Our basement is home to a sixteen-year-old relic of a water heater. The beast was inefficient when it was purchased (I think the “your model” indicator on the Energy Star label is in the “so inefficient you may as well go out back and boil your water over your fire pit” realm); it now treats us to the auditory equivalent of a Fourth of July fireworks display every time we deign to use a bit of hot water. Before we find ourselves shivering in the shower because our friendly beast has quit working, we thought we’d look into finding a replacement.

I called our plumber. “All the newer models are energy efficient,” he proclaimed. “It doesn’t matter what one you choose.”

I called our local plumbing supply store. “You really pay a premium for that extra efficiency,” the man on the phone declared. “Most people just stick with the standard model.”

I did some research.

First off, it took me a while to find what I wanted: a cost vs. efficiency breakdown. I finally ran across it here. Unfortunately, their chart didn’t go quite as high as I’d hoped—but my elementary math skills stood me in good stead. I noticed a pattern: for each .04 increase in efficiency rating, you save $11 per year. That savings gets multiplied by 13, the average life span of a water heater. So here’s what I figured out (hopefully accurately):

.53 = their “standard” water heater

.65 = our local plumbing supply store’s standard model.

- The difference between the local standard and the internet standard is .12.
- This efficiency difference divided by .04 is 3.
- For each year I run this model, I would save 3x$11 or $33 over the internet standard.
- Over the 13-year life of the water heater, I would save $429 over the internet’s .53 model.

.90 = our local plumbing supply store’s high-efficiency model.

- The difference between the local high-efficiency and the internet standard is .37.
- This efficiency difference divided by .04 is 9.25.
- For each year I run this model, I would save 9.25x$11 or $101.75 over the internet standard.
- Over the 13-year life of the water heater, I would save $1322.75 over the internet’s .53 model.
- Over the 13-year life of the water heater, I would save $893.75 over the store’s .65 model.

.95 = our local plumbing supply store’s ultra-high-efficiency model.

- The difference between the local ultra-high-efficiency and the internet standard is .42.
- This efficiency difference divided by .04 is 10.5.
- For each year I run this model, I would save 10.5x$11 or $115.5 over the internet standard.
- Over the 13-year life of the water heater, I would save $1501.50 over the internet’s .53 model.
- Over the 13-year life of the water heater, I would save $1076.50 over the store’s .65 model.
- Over the 13-year life of the water heater, I would save $178.75 over the store’s .90 model.

The plumber will install the standard .65 water heater for $825. He’ll install the efficient .90 water heater for $1200. That’s a $375 cost increase for a savings of $893.75. The ultra-high-efficiency water heater is $1700 installed, which is a cost increase of $500 for only $178.75 additional savings. Can you guess which water heater I ordered?

Bonus Update: I waited until we got the new .90-rated beauty so I could include a picture. At today’s visit, the plumber said our water heater was such an easy install that he’s knocking $100 off the price, and oh-by-the-way the utility company has a $150 rebate for efficient water heaters like ours. So make that a $125 cost increase for nearly $900 savings. Wa-hoo!