Well, this unit was at my place of employment.
The boss has already had the heater replaced with a new one.
I figured out Why this one wasn’t working… corrosion / calcium build-up caused too low a water flow to trigger the relay that turns on the heat.
The corrosion even ate a hole thru this manifold.
I Could fix it with a patch of rubber and a hose clamp, but…
I don’t want this thing… I just want to Sell it on Ebay or Craigslist.
That’s why I need the new manifold.