, and if it's a small area, likely be lethal.

crewzer · January 2008

Re: Power-Save 1200?

Phil,

No ice maker... we still use good ol' plastic trays.

Regards,
Jim / crewzer

PhilS · January 2008

Re: Power-Save 1200?

crewzer wrote: »

No ice maker... we still use good ol' plastic trays.

Thanks again Jim. That was the way I've been leaning. I'd have to engineer a 12V pump out of a 5 gallon bottle to supply an icemaker. But that's not too difficult since there's already a battery, 115V charger & 7amp solar controller under the RV fridges (and 100w of solar on the roof above dedicated to 'em). Those RV fridges require 12V to operate on propane or 115V. That'll all have to be moved when a regular fridge goes in (except for the panels if there's a reason to leave them). But there is room right next to the fridge space for all that and a 5 gal bottle of water.

I was more concerned about the power usage for the heating element to free the cubes... maybe after typing the previous paragraph I'm becoming more inclined to get the icemaker. Most of the system is already there and paid for.

I remember seeing a post listing some general wattages for ice makers and they seemed high but the duty cycle shouldn't be very long. I know there's slim chances of getting the breakdown from any fridge dealer.

I appreciate the inputs and will post back when I have some specific models in mind.

And thanks for the info on ammonia. I've been concerned about that since Dometic's problem was discovered. Hopefully the animals would simply head to the other end of the house and be fine. I really hope that's not going to happen since I never use the 115V elements anymore.

Phil

icarus · January 2008

Re: Power-Save 1200?

Phil,

In my opinion (worth just what you pay for it however!) is that the amount of ammonia in a Dometic is not enough to be dangerous UNLESS you are in a confined (closet) type space. I have had and worked on Dometics for better than 20 years and Servels before than. I have had only one failure and that was from running it out of level. (PS. I know of a couple of good cooling loop rebuilders for them. If you have one that is damaged, don't just toss it, because it does have value even with a busted cooling unit.

As to the cost of Propane,,,An average sized Dometic will burn about ~1 quart of propane per day at 75f. One can reduce propane consumption by adding insulation to the fridge cabinet, and if needed add a low wattage fan to blow over the fins at the back. At 1 quart per day, at an average cost of say $3.50 per gallon, that works out to about $.87 day or about $26 per month.

If you can increase the efficiency a bit the cost comes down. I have made the calculation (partly because I am stocked with propane fridges) that is is way cheaper to keep them rather than trade them for something else. Since I have gas hot water and gas range and need the tanks filled anyway it becomes easy. Between hot water, range and fridge, I burn 100# (20 gal) every 6 weeks.

If I was building a system from scratch I would have to consider up sizing the solar to use a 120vac fridge.

As I said before, this opinion is worth just what you pay for it. One final note, (most people know this) running an absorption fridge on electricity is very inefficient.

Icarus

SavingEnergy · January 2008

Re: Power-Save 1200?

Regarding Dometic refers with the recall defect. We have an RV that has a Dometic refer that is part of the recall. We had it fixed about six months ago. At that time, we had been living full time in the RV for 3 1/2 years. We are not traveling, just living on property we own. It's been operating on AC for the entire period, and we never had a problem. Your mileage may vary....

PhilS · January 2008

Re: Power-Save 1200?

icarus wrote: »

As to the cost of Propane,,,An average sized Dometic will burn about ~1 quart of propane per day at 75f. One can reduce propane consumption by adding insulation to the fridge cabinet, and if needed add a low wattage fan to blow over the fins at the back. At 1 quart per day, at an average cost of say $3.50 per gallon, that works out to about $.87 day or about $26 per month...

... running an absorption fridge on electricity is very inefficient. Icarus

I agree totally Tony. I don't defrost these fridges as often as I should (usually 3 times/year) so my propane usage may be more than it could be, but even with your figures both of my fridges use $50 per month. When I installed them, it was closer to $15 per month. These units are in a cavity that vents directly through the roof and I've tried fans behind them but couldn't stand the constantly changing fan noise (solar powered and changed speeds as clouds passed over).

I know those electric heating elements aren't efficient but that was outweighed by the fact that I could switch to propane during stormy weather (and no solar power). It seemed like the best compromise at the time. However I must run the propane generator anyway after a day or two of stormy weather so it wouldn't make much difference if the fridge was propane or electric.

And I agree with SavingEnergy that the chances of a fire are remote, but considering the consequences I can't ignore the possibility. A fire would destroy our home and pets. Coupled with the increasing cost of propane I consider myself forced to rethink my plans.

This isn't the first time.

If this forum was available 20 years ago my decisions may have been different. I'm guessing a class-action suit against W-S for not hosting this forum back in the eighties won't go far. (Mike, you still haven't shipped my new inverter.... ordered last week. I'm like a kid on Christmas Eve).

Phil

On edit: I don't figure Mike at W-S would even be reading this post, but the new Magnum inverter arrived a few minutes after I posted. I was monitoring the shipping status at W-S which doesn't show anything other than the order being received.

PhilS · January 2008

Re: Power-Save 1200?

SavingEnergy wrote: »

Regarding Dometic refers with the recall defect. We have an RV that has a Dometic refer that is part of the recall. We had it fixed about six months ago.

And although I agree the chances of a fire are slim, you DID NOT have the PROBLEM "fixed". You had a shield installed that would reduce the chances of a fire developing from the problem that STILL REMAINS: inadequate tubing thickness coupled with a weld that after repeated heating/cooling (from the electric heating element) can fail, dumping the ammonia. Dometic claims that a 154 watt heating element causes the problem and that they should have used a 125W element, however they don't change the element when doing the recall, do they? Correct me if I'm wrong.

For you the ammonia would simply dump out the vent to outside. For me, the ammonia would dump into our kitchen (provided it didn't start a fire). Coupled with the acknowledged inefficiency of using solar power to heat ANYTHING, I'm simply admitting the error of my plans and changing them.

Phil

Power-Save 1200?

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