Problems with Tankless Heater and Shower
We recently installed a Rinnai tankless hot water heater in our new addition. The water leaves the heater, then travels to the master bath tub, out to a secondary bathroom, then back to the master sinks, the master shower and then back. We've installed a timer/pump based recirculation system. both the master and secondary showers are using thermostatic valves.
We've had nothing but problems with the shower since the system was finished. While the sinks and tubs get hot water after just a few seconds, the showers take anywhere from 15-90 seconds to get hot. We lose water pressure in the master shower when a sink is turned on. We get cold water slugs in the master shower. The thermostatic valves don't appear to regulate temperature properly, if at all. The pipes bang ferociously if we try to run both the master shower and bath.
The plumber our contractor uses thinks the valves need to be adjusted and/or the pipes need to be blown out, but after doing both, the problem doesn't seem to be fixed.
any ideas on what the problem(s) could be? We're at a complete loss.