Norcold Fridge on Propane Question

[KenS999]

Hello I have a Norcold fridge model # 306RM8 in my travel trailer. I am boondocking so always running refrigerator in propane mode. From what I have been told, the temperature dial basically just controls the height/intensity of the burner flame as opposed to a thermostat setup. While daytime refrigerator interior temperature levels are good, later in the evening I have to back down the temperature dial otherwise by morning everything in the refrigerator department compartment is frozen. Just wondering if anybody has figured out a solution for this issue that doesn't involve buying a new refrigerator? Thanks.

[KenS999]

Thanks all for the insight on how my absorption fridge works. -OP

[Boon_Docker]

dougrainer wrote:

Boon Docker wrote:

MT BOB wrote:
Really? What is an RM8,there is virtually no info on the net.And,seems you do not understand logic,when the thermostat calls for more cooling, the flame gets higher, and the increased flame makes the ammonia heater work harder, producing more potential to remove heat from the inside of the refrigerator.AND,as it appears you do nothave/own a fully electronic refrig. your symptoms are perfectly normal.same as if you do not take your foot off the gas pedal, when rushing downhill.

:h

So when the fridge is running on 120V instead of propane does the heating element receive more power to make it hotter.

It seems someone here does not understand how an absorption fridge controls the temperature in the N306. 🙂

BYPASS Refers have a BYPASS tstat that regulates the flame height. These refers have an additional mechanical 120 volt point Tstat. You do not understand how it controls.
This particular refer does NOT have a Bypass tstat. It has a mechanical GAS tstat. The instructions clearly state that it has LOW-MED-HI for Gas control. YOU have to manually go from the 3 settings to change the temp if it gets too cold. It does NOT change the flame height like a bypass gas control. Doug

I guess I am the one that does not understand the operation of the N306. :S

My apologies to MT BOB

[Old-Biscuit]

Almot wrote:

Gdetrailer wrote:

Some of the newer RV fridges have a makeshift T stat control, basically a thermistor attached to one of the cooling fins in the fridge section, you slide it up and down the fin to control the fridge temps.. No thermistor, no control you can adjust..

My 6 cu.ft Norcold has this thermistor on the fin. It's position has very little effect on the temperature or the On-cycle duration, not nearly as much as the thermostat position. Gas thermostat has High-Med-Low setting and I sometimes put it on the Low in the evening or when the freezer section is empty and/or items in the fridge section are not critical - and then it runs less often. Propane fridge sucks, but this is the easiest option in off-grid.

That is because the thermistor position should be fixed as the thermostat is OEM calibrated for temp range based on that thermistor position

Adjusting thermistor position UP/DOWN can affect fridge overall temps (minor affect 4*F - 6*F) IF---IF fridge uses an 'Automatic Temp Control' (No temp setting adjustments)

[time2roll]

MT BOB wrote:
Really? What is an RM8,there is virtually no info on the net.

Actually there is. See remarks below your post.

[Almot]

Gdetrailer wrote:

Some of the newer RV fridges have a makeshift T stat control, basically a thermistor attached to one of the cooling fins in the fridge section, you slide it up and down the fin to control the fridge temps.. No thermistor, no control you can adjust..

My 6 cu.ft Norcold has this thermistor on the fin. It's position has very little effect on the temperature or the On-cycle duration, not nearly as much as the thermostat position. Gas thermostat has High-Med-Low setting and I sometimes put it on the Low in the evening or when the freezer section is empty and/or items in the fridge section are not critical - and then it runs less often. Propane fridge sucks, but this is the easiest option in off-grid.

[Gdetrailer]

Boon Docker wrote:

MT BOB wrote:
Really? What is an RM8,there is virtually no info on the net.And,seems you do not understand logic,when the thermostat calls for more cooling, the flame gets higher, and the increased flame makes the ammonia heater work harder, producing more potential to remove heat from the inside of the refrigerator.AND,as it appears you do nothave/own a fully electronic refrig. your symptoms are perfectly normal.same as if you do not take your foot off the gas pedal, when rushing downhill.

:h

So when the fridge is running on 120V instead of propane does the heating element receive more power to make it hotter.

It seems someone here does not understand how an absorption fridge controls the temperature in the N306. 🙂

No.

