e.alleg wrote:I am getting ready to hook up my hot water coil, I was thinking of hooking it separate from my existing HW heater and isolating the 2 separate heaters with simple ball valves. It appears that I can just T off of the fill line into the boiler and plumb that cold incoming well water to one side of the coil, then the other side will get hooked to the hot water pipe that goes to the shower. I 'm not sure what will prevent the boiler from heating the cold tap water and warming up all the pipes in the house...maybe I'll need a one-way valve on the inlet side?
Yes, T off of the supply line from your well to the boiler. I just ran a ½ in. copper line into the hot water coil and the other end of the coil to all hot water faucets. You may want to put a valve between the T and coil. Between the T and boiler you will install either an automatic fill valve or a gate valve if you wish to fill and maintain boiler pressure manually. Your boiler should always be at a lower pressure than the domestic water and the valves filling the boiler are almost always closed so getting water from the boiler into your domestic hot is highly unlikely. If you are paranoid about it you could put in a check valve between the T and boiler fill valve. An auto-fill boiler valve may have a check valve built into it but I do not know if they do.
You only loose heat in the pipes that heat the house if your water temperature drops below the low limit of the aquastat. The circulator stops until the set temperature is satisfied. Only on rare occasions will you ever have such a demand on the boiler that you lose domestic hot water temperature. Check with EFM’s web site to see what their coils are rated for, I think you can find the info there somewhere. You may have to download the owner’s manual for the 520.