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Old 12-30-10, 12:00 PM   #30
strider3700
Master EcoRenovator
 
Join Date: Dec 2008
Location: Vancouver Island BC
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It was explained to me that I was probably using the wrong value for kw when the heater is running. It's likely that only one of the elements is turned on at any given time so since it's wired for 240V I'm probably using 3800 Watts not 5000. The explanation is good enough that I will recalibrate based on that and redo the math.

Yesterdays numbers are in and the water heater ran for 133 minutes. By far the biggest user was the kids baths and the hotwater load in the washer at the same time. My wife and my quick 4-5 minute each showers made the heater run for about 20 minutes total. THe kids baths and washer had it running for over an hour.

Once again the distinctive every 3 hours temp top up for 3 minutes spike was visible during periods of us not being at home or in bed.

So doing the math based on 133 minutes of 3800 watts means 8.42Kwh costing $0.67 for a monthly total of $20 or a yearly total of $242 This pushes non adjusted rates/usage payback of the solar system out further but it's still worth it.

On the more tech implementation side of the project I'm thinking I need to adjust how I'm handling the readings/data. Averaging on the arduino and dumping the data off every minute rather then every 2 seconds and averaging on the PC should give me the same results but make it easier to store data on the arduino when the PC isn't running. I'm wanting to do a reboot and install some hardware on the PC but don't want to lose data while it's down for 10 minutes.... I'll look into datalogging on the arduino and setting up some sort of system where the PC requests the data from it. That makes a bunch of potential issues go away but adds complexity to get the times synced up.

Last edited by strider3700; 12-30-10 at 12:06 PM..
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