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Open Roads Forum  >  Tech Issues

 > Duty cycle of a Norcold 1200 Fridge

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John & Angela

Full Timers in Canada, USA and Mexico

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Posted: 03/01/12 04:39pm Link  |  Print  |  Notify Moderator

Hi folks. I am just trying to figure out what a Norcold 1200 series fridge was costing to run on average compared to our Residential we have now. I can measure and time the Residential but no longer have a Norcold to check. I know it draws around 4 amps AC current (as far as I remember) but I never checked the duty cycle, eg how long the heating element was on compared to off. I wonder if someone could check for me. lets say average temperature , 70 degrees outside etc. Obviously running on electric.

I know our energuide rating is 533 so that kinda makes it easy but I don't know if there is an energuide rating for a Norcold 1200.

Thanks in advance for any info you can contribute. It just came up in conversation and we are all now curious.

* This post was edited 03/01/12 05:13pm by John & Angela *


2003 Revolution 40C Class A. 2002 Vanguard 22 foot Class C. Diesel smart car as a Toad on a smart car trailer or pulling a 2009 Timeout Tent Trailer.

Life is not measured by the number of breaths we take but rather by the moments that take our breath away.

mlts22

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Posted: 03/01/12 04:50pm Link  |  Print  |  Notify Moderator

Because it uses a different method than a residential refrigerator, it probably is more energy efficient, just because it doesn't have to spin up a compressor motor versus just warming up the boiler.

past-MIdirector

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Posted: 03/01/12 04:52pm Link  |  Print  |  Notify Moderator

On you residential you also have to figure in the defrost system duty cycle which varies between manufactures from 2 to 3 cycles per day for up to 45 minutes and can draw up to 12 AMP depending on what type heater is used.
The absorption type fridges is around 80% to 85% for the heater to be on during a 24 hour period depending on how often the door is opened.





John & Angela

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Posted: 03/01/12 05:10pm Link  |  Print  |  Notify Moderator

past-MIdirector wrote:

On you residential you also have to figure in the defrost system duty cycle which varies between manufactures from 2 to 3 cycles per day for up to 45 minutes and can draw up to 12 AMP depending on what type heater is used.
The absorption type fridges is around 80% to 85% for the heater to be on during a 24 hour period depending on how often the door is opened.


Thats the info I am looking for. So lets say optimistically 75 percent duty cycle for the Norcold. So at 4 amps @ 117 volts = 468 watts. X run time of 18 hours per day = 8.4 KWH per day X 30 days per month = 252 KWH per month x 10.6 cents per KWH = 26.71 per month.

I don't need to figure in defrost cycles or anything else for the Residential as all of that is calculated in the energuide number of 533 KW per year. At 10.6 cents per KWH they figure it out to 57 bucks per year. Divided by 12 months = 4.70 per month. So roughly a savings of 22 bucks per month. That and it is 22 cubic feet instead of 12 cubic feet.

Absorption fridges have their pluses but power usage is not one of them.

pianotuna

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Posted: 03/01/12 06:33pm Link  |  Print  |  Notify Moderator

Hi mts22,

You would be wrong about that. My Dometic draws 305 watts and has a duty cycle of 2:3 (i.e. it is ON for 40 minutes per hour). It draws about 5 kwh per day. It was spring so it was not very warm outside.

I used a kill-a-watt to measure the energy consumed.


Regards, Don
Full Time in a Kustom Koach Class C 28'5", 256 watts Unisolar, 875 amp hours in two battery banks 12 volt batteries, Magnum 3000 watt PSW inverter.

dougrainer

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Posted: 03/01/12 06:49pm Link  |  Print  |  Notify Moderator

Sorry folks, there is NO WAY to figure out a duty cycle. It all depends on the outside ambient, how often the doors are open and closed and also the temp of objects installed in the refer. The amp draw on 120 for a 1200 is 3.4 amps. There is also a Defrost cycle on the 1200. That shuts down the refer every 48 to 54 hours for about 2 to 3 hours as long as the refer is left on continously. This is like trying to figure out the MPG in a car. But, how FAST do you drive and what are the roads like and is there stop and go traffic and what about idling at lights and it goes on and on. VERY hard to get a definite figure, but you can get a fair idea. Doug

dougrainer

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Posted: 03/01/12 06:52pm Link  |  Print  |  Notify Moderator

