[khgeisler]

The left pump normally supplies the rear heating loop, bedroom.  It runs when the rear zone interior thermostat calls for heat.  Turn rear thermostat to OFF.

If you remove the bottom clear relay, that should stop the rear zone and the related pump.

Rudy, I have coach #385, it has 4 thermostats for heat, basement, bathroom, bedroom, living room.  The Aquahot was replaced 3 years ago at Newell and only has 3 pumps.  I do not have heat in the bedroom and living room and I think during the last major engine work the mechanics did not hook the bedroom back up.  Is it possible the two are run in series and this is why no heat.  All three pumps feel like they run, fans run when heat is called for from Thermostat.  I just have not torn apart the bed yet.  Thoughts?