BUT what DOES happen is the electric heating element is turned ON more than turned OFF. In other words, the control board regulates the heating element just like a PWM (pulse width modulation)control..

Fridge T stat calls for more cooling the heating element is turned on LONGER until the fridge T stat sees the correct temp..

In reality, the gas burner should also do the same, it would take some fancy variable regulator on the gas side to make a "variable flame"..

I do know on older "pilot" type RV fridges they had a fixed pilot sized flame and when cooling was needed the gas valve would open creating a larger flame.. I had one of the older fridges with a pilot that didn't have electronic control board..

My current TT HAD a RV fridge with electronic control board, never got to see how that one worked since the cooling unit had ruptured before I bought the trailer..

And as far as the OPs temp swing issue, yeah, your gonna have to live with those large temp swings.. My first TT, that one would freeze everything in the fridge section solid over night (20s in the fridge section) when outside temps dropped to 70's and swing up to 50F or higher with the daytime temps in the upper 90's..

Some of the newer RV fridges have a makeshift T stat control, basically a thermistor attached to one of the cooling fins in the fridge section, you slide it up and down the fin to control the fridge temps.. No thermistor, no control you can adjust..

[Old-Biscuit]

See pg. 5 in the 306 Manual LINK for explanation of Gas Control

*gas has a thermostat for temp control ------YOU

Very simple absorption fridge....no bells/whistles no circuit board no automated controls...what do you expect with a 2.7 cu/ft fridge

[dougrainer]

Boon Docker wrote:

MT BOB wrote:
Really? What is an RM8,there is virtually no info on the net.And,seems you do not understand logic,when the thermostat calls for more cooling, the flame gets higher, and the increased flame makes the ammonia heater work harder, producing more potential to remove heat from the inside of the refrigerator.AND,as it appears you do nothave/own a fully electronic refrig. your symptoms are perfectly normal.same as if you do not take your foot off the gas pedal, when rushing downhill.

:h

So when the fridge is running on 120V instead of propane does the heating element receive more power to make it hotter.

It seems someone here does not understand how an absorption fridge controls the temperature in the N306. 🙂

BYPASS Refers have a BYPASS tstat that regulates the flame height. These refers have an additional mechanical 120 volt point Tstat. You do not understand how it controls.
This particular refer does NOT have a Bypass tstat. It has a mechanical GAS tstat. The instructions clearly state that it has LOW-MED-HI for Gas control. YOU have to manually go from the 3 settings to change the temp if it gets too cold. It does NOT change the flame height like a bypass gas control. Doug

[wildtoad]

What happens with the burner turned down to a lower setting during the day? Does the temp inside the fridge get too high? Is there anyway to better insulate the fridge?

[wnjj]

306 manual

It looks like the 306 is like you describe (3 manual selections of gas flame setting). I can't think of any easy way to automate that as gas the control is likely fully mechanical.

Turning the fridge down at night and up in the morning will just have to be part of your routine.

[Boon_Docker]

MT BOB wrote:
Really? What is an RM8,there is virtually no info on the net.And,seems you do not understand logic,when the thermostat calls for more cooling, the flame gets higher, and the increased flame makes the ammonia heater work harder, producing more potential to remove heat from the inside of the refrigerator.AND,as it appears you do nothave/own a fully electronic refrig. your symptoms are perfectly normal.same as if you do not take your foot off the gas pedal, when rushing downhill.

:h

So when the fridge is running on 120V instead of propane does the heating element receive more power to make it hotter.

It seems someone here does not understand how an absorption fridge controls the temperature in the N306. 🙂

[BFL13]

You are not alone--but this guy didn't get much of an answer.

EDIT---oops, that's you! Sorry. Oh well.

https://www.forestriverforums.com/forums/f113/norcold-refrigerator-temperature-swing-185567.html

[MT_BOB]

Really? What is an RM8,there is virtually no info on the net.And,seems you do not understand logic,when the thermostat calls for more cooling, the flame gets higher, and the increased flame makes the ammonia heater work harder, producing more potential to remove heat from the inside of the refrigerator.AND,as it appears you do nothave/own a fully electronic refrig. your symptoms are perfectly normal.same as if you do not take your foot off the gas pedal, when rushing downhill.