ndrober
Thank you. It should like they were only relying on the pump to set the flow direction. It turns out that the is a swing check valve next to the pump but it does not restrict flow between the two lines.
To clarify the luke warm. With the system valved open and pump running everything works fine (except for the $240 extra dollars a month in propane). When the pump is off and the valves left open, every faucet gets cold water. ( the return is attached to the bottom of the hot water heater. There is what looks like a PRV or maybe a burst disk in the upstream side of the pump. It is between the two isolation valves around the pump. No other signs of any flow or pressure control anywhere in the system.
The way I have been using is with the pump off and both the valves closed. ( at least until my wife complained the kids were washing with cold water) This isolates the two return lines from the hot water heater but not each other.
For reference at my kitchen sink closest to the hot water heater ~15′ the temperature is 135 deg. In the mater bath another ~75′ away one shower is 120 deg and the other is 94 deg. The two sinks run at 115 and 110. The bath (separate from the shower) runs at 120 for the main spout and 115 for the hand shower.
I have tried running the hot water and checking the faucets, the hot line stays hot and the cold line cold, so I do not think anything is flowing the other way.
I tried to look at the photos during construction but I could not make sence of what was going on. It looked like there was two hot line running to each fixture, however I would have expected a hot supply manifold and hot return manifold, instead I only found one manifold with about half of the pipe being a large size and half the smaller size.
My brute force solution, is the one one I have right now is to install check valves in the two return lines and use occupancy sensors to activate the pump. I would expect with check valves the system would not pull water from the bottom of the tank and this would minimize the energy waste. My wife and kids are home all day so a time would not due much good.
Thanks
Nathan
