Jrangelini
New Member
I am struggling to make sense of the movement of the leak detection triangle on my water meter. I had a leak in the garage (evidenced by moisture coming through the slab), and after various vicissitudes (e.g., having the leak detection company jack-hammer the pipes, which apparently had been roughed in short of the wall, then encased in the slab without sleeving, etc.) the entire area was re-piped, so I decided to run a follow-up leak test overnight. The original leak had tested at 0.5 gallons; now after the repair the meter moved 2.1 gallons overnight!
So I determined that I had a new leak somewhere. I have been running leak tests since then, but getting very strange and inconsistent results. The triangle moves (counterclockwise) with a fitful (start and go) motion, making one full rotation in about 1.5 minutes, when all the lines are open. I then turned off the hot water (handle before the hot water heater), and the triangle appeared to stop, but as I watched it over a 5 minute period, it did move (I'm using a piece of tape to measure movement from side to tip, etc.), then stopped, then after another long period, it moved again. I turned off all the toilet valves to eliminate the flappers as a cause, but the very slow, intermittent movement continued. I then turned off the water at the house to test the service line (from the meter to the house), and even this had an extremely slow movement (10 minutes to move from one side to tip). At this point I thought ALL my plumbing is bad (house was built in 1993), but I wanted to make sure before re-piping the whole thing, so I ran overnight tests again.
The first night, I tested the service line--no meter movement at all.
The second night, I tested the cold water side--no meter movement at all.
So, essentially I am seeing movement in the leak detection triangle during the day that is then NOT confirmed when I test the meter overnight (from 11:00 p.m. or midnight until 7:00 a.m.). Most recently I closed the hot water lines (yes, I have installed valves on basically every line in the house at this point) AFTER the hot water heater, and found the meter moved 0.7 gallons during a 2 hour (daytime) period. So I'm wondering whether the hot water heater, as it heats the water, and then it cools, and re-heats, can essentially be causing pressure fluctuations that would cause water to flow back and forth between my system and the city system (i.e., main).
There is no backflow preventer on the supply line to the house (I have one on the sprinkler line, and I've already replaced this, and currently have the valves shut off to eliminate that and sprinklers as a cause). I don't see any check valve or pressure reducer in the meter box or on my supply line. The water heater is also brand new, and does not have an expansion chamber. I have never seen the triangle move "backwards" (i.e., clockwise), but I wonder if what is happening is a result of pressure differentials between my house and the city water:
- In the daytime, when more people are using water, the city pressure could drop and my water could flow into the system (this would presumably not be registered by the triangle, since I don't believe it can ratchet backwards). When the city pressure builds back up to exceed my pressure, the water would return to my house and move the triangle forward (which incidentally would mean I pay more than once for the water I feed back into the system-!). This could explain why the cold/supply line tests show (SLOW) movement in the daytime but NONE at night, when not as many people would be using water.
- Thermal expansion caused by the hot water heater would increase my pressure and accelerate the rate of displacement to the city supply. This could explain why the triangle moves faster when the hot line is open, and also why the meter moves even when the hot lines were closed AFTER the hot water heater (couldn't be a leak because the cold and supply lines already tested good and I can see everything else!).
If this theorizing is right, then it would never be possible for me to have ZERO triangle movement so long as the hot water heater is on. I'm planning on running more tests (each hot water line with heater both on and off), but I wondered if anyone has experience with this. A simple rule--if your triangle moves, you have a leak--makes sense to me, but this is defying all logic so I'm coming to believe the interplay of pressures actually makes this more complicated. If it is indeed possible for my triangle to move without there being a leak, then I can patch up all the holes in my house and move forward!
So I determined that I had a new leak somewhere. I have been running leak tests since then, but getting very strange and inconsistent results. The triangle moves (counterclockwise) with a fitful (start and go) motion, making one full rotation in about 1.5 minutes, when all the lines are open. I then turned off the hot water (handle before the hot water heater), and the triangle appeared to stop, but as I watched it over a 5 minute period, it did move (I'm using a piece of tape to measure movement from side to tip, etc.), then stopped, then after another long period, it moved again. I turned off all the toilet valves to eliminate the flappers as a cause, but the very slow, intermittent movement continued. I then turned off the water at the house to test the service line (from the meter to the house), and even this had an extremely slow movement (10 minutes to move from one side to tip). At this point I thought ALL my plumbing is bad (house was built in 1993), but I wanted to make sure before re-piping the whole thing, so I ran overnight tests again.
The first night, I tested the service line--no meter movement at all.
The second night, I tested the cold water side--no meter movement at all.
So, essentially I am seeing movement in the leak detection triangle during the day that is then NOT confirmed when I test the meter overnight (from 11:00 p.m. or midnight until 7:00 a.m.). Most recently I closed the hot water lines (yes, I have installed valves on basically every line in the house at this point) AFTER the hot water heater, and found the meter moved 0.7 gallons during a 2 hour (daytime) period. So I'm wondering whether the hot water heater, as it heats the water, and then it cools, and re-heats, can essentially be causing pressure fluctuations that would cause water to flow back and forth between my system and the city system (i.e., main).
There is no backflow preventer on the supply line to the house (I have one on the sprinkler line, and I've already replaced this, and currently have the valves shut off to eliminate that and sprinklers as a cause). I don't see any check valve or pressure reducer in the meter box or on my supply line. The water heater is also brand new, and does not have an expansion chamber. I have never seen the triangle move "backwards" (i.e., clockwise), but I wonder if what is happening is a result of pressure differentials between my house and the city water:
- In the daytime, when more people are using water, the city pressure could drop and my water could flow into the system (this would presumably not be registered by the triangle, since I don't believe it can ratchet backwards). When the city pressure builds back up to exceed my pressure, the water would return to my house and move the triangle forward (which incidentally would mean I pay more than once for the water I feed back into the system-!). This could explain why the cold/supply line tests show (SLOW) movement in the daytime but NONE at night, when not as many people would be using water.
- Thermal expansion caused by the hot water heater would increase my pressure and accelerate the rate of displacement to the city supply. This could explain why the triangle moves faster when the hot line is open, and also why the meter moves even when the hot lines were closed AFTER the hot water heater (couldn't be a leak because the cold and supply lines already tested good and I can see everything else!).
If this theorizing is right, then it would never be possible for me to have ZERO triangle movement so long as the hot water heater is on. I'm planning on running more tests (each hot water line with heater both on and off), but I wondered if anyone has experience with this. A simple rule--if your triangle moves, you have a leak--makes sense to me, but this is defying all logic so I'm coming to believe the interplay of pressures actually makes this more complicated. If it is indeed possible for my triangle to move without there being a leak, then I can patch up all the holes in my house and move forward!