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Piping Reverse Indirect
I am finally upgrading my heating system. New boiler is 110,000 BTU input gas fired mod con, new reverse indirect is 34 gallon with very large domestic coil. There are four small high temperature zones (total 43,000 BTU) that I plan on using a variable speed circulator and four zone valves. There is one radiant zone (16,000 BTU) that will have a dedicated RMB to control the temperature of the radiant water. I plan on using the reverse indirect primarily for dhw needs, this includes two full baths and the dreaded whirlpool bath tub.
I am very much aware that I could easily heat the house with a much smaller boiler. I also realize that if I had the room for something like a 120 gallon indirect I would likely never run out of dhw with the small boiler (recovery time might be a little excessive...). Unfortunately, there is no basement (Levittown style cape, expanded a few times) and the system will be installed on the second floor, with a large drain pan under all of the equipment..
I've been following page 33 of the Caleffi Idonrics #17 guide, Figure 7-3 very closely (except my house will have a single boiler). The heating side of the reverse indirect tank comes with 1.25" steel nipples. My plan in to put a 1.25" black union on the threads (inlet and outlet) and immediately up-size the piping to 2" steel with two cast iron tees. The bull of the tees will feed the radiant and the high temperature zones. The run of the tees (1.25") will connect to the boiler and primary circulator. I'm hoping the reverse indirect will meet all of our dhw needs and act as a buffer tank, especially with only one or two zones operating. In my mind the two sets of closely spaced 2" tees will act as a hydraulic separator.
My first question is there are no check valves shown in this drawing, do I need any? On page 34 of Idronics #17 check valves are shown near the bottom of the reverse indirect, Figure 7-4. My second question is can I get away with just two circulator pumps (in addition to the Taco RMB)? One pump is for the primary loop and the second is for the secondary loop (high temp).
Please see attached sketch, note the software I use does not have reverse indirect tanks so I improvised with a odd looking buffer tank. My tank actually has the boiler inlet on the top of the tank and the return on the side of the tank a few inches above the bottom.
Thank you in advance,
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