I think my other thread is too long, so I'll ask my question here. I built my sidearm yesterday. I used 1-1/2” outer pipe (boiler loop is 1-1/4) with a 3/4” pipe on the inside. This connects the cold inlet and hot outlets of the indirect storage tank. I had to ream out the stop in the reducer coupling to get it to slide over the 3/4” pipe. The picture at the bottom of the tank shows the cold coming in, the bottom of the sidearm and a drain. At the top you can see the mixing valve to temper domestic water. The valve to the left is to supply untempered water to the dishwasher. The domestic loop still held pressure when I was done, so that’s a good sign! I put a valve at the top of the thermsyphon loop...I was worried that water might jump directly from the cold supply to the hot without going through the tank. Tank outlets are 1-1/2”, versus 3/4” in the sidearm, and the valve will let me sqeeze it down to a very small orifice. Any comments?