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    Tracy tapes cardboard circles over the now unused outlets on the fan housing. These were later replaced with metal freeze plugs that are sold for this very purpose.
 
    Another problem with our heater is that the cardboard tubes keep burning where they come too close to the exhaust headers. I fabricated this heat shield out of aluminum flashing and a hose clamp.
 
    Here is the heat shield clamped onto the exhaust. You can see the round inlet of one of the heater boxes that the heater hose fits over just below the heat shield. Unfortunately this didn't work and the hose burned through anyway.