Tankless heater confusion

[jhawkwest]

I have a precept 31UL. When the utility panel is in normal position the water draws from the fresh tank and the heater works just fine. However, when I set the controls to city fixtures I get water at the taps but the hot water heater does not function. In the first case above, the water heater control shows the current water temperature as it heats. In the second case, there is no such display. How do I hook to a water source and heat water without draining my fresh tank? I'd appreciate any insight - the manual references a bypass valve but I can't find any such thing and assume it would be in the normal position anyway.

[edfgrf]

psi is critical no restrictors on water hose. I have a adjustable water reg. on my hose. psi 45-50lbs.

[mike837go]

The tank-less WH have to detect hot water flowing. They do that by sensing a pressure drop from their inlet to outlet.


If the city water pressure is too high or the flow too plentiful, the WH won't detect usage and therefore not cycle.


My opinion is that they are an overrated solution to a problem that doesn't exist. Tank-type water heaters have been doing a great job in RV's for 50 years. The modern pilotless ignition saves plenty of fuel.


You've got a couple of choices:
- Buy a pressure regulator to limit the pressure and flow from the city water
- Keep your fresh water tank topped up and only use the RV's water pump
- Downgrade to a tank-type water heater


Others will chime in with suggestions...

[Djtommysr]

I don't know if this will help but it is worth checking. I once used my outside shower hose and left both valves opened and had the shower head closed. When I went to city pressure the water went from the cold water side back to the hot water side without ever going through the water heater. A stupid mistake that took me a long time to figure out. Just a thought.

[jhawkwest]

Think I may have found an answer. The tankless heater requires a 45psi flow to operate. My pressure regulator throttles flow down to 45psi. Unless the calibration is exact flow may not be adequate. I'm planning to try an adjustable regulator set at about 55psi.

[StevL]

We use a preset regulator, it delivers from 50 to 55 psi, we have no issues with the water heater.

I have had fluctuations using the water pump. We do no boondocking so it isn't a problem for us.


Steve

[jhawkwest]

Thanks - thinking getting the pressure up in that range will do the trick. Happy travels

[Arniesports60]

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