Community Forums

Robin_M · 06-02-2014, 01:16 PM

From reading various threads it is easy to see that MANY RV'ers are now converting to residential refrigerators. And there are many good reasons to do that.

We've done it as well. But I am still curious about residential refrigerators and inverters. I know that our Samsung, and the Fisher & Paykal, refrigerators have their own on-board inverters, so they run fine with the MSW inverters that come installed on most coaches (other than some high-end units). I've seen several posts that imply that, for this reason, these are the only two residential refrigerator brands that are "rated to work" with a MSW inverter.

But several folks have installed other counter depth models made by Whirlpool, Frigidaire, Haier, LG, etc. Could some of you who have installed these other brands please chime in here and discuss how you dealt with this issue?

Did you...

Replace your inverter with a PSW inverter
Already have a PSW inverter installed in your coach or trailer
Install a small second dedicated inverter for the fridge
Use your coach's MSW inverter with no problems
Use your MSW inverter and did discover some anomalies
Think this whole MSW/PSW issue is just mis-informed hogwash
Just didn't worry about it

Have I forgotten any?

Thanks in advance for your comments.

al2ride · 06-02-2014, 01:26 PM

We were lucky that our coach came with a nice residential refrigerator and PSW inverter installed.

Being that these refrigerators are not cheap, I wouldn't mess around with a MSW inverter. Ours runs great with a dedicated 1000 watt inverter.

Winepress · 06-02-2014, 02:00 PM

As far as I can tell in looking at the schematic for the RF197, there is no inverter within the refrigerator. The 120VAC goes straight into the compressor. My appliance dealer friend got me the wiring diagram and said it was nothing special. The compressor is a standard model. Some of the higher end Samsung's do utilize a variable speed compressor, but not the 197. He did say that the unit would be better off on a PSW, so that's another future project if I keep this coach.
That said, the unit appears to run fine on the MSW and the members experience seem to indicate there are no issues.
I also have a small "dorm" style refrigerator in one of my outside bays. It runs fine as well.

Try and live up to your dogs opinion of you.

vsheetz · 06-02-2014, 03:15 PM

What is your usage model? Do you dry camp or just want to operate the refrigerator when traveling?

Unless the residential refrigerator is specifically noted by the manufacturer as ok on a MSW I would use a PSW.

And as I am a fan of point of use inverters to maximize efficiencies I would suggest to install a separate inverter for the refrigerator.

charles tuit · 06-02-2014, 04:26 PM

I installed a Haier 10.3 CF. I run it when not plug in on a Xantrex 458 modified sine, 2000 watt inverter/charger that was installed before the change. In approx. 1 year's time I have had zero problems. The only adjustment I have to make is when on inverter it runs slightly colder. I have 2 settings on the thermostat. One for inverter and one when plugged into 110 volts.

AFChap · 06-02-2014, 05:57 PM

I am installing a Frigidaire because DW didnt like the Samsung and other msw tolerant models I found. I can count on one hand the times we have run the refer on the inverter in the 11 years we have had this coach, so figure we just won't be doing that.

Robin_M · 06-02-2014, 05:58 PM

Quote:

Originally Posted by Winepress

As far as I can tell in looking at the schematic for the RF197, there is no inverter within the refrigerator. The 120VAC goes straight into the compressor. My appliance dealer friend got me the wiring diagram and said it was nothing special. The compressor is a standard model. Some of the higher end Samsung's do utilize a variable speed compressor, but not the 197. He did say that the unit would be better off on a PSW, so that's another future project if I keep this coach.
That said, the unit appears to run fine on the MSW and the members experience seem to indicate there are no issues.

Hmm. Looking at the schematics myself, it appears that you are correct. Although there is a circuit on the main circuit board labeled "PBA Sub Inverter", who's output goes to the main logic chip. Don't know exactly what that does. I also do not see anything in the schematic (or anywhere else in the service manual) that would indicate that the compressor is variable speed, unless that function is handled again by the main logic chip. There is an input to the compressor controller from the large main processing chip on the control board.

The Fisher & Paykel does have an entirely separate inverter module that is located behind the bottom access cover and sits right next to the compressor. I see no such module anywhere on the Samsung. If everything you said above is correct, there are a lot of folks here that are confused about the Samsung RF197. Although I will say that it does indeed seem to run flawlessly with the MSW inverter in my coach. Perhaps it is true that there is no separate inverter module in the Samsung, nor a variable speed inverter, but that its power logic is designed to support a MSW inverter just the same. Looks like some additional research about the Samsung RF197 may be in order.

Can anyone shed some additional light on how the Samsung actually works?

Robin_M · 06-02-2014, 06:36 PM

Quote:

Originally Posted by AFChap

I am installing a Frigidaire because DW didnt like the Samsung and other msw tolerant models I found. I can count on one hand the times we have run the refer on the inverter in the 11 years we have had this coach, so figure we just won't be doing that.

Paul,

I know you realize that means that any time you are not plugged in to shore power, you will have to have the genset running in order to run the refrigerator - like when driving all day, or loading up the motorhome to go on a trip, etc.. Won't that be awfully inconvenient? Not sure I'd want to settle for that option.

