Tin Solders…

Musically, 1970 was not all bubble gum and Rosemary.  Some pretty ugly stuff happened that year, and one particularly ugly event prompted Neil Young to write one of the angriest songs ever recorded…


“Ohio” by Crosby, Stills, Nash and Young was on the airwaves less than a month after the Kent State Tragedy.

A couple of blog posts ago we compared electrical consumption for a five zone hydronics job using circulators and zone valves over a standard 2,500 hour heating season.  While percentage-wise the difference was startling, dollar-wise the difference wasn’t what you’d call life-changing.

When projected over 10 years (at a rate of 10 cents/KWh with a 5% annual rate hike), the difference in operating costs was about $755.00. If your rates are higher, the difference will be greater.  For instance, if your KWh rate is 15 cents, and the circulator runs 3,000 hours (plausible with outdoor reset), the 10-year difference may hit nearly $1,400.00

But the question remains – is an average savings of $75.00 per year – or $140.00 or whatever, over 10 years –  a big deal?

That’s for you and your customer to decide.

The circulator example used for the zone valve example was the Taco-00VDT, a variable speed circulator.  We estimated an average consumption of about 55 Watts, since the slower it goes the less power it uses, and vice versa.

But what about a newfangled ECM circulator?  Won’t that make a HUGE difference?

At 10 cents per KWh and 2,500 operating hours, we estimated the 00-VDT (which is NOT an ECM circulator) and zone valves would cost slightly less than $13.00 per year to operate – again, based on the stated assumptions. ECM circulators (such as the upcoming Taco Bumblebee), use considerably less electricity than the permanent split capacitor (PSC) motor used in the VDT and all other wet rotor circulators.

How much less?  Depends on whose literature you read.

Let’s say it’s 50% less.  We’re now down to $7.50 to operate at 10 cents per KWh.  Let’s say it’s 75% more efficient.  Now we’re down to $3.25 to operate.

Yes, cutting electrical consumption to the bone is a good thing.  And over 10 years, the difference in operating costs between a VDT and an ECM circulator might hit $100.00.

Over a decade.

You can do this math yourself by plugging in your own electrical rates and your own estimated hours of operation.  We used 2,500, but you can plug in whatever you want.  The higher the rate and the more hours of operation, the bigger the difference will be.

I’ve seen comparisons of ECM pumps vs. standard motors based on 6,000 hours of continuous operation.  Pump to pump the difference was dramatic – nearly $80 per year compared to only $12.00 for an ECM pump.  But when you whip out the calculator and do the math, 6,000 hours of continuous operation is 250 days, or slightly more than 8 months.  If your circulator runs continuously from Labor Day to Memorial Day, I’d like to introduce you to my friend, the Pump Relay.

After all, the most efficient circulator is the one that’s off.

Now don’t think I’m hatin’ on variable speed circulators or ECM motors, ‘cause I’m not.  Next post we’re going to discuss how a variable speed circulator can help your boiler operate more efficiently.  It’s just  important to look at potential electrical savings with a clear eye.  You would come reasonably close to the same electrical savings swapping out 5 fixed speed circulators with 5 zone valves and one fixed speed circulator.

Do the math – you don’t need variable speed or ECM or Delta P or Delta T to make a dent.

But those things will certainly help make the dent a little bigger.

Every little bit helps, just don’t expect to retire on the savings.

And after the anger waned in 1970, the mood of music changed a bit, as we hear in this classic from James Taylor…

Just a few months between the two, but a different feel, no?


2 Responses to “Tin Solders…”

  1. If it saves a diff bypass valve,the incremental cost of the ECM is well worth it. The cost difference between a standard pump and ECM has gotten much smaller lately as well

  2. Couple of points Robert…

    1. Use a flat curve pump — like to old reliable, if not terribly sexy 007 — with zone valves and a pressure differential bypass valve usually isn’t needed. The bypass valve is usually installed due to incorrect circulator application (steep curve pump with zone valves).

    2. Similar electrical savings are incurred with a non-ECM 00-VDT circulator — not as electrically efficient, but will have tremendous impact on boiler operation and efficiency – as we’ll see in the next blog post. As for the BumbleBee — it’ll be a Delta T pump and an ECM pump, so it’ll be more electrically efficient and it’ll make the boiler work more efficiently.

    I think it’s important to realize the electrical operating costs between a 00-VDT and an ECM pump – when we’re talking about 1/25th HP circulators – aren’t that huge…even over the long term.

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