Ahu condensate drains 3

[Atomarc10]

If you do not have enough room for proper depth for trap, are there any other options before demolishing the floor? I've also got questions on solutions. For one does volume have anything to do with proper draining or is it all head pressure. For instance, for a 1" drain could you increase the trap to say 2"? And second can you put traps in series to take care of the problem or again does it have to do with head pressure? Thanks

 

[berkshire]

The depth of the drain trap is determined by the Pressure above static in the duct. The trap is there to stop air venting with the condensate.
B.E.

 

[KiwiMace]

No, nothing to do with volume and you can't put 2 x 1" traps in series to make a 2" trap. It is all to do with hydrostatic head. If the static pressure in the AHU exceeds the pressure of the water column in the drain then the air pressure will suck or blow the water out of the trap depending on which side of the fan your coil is on.

You either raise the AHU on a baseframe, or less ideally, run drain pipe to a location where you can put a trap.

 

[BronYrAur]

I see improperly trapped coil drains all the time. Some are due to space restrictions, but mostly I suspect that the installers just didn't know what to do. You need to know if your coil is blow through or draw through. In other words, is the coil on the discharge of the fan or the suction? Attached is a great article on how to properly pipe condensate drains.

 

[BronYrAur]

OK, let's try that attachment again.

 

[DRWeig]

Nice paper, BronYrAur! Thanks.

Best to you,

Goober Dave

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[ChasBean1]

Atomarc10, see this detail. Yes, there are other options.

 

[ChasBean1]

Atomarc10, see this detail. Yes, there are other options.

 

[BronYrAur]

I'm confused. What is that detail showing?

 

[KiwiMace]

An overflow trap into a floor drain implies that the floor drain is 'directly' piped to the sanitary system. Condensate needs to go to an indirect drain (typ. a 2" air gap) to prevent sanitary backflow from entering the HVAC system. I am not sure that this configuration is accepted by the code and AHJ. Backing up the floor drain would flood the floor and should not rise up the cond drain, but i'd want to ask.

 

[ChasBean1]

