Bypass damper


Old 02-27-18, 05:21 AM
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Bypass damper

can anyone stupidfy a bypass damper for me. I get it relieves excess pressure. But where does this excess pressure come from?

when I had my manual j and manual d done I was told bypass dampers are illegal now and they designed the duct so I wouldn't need one.

Is this possible? I don't want to damage my system/ freeze coils

my zone board came with a sas sensor(supply air sensor)
but im not sure if that would actually protect anything. It reads temps.

if my coil's were freezing with they run a lot colder?
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Old 02-27-18, 12:02 PM
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When you have a zoned system... only the zone calling for conditioned air opens. If the system is designed to operate properly with all ducts flowing air and one gets closed..... there will be higher than normal pressure to the open zone and decreased airflow across the evaporator coil. This decreased flow can cause the coil to ice up.

Your installing company should be aware of this if and if it's going to be a problem.
I haven't heard that a bypass damper is illegal and can't see the reason why it would be.
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