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Residential Refrigerator Upgrade


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About 70% done with the workstation installation in the Sonshine Express, and the doggone Dometic croaked. Yup, got up one morning to see 46 degrees on the display and saw yellow powder beneath the burner. Mr. Penner pronounced it "dead", mentioned the cost of a cooling unit, and after a short meeting with my Bride decided to put in a residential unit. We have a maximum space of 70" high, 36" wide, and 30" deep, but a bit shorter and narrower would mean less cabinet work and time. This is going in a 2010 Mobile Suite 36RSSB. Got any suggestions on brand and model numbers that have been used? Also, I remember reading (possibly on another forum) about fridges that have a "soft start" compressor that is supposed to be much easier on power drain on start up. Looking for some education on this as well. Always thankful for the wealth of knowledge here.

 

Jeff

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Jeff,

We are amazed how little power our soft-start VFD (Variable Frequency Drive) Fridge uses, The unit model it is: Frigidaire, Mode:l FFT1222QB

 

We converted to a 12 Cu ft VFD shop / patio model VFD (Variable Freq Drive) fridge almost two years ago.

 

The solid-state VFD in this fridge makes this unit insanely efficient power-wise.

 

We have boon docked many times more than two-weeks solid with only two group 31 deep cycles and a cheap modified 400W inverter driving the fridge and our coffee grinder and still never had any issues.

 

The real advantage of the VFD is that it NEVER starts the fridge compressor at full speed and almost never runs the compressor at full rated power often the entire on-time for a 24 hour period is measured in minutes of low-speed / low load compressor operation ONLY as needed to maintain the desired temps.

 

"Normal Fridges" are like hot-rod teens that peel-off at every stop light ...... most fridges start at "Full-Throttle" and thats a HUGE waste of power.

 

Be careful when selecting a new residential fridge for RV use.....many new fridges only operate at a limited ambiant temp range of about 60f to 85f and then a internal kill-switch powers them off ........ this is a ploy to better energy-star ratings ...........

 

We enjoy -10f freezer temps and NEVER worry about out-of-level parking or being without cold food storage..........

 

Our led lights use about the same power as our fridge on a weekly basis.....

 

Take a look at the size and specs it might fit your needs ........it sure has worked well for us........

 

Drive on............(Enjoy the hard ice cream........)

Edited by Dollytrolley
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Jeff we changed over about 3yrs ago. Best move we made. You will like it. I had a std 7.5 cuft Dometic so your space is bigger so our 11 cuft Whirlpool is too small. But the install is not bad.

 

Since the space for the fridge is vented outside now, and your opening will likely be a snug fit, you will want to create an airflow around the fridge and a way for the heat to escape from behind. Venting to outside ambient has the fridge designed to operate at room temp actually running at what ever the Outside air temp is. Blocking the outside vents when done, putting some vent holes inside the cabinet next to the fridge say beside the fridge down low where the drawers are, and an exit vent above fridge will create a natural heat rise and vent. Then fridge runs at room temp as designed.

 

We also find no issues with power. I ran a separate circuit to the fridge and use a 1000W PSW inverter with an auto transfer sw. Fridge runs all day when we travel and my batt levels are the same when we arrive as when we left. Thats with just the little #12 wire on the 12V side from the truck plug charging the 4 6V batts. Boondock we have the 4 batts and genny to recharge. Has worked out fine for us.

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I put a Samsung RF18 fridge in my Teton a month or so ago. I had a bit more work because a heater was below the fridge. The Small three door Samsung fridges, they make an 18 and 20 CF model are a good fit. The 18 CF is 29 deep less the handles, the 20 CF is 2" deeper. The inverter for these sit on top of the case in the back and you would need 72" clearance or the ability to tilt the fridge to clear a cabinet lip? Generally there is vent space in the back that would allow the inverter to work in that opening size. The case nominal height is 69 inches. I had considered the 20CF model but, the extra 2 inches would have been quite noticeable, the doors on my 18CF are just proud of flush to the cabinet.

 

Steve

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Several (many) threads on RV Net - both in the MH & 5th wheel forums.

Search current threads as well as the (over 12 month old) archives..

 

Worth the effort to see the various brands & models the owners have utilized.

 

Some mfgrs of new RVs have been offering residential fridge as an option to AC/propane..

