bad foot valve
Tuesday, April 15 2014
It was warm but rainy this morning, and over the course of the day the rain came down harder and the winds picked up. If I'd set out this morning, I might have been able to gather firewood. But there was no point later in the day when I would have wanted to take my electric chainsaw out into the weather.
For the past few days I've been spiraling in on the solution to a strange problem with the solar hydronic loop. To evacuate air pockets in the line, I've been using the antifreeze recharge system to circulate antifreeze at high pressure (30 psi or so) up through the loop. At that pressure, it's possible to push air bubbles 30 feet above the basement back down to it, where they can be flushed (along with surrounding antifreeze) out of a hose and into a 5 gallon bucket that I use as the source for antifreeze to pump back into the system. The problem I've been having is that the recharge system hasn't been able to hold onto its charge pressure. After an hour or so, its pressure would fall to zero. This was bad, because I depend on the recharge system to put antifreeze back into the system should any spill out or evaporate. The question was: where was that antifreeze going? I looked for leaks on the solar deck and in the boiler room, but there was nothing obvious. It was also clear that I wasn't losing much or any volume of available antifreeze.
This morning I figured out what the problem was: the recharge system's foot valve (which is like a check valve in that it only allows fluid to flow in one direction through it) was leaking slowly in the wrong direction. This meant that once the recharge system held a fluid under pressure, it would gradually leak back through the foot valve, through the pump, and into the five gallon bucket that serves as the unpressurized supply of antifreeze. I could hear the leaking as a soft hissing sound whenever the recharge system was pressurized.
This evening I depressurized and drained the recharge system and replaced the foot valve with a simpler check valve (one that contains a simple door on a hinge instead of a disk held out on a spring). Despite the fact that I was soldering with a MAPP gas torch among RCA cables and other things that could have easily caught on fire, the replacement went without a hitch. The only fuckup came when I knocked over a hose full of water and it began siphoning antifreeze out of the five gallon bucket onto the floor. I lost nearly a half gallon of antifreeze (worth about six dollars) from that fiasco. (If I hadn't been listening to podcasts on headphones, I probably would have heard the gurgling earlier.)
For linking purposes this article's URL is:feedback
previous | next