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Old 01-15-11, 01:56 PM   #4
strider3700
Master EcoRenovator
 
Join Date: Dec 2008
Location: Vancouver Island BC
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My tank is a conventional 40 gallon tank that was mid range when new about 8 years ago with a 9 year warranty. It's electric with 2 elements each at 3800 watts and thanks to some help from here we figured out that only 1 element is on at any given time. It does not have an insulating blanket and I can't fit one because the tank is 1/4" from the metal furnace on one side.
Also of note there are no heat traps in the plumbing, and the majority of the pipe is uninsulated. They insulated up until it goes into the roof. All the plumbing is copper.

Due to not having a tempering valve and having young kids the tank is set to 108-110 F. I'm sure the standby losses at 140 are much worse.

It sits in my heated basement that averages about 19 degrees, dropping as low as 16 at night lately. I can post temperature charts of the room beside it if anyone cares.

For the graph I have an arduino hooked up to two current sensors taking reading every 2 seconds. The current sensors are not calibrated hence the 4200 watts instead of 3800. For my purpose I just care on or off and use 3800 for any acutal kw math.

That is sent to the PC that averages every minute and saves that to csv. I then take that csv each night and check if the average is >300 then it was on if not it's off. THis is to remove noise in the readings. I sum the on minutes for the total and create the graph posted. Complete details on my homebuilt data logger are here
http://ecorenovator.org/forum/applia...html#post11051

My math works out to $60 lost to standby heat. When I get the new tank it will be in at least a blanket and I will insulate the pipes because they will all be exposed.
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