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Old 08-13-2017, 07:05 PM   #1
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refrigerator power question

my wife and I just purchased a 2018 Flagstaff T12RBST. we pick it up this Wednesday. this unit comes with a Dometic 2.5cu ft 3way refrigerator- i'm guessing (from checking various sites) that this is probably a model RM4223RB. I also understand that it is an absorption cooling operating system as opposed to a compressor type. my question concerns operating a generator in conjunction this appliance. I have a little 1000watt Yamaha generator. I have always heard where A/C units and anything else with a compressor system requires at least 3000watt minimum power rating to handle "kicking" on the compressor. what are the power requirements for the absorption systems? I don't know much about the A/C heatpump except it is listed as a "Cooll Cat". I don't expect that my generator would be up what's necessary for an A/C unit, but what about the refrigerator, and the microwave? this little Yamaha is super compact, extremely quiet, and has been very reliable- i'm hoping that with the exception of the air conditioning it would provide a source of "shore" power for everthing else. thanks.
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Old 08-13-2017, 09:39 PM   #2
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My Honda 1000 powers my 25 foot trailer with no issues I have a 7cf Dometic refrigerator . It will not run the a/c. It may run your microwave depending on the wattage.
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Old 08-14-2017, 06:10 AM   #3
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Your microwave oven's label should list the running wattage. The refrigerator should have a label inside with the model number and wattage.
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Old 08-15-2017, 12:30 PM   #4
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The 120 volt heating element on those units is about 325 watts, so your generator should power that as long as there isn't too much else consuming power.
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Old 08-15-2017, 01:32 PM   #5
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You might want to have this thread moved to the A-frame forum. The fridge, in particular, is different from the model used in most travel trailers.

The Dometic 4223 (what is in my A-frame) has a 160 watt heating coil for AC, and the same 160 watt coil for DC. The fridge is manual start and continuous run, and is NOT thermostatically controlled.

On AC, there is a knob in the upper outside panel that works like a light dimmer in your house, controlling the amount of power to the fridge heating coil. This indirectly raises or lowers the temp inside the fridge.

On DC, the fridge run continuously at full power (160 watts/13.3 amps@12V) as long as the battery holds out. You don't want to run on DC unless your battery is being charged at the same time.

On propane, the flame size is controlled by a knob in the lower outside section. You have to start the flame on propane by simultaneously pushing in the on/off valve (in the on position) and pushing the red ignitor button. You hold in the on/off valve for about 20-30 seconds to allow the flame to get hot enough for the flame sensor to keep the valve open.

On propane, the fridge uses zero electricity. There is no 12V control board.

To control fridge temperature, you dial back the propane or AC using the adjustment knobs. Use of a battery-powered wireless outdoor thermometer ($10 at Walmart) is highly recommended for monitoring fridge temps. My unit will read into the console in our minivan while towing. I set the receive head inside the camper when camping.

Many of the A-frame owners (I'm one) have struggled with getting enough airflow across the fridge cooling coils to maintain safe fridge temps when it is hot outside. There are several fixes and helps, including installing a computer case fan on the upper (exhaust) vent.

I have been able to run the Cool-Cat off a 15A house circuit at home. Others have been successful with a 2000 watt generator. The 2000 watt generator starts running out of power for the Cool-Cat at altitudes above 4,000ft. I don't have a generator, so I can't give you specifics.

The microwave probably needs 1300 watts when starting, and 1100 watts running (what mine says). This rules out a 1,000 watt generator doing anything more than recharging your battery and powering low power appliances plugged into sockets.

Congratulations on your new A-frame. I hope you enjoy it as much as we do ours.

hope this helps
Fred W
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time
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Old 08-15-2017, 02:14 PM   #6
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Moved to A-frame sub-forum.
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Old 08-15-2017, 02:21 PM   #7
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Originally Posted by pgandw View Post
You might want to have this thread moved to the A-frame forum. The fridge, in particular, is different from the model used in most travel trailers.

The Dometic 4223 (what is in my A-frame) has a 160 watt heating coil for AC, and the same 160 watt coil for DC. The fridge is manual start and continuous run, and is NOT thermostatically controlled.