PushedAround · 06-02-2014, 07:02 PM

Quote:

Originally Posted by Robin_M

Can anyone shed some additional light on how the Samsung actually works?

Robin, I haven't seen the schematic for the Samsung (you can send it to me if you want) so can't help you with that but I can tell you that an inverter has solid state relays that modify the frequency of the power going to the compressor. Therefore, it must be in line with the main power wiring to the compressor. You are correct in that the F&P has a typical external module. Alternately, and I have never seen this before, Samsung could have it contained with-in the compressor itself, but I really doubt it.

Robin_M · 06-02-2014, 07:30 PM

Thanks for your response, Larry. The Samsung compressor does have a small box attached to it's sidewall on the far side of it. (Can't see it from the back access cover.) But it does not seem large enough to be an inverter, and there's no mention of it in the service manual. I suspect it's nothing more than a junction box. If you would like to take a look at the service manual (which contains pictures of the control board, block diagrams, wire diagrams, and a full schematic) I'd be happy to send it to you. Drop me a PM with your email.

______________

We've gotten off topic with this interesting discussion about the Samsung. Still love to hear responses to the original question.

PushedAround · 06-02-2014, 08:13 PM

Rob, thanks for sending the diagram. The PCB board definitely contains the inverter circuitry. They have everything integral to that board, which certainly makes it more economical. Remember that the loads are small and therefore so is the inverter. The solid state switching relays are the 3 silver heat sinks with the black chips on them labeled #2 on the page 93 picture. And it does say inverter control on item #13 on the diagram on page 92.

Robin_M · 06-02-2014, 11:29 PM

Quote:

Originally Posted by PushedAround

Rob, thanks for sending the diagram. The PCB board definitely contains the inverter circuitry. They have everything integral to that board, which certainly makes it more economical. Remember that the loads are small and therefore so is the inverter. The solid state switching relays are the 3 silver heat sinks with the black chips on them labeled #2 on the page 93 picture. And it does say inverter control on item #13 on the diagram on page 92.

Larry,

I think you have hit upon it - almost. Those three black chips with the heat sinks appear to be transistors (Q701, Q702, Q703) in the fan control section of the board. The fan power terminal is right next to them. They appear to supply variable voltage to the three fans: the compressor fan "C-FAN", the freezer fan "F-FAN" and the fan for the fresh food compartment "R-FAN".

However there definitely is that section 13 near the other end of the board which is clearly marked as an inverter circuit for the compressor ("Inverter COMPor"), and it is near the terminal connector that triggers the compressor. After studying the schematic again, I believe the solid state switching relays you were looking for may be in that tan colored module on the edge of the board (in the same Area 13) that is labeled "PBA Sub Inverter" both in the picture and in the schematic. It looks like the output from that goes through the main logic chip (the long IC) and then to the compressor via the RY73 relay module which is in the area marked "High Voltage" near the same terminal connector. I believe the purpose of RY73 is to "echo" these low voltage trigger signals into the 120v circuit that feeds the compressor via the PTC relay located on the sidewall of the compressor. I believe this whole mechanism is what is labeled "Load Control Circuit" in the block diagram on page 95. Do you agree?

So you are correct... the circuitry that acts as the inverter for the compressor is all integral to the main circuit board. I guess this all means that the compressor probably does have a variable speed after all. Correct? Otherwise, what would be the point of all that circuitry?

Therefore I suppose that it can logically follow that another benefit of all this is that the compressor would indeed not be sensitive to the MSW inverter on board the coach (even though the other side of the compressor motor is directly connected to the line voltage through an overload protector).

Larry, thanks again for helping me to figure all this out. For other readers... sorry to get so technical here. After reading the message from Winepress (Post #3 above), this was really starting to bother me. Didn't mean to be so anal.

Winepress, would you (or anyone else) like a copy of the service manual so you can follow all this? If so, send me a PM with your email address.

PyrateSilly · 06-03-2014, 06:35 AM

We had already taken out and replaced our 1500 watt modified inverter with a 3000 watt pure sine inverter about a year before changing the fridges. We also changed out the 20 yr old TVs for LED's. With so many electronics aboard Thom just did not want to take any more chances with things going bad.
We already had to replace a microwave/convection oven from the inverter not being quite big enough to handle the load and add in a new solar controller when we realized that something did not have a stop to stop charging batteries and ended up needing to also replace all the batteries when they got cooked. Have not had any problems so far since we added the larger pure sine inverter. Pretty much everything in the coach runs thru the inverter, that's the way it was built, so just better for us to go the route of a new, larger pure one.

Ramets · 06-03-2014, 07:08 AM

When I finally threw out my Dometic fridge, I put in a Whirlpool. I already had a Magnum 3000w PSW inverter & 480 watts of solar, along with my AGM's. But the main reason we went with the Whirlpool was the ease of any maint. that might have to be done. By removing the outside panel a tech can easily get to all the working parts of the fridge. Don't have to worry about trying to slide it out to fix anything.