EcoRenovator - View Single Post - standby losses from the hotwater tank add up

strider3700 · 11-12-12, 11:04 AM

Ok I've been turning the breaker off for a few weeks now. so the heater hasn't been kicking on in the middle of the night to top up temperatures. This does result in a drop in power usage. The next morning however I turn the heater back on and there is a long run time as the heater recovers back to temp.

The result is a big spike early in the morning that although physics suggests it's should be less then the little spikes added up the difference is so small I'm not really seeing it in my numbers.

So I'm stopping with the turning the tank off testing. It's now obvious to me that lost heat is lost heat and I'd be better off spending the timer money on more insulation for the tank. Should we go to a time of use billing system for our electricity I would definitely add a timer so long as the difference in prices is big enough. The tank easily went an entire day without being turned on.

Since I started recording HW power usage I've been averaging 4.94 kwh or 65 minutes a day in HW heating. That's working out to 25% of my total usage. This is costing $0.42 per day or $153/year

Using those numbers in a perfect world I stand a chance at getting almost 100% solar heating from my planned 64 sqft collector. From my Gain calculations my worst months are december and january at 4.12 kwh/day and 4.31 kwh/day. Of course due to our weather patterns I'd have more then enough some days and then not enough for a week.

I also need to redo my calculations on money saved. I'm using about half as much hot water as when I initially took measurements 2 years ago. The savings aren't as high because my costs aren't as high.

11-12-12, 11:04 AM	#40
strider3700 Master EcoRenovator Join Date: Dec 2008 Location: Vancouver Island BC Posts: 745 Thanks: 23 Thanked 37 Times in 30 Posts	Ok I've been turning the breaker off for a few weeks now. so the heater hasn't been kicking on in the middle of the night to top up temperatures. This does result in a drop in power usage. The next morning however I turn the heater back on and there is a long run time as the heater recovers back to temp. The result is a big spike early in the morning that although physics suggests it's should be less then the little spikes added up the difference is so small I'm not really seeing it in my numbers. So I'm stopping with the turning the tank off testing. It's now obvious to me that lost heat is lost heat and I'd be better off spending the timer money on more insulation for the tank. Should we go to a time of use billing system for our electricity I would definitely add a timer so long as the difference in prices is big enough. The tank easily went an entire day without being turned on. Since I started recording HW power usage I've been averaging 4.94 kwh or 65 minutes a day in HW heating. That's working out to 25% of my total usage. This is costing $0.42 per day or $153/year Using those numbers in a perfect world I stand a chance at getting almost 100% solar heating from my planned 64 sqft collector. From my Gain calculations my worst months are december and january at 4.12 kwh/day and 4.31 kwh/day. Of course due to our weather patterns I'd have more then enough some days and then not enough for a week. I also need to redo my calculations on money saved. I'm using about half as much hot water as when I initially took measurements 2 years ago. The savings aren't as high because my costs aren't as high.