On AC, there is a knob in the upper outside panel that works like a light dimmer in your house, controlling the amount of power to the fridge heating coil. This indirectly raises or lowers the temp inside the fridge.

On DC, the fridge run continuously at full power (160 watts/13.3 amps@12V) as long as the battery holds out. You don't want to run on DC unless your battery is being charged at the same time.

On propane, the flame size is controlled by a knob in the lower outside section. You have to start the flame on propane by simultaneously pushing in the on/off valve (in the on position) and pushing the red ignitor button. You hold in the on/off valve for about 20-30 seconds to allow the flame to get hot enough for the flame sensor to keep the valve open.

On propane, the fridge uses zero electricity. There is no 12V control board.

To control fridge temperature, you dial back the propane or AC using the adjustment knobs. Use of a battery-powered wireless outdoor thermometer ($10 at Walmart) is highly recommended for monitoring fridge temps. My unit will read into the console in our minivan while towing. I set the receive head inside the camper when camping.

Many of the A-frame owners (I'm one) have struggled with getting enough airflow across the fridge cooling coils to maintain safe fridge temps when it is hot outside. There are several fixes and helps, including installing a computer case fan on the upper (exhaust) vent.

I have been able to run the Cool-Cat off a 15A house circuit at home. Others have been successful with a 2000 watt generator. The 2000 watt generator starts running out of power for the Cool-Cat at altitudes above 4,000ft. I don't have a generator, so I can't give you specifics.

The microwave probably needs 1300 watts when starting, and 1100 watts running (what mine says). This rules out a 1,000 watt generator doing anything more than recharging your battery and powering low power appliances plugged into sockets.

Congratulations on your new A-frame. I hope you enjoy it as much as we do ours.

hope this helps
Fred W
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time
I have nothing to add except this is a well written explanation of the systems in an A-frame camper. Hopefully others will see it and it will remove some of the 'myths' floating around about how the systems in these models operate.

Thank you Fred... well done!
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Old 08-15-2017, 04:49 PM   #8
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I have nothing to add except this is a well written explanation of the systems in an A-frame camper. Hopefully others will see it and it will remove some of the 'myths' floating around about how the systems in these models operate.

Thank you Fred... well done!
I have to chime in on the refer. The newer ones are totally automatic. It decides the most efficient power source available (AC/DC/Gas). On gas it lights itself. There is a 5 position temperature control (touch pad). But there is no thermostat. The control just controls how hard it runs. On hot summer days turn it to 3 at night and 5 in the morning. With all of that the refer control board does use a small amount of electricty when it is on. Very small.

We've only had ours two years, but it is by far the best RV/Boat small refer we've ever had. <--- will no doubt fail next trip.
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Old 08-15-2017, 05:07 PM   #9
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So in response to oldgrays refer question.

It will run on gas if there no AC present, using 12v for the control panel. I don't know what the AC draw on your generator might be if it is runing, but my Honda i2000 doesn't notice.
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Old 08-15-2017, 06:39 PM   #10
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refrigerator power question

When I'm traveling during the day and my truck is changing the battery should I be using DC or just keep it on propane?
I normally leave it on propane but the flame normally blows out by the end of the traveling day.
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Old 08-15-2017, 06:55 PM   #11
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I'll venture that you may want to run the fridge on propane regardless. The fridge's propane draw is trivial such that it may be more efficient than using the generator to power the 110V fridge element.

Granted, I don't know much about generators and fuel consumption.

Edit: This pertains to a smaller fridge my unit has. Propane consumption may be greater for yours.
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Old 08-15-2017, 09:26 PM   #12
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I have to chime in on the refer. The newer ones are totally automatic. It decides the most efficient power source available (AC/DC/Gas). On gas it lights itself. There is a 5 position temperature control (touch pad). But there is no thermostat. The control just controls how hard it runs. On hot summer days turn it to 3 at night and 5 in the morning. With all of that the refer control board does use a small amount of electricty when it is on. Very small.

We've only had ours two years, but it is by far the best RV/Boat small refer we've ever had. <--- will no doubt fail next trip.
You have to be careful. The Forest River HW A-frames and PUPs have very different fridges than the standard height models.