 

When my AC/propane fridge bites the dust - the residential will be a "no brainer" for me.

Only decision - as with you - is which one to choose.

 

.

 

 

 

.

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Dollytrolly,

that's good info on the soft start - VFD unit. We are looking for 18 cu. ft. or a little bigger if the unit will fit in the opening without too much modification.

 

Hone Eagle,

I'm a bit nervous of the Samsung units after reading numerous negative reviews on their potential for icing the coils. How has yours performed?

 

Billr, I remember your posts on your upgrade, and our opening offers a gain in size of about 6 cu. ft. or more with minor cabinet mods. Will keep in mind the air flow around the unit.

 

 

Steve in SoCal, like I wrote to Hone Eagle - a bit concerned about all the negative reviews on the Samsung after the 1 - 2 year period of operation. How is yours running?

 

Pappy Yokum, we be/been searchin' but are a bit overwhelmed with the different applications, i.e. the make and model of RV and the variations in dimensions of the area.

 

GeorgiaHybrid, we see the numerous optional factory installed residential units, but it would seem that the dimensions are considered in the design and engineering of the unit before construction. We are trying to consider where we "Rob Peter to pay Paul" with the cabinetry as we shop the available refrigerators.

 

We are going to look at a few units tomorrow with tape measure in hand and the ideal dimensions on paper. We'll see how our fact finding mission goes. Thank you everyone for the input.

 

Jeff

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Dollytrolly,

that's good info on the soft start - VFD unit. We are looking for 18 cu. ft. or a little bigger if the unit will fit in the opening without too much modification.

 

Hone Eagle,

I'm a bit nervous of the Samsung units after reading numerous negative reviews on their potential for icing the coils. How has yours performed?

 

Billr, I remember your posts on your upgrade, and our opening offers a gain in size of about 6 cu. ft. or more with minor cabinet mods. Will keep in mind the air flow around the unit.

 

 

Steve in SoCal, like I wrote to Hone Eagle - a bit concerned about all the negative reviews on the Samsung after the 1 - 2 year period of operation. How is yours running?

 

Pappy Yokum, we be/been searchin' but are a bit overwhelmed with the different applications, i.e. the make and model of RV and the variations in dimensions of the area.

 

GeorgiaHybrid, we see the numerous optional factory installed residential units, but it would seem that the dimensions are considered in the design and engineering of the unit before construction. We are trying to consider where we "Rob Peter to pay Paul" with the cabinetry as we shop the available refrigerators.

 

We are going to look at a few units tomorrow with tape measure in hand and the ideal dimensions on paper. We'll see how our fact finding mission goes. Thank you everyone for the input.

 

Jeff

 

Jeff,

 

Indeed you likely want a 18 C U Ft unit somewhat like your old unit.........

 

We continue to be amazed with our VFD fridge in that the designers really "thought-out" the design very well including the interior of the fridge.......don't try this at home......the middle "door-shelf" in our VFD easily holds THREE one-gallon Jugs of milk and two bottles of wine AND the door still has TWO more of these shelves!!

 

The crisper drawers and meat compartment drawers slide very well and the shelves adjust very nicely ........Wish our two +$2500 other big house fridges were as well thought-out and designed......

 

The freezer compartment holds a TON of items as well....

 

The VFD is the "future of fridges" but...... I would really advise that you REALLY look hard at fridges that are approved for patio / garage installations as these fridges do NOT have the kill-switches internal that limits the fridge operations to ambient temps of 50f to 80f and then shut the fridge down outside these temp ranges.........

 

We downloaded a ton of fridge manuals before we found the NON-KILL-SWITCH fridge that we purchased.

 

Best of luck fridge shopping......

 

Drive on.......(Keep your.....cool)

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Jeff,

 

I have only had the fridge for 5 weeks so I can't give you a long term report. I did read negative comments about this AND every other fridge out there. I don't know how it will perform in 3 years BUT, in a consumer report review of all brands and models Samsung was the least problematic followed by GE.

 

In my Teton I didn't have a lot of width to play with and shallow depth. The only option beside the fridge I choose was several thousand more or a small fridge like Dollytrolly. The small fridge was just too small and a wider fridge wouldn't work so this was really the only practical choice.

