Kilowatt Wars

Still thinking about the musical year that was 1970.  Remembering a dance at summer camp (a mixer with the girl’s camp on the hill!) with this one blasting on a pair of tinny speakers:

“War” by Edwin Starr hit #1 on the Billboard charts the summer of 1970.  It’s one of the few protest songs to make it has a hit single, and earned Starr a Grammy in ’71 for Best R&B Male Vocal.  I’d say he earned it!

There’s been a long-standing war (uh!) over whether to zone with circulators or zone valves.  I’ve yet to meet the person who can actually feel the difference between zone valve heat and circulator heat, so it’s pretty well established that both work.  (Click here, here and here for further discussions on the topic).

Got an email today firing another salvo in that war.  The e-mailer asked how much electricity would be saved by converting a 5-zone baseboard system from circulators to zone valves.

A fair question. Let’s take a closer look.

The system in question has 5 Grundfos 15-58 circulators – one for each zone – with each circulator set to Speed 1.  According to Grundfos the 15-58 at Speed 1 uses 60 watts.  There’s no outdoor reset on the boiler, and the customer pays 0.0907 cents per Kilowatt hour.

The heating system is in New York, which averages roughly 2,500 hours of heating run-time per winter.  That means the circulators will run roughly that much each winter.

Armed with that information, the math to guesstimate electrical costs is pretty simple:

  • 5 circulators × 60 Watts each = 300 Total Watts
  • 300 Watts ÷ 1000 = .3 Kilowatts (KW)
  • .3 KW × 2,500 hours = 750 total KW
  • 750 KWh × .0907 cents per KWh = $68.03 per heating season.

So should this guy switch to a 00-VDT variable speed Delta-T circulator and 5 Zone Sentry zone valves?  We need more facts.

One Taco 008-VDT variable speed circulator uses an average of 55 watts, while the Taco Zone Sentry zone valve uses only 1.44 watts.  So five of them will be a total of 7.2 Watts.

  • 55 Watts (circulator) + 7.2 Watts (zone valves) = 57.2 Watts
  • 57.2 Watts  ÷ 1000 = .0572 Kilowatts (KW)
  • .0572 × 2,500 hours = 143 total KWh
  • 143 KWh × .0907 cents per KWh = $12.97 per heating season.

That’s $68.03 per heating season compared to $12.97 per heating season.

The marketing people will tell you that’s a whopping 81% reduction in your electric bill!


A calculator will tell you it’s a savings of $55.06 over a 6 month heating season, or a little over 9 bucks a month.


If you rather use 3,000 hours of run time– realistic if the boiler has outdoor reset since the circulators might run a bit longer – just plug in the numbers and see the difference.  (It’s a difference of $66.00 per year).

If your electrical rates are higher, plug those numbers in, too. At 2,500 hours and 15 cents per KWh, the circulators would cost an estimated $112.50 to run while the 00-VDT and zone valves would cost $21.45 to run, for a savings of $91.00 per year.  At 20 cents per KWh, the difference is $121.00.

It’s important to understand your KWh charge won’t remain static.  It could go down, but somehow I doubt it. According to the US Energy Information Administration,  the average residential electrical rate in the US has jumped roughly 60% since 2000.  However, much of that jump occurred in 2006.  Since then, rates have jumped about 20%.

That 60% increase since 2000 averages out to an annual 5% increase. If you project that annual increase over the next 10 years (sure, some years may be more, some may be less), electrical savings starts to add up a bit – around $755.00 savings over the next decade.


Now is it worth it?

Your call.  What do you say?

And just for fun, we’ll look at ECM circulators and those things will affect electric usage next week.

And just for more fun, here’s another big hit from 1970 – one of my favorites from The Guess Who:

The best in Canadian Prairie Boogie!


One Response to “Kilowatt Wars”

  1. Burton Cummings best Canadian singer next to Neil Young

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