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Old 02-27-11, 05:34 PM   #1
Xringer
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Default Am I reading this current (amps) chart correctly?




Looking at Heating mode chart #2, it seems like, when the indoor set-point temp is 70F, and the outside temp is:

32F, the Sanyo uses 6.4 Amps
41F, the Sanyo uses 7.0 Amps
59F, the Sanyo uses 8.4 Amps

And if it was 70F indoors and 70F outdoors, it would be using over 9 Amps??

Is it me? Or is something wrong with this picture??

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Old 02-27-11, 07:15 PM   #2
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I think you're reading that correctly. Heating capacity declines with temperature.
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Old 02-27-11, 11:10 PM   #3
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But, when it's cold outdoors, I use about 10 or 12 kWh per day.
When it's warmer (like 59F), I only use 5 or 6 kWh per day.

If it was 70F indoors and 70F outdoors, the dang thing wouldn't even turn on..(Not use 8.4 Amps).
Just 60 watts for the crankcase..

I think the amps scale is upside down..?..
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Old 02-28-11, 04:51 PM   #4
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The thermostat regulates duty cycle to match the heating/cooling needs of the house.
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Old 03-01-11, 08:25 AM   #5
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The house stays at about 70F 24/7.

Right now, it's 30F outdoors and the Sanyo is using about 480 watts.
If it was 15 or 20F outdoors, it would be using more power, 600 to 800 watts.

The colder it gets, the more power is needed to extract heat from the extra cold air..

The chart seems to show that colder means using less power!
If it were true, then it would be cheaper to heat your home at when it was -12 deg outside!
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Old 03-01-11, 05:35 PM   #6
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So your thermostat scales back power draw instead of duty cycle. The effect is the same. Although the above plot shows how much power the heat pump is capable of drawing at any given temperature, that doesn't mean it will do so 24/7.
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Old 03-01-11, 06:35 PM   #7
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Like any other heating system, when it's real cold outdoors, it uses more power to keep the house warm.

Plus, I can see the power used instantaneously. (and by the day, week and month).

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Old 03-01-11, 07:50 PM   #8
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The chart doesn't seem to make sense. Sure, the maximum capacity of the system declines as the outdoor temperature drops. But, does the power draw of the compressor also drop? I fail to see why that would be so.

The compressor may have a limited maximum RPM, and when it is colder outside, the maximum refrigerant temperature may be colder. Perhaps it takes less power to compress colder refrigerant, and the power draw is limited because the compressor RPM is limited due to friction at internal seals or some other mechanical limit? This is the only practical reasoning I can find. However, I would find it surprising that the max refrigerant temperature is so much lower that it could affect power draw so drastically.
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Old 03-01-11, 09:42 PM   #9
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Default It sucks warm air out of the cold

and when it's really cold, it starts sucking the money out of my wallet..

I've seen the power increase and can heard the fan cranking up to max speed
on really cold nights.

When I saw the mistake in chart (2), I started worrying about Chart (1)..
I need that chart to be accurate, because I want to measure the R410A pressure.

It shows the pressure going up as the outdoor temp goes up..
Cold air is going to lower the pressure.. Sounds logical.?.
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Old 03-02-11, 06:26 AM   #10
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Capacity declines faster than CoP as outdoor temperature falls. I assume this takes the form of lower RPM, lower pressure, and less current draw at lower temperatures.

A plot of total daily power consumption versus time would require them to know what sort of house you've installed it in, the orientation of your windows and the sun, etc. Do you think that's the sort of plot Sanyo has supplied you with here?

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