Sunday, November 20, 2011

Water Heater Upgrade: The first month

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In an earlier blog entry I covered our purchase of a new hybrid water heater which has now been running for a full month and we're starting to realize some of the power savings.  

We finally received our first PG&E bill with this new water heater.  As mentioned I had measured my electrical usage on the water heater circuit for 19 days prior to the installation.  For those 19 days we used 197 kWh of power just on the water heater.  The 19 days after the installation, we used 117.60 kWh, a 40% savings in power usage.  

Now, the original water heater was about 20 years old (best guess, it came with the house) and was set at 130 degrees, the new one we have set at 140 degrees, so we had a 40% drop in power even though we are running it 10 degrees hotter.

I also had a full month PG&E bill (it was installed on the 19th, billing period started on the 20th).  The month prior we used 1,988 kWh of power, the first month with the new water heater we used 1,366 kWh, roughly 32% less, which roughly correlates with my water heater circuit measurements.  We did use the heater a little this month too (it's an electric heat pump) and hardly used it the month before.  

Just one months data, but I'm thinking it would be safe to say a 30-35% drop in power use is easily achievable if you're moving from a standard water heater to this one.  The tough thing is figuring out how much dollars that equates to because of PG&E's tiered billing.  If I look at last months bill it was $505 for the house, this month was $306.  Can I say that’s all due to the water heater, I'd like to think so, but we’ll see how it goes after a few months usage.

Other than that, it's been uneventful, hot water has been plentiful, no issues with hot water supply, recovery, etc.  

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