 

I mentioned an inverter; that is synonymous with vfd, an inverter variable frequency drive uses AC current, converts it to DC and, inverts that to chopped AC. That in turn powers a pollyphase motor from 0 to could be 60-400Hz. They are widely used in machinery and process control, I have VFD's up to 50 HP. About 15 years ago they became popular in HVAC and refrigeration, most new fridges at least the bigger ones have a VFD. The operation low temp range of the Samsung is 50F according to their lit, it says it may not function optimally below that?

 

Steve

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Dollytrolly.....is THIS the fridge you have?

 

You say you "converted it"....what does that entail?

 

Jack,

 

Yes that is the Fridge we installed in our small 30 ft Dolly-the-Paint-Horse Toyhauler and life has been very .... cool since..........

 

Perhaps I misused the word "Converted" in that the fridge needs no real rework to install it ......however the RV needs some rework since the installer needs to CAREFULLY plug and LEAK-TEST the no longer needed propane line that used to power the RV fridge.

 

Next we needed to deal with terminating the 12 VDC line to the old RV fridge AND deal with the power indicator on the trailer warning panel.

 

Next we blocked off the old RV fridge chimney since the heat-loss is a tiny fraction of the original RV fridge. We felt that at lower temps we did not want to over-cool the fridge so much that it would trip into heat mode to prevent the refer-section using unneeded power to keep the reffer-section from turning into a freezer........

 

The last item was to properly secure the new unit in the old fridge location so that the unit becomes one with the trailer structure.

 

Initially we used a 2K modified inverter to see if the compressor would be stressed with the less-than-ideal wave form .....but compressor temps and power plots were the same as standard 120 VAC line power so.........we decided to downsize to a smaller 400 watt inverter to lessen the inverter only power drain with the fridge off. Seems to have no problems with the cheap 400 W modified for weeks on end.

 

A lot of folks tend to think of fridge operations as simple as straight-line-power-calculations however this is not the real world.........this VFD fridge spends a LOT of time powered down.......when it does operate the compressor the power ramps up and down only as needed so.......the amp draws tend to be VERY LOW overall..........insanely low when you plot the power (or off-time) in real time.........

 

I used to have to deal with DETAILED REAL-TIME TESTING however these days I have lowered my pay-grade to the level if the Dr. Pepper is cold...... (NOT frozen)...... then the fridge has.........passed the Test.......

 

This fridge is pretty plain-jane looking outside but inside it has very well designed spaces and the power draw is insanely-low and that has worked very well for us........

 

Try it you will likely keep your ......cool

 

Drive on ...........(Enjoy the ........cool)

 

Drive on

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Went shopping today and brought this little gem home in Darth, our smart. It fits without any modification! Actually we found a Kenmore side by side that will fit comfortably with only a small modification to the little cubby hole above the fridge and relocating the LP line to the oven. This will then move to the "belly of the beast" to become the beer fridge. Also got a reasonably good deal on a compact LG front loading washer to replace the 6 year old Whirlpool that has been busting our butt for a few months. Pretty sure that Vern (Wrknrvr) will have a post on strengthening the the base of the slide prior to the refrigerator installation.

 

 

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What's wrong with this fridge on the pic ? A few tie down straps and a trimmed up curtain for beauty and your all set. No??

X 10 Bill.........PLENTY of room ........just wander down to Wal-Mart and get one of those Cheep 60'HDT/ LED Tvs and Duck-Tape it in Portrait-Mode above the fridge and then reach down to the fridge and peel-tha-top-off-ah- Dr. Pepper...........Red-Neck Home Theater.............

 

Drive on........(Don't spill your ......Dr Pepper)

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Is the 70" from the top of the shelf the bar fridge is sitting on? If so, you could buy some more height by removing that shelf. This was done in my TS. The drawer, roughly 6" high was removed along with the shelf above which the old RV fridge sat on.

 

The remaining cabinet bottom wasn't deep enough or strong enough to handle the 36" retro 50's fridge from Elmira Stove. The existing lower shelf was beefed up by doubling up 2 pces 3/4" plywood and projecting it beyond the existing box by 4".

 

Widthwise we were OK after removing a 12" pantry, adjacent and the divider.

 

The fridge has 4 tie back brackets installed through the top rear vent from wood framing to the back of the fridge. the front is lagged to the doubled up shelf at the front.

 

We were pretty tight for space, but not too tight. Had we been too loose, filler panels could have been made to pick up the slack.