The OP has a standard height A-frame, which has a Dometic 4223 2.5 cu ft fridge. It works as I stated. There is no automatic mode selection, no automatic ignition, no front panel, and no control board.

The High Wall PUPs and A-frames have a larger fridge, which often work very much like conventional TT fridges. They usually have a 12V control board and a freezer section. I don't pretend to be an expert on these because I have never owned a High Wall or TT.

Were I to buy again, I would consider a HW for the bigger fridge, higher cabinets, and more importantly, more headroom over the bed and dinette.

But the drawbacks of the HWs are the extra frontal resistance, especially in mountain and prairie winds; greater difficulty in manually popping up the roof; and reduced visibility out the back of the tow vehicle. Also, there is limited choice in HW floor plans that will fit in my garage.

Fred W
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time
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Old 08-16-2017, 06:30 AM   #13
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You have to be careful. The Forest River HW A-frames and PUPs have very different fridges than the standard height models.

The OP has a standard height A-frame, which has a Dometic 4223 2.5 cu ft fridge. It works as I stated. There is no automatic mode selection, no automatic ignition, no front panel, and no control board.

The High Wall PUPs and A-frames have a larger fridge, which often work very much like conventional TT fridges. They usually have a 12V control board and a freezer section. I don't pretend to be an expert on these because I have never owned a High Wall or TT.

Were I to buy again, I would consider a HW for the bigger fridge, higher cabinets, and more importantly, more headroom over the bed and dinette.

But the drawbacks of the HWs are the extra frontal resistance, especially in mountain and prairie winds; greater difficulty in manually popping up the roof; and reduced visibility out the back of the tow vehicle. Also, there is limited choice in HW floor plans that will fit in my garage.

Fred W
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time
Thanks for the clarification.
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Old 08-16-2017, 07:20 PM   #14
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It's my understanding, or so I have been told, that it is not recommended to run the fridge on propane while in motion.

For one thing, if you stop for gas, you are bringing an open flame into the gas station. Secondly, if you travel through any tunnels, it is very important that your propane be shut off at the tanks.

From a practical standpoint, it would work, and propane seems to work great on them, but leave it for while you are parked.

While in motion, and connected to the 12v from the tow vehicle, I see no problem running off 12v.

I'm not an expert and new to this myself, so any ideas on this are welcomed.
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Old 08-19-2017, 08:40 AM   #15
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When I'm traveling during the day and my truck is changing the battery should I be using DC or just keep it on propane?
I normally leave it on propane but the flame normally blows out by the end of the traveling day.
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It's my understanding, or so I have been told, that it is not recommended to run the fridge on propane while in motion.

For one thing, if you stop for gas, you are bringing an open flame into the gas station. Secondly, if you travel through any tunnels, it is very important that your propane be shut off at the tanks.
I'm back from a 3 week trip where we used only propane and we travelled every days but one. The flame blew off only once. In fact, the fridge door opened 3 times during travel, so I am not worried about the flame turning off during travel (although yes it should be turned off during refulling or in tunnels; I am just lucky there was no tunnel on my route).

Last year, I ran on 12V and depleted the battery in 2 days (meaning I have to connect AC every 2 days. Not great for boondocking). This time, I used only propane and ran out after 17 days if my memory is right. One tank of propane is about the same price as electricity for a single night at a camping so it is a no-brainer for me to run the fridge on propane.

This being said, I found (and fixed) a problem with my DC power from the car to the fridge. So maybe I was depleting the battery last year because of lack of recharge during travel. I'll check that on my next trip (after I put the voltage meter on the battery).

jf
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Old 08-19-2017, 02:23 PM   #16
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I have a datapoint.

My tow vehicle is a 2015 Jeep Grand Cherokee. I run the fridge on 12V while towing. Although the longest tow I have had is only a couple of hours (been camping close by).

With the Jeep Grand Cherokee connected and reading the voltmeter I installed which is feed by the radio power wiring:
Refrigerator on 12V, voltage at voltmeter 13.5V.
Refrigerator off, voltage at voltmeter 14.2V.

