Hydronics Hindsight
John Siegenthaler
Over the years I've had the good fortune of meeting many individuals I regard as true hydronic-heating pros. Many have willingly shared stories of their experiences and their experiments. I can't think of a single one who wouldn't admit they've made significant changes in their design or installation practices over the last few years.
Like many of them, I've spent many hours watching hydronic-heating systems go through their paces. Each time I compare what I see, feel and hear to what theory says I should see, feel and hear. The inevitable discrepancies between the theoretical and the observed are what drive most of us along a continuous improvement plan. Not because some ISO standard mandates it, but because it's what any professional logically strives to do.
Here are a few lessons I've learned over the years. Some came as the result of improved technology. Others were learned through the school of hard knocks. All have influenced the way I currently design systems in pursuit of the best hydronic heating has to offer.
During my hydronics adolescence I was so concerned about delivering the proper supply temperature to the distribution system, I didn't even think about what went back to the boiler. However, after seeing first-hand what sustained flue gas condensation can do to boilers and vent connectors, I now wouldn't think of letting a system design leave home without proper protection.
My experience aside, boiler protection is still not fully understood in our industry. Myths abound about what does and doesn't provide proper boiler protection. Boilers continue to be installed unprotected in both residential and large "engineered" systems.
Case in point: I just visited a building that's heated and cooled by a large water source heat-pump system. Each of the 32 heat pumps connects to a constantly circulating piping loop. The loop's temperature is maintained below 90 degrees F by a cooling tower (when necessary), and above 70 degrees F by a staged multiple-boiler system.
The boilers are connected to the main loop using primary/secondary piping. These boilers have never operated above the dewpoint of their exhaust gases. The result: All three boilers have been replaced at least once over the last decade. The replacements are piped the same way, and doomed to the same premature death-by-condensation as their predecessors. All because the design engineer wasn't aware of, or ignored the need for boiler protection.
To properly protect a boiler there must be a "clutch" (a mixing device) between the "engine" (the boiler), and the "drive train" (the distribution system). In a car, proper control of the clutch allows the full power of the engine to flow to the drive train without "lugging down" the engine.
Likewise, a mixing control that senses and reacts to low return temperature allows the full heat output of the boiler to reach the distribution system without pulling the boiler temperature down to where sustained flue gas condensation occurs.
To properly protect the boiler, the mixing control must sense the return temperature and "feather the clutch" when necessary (by reducing hot water flow through the mixing device). If a proposed boiler-protection scheme doesn't sense return water temperature, it can't properly protect the boiler. If you can't "see it," you can't control it!
When it comes to heating systems, you're the professional who should make the decisions regarding hardware. You know what the system needs to assure a long and reliable life. If your customers hear that option B does "essentially the same thing" as option A, but costs half as much, why would they ever choose option A? Why even bring such a possibility up for discussion? Why let people who are usually unfamiliar with the technical intricacies of hydronic heating select the hardware you will use?
Select what you feel provides a quality system and price the job accordingly. If that's not acceptable to the potential customer, move on to the next job. You won't regret it.
It's impossible for designers or installers to remember every detail of every system they work with. Even if you're blessed with a photographic memory, there's no guarantee you'll be available when its time to print out those neural images.
I always make piping and wiring schematics for the systems I design, and encourage anyone who'll listen to do the same. Proper documentation of systems is not only indispensable during installation, it offers lasting value over the life of a building. It's also evidence of professionalism that, when properly dispensed, can be a tremendous marketing tool.
It has never been easier to document your systems using tools such as low-cost, computer-aided drawing (CAD) software, digital cameras and video cameras. Make it a part of your professional routine and price it into the job.
It might have worked had those flange gaskets not have rolled over when I tried to shove the replacement circulator between a pair of immovable flanges. Let's just say that a good bath of "dead" water from a hydronic system teaches one valuable lessons.
However, don't put a sidewall vent a few feet away from a backyard patio assuming your customers enjoy the aroma of various hydrocarbon emissions as much as you do.
Some hydronic piping systems seem to evolve fitting by fitting. They expand out from the boiler, meander around the mechanical room and through the building, eventually finding their way back to the boiler.
Along the way, the installer miraculously receives "inspirations" about how best to proceed for the next five minutes. Such installers are like artists who throw globs of paint at a canvas until some indescribable impulse tells them what they've created constitutes a masterpiece.
I continue to see the results of morphing proven piping concepts together the way biologists splice genes in hopes of retaining only the desirable traits. Judging by some of the "inspired" piping layouts that arrive on my fax machine this approach is more likely to produce a Frankenstein than a Superman.
Piping aberrations continue to waste time, material and customer patience in our industry. Larry's concept of primary/secondary piping differs from Curly's gut feeling of how it should be installed. Meanwhile, Moe doesn't see why everything can't just be connected in one big series loop!
Study the basic hydronic piping layouts. Learn where each is best applied. Plan you layout with paper and pencil instead of tubing and torch.
Picture the hardware you select after it's been installed for 20 years. Do you see it holding up in the environment you are about to place it in for that period of time? Is the continued service of the systems you install critically dependent on a single component? If so, will that component, or an updated/compatible version of it be available 20 years from now? Can you replace it, if necessary, without performing major surgery on the rest of the system?
Reasonable customers accept the fact that mechanical components fail over time. They shouldn't accept that when that happens we can't expeditiously correct the problem.
If, after explaining the benefits your systems offer, your potential customer still wants price over performance, walk away from the situation with a smile on your face. You've made the right decision. A new opportunity to practice your profession without compromise is right around the corner.
I expect my list of hindsights to grow a bit over the next few years. Hopefully most of the changes will result from improved technology instead of previously undiscovered mistakes. Whatever the case I'll do my best to keep you posted. Let the learning continue -- for all of us.
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