It seems to me there is a range of likely leak rates it can't deal with because they would match regular use (eg - lawn water is high use, long duration).
So I guess it is important to be aware of what level of protection you are getting for the price.
TBillT wrote: ↑
Thu Oct 24, 2019 3:15 pm
Not a bad idea pending more research.
We had a crazy thing happen last summer, when we went on vacation, I manually turned the house water off.
For some reason this caused a flood in my kitchen, apparently there is a valve in dishwashers which requires pressure to keep it closed. In the lack of water pressure there can be slow leak into the dishwasher....where the water is came from , I do not know. Backflow from 2nd floor or slow leak thru the water main valve. Also a concern might be hot water heater if on when water off. I replaced the damn dishwasher valve for $300 bucks (valve is $15 so $285 labor). But nothing is as simple as it sounds when it comes to water. The guy said the high repair costs was due to extreme insurance they pay for water jobs in case there is a leak.
Electric valves usually use a small solenoid to actuate a very small valve, which then allows the fluid into a piston which actuates the main valve. This is called a pilot-actuated valve. This kind of arrangement is common not just in household appliances, but even in industrial machinery.
If pressure is lost, it should stay in or return to its neutral position, but I suppose as pressure declines, it will at some point transition through a semi-open position. If it stays there long enough, you could get a lot of water pass through the valve. In typical 3/4" pipe, roughly 40 feet of pipe holds 1 gallon of water.
Water would indeed drain into the dishwasher from the second floor pipes. One way to prevent this is after shutting off the water, open a low-elevation faucet in the house. This is also a normal recommendation when shutting off water for freezing concerns.
I'm not positive, but I would have thought dishwasher ejector pumps should be controlled by a float switch and operate even if there is no cycle running, in part to protect against this scenario. However, if the power was off, that would not happen.