VIA E-MAIL — I have a gravity return line in my home that I personally built (I was an upscale builder). It has worked fine for the past 10 years until I went away for 10 days recently and decided to shut the water off to forestall any damage if a hot water heater leaked while gone.
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In the meanwhile, after about 10 days, the gravity system kicked in again. Yesterday, we had to shut the water off again and drain the system in order to repair a faulty valve in the water closet in this same master bath. Again, the gravity system doesn't work, but I suspect it will after some time.
Does Dave Yates have any ideas? In his column, he made a point of drilling a 1/8-in. hole in the swing-check valve. What is the purpose of this hole? This small detail appears to be the only difference between my system and the one Dave describes.
My plumber quit installing the gravity systems some years ago, claiming they were unreliable — some worked and some didn't. He had everyone who wanted a circulating system go to a pump, which was quite expensive.
I look forward to hearing from Dave.
—Robert Schoenberger
Dave Yates replies: Sounds like the swing-check is sticking in the closed position, which is not unusual without the drilled hole. Water tends to "stick" to itself, which you can demonstrate by trapping a drop or three of water between a sheet of glass and smooth countertop. Virtually impossible to lift the glass unless you can break the water-seal. The same thing occurs between the smooth surfaces within the swing-check valve.
Drilling a 1/8-in. hole (or slightly larger) through the swing-check breaks the water seal by removing any pressure differential, which allows the gate to swing freely. It also acts as a governor to limit flow and eliminates any chatter (a noise complaint that occurred infrequently prior to our drilling the hole). Start small because you'll have reverse flow during hot water usage and, if the hole is too large, the bather will sense the change.
Pass this information on to your plumber and he might be inclined to try gravity once again. We have hundreds of gravity systems in place without any problems. The gravity system here in our office/apartment building dates back to long before I ever twisted a wrench.
Questions On Solar DHW
GLENVIEW, ILL. — Great article by Dave Yates about his domestic hot water solar application in CONTRACTOR ("Liquid sunshine," May, pg. 40).
Several quick questions: How did he decide on sizing for the collector and also the storage tank? Where did he purchase the collectors and who helped design this system?
—Jonathan R. Smith
Effective Air
Dave Yates replies: I did all of the design work myself after several years of reading, studying and asking questions. The site assessment is a required first step. Sizing was a multi-faceted combination of things. After visiting the Solar Decathlon in D.C., I was convinced I wanted to use a vacuum tube array. Long story short: I was at Viessmann's training facility and had an opportunity to visit the roof-top vacuum tube array that was connected and working. I inadvertently placed my hand on the incoming copper in the test lab and it was a scorcher — in spite of that day being cloudy and overcast.
While I'd been looking for the various components, I repeatedly saw and read that a "normal" DHW system would require a 30-tube array for heating up to 80 gal. per day during peak solar harvesting conditions. I was getting tired of picking a piece here and another piece there with no real knowledge of how they would work together. Viessmann had a total system approach and that was my tipping point! I'd already purchased a Bradford White 120-gal. indirect with the thought of using its inner coil for exchanging the energy.
The other appeal for using a 120-gal. tank is that each rise of 1˚ equals 1,000 Btu harvested. I deliberately oversized my storage capacity as an experiment. Given that I can't turn off the system to stop harvesting the sun's energy, I wanted a buffer to allow me time away from home. That's turned out to be a handicap during the lower energy harvest with the sun at a low angle in the sky and the tank's temperature fluctuated quite a bit between cloudy/noncloudy days.
In hindsight, a smaller storage vessel would have permitted me to maintain much higher temperatures. However, now that the sun's angle is higher and incoming cold water temperatures are rising, I'm becoming aware that the extra storage capacity won't be such a great buffer for extended time away. We're already passing the 150˚F mark after a full day of sun!
Sid Harvey handles the Viessmann line in the York, Pa., area and York Corrugating the Bradford White products.
I had some issues with trees that cast long shadows late in the afternoon but had one spot just large enough for the 30-tube array that received sun until late in the afternoon. The offending shadow-casting trees were dying from a non-treatable disease. They were almost 85 ft. tall and they're now gone. My roof is sun-lit from end-to-end all day, so I'll be adding and expanding.
Most Want To Do A Good Job
VIA E-MAIL — I did a Google news search about morale and H. Kent Craig's column was one of the selections ("Have a clue how much workers don't work?" March, pg. 48).
I want to thank Kent for emphasizing the "complete lack of morale for the employees who are on the job and want to do a good job for the company because they know that their own job security is at stake if they don't."
There are wonderful people in the workplace who do care, who treat the company as is they were the owners. However, they don't get much press.
—Paulette Wagner
H. Kent Craig replies: Yes, the vast majority of people in general do care, a lot, about not just doing a great job for their company but about being the best they can be in all aspects of their life, period. Give someone a chance to care, to do the right thing and they will; I've always firmly believed that.