 

Not all fridge specs include the top mount hinges or covers that cover them.

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Shoot, just fill in above with shelves and Ramen noodles and fridge with beer and its college dorm all over again.

Roomee in school was premed.........he calculated that a "defined-mix" of regular and lite-beer would provide "proper-nutrition" AND then you could just skip the Ramen all together.........

 

Doctors orders.......

 

Drive on......(Keep the fridge well stocked.......)

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Hummmm........ I noted in the specs that this fridge is showing a minimum of a 15 amp 120 VAC supply circuit and has a current draw rating of 6 amps at 120 VAC. I am encouraged by Paul's findings of the actual current draw of the VFD compressor. If one were to go by the manufacturer's specs you would think that a 1500 watt inverter would be needed to meet line voltage supply specs. (15 amps = 1,800 watts x 80% = 1,440 watts). The 6 amp spec translates to 720 watts leaving me thinking that the minimum rated wattage for a MSW inverter (remember these units P-to-P voltage is = to 110 VAC RMS, not the 168 P-to-P of a true sine wave) would be 1,000 watts. Learning that Paul is running his unit off of a 400 watt MSW inverter is great. But, as with any refrigeration unit the duty cycle of the compressor is often determined by the ambient temperature, how frequently one opens the door and what the temperature is of any items placed in the frig. I can see this unit putting a real strain on a 400 watt MSW unit on a hot day when the 12 pack of Dr. Pepper placed inside is not pre-cooled, and those close at hand are frequently opening the door to snatch another can. What I would be interested in learning is how well the 400 watt MSW inverter performs under the above conditions. When an inverter is operated at or near its maximum rating they generate a lot of internal heat thus extended use beyond 60% to 70% is frowned upon and can result in premature switching transistor failure. So, if we use 70% as the max continious load (with adequate cooling air flow) the 400 watt MSW unit would need to be delivering no more than something in the area of 280 watts for continued reliability. There is a big difference in the manufacturer's 720 watts and my computed 280 watts from a MSW inverter. I really like Paul's results and findings related to his choice for a refrigerator and have a tremendous respect for his extensive evaluation and testing of equipment. Since I will most likely be switching to a residential unit in the near future, the "wire jiggler" side of me would like to know more about how the 400 watt MSW inverter is surviving.

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Hummmm........ I noted in the specs that this fridge is showing a minimum of a 15 amp 120 VAC supply circuit and has a current draw rating of 6 amps at 120 VAC. I am encouraged by Paul's findings of the actual current draw of the VFD compressor. If one were to go by the manufacturer's specs you would think that a 1500 watt inverter would be needed to meet line voltage supply specs. (15 amps = 1,800 watts x 80% = 1,440 watts). The 6 amp spec translates to 720 watts leaving me thinking that the minimum rated wattage for a MSW inverter (remember these units P-to-P voltage is = to 110 VAC RMS, not the 168 P-to-P of a true sine wave) would be 1,000 watts. Learning that Paul is running his unit off of a 400 watt MSW inverter is great. But, as with any refrigeration unit the duty cycle of the compressor is often determined by the ambient temperature, how frequently one opens the door and what the temperature is of any items placed in the frig. I can see this unit putting a real strain on a 400 watt MSW unit on a hot day when the 12 pack of Dr. Pepper placed inside is not pre-cooled, and those close at hand are frequently opening the door to snatch another can. What I would be interested in learning is how well the 400 watt MSW inverter performs under the above conditions. When an inverter is operated at or near its maximum rating they generate a lot of internal heat thus extended use beyond 60% to 70% is frowned upon and can result in premature switching transistor failure. So, if we use 70% as the max continious load (with adequate cooling air flow) the 400 watt MSW unit would need to be delivering no more than something in the area of 280 watts for continued reliability. There is a big difference in the manufacturer's 720 watts and my computed 280 watts from a MSW inverter. I really like Paul's results and findings related to his choice for a refrigerator and have a tremendous respect for his extensive evaluation and testing of equipment. Since I will most likely be switching to a residential unit in the near future, the "wire jiggler" side of me would like to know more about how the 400 watt MSW inverter is surviving.