So it appears that my tow vehicle is able to recharge the battery during towing. Not sure if it can effectively recharge the battery while the refrigerator is running on DC though.

Next time I should open the battery box and take a measurement right at the battery terminals.
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Old 08-19-2017, 03:21 PM   #17
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I achieved similar results with my Rockwood A122 A-frame and Hyundai Entourage minivan.

The 13.5V means the A-frame battery is being trickle charged while running the fridge on DC - and being normally charged when the fridge is off. The problem is when you stop for gas, lunch, campground check-in, etc. The AH consumed by the fridge out of the A-frame battery during the stops is never recovered by trickle charging.

By monitoring the temps inside my fridge, I have found that if the fridge is pre-cooled before departure, and outside temps are below 90, the fridge will pull down to below 30 degrees in about 4-5 hours. I can then turn the fridge off for the remainder of the drive, and it will hold below 40 for 2-3 hours. This gives the minivan a chance to recharge the A-frame battery.

If outside temps are above 90, we're not camping without electric to run the AC, so the A-frame battery not being fully charged is not a big deal.

Knowing the above, I do make sure I turn the fridge off while I am setting up the campsite. This preserves the battery AH until I can turn the fridge on propane or AC.

The wind blows the flame out while towing on my A-frame, so propane is not an option. My other alternative is simply to use coolers for the food and drinks while traveling and load the fridge upon arrival at the campsite.

just our experiences
Fred W
2014 Rockwood A-122 A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time
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Old 08-19-2017, 05:10 PM   #18
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Knowing the above, I do make sure I turn the fridge off while I am setting up the campsite. This preserves the battery AH until I can turn the fridge on propane or AC.
After I arrive at a campsite and get parked, typically the very first thing I do is start the fridge on propane or connect to electricity if there's a hookup. Just curious, why wouldn't you do that?

I have also used your tactic of keeping food and drinks in a cooler prior to arriving at the campground. I've found this is particularly important if I will be parked somewhere unlevel for an extended time before leaving for the campground.
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Old 08-19-2017, 05:23 PM   #19
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You might want to have this thread moved to the A-frame forum. The fridge, in particular, is different from the model used in most travel trailers.

The Dometic 4223 (what is in my A-frame) has a 160 watt heating coil for AC, and the same 160 watt coil for DC. The fridge is manual start and continuous run, and is NOT thermostatically controlled.

On AC, there is a knob in the upper outside panel that works like a light dimmer in your house, controlling the amount of power to the fridge heating coil. This indirectly raises or lowers the temp inside the fridge.
So are you saying the AC is not on a thermostat? I have read this in other threads as well, and for awhile I thought this was the case, but I am looking at my installation & instructions manual for this model right now, and it indicates the AC knob is a thermostat. I believe this is correct because when I turn the knob it lightly clicks at a point at which the thermostat kicks on/off. Also, my fridge does seem to self-control temperature better on AC as opposed to propane.

Granted, the manual also says the gas control is a thermostat, and I know this is false, so it all must be taken with a grain of salt.

Hope I'm not sounding too contrarian with this post and my last one!
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Old 08-19-2017, 07:12 PM   #20
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So are you saying the AC is not on a thermostat? I have read this in other threads as well, and for awhile I thought this was the case, but I am looking at my installation & instructions manual for this model right now, and it indicates the AC knob is a thermostat. I believe this is correct because when I turn the knob it lightly clicks at a point at which the thermostat kicks on/off. Also, my fridge does seem to self-control temperature better on AC as opposed to propane.

Granted, the manual also says the gas control is a thermostat, and I know this is false, so it all must be taken with a grain of salt.

Hope I'm not sounding too contrarian with this post and my last one!
If you can find the thermostat control inside the fridge, the wiring from the thermostat to the control board or relay, and the control board or relay itself on a Dometic 4223 fridge, then I'll admit I'm wrong.

Another proof would be the AC current shutting off when fridge is running on AC.

I usually get my fridge to freezing within the first 12 hours of camping, and then have to back off the AC or propane.

No disrespect intended or taken. Dometic likes to pretend their fridges are more complicated/sophisticated than they are.

Fred W
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