Hi all, I would like your feedback on the system outlined in the attachement. Background: the system here heats a 12 unit condo complex in SF, CA. The heating loads are a mix of hydronic baseboard and radiant floor in light weight aggregate. The ergomax label is incorrect, the unit is actually a E44. It is an older model and doesn't have the connections to bring the returns from the load directly to a fitting on the tank. The existing system, not including red markups, is shown. Red markups are suggested changes to solve some problems. First off, the two lochinvar units were installed 6 months ago and have at least 35,000 ignition cycles between the two 20k on one, 15k on the other. The units are hitting over temperature shutdown a lot. The existing layout was not the intended design. The original design called for the ergomax to be connected like the new models, but the contractor may have not realized the the fittings for the load returns were not there. My question is, does it seem reasonable to use the ergomax as suggested in the red markups? The way I see it, why not pipe it in series with the boiler loop and eliminate a pump, which also allows for a backup boiler in case of an issue and utilizes the tank as a buffer tank. With the ergomax in series, I wonder if there will be a sufficient delta T across the boilers though. Any advice would be greatly appreciated.