 

 

Initially we used a 2K modified inverter to see if the compressor would be stressed with the less-than-ideal wave form .....but compressor temps and power plots were the same as standard 120 VAC line power so.........we decided to downsize to a smaller 400 watt inverter to lessen the inverter only power drain with the fridge off. Seems to have no problems with the cheap 400 W modified for weeks on end.

Now that I think about it it seems that the slooow-ramp-up of power is likely what keeps the 400W inverter happy.......IF you dig deep into the electrical specs under the wire diagram it gives you some rather vague clues as to the insanely low power draws on out fridge.......I used a Fluke Scope meter (Fluke cost 4X the fridge price) for some test logging but for the most part we saw 90W and lower for most of the run times ........here is the catch......this fridge has fairly short run-times even when the door is opened often....

 

I did "perform" a "Red-Neck" fridge-power-test by..........not latching the refer door and the door was open for more than 2 hours from Yuma to Buckeye AZ on a 85f day while running on the 400 W inverter.....and the freezer remained below -5f refer was pretty warm and the floor was not pretty.......

 

DISCLAIMER: Maybe I am taking a chance using a 400W inverter to power this fridge but so far it seems to be working for .....US......and my GOAL was to have a very LOW power drain smallish-inverter since the fridge is powered OFF for much of the day so hence the effort to conserve inverter power in the fridge-off cycle..........now the 400W inverter has a 800W surge capacity but I do not recall seeing any power plots that high when I reviewed the Fluke plots.......

 

A lot of folks tend to think of fridge operations as simple as straight-line-power-calculations however this is not the real world.........this VFD fridge spends a LOT of time powered down.......when it does operate the compressor the power ramps up and down only as needed so.......the amp draws tend to be VERY LOW overall..........insanely low when you plot the power (or off-time) in real time.........

 

Maybe I got lucky with this fridge .......but it has worked really well for us....

 

Drive on .........(Cool is.......Kool)

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Question for you guys.... what is the difference between a "VFD" type refrigerator and an "inverter" type of refrigerator?

 

Thanks

 

 

Pretty much the same animal........

 

Inverter compressor: uses an external variable frequency drive - to control the speed of the compressor. The refrigerant flow rate is changed by the change in the speed of compressor. The turndown ratio depends on the system configuration and manufacturer. It modulates from 15 or 25% up to 100% at full capacity with a single inverter from 12 to 100% with a hybrid tandem.

 

Link from .........https://en.wikipedia.org/wiki/Inverter_compressor

 

Drive on........... (Your cool may.......be variable)

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Paul, cool and as said, "Drive On"

 

I trust your measurments and remain amazed at the results. I'm an old man that earned his EE when we were still using knob and tube house wiring and vacuum tubes. All this "new stuff" like VFD refrigeration compressors are not unfamiliar conceptionally but require additional study to fully understand how well they perform.

 

Getting back to some of the "old stuff" like MSW inverters - just for back pocket reference the difference between the "lost" battery reserve between a 400W and 1000W inverter is really insignificant. Over a 25 hour period you are looking at something like 10 minutes more with the 400W unit.

 

I also hate the way manufacturers advertise a 400W MSW inverter as having 800W of surge power. Shucks, some even advertise them as 800W units :angry: . The "surge" power is supplied by one or more electrolytic capacitors on the DC side of the switching transistors. If you were to do a current plot for this surge on the AC side you would find it in the order of 2-3 milliseconds - way short of anything of significance in getting an electric motor rolling (my digital o'scope records and is fast enough to capture that time frame). For those not familiar with such trivia, that is no more than 3/1000th (.003) of a second. Considering the frequency of a typical AC sine wave being 60 Hz, or switching polarity 60 times a second, that is just a tiny map dot at the beginning of the first cycle and way short of the needed time to charge even a small AC starting capacitor which normally needs at least two full cycles for a X2 surge of 33 ms. Now, that said, a VFD compressor that ramps up from locked rotor current slowly might just benefit from that .003 second surge - I'll have to do some more "learning" on these VFD units to definatively give a yes or no. It also comes to mind that it is a shame we do not have a control board option that powers the refrigerator's inverter directly from a DC source, eliminating the need for us to use an external inverter to provide the residential 120VAC. Maybe if there is enough demand some injun-ear will develop one for us?

 

Anyway, thanks for sharing the background and results you have found. You have raised my level of curosity on the innards of these new animals. Might just have to buy one so I can learn more :rolleyes:

Edited by RandyA
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