Top positive review
9 of 10 people found this helpful
High flow rate, low pressure drop, lots of hot water
on July 8, 2012
This is a great unit. It provides key attributes of high flow rate and low pressure drop while providing lots of hot water. This is the largest unit Noritz make. If you size just by GPM you may think their next smaller unit is adequate for your needs. Maybe it is, I don't know what your requirements are. But only this beast has the large heat exchanger, which allows high flow without dropping 15 - 20 psi across the exchanger when you are drawing lots of hot water. A tub spout, for example.
The unit is very efficient, 94% I believe. It is a condensing design that vents with 3" or 4" PVC and uses fan-assisted combustion. The burner modulates over a wide dynamic range, allowing small flows of water to still cause the heater to light off.
It is my understanding this is one of the few cases where there is not a downside to installing a larger unit. Only the amount of gas required is used to heat the water. The larger heat exchanger causes minimal, if any, efficiency penalty.
You will want to ensure a 200,000 BTU gas supply pipe, which is not likely what your tank heater came with. Also large water pipes (it helps to run 1" pipes up to the 3/4" water heater fitting) will improve this unit's capability.