Couple of years ago, I saw in This Old House magazine, I think, a valve attached under the kitchen sink water pipe. When the temperature drops to a low trigger point, the valve starts to drip. It is not a fast drip. It is a very slow drip. The slow controlled drip is sufficient to prevent pipe freeze. Please help me find it.
I have a kitchen built on top of an enclosed porch. The underside of the porch was been enclosed with concrete blocks. The underside of the joists had been boarded up. Only access to the underside of the porch is a small basement window under the porch. Crawling in there is not an option.
The cavities between the joists were not insulated. One of the cavity is used to run the hot/cold water and drain pipe. ONE time per year, after a few consecutive cold days, my water pipe freeze up. To clear the ice clog, I stick a hair dryer in the cavity from the basement and run it for 15 minutes or so.
Last summer, I cut open the sink cabinet bottom, then cut open the kitchen floor under that, and reach the point where the water pipe turns up, through the floor and the cabinet bottom, into the sink cabinet. I lifted the pipe up an inch or so so they are not resting on the bottom of the cavity, where the other side is open cold air. In the created air space gap, I sprayed expanding insulating foam. Then, more foam to insulate the top side of the pipes. Then, finish up with fiberglass insulation to fill up the remaining space between the pipe and the joist and the back side (outside wall) of the cavity.
I kept the 2.5 feet of joist cavity space between the foundation wall and the newly insulated area NOT inulated. My reasoning is that the warmer basement air will reach the exposed pipes. Had I inslate that portion, I would have isolating the pipes to the cold side as oppose to the warmer basement side.
I was hoping this project will provide a delay of heat loss till a warm day comes along. Instead of 3 cold days to freeze, it may take 5 days to freeze. The likelyhood of 5 cold days is less than 3 days. Well, I think it worked. After a few days of very cold temperature, it freezed overnight. This time, it only took the hair dryer about 2 minutes to clear up the ice clog.
BTW, I have split seam pipe insulation wrap on the pipes already.
So, my project worked, but not 100%. I have been looking for the anti freeze valve for a while. Cannot find it.