Internal Drain trap

[RODRIGO BR]

Hi ,

What's the purpose of the internal drain trap on dowflow self contained units installed on raised floor ?
is it to avoid outside air flow to the internal unit through the drain line due the diferencial pressure (External - internal)?

Thanks a lot.

[Brian_UK]

A drain trap will ensure that air pressure does not affect the water flow through the drain.

For example, if the drain should be on the inlet side of the fan then it will operate under a negative pressure and no water will flow out through the pipe.

[RODRIGO BR]

Ok. So , if the drain shoud be on the outlet side of the fan (positive pressure), then the drain trap will not have effect, correct? In this case could I eliminate the drain trap?

Thanks.

[Brian_UK]

I would use a trap on both sides of the fan.

It stops air leakage from the unit, it will also stop any air noise that may be generated by the leaking air.

It will stop any foul odours flowing back into the unit and reduce the risk of mould spores getting into the unit/ductwork.

http://www.cfm.va.gov/til/sDetail/Div23HVACSteam/SD232113-08.pdf

[Segei]

It prevent moisture migration as well.