In last month’s column I introduced you to a very angry boiler and its poorly installed components. My admiration for the deductive ways of a certain Sherlock Holmes had me taking on the case and gathering clues. Here is the conclusion of the story.
Remember that saying by my favorite super detective from across the pond? “The world is full of obvious things which nobody by any chance ever observes.” Well, as I stood there asking the occasional question of the homeowner, I found myself wondering over and over again why the previous contractors misdiagnosed any problems with flow and how they explained why the boiler was producing steam. In each case the homeowner was told that the boiler circulators were working fine and that the relief valve was faulty. Under his own volition he admitted to not understanding exactly how the system was supposed to work and that he may have been too trusting of the last couple service technicians. To that I responded with assurance that he probably knew more than he thought, and even if he did trust the previous techs, they were wrong and had apparently been out-sleuthed in this matter. Well, at least the last guy who installed an industrial-sized relief valve was definitely on the wrong track. Too bad the owner had to foot the bill for such an unnecessary item.
After I was given the go-ahead to stay awhile on billable time, I quickly pulled out my trusty multi-meter to dig deep into the rat’s-nest-like wiring situation. Over the years I have grown very fond of zone valve controls and circulator switching relays. This job had neither, and by the look of the jumbled wiring and excess electrical tape, I knew I was in for the long haul. Not unlike like a scene from a cheesy cop movie where the main character is forced to hit the streets in search of the perpetrator. No, with five zone valves scattered throughout the house, I knew I had my work cut out for me.
After finding all the zone valves and verifying their operation, it was easy to pinpoint the major problems on the near boiler piping. Oh, and if you’re paying attention, you might have picked up on the fact that there was more than one boiler pump. Somewhere between the second and fourth service tech an additional circulator was installed on the supply side of the boiler heat exchanger in an attempt to increase the flow and decrease the steam production. To this day I am still in awe that the heat exchanger never failed. It never even leaked, and after a thorough checkup, I found only the need for an air pressure switch and control wiring harness! To think you can abuse such a product is a real testament to its robust design. Too bad the folks at Scotland Yard aren’t in the market for a boiler detective, or at least that’s my impression since I’ve received no reply upon sending them my resume. Twice!
The answer was quite simple
To the untrained eye one might wish to walk away from a problem-ridden job such as this. That may be the recommendation given to the techs that preceded me if ever given the chance. And to borrow from the famed Sherlock Holmes, upon further examination the solution to this problem was quite clear. As many of you know flow rates through a boiler heat exchanger are to be adhered to at all costs. Nearly all heat exchanger designs will “give” a little, but those with small ports and high head losses are the least likely to allow for poor piping practices.
My solution, based off the many clues I gathered while on the scene, was to simply remove all the near boiler piping and start over. Yes, start over. The first order of business called for raising the pintsized box off of the floor, so that access to the condensate trap was gained (a detail often overlooked on this particular model). Once the boiler was at home atop a wall-hung shelf, primary/secondary piping commenced. Armed with the required flow rates and specs on the boiler via my tablet it was now time to install the boiler circulator and system pump. The owner opted for the “better” option and chose to go with a variable speed system circulator and a well-known brand of zone valve control to maximize the heat delivery and minimize the potential for wiring nightmares now, and in the future.
From start to finish, armed with the desire to gather all the necessary clues, I was able to have the [formerly] dying boiler up and running in just over one day. This makes for a very happy homeowner and now, a well-earned customer. My only hope is that I have earned the opportunity to be considered by this client for the next job.
Eric Aune started Aune Plumbing LLC, in 2004, and to carry on the tradition of family members before him, he has specialized in residential and small commercial hydronic heating systems and service. He is a graduate of Dunwoody College of Technology and Plumbers Local 15, Minneapolis Apprenticeship Training Program. Aune is currently a United Association Instructor and teaches for the Plumbers Local 15 JATC. Eric Aune is also founding partner and vice president of mechanical-hub.com. Contact him at: [email protected].