Myth-Busting - ECM Pumps Edition
You may be surprised to learn that two of the world’s most famous folk have given hydronics pros real insight into the world of ECM pumps. Barbara Streisand once said, “Myths are a waste of time. They prevent progression.”
Mike Rowe – a real hero of mine – recently said that, “In a very general way, our society has fallen out of love with the skilled trades. Part of the problem [are] myths and misperceptions that surround the jobs themselves, but the biggest cause is our stubborn belief that a four-year degree is the best path for the most people.”
Who’d’ve thought that Barb n’ Mike would add insight and balance to myths about residential ECM circulators? Well, they have – and I’ll do my best to explain it.
So many myths, many of them down- right crazy, make it nearly impossible to make clear-headed and smart decisions for your customers. So, with that as a backdrop, let’s do a little myth- busting, shall we?
“ECM circs can do everything.”
Well, no they can’t. They can do a lot of things, but everything isn’t one of them. Whenever someone presents a pumping problem in an online forum or on social media, invariably someone else chimes in with, “just throw a variable speed pump in and be done with it.”
Variable speed circulators are very good circulators, but they can’t, for ex- ample, size themselves. They also don’t do the thinking for you, nor do they take the thinking out of it. And for goodness sake, they’re not freaking “magic.” Believe it or not, I’ve heard those very words – “ECM circulators are magic” – come out of the mouth of a so-called “industry expert.”
As a trainer, I’m lucky enough to speak with thousands of you every year. I learn a lot when we get together, and I love asking you questions because you’re always ready to answer. For in- stance, I like to ask who in a given group is using variable speed circulators, and who isn’t. The follow up question, of course, is why, or why not?
This is where more myths start floating to the surface.
“ECM/variable speed is more efficient.”
Myth? Well, it depends. What sort of efficiency? The typical answer: “Electrical.” OK, how much electricity will it save? “Butt loads.”
Keep in mind we’re talking about itty-bitty residential circs which, at most, are in the 80- to 85-watt range. In reality, we’re talking about a very small butt. Many trade pros are being told ECM circs save a lot of electricity. That is, in fact, true: they provide an 85-90 per- cent reduction of electrical consumption, but a calculator will tell you the rest of the story. Depending on what you pay per kilowatt hour, that electrical savings may translate into $3 to $5 per month during the heating season.
What does that mean? It means that within two, maybe three years after installation, the added cost of the circulator (depending on which one you buy) will be offset by the estimated $28 to $35 you save each heating season. In other words, your customer is going to buy the variable speed ECM circulator no matter what; it’s just a question of whether you give it to him or not.
Variable Speed ECM circulators certainly do provide electrical savings, and it’s not insignificant. But it’s a bit of a know open or closed.
What’s more, when used as a zone pump, a Delta-P pump – because it var- ies its speed based on changing pres- sure differentials – will never vary its speed since there’s nothing in a single zone that would cause the zone’s pres- sure differential to change.
“Push a button and it figures out everything for you.”
ECM’s aren’t plug n’ play. We’re talking about your profession here, your livelihood. Seems to me that whoever’s perpetrating that myth needs to learn that many of us in the trade have greater
Let’s say you’ve just installed your industry-standard three-speed circ on a single zone of heat. That circ, no matter which speed you select (and we all know which one that’ll be) will deliver either a lot more, or a haaal of a lot more flow than the zone needs under design conditions. That excessive flow leads to shrinking up the supply/return ∆T . . . and that leads to short-cycling, reduced overall efficiency, and excessive wear and tear to all the important components.
And none of those are good. Keep in mind that this unpleasant situation is under design conditions – when stretch to classify it as a buttload.
“They always give me the right flow.”
That’s mostly accurate. But the statement’s missing only two words. “. . . hardly ever.”
This myth ties back to that “magic pump” nonsense. ECM’s aren’t magic. They don’t think for you, and they aren’t a plug-n’-play electrical component. Dedicated trade pros should demand answers about how these things work. ECM circs can’t always deliver the right flow because most of them have no way of knowing the changing BTU load of the structure in which they’re installed. In a zone valve job, Delta-P style pumps only know whether zones are opening or closing. They don’t know the load because they don’t know how cold it is outside. They only respect for others, and ourselves. They don’t size themselves, nor do they automatically adapt into the right size circulator. You still need to know pump sizing basics in order to program these things for maximum benefit.
The next myth is . . .
“All a circulator has to do is make the water go round n’ round.”
Of the three major components in any hydronic system – the boiler, the heat emitters and the circulator(s) – a compelling argument can be made that of the three, the circulator is the most im- portant in determining overall system efficiency. That’s a lot more than just making the water go round and round.
The boiler makes heat, and the heat emitters – radiant, fan coils, baseboard or radiators – deliver the heat. But it’s the circ that facilitates the BTU journey, out and back. The system should be running at peak efficiency. As it gets warmer outside, the circ’s still pumping at the same rate, even though the load has decreased – making the problem even worse.
The important point here is this: Most folks don’t consider it to be a problem because no one will ever complain that they’re cold and it’s your fault. You are delivering the heat, so from that stand- point, there’s no problem. But if you factor in a slightly (or maybe grossly) oversized boiler and oversized heat emitters, you’re further shrinking the supply/return Delta-T, which leads to short-cycling, reduced overall efficiency and excessive wear and tear to all the important components.
And none of those are good.
We can do better.
It’s our job to make sure the customer gets the overall system efficiency, performance and trouble-free life they’re paying for. Putting a hydronic heating system together isn’t really that hard to do if your only goal is to keep people from freezing to death. A reasonably competent handyman can pull that off.
The professional, however, knows the components he chooses can either enhance efficiency and performance, or limit them.
The real joy of using variable speed ECM circulators isn’t electrical savings (although it’s nice) and it certainly isn’t the “magic.” It’s knowing you’re using the right tool for the job and taking advantage of the technology avail- able to make sure circulator operation matches system needs as closely as possible.
To do that, you have to know what they do, how they work and how to pro- gram them. It’s not hard, but it’ll make your systems as efficient as they can possibly be and will enhance the life of all the important components.
And all of those are good.
John Barba, National Director of Training for Cranston, RI-based Taco Comfort Solutions, is now celebrating his 25th year as a trainer. He’s been in the heating industry most of his life, growing up in his family’s plumbing and heating business outside of Boston. John’s practical experience includes everything from ditch digging and drain cleaning to boiler piping and PEX installing, as well as business management and contractor sales. He is the 2012-2014 winner of the Carlson-Holohan Industry Award of Excellence, and was voted the Industry’s Best Instructor and Trainer in 2015 by AHRI.