Originally Posted By: Matthew Metzger This post was automatically imported from our archived forum.
Wished I had a better photo, the tube coming up from the bottom of the tank is connected to the drain at the bottom. I know that this concept circulates hot water throughout the hot water lines so that you don’t have to wait for hot water. My question is what is this system called and how does it work with no pumps and so forth? Thanks Matt
Originally Posted By: jpeck This post was automatically imported from our archived forum.
That would be a gravity flow hot water recirculating system, versus one driven by a re-circulating pump.
There is a major problem with the setup shown in your photo, though.
That is a gravity flow system (hot water rises, cools, then falls back down the other line to the drain) and it contains two heat traps fittings.
Sorry 'bout that, but ain't no hot water going to flow upwards through that system 'cause of those heat traps. 
And I know you got the 'no drain line on the T&P safety relief valve'.
Plus, looks like you've got a crimped hot line from the water heater on the left.
Sorry, couldn't help but notice, I'll quit inspecting that photo now.
Originally Posted By: Matthew Metzger This post was automatically imported from our archived forum.
No problem J. Yah I caught the abscense of discharge lines, actually both tanks were missing them. I’m sorry but I don’t follow you on the heat traps, I don’t see what your talking about. They seem to work, it’s my folks’s house, I lived there for several years and had hot water pretty much on demand. Thanks Matt
Originally Posted By: jpeck This post was automatically imported from our archived forum.
The heat trap fittings, unless defective or tampered with, stop the upward flow of hot water by gravity. As soon as a use flow is started, the heat trap passes hot water.
Because heat trap fittings can fail, I prefer the heat trap made from the pipe itself, i.e., up about 9", over horizontally a few inches, then down about 6 inches, the horizontal to the hot water supply to the house.
This 'traps the heat' as the heat wants to rise, and it cannot make than 6" turn down in the heat trap. Thus, the gravity flow effect is lost.
With heat trap fittings, when they fail, or if tampered with, the heated water will rise right on up through them.
The purpose of heat traps is for energy efficiency, to keep the heated water in the tank an not let it out so it cools, having to re-heat it all over again.
Originally Posted By: Matthew Metzger This post was automatically imported from our archived forum.
Blain you are correct on both accounts, they are plumbed in parallel. I am almost positive he used simple nipples, to my knowledge he doens’t handle the heat trap fittings in his store.
Originally Posted By: phinsperger This post was automatically imported from our archived forum.
Matthew Metzger wrote:
... they are plumbed in parallel. ...
From the photo it looks like they are plumbed in series. I could be wrong as I can't see the "jumper flex hose" continously. If I am correct then this wrong. To increase the hot water reserve they should be paralell.
Is that the furnace flue in the forgound and ties in with the flue from the water heaters above the photo?
No problem J. Yah I caught the abscense of discharge lines, actually both tanks were missing them. I’m sorry but I don’t follow you on the heat traps, I don’t see what your talking about. They seem to work, it’s my folks’s house, I lived there for several years and had hot water pretty much on demand. Thanks Matt