What happened

Joew2604 · Oct 30, 2017

I just installed a new Raritan water heater , Yamaha 3HM35F engine. The electric works just fine, hot and cold water runs great. FW hoses are connected up. Couple of days later started engine and the alarm came on. Think did I connect the FW in and out correctly. Does it make any difference which way the FW flows through the heater? Could it be an airlock? If so what should I do. Appreciate any suggestions. Many thanks

boathealer · Oct 30, 2017

Joew2604 said:
I just installed a new Raritan water heater , Yamaha 3HM35F engine. The electric works just fine, hot and cold water runs great. FW hoses are connected up. Couple of days later started engine and the alarm came on. Think did I connect the FW in and out correctly. Does it make any difference which way the FW flows through the heater? Could it be an airlock? If so what should I do. Appreciate any suggestions. Many thanks

Probably an air lock. No difference in "direction" of flow.

Find the highest point in the entire engine/water heater system as a whole and bleed out any air.

If you didn't add any coolant, you'll probably need that, too, to account for the new hoses and exchanger volume.

Joew2604 · Oct 30, 2017

Thank you for your reply

FlyWright · Oct 30, 2017

Along the lines of BH above, was the alarm sounding for engine heat? Have you checked the coolant level?

Let us know what you find.

Joew2604 · Oct 31, 2017

Thanks all. Problem solved. The tank was full of coolant when I finished the job, but when I started the engine all the coolant went into the new hoses and heater coils leaving the tank almost empty. Topped off the coolant and all went well. Thanks again.

FF · Nov 2, 2017

Some of the HW tanks have an anti-scald valve built in that shuts down the circulating water at a preset temperature.

These do require the proper direction of engine circ water flow.

Do not put one of these in series with a box heater.

boathealer · Nov 2, 2017

FF said:
Some of the HW tanks have an anti-scald valve built in that shuts down the circulating water at a preset temperature.

These do require the proper direction of engine circ water flow.

Do not put one of these in series with a box heater.

Good point. Thanks.

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