tankless water heater diagrams

this is for all you diagram buffs (like me). you may never need it, but it’s common in my other job. i helped the plumber install this on monday. ours is the first configuration on the second diagram. the others are interesting. just incase anyone comes across an “Everhot” tankless water heater. enjoy.

Thanks Jay for the info.

I do not see where the return water from the heaters get back into the system .I am concerned that used water from the base boards or pool heater can come out of the kitchen tap and this is not a good thing in my openion.
Roy Sr.

Imposible Roy. well not 100%. but if you think of the fact that the street presure is higher than the boilers altitude or pressure, any breach in the system will cause pottable water to infuse into the “heat” water. that’s actualy the presice reason this particular tankless had to be replaced. the “tank” part of the water heater is actualy the furnace water (about 35 gallons at 180-200 degrees f.) then the fresh water is fed in at street presure and runs threw a coil of finned copper. as it comes out it’s been heated in a reverse of a base board radiator. then it’s mixed at the mixing valve with cold water from the “T” you see at the supply, regulated by a bi-metal expanding device inside the mixer. all the while still at steet pressure. if the coil developes a leak, the higher pressure from the supply (usualy 40-60 psi) pushes fresh water into the furnace loop (usualy 12-20 psi) and if that gets too high (over 30 psi) the TPR opens to releive pressur…and flood the apartment next door, calling out attention to the problem. I just hope i was helpfull to your concerns Roy. Have a good day.