Water pressure is critical for the Girard heater to work properly. When using city water, if you use a non-adjustable pressure regulator, they are set to 45psi. We had some problems with intermittent hot water and varying temperatures. I read, somewhere, you need between 50 and 55psi for consistent hot water. I bought an adjustable pressure regulator, set it for about 53psi, hot water is now very consistent. Have no problem showering, turning hot water full on and mixing with cold for temp control.
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