To where are you targeting the delivery of it? If to a dishwasher or washing machine, a simple method is to run a faucet near the machine until the flow is hot ... such as at the kitchen sink. Otherwise, pretty much the only way is via a recirculation pump on a flow loop from the water heater across all the taps. Some plumbing systems are constructed with a dedicated recirculation loop. There are retrofit pumps that are installed at the furthest usage point from the heater, feeding water from the hot line into the cold to create a flow loop ... usually operated on a timer or on-demand a few mins before hot water is needed. One such product is the Metlund D'MAND System. There are others.

Actually, after futher review of what happened, it was maintenance that possibly (kinda sorta) contributed to the water leak. The day before the leak, I was doing maintenance on my washer and dryer. I was cleaning the lint from the dryer vent. Also, I was cleaning out the washer tub. I think I must have moved the utility sink a bit and caused the pex supply line that goes to the sink to move a bit, maybe causing it to loosen and then the heat and water pressure built up and popped the hot water supply line out of the bottom of the faucet connection. Either that or the rubber o-ring just gave out from the heat and water pressure. So, I changed both lines to the steel braided type that I have on my washing machine supply lines. This should hopefully prevent any further issues. And, yes, live wire oak, although you seem to assume I do not do maintenance around my house, I do indeed regularly perform maintenance around my house, to include: flushing the water heater twice a year, cleaning the dryer vent, cleaning the gutters, cleaning and servicing my water softener, changing the carbon and sediment filters for my well water, prepping and staining my deck, lawn/landscaping maintenace, maintenance of lawn equipment (riding mower, trimmer, blower), maintaining and cleaning of pellet stove, maintenance on two automobiles....etc...etc...etc... I guess I have to add inspecting supply lines to that list. And, yes, brickeye, I could not agree with you more. Maintenance is less work than paranoia......that is why I try to do as much as I can around my house to avoid the catastrophes..... thanks. mm

Fixing the running toilet fixed the usage problem and the softener appears to be functioning perfect, which I guess begs the question, is it OK to leave the check valve in? It does not appear to be restricting flow in any way (valve shows maximum SFR to date of 13.9 gpm) and I don't think it is creating any back pressure. Wouldn't the check valve actually prevent any back pressure from reaching the valve and resin tank and in turn protect the resin tank and valve? Say for instance that the expansion tank was malfunctioning for whatever reason, and the water heater kicked on and created a brief expansion that drove the psi up to say 150 psi and that back pressure pulse was pushed back to the check valve since the expansion tank didn't work correctly. Wouldn't the check valve slam shut and prevent this back pressure from reaching the resin tank and valve? If the normal line pressure on either side of the check valve is the ambient 60-70 psi of the system under normal conditions and a back pressure pulse of 150 psi comes from the water heater side of the installation, isn't that precisely the set of conditions that would cause the check valve to close and keep the pulse on the water heater side of the system? I realize that with check valve in place and the theoretical malfunctioning of the expansion tank, the pressure pulse will seek some method of escaping which could cause damage somewhere in the house like a faucet or toilet, but at least it will not have blown the resin tank or destroyed the control valve, correct? I hope this rationalization makes sense, but I'm not sure that I have done a very good job of positing my questions or explaining the scenarios. Oh well. Take a swing at it if anyone feels like it. I am interested to hear some opinions on this one. I'm thinking more potential bad will come from disassembling a functioning, dripless install than from keeping the check valve in place. Thanks. Drew

Since you didn't have the smell before you went away you may have sulfur reducing bacteria in the electric WH. Check the toilet tanks to see if there's any slimy stuff in there. Note what the temp setting is on both WHers. Turn the temp on both water heaters up to 140 for 2 hours. Be VERY careful if using hot water during this time cause it will be REALLY hot but best not to use any hot water during this 2 hours.. After 2 hours set the temp on both WHers back to where it was. Open all the faucets everywhere till the smell is gone. If that doesn't solve the problem then your entire plumbing system will need to be sanitized. If you have water treatment equipment that will need to be sanitized also.