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Weil McLain ECO 70. Odd sound.
Just finished cleaning Inside my heat exchanger with water and soft brush. Got it all nice and clean and got it back together just fine.
I fired it up, purged and ignited just fine. When it ramped up to 65% I could hear a slight hissing sound from the heat exchanger. If I covered the blower intake, the sounds went away. When the blower speed got below 65% or around there it was normal. No sound.
Only thing I could see it being is that I didn't tighten the igniter down enough or the heat exchanger cover plate. I don't have a torque wrench and didn't want to tighten that stuff down too far. The Manuel says for the exchanger cover no more than 45in lbs. The igniter is no more than 20in lbs.
Any idea? Will be picking up a torque wrench this week to get those bolts where they need to be and hope it solves the problem.