Now bear with me on this one. The story might get a little long, but it is a good story.
In about 1984, I designed the hot water system we currently use in our house. It depends heavily on the concept of convection. In a nutshell, convection means that hot water is lighter than cold water, and given an unimpeded path, hot water will rise to the top of the system. The core of our hot water system is a recycled 50 gallon tank in a small closet in our bathroom, which is on the second floor of the house. The tank has 3 separate heat sources, all of which sit lower than it does. There is a hot water jacket in our woodstove, a home made solar collector outside, and a small electric hot water heater in the basement.
All 3 of these heat sources feed the tank by convection, which is a fairly low pressure system. This is important, because we have a lot of minerals in our well water, and over the years, the minerals coat the insides of the pipes, reducing the potential for convection. The first set of pipes to plug are usually the electric hot water heater, probably because it is so seldom used.
For the past few months, we’ve been noticing the electric hot water heater wasn’t doing its job. I bought a selection of parts and headed into the basement with my wrenches. I had Alice turn it on while I watched it work. Everything did what it was supposed to do, which left one alternative… the system of pipes was probably clogged and in need of cleaning.
Over the years I’ve devised a technique for cleaning out the system that seems to work well for us. I drain the entire system and add about 30 gallons of distilled white vinegar. Then I fill the rest of the system with water, and start up each heat source so hot vinegar solution circulates. I allow this to cook for about 3 hours, drain everything, and usually get a pound of mineral gunk out.
My technique for getting the vinegar into the system has varied over the years, but was never elegant. So this year I engineered a better system, bought some pipe fittings, and planned to reconfigure things so I’ll have a better way to add the vinegar. I’m always reluctant to tear into a functional system and make a change like this, because my experience has shown me that there are often unintended consequences. But last weekend, I hauled my fittings and tools up the the bathroom and started taking things apart.
I literally had the copper tubing cutter on the pipe when I took one last look at the project, and thought of a simpler and better way to do it. And amazingly, it seemed this change would use up many of the fittings I had purchased for the more complicated way I’d originally planned. I removed the tubing cutter and put it away, and went to work. It is a bit difficult to tell in this picture, but where the vinegar bottle is standing is where the new fitting is located that allows me to much more easily add the vinegar.
Things were looking up! I added the vinegar, and had no problems. I turned on the water to fill up the system with water; and again no problems. I added heat to all three sources, and that worked too. “I’m on a roll,” I unwisely said to myself. After 3 hours, there was a system full of very hot vinegar and water circulating through the system. Now the next job was to attach the hose to the drain in the bottom of the electric hot water heater, open the valve, and thereby drain the system. What could possibly go wrong?
I will say that whoever designed the valve on the bottom of the electric hot water tank must have saved the company literally dollars, versus putting a decent valve down there. I’ve only used this valve a few times in the 30 years the tank has been in use. I crawled over to the tank with the end of the drain hose in one hand, and started screwing the fitting onto the nipple. I got part way done when the cheap plastic fitting exploded off the tank, shooting hot vinegar solution all over the dirt floor of the basement. I stared in disbelief for about 2 seconds, and then attempted to attach the hose to the steel fitting that was exposed when the cheap plastic thing fell off.
There are two kinds of threads that are relevant here. Hose threads and pipe threads. The hot water heater fitting was pipe, and the hose was, well, hose. The two are close, but not compatible. All I could do was try my best to hold the hose over the steel fitting and force as much of the vinegar solution as I could through the hose. The connection was not water tight, meaning streams of hot vinegar were how shooting all over the crawl space. This went on for several minutes. My only words as I recall, as I was being bathed in this stuff was, “ugh.” It got in my eyes, making them sting, but I couldn’t spare a hand to wipe my eyes. Even if I could have, my whole body was covered with vinegar and mud anyway. A renegade drop or two of the liquid landed on the light bulb 10 feet away and blew up the bulb. So now I was also in the dark. Alice valiantly came to the door of the crawl space and offered assistance, but there was nothing I could think of she could do.
After several minutes of this torture, the system emptied itself and I was able to move around and try to pick up the pieces. I replaced the crappy plastic valve with a decent one, refilled the system with clean water, cleaned myself up, and started the sauna. If ever there was a day in my life I needed and deserved a sauna, this was it.
Several days later, we are still working with the system. We still get a whiff of vinegar from the hot water, and see traces of minerals on occasion. We can’t use our dishwasher because of the minerals in the hot water system, so we’re doing the dishes by hand. Now I remember why I put this hot water cleansing procedure off as long as I possibly can.