I finally finished installing my Pinnacle PB 150 over the Thanksgiving holiday. I took me about two months widdling away at it after work and on the weekends. My 1.5 and 3 year old donâ€™t leave a lot of time for â€œthe projectâ€ as my wife referred to it! Anyway, here are the highlights of the install. 1. The PB 150 was installed in series with my propane boiler. 2. The supply side of the PB 150 enters the return on the propane boiler to satisfy the propane aquastat that is set lower than the PB 150. The water exits the supply of the propane boiler, goes through the radient floor manifold, and returns to the PB 150. I have it plumbed so that the pb 150 can be zoned off and shut down and I did this by putting 2 Tâ€™s with a valve between them in the old return line on the propane boiler. The supply and return for the PB 150 also have a valve soâ€¦ If the propane is running by itself or if I need to clean the PB 150, I can open the valve between the 2 tâ€™s and close the valves on the PB 150, and it operates as it always did. The only thing that I had to do was make sure that the supply line from the PB 150 entered the system closest to the propane boiler so that it satisfied the propane aquastat before entering the manifold. I can send pictures if anyone is interested. 3. I have a Taco control board that all the thermostats connect to and that controls the zone pumps and circulator pumps which greatly simplified the process. 4. I wired the propane and PB 150 ciculator pumps in parallel. In order to do so I did not connect the cuculator pump on the PB 150 to the aquastat on the 150. I also installed a switch on the line between the circulator pumps so that I can turn the PB 150 cirulator pump off. The propane boiler and taco control board control booth pumps. 5. I wired the yellow wires together on the PB 150 which allows the aquastat to control the boilers operation. 6. Unlike the manual pictures, I installed the breather vent, and the preasure/temperature releif valve on the top tapping in the back of the boiler. I did this so that I could install a honeywell 4006B in the middle back tapping for dump zone control. The 4006B closes above its set point completing the circuit. I then ran a thermostat wire between the aquastat and my largest zone on the taco board. At 200 Â°F, the contacts close the same way that an thermostat will, turning on the curulator and zone pump to â€œdumpâ€ heat preventing over heating of the boiler while it is on pilot mode. My aquastats do not send voltage to the system so there is no danger of sending too much juice to the control board. If anyone would like a diagram or needs help, I would be happy to. It is because of folks on these forums and my Brother-in-law that I was able to muddle my way through this project. I even gave myself 30 stitches on my head as a result. That is what I get for using my head. Maybe I can save someone else the headache of all of the research that went into this.