Rinnai E50C System Piping And Applications Design Manual page 20

4) Add up the number of each type of fitting and multiply the number of each type of fittings by its equivalent length
see Appendix A table 3 for equivalent lengths of fittings. Then add up the equivalent lengths of the fittings using
Worksheet 1 for you calculation; remember to account for the both the air separator and the dirt trap
(Abbreviated Sample of Worksheet 1)
5) Add the equivalent length of the fittings to the length of straight tubing:
48.76'+40'= 88.76'
6) Determine if the total equivalent length of the loop is greater than or less than the maximum allowable length for
the BTU output of the boiler at the maximum flow rate.
For a single loop, the maximum allowable length is 92' of ¾" type M copper tubing, so 88.76'<92' which means
the boiler can pump the loop without needing to use a low loss header plumbing kit as an accessory.
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