John & Angela wrote:

past-MIdirector wrote:

On you residential you also have to figure in the defrost system duty cycle which varies between manufactures from 2 to 3 cycles per day for up to 45 minutes and can draw up to 12 AMP depending on what type heater is used.
The absorption type fridges is around 80% to 85% for the heater to be on during a 24 hour period depending on how often the door is opened.


Thats the info I am looking for. So lets say optimistically 75 percent duty cycle for the Norcold. So at 4 amps @ 117 volts = 468 watts. X run time of 18 hours per day = 8.4 KWH per day X 30 days per month = 252 KWH per month x 10.6 cents per KWH = 26.71 per month.

I don't need to figure in defrost cycles or anything else for the Residential as all of that is calculated in the energuide number of 533 KW per year. At 10.6 cents per KWH they figure it out to 57 bucks per year. Divided by 12 months = 4.70 per month. So roughly a savings of 22 bucks per month. That and it is 22 cubic feet instead of 12 cubic feet.

Absorption fridges have their pluses but power usage is not one of them.



"I don't need to figure in defrost cycles or anything else for the Residential as all of that is calculated in the energuide number of 533 KW per year"

According to Consumer Reports, ALL such "guides" are extremely misleading and greatly error on the favorable side. Actual use is a LOT more. Doug

John & Angela

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Posted: 03/02/12 07:56am Link  |  Print  |  Notify Moderator

dougrainer wrote:

John & Angela wrote:

past-MIdirector wrote:

On you residential you also have to figure in the defrost system duty cycle which varies between manufactures from 2 to 3 cycles per day for up to 45 minutes and can draw up to 12 AMP depending on what type heater is used.
The absorption type fridges is around 80% to 85% for the heater to be on during a 24 hour period depending on how often the door is opened.


Thats the info I am looking for. So lets say optimistically 75 percent duty cycle for the Norcold. So at 4 amps @ 117 volts = 468 watts. X run time of 18 hours per day = 8.4 KWH per day X 30 days per month = 252 KWH per month x 10.6 cents per KWH = 26.71 per month.

I don't need to figure in defrost cycles or anything else for the Residential as all of that is calculated in the energuide number of 533 KW per year. At 10.6 cents per KWH they figure it out to 57 bucks per year. Divided by 12 months = 4.70 per month. So roughly a savings of 22 bucks per month. That and it is 22 cubic feet instead of 12 cubic feet.

Absorption fridges have their pluses but power usage is not one of them.



"I don't need to figure in defrost cycles or anything else for the Residential as all of that is calculated in the energuide number of 533 KW per year"

According to Consumer Reports, ALL such "guides" are extremely misleading and greatly error on the favorable side. Actual use is a LOT more. Doug


Good morning Doug. I don't doubt that its not accurate but more of a guide. I know houses with kids where the frudge is opened and closed a lot have higher duty cycles. Our 1200 seemed to pull around 4 amps when on but I never kept track of how often it would cycle. Unlike the Residential it did not make any noise. You can tell when the residential cyles on. According to our inverter display the residential pulls around 155 watts when on and about 20watts when in standby. That is a lot less than the 1200 so I would still guess that it uses about 1/3 to a 1/4 of the power.

Sooner or later I'll put a "Kilowatt" Meter on it for a week or so and see where its average usage is. Maybe someone out there can do the same with a 1200.

dougrainer

Carrolton, Texas

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Posted: 03/02/12 09:17am Link  |  Print  |  Notify Moderator

Resedentials in the RV's pull less amps when running than the 1200. Doug

mlts22

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Posted: 03/02/12 09:55am Link  |  Print  |  Notify Moderator

That is good to know... thought absorption fridges would be more economical than they are.

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