bks0005

Hose #2 ( bypass hose ) needs to go back to your water tank not the pump. That should correct the problem with the unloader. What type of switch do you have ie -flow or pressure that turns your burner on? Not sure why your thermal relief valve is located there, mine is on the outlet side of the burner coil. To double feed the pump you could have a elbow on the right side bottom of the pump and a tee on the other side. I would strongly recommend using a 1" suction line for this. The left, top side of the pump is the high pressure, this line goes to the unloader valve. On the unloader, I would have the bypass line run directly to the tank with a clear braided hose. The hose I use for this is rated for 800 psi.

Your bypass line comes from your unloader valve to the tank. From what it appears you have is a bypass from the hi pressure side of the pump back to the inlet side of the pump, that will do nothing for you. I believe if you remove the line altogether that will fix your problem as long as you have a bypass line from the unloader valve to the tank. If you need any help message me and ill talk you through it on the phone.

Take Russ's advice and change the suction hose. I have a 1 1/2 ribbed suction hose with a 1 1/2 strainer on mine and it works great. Mine runs like this: tank, cut off valve, strainer, then the pump. I fill the tank directly from the supply line with a float valve.

EnviroSpec sever duty oring rated to 450 have been using the same set of O rings for the last month. Here is the link for these Orings -Quick Connect Couplers

I would by the 5.6 gpm hot because you are doing residential work with the occasional commercial job and parts for the 5.6 are much easier to find and cheaper. I personal I have a 5.6 hot water machine and love it I went from a small 3gpm to this 5.6 and have never looked back. But if you are going for the larger commercial accounts get an 8 gpm or larger hot water unit for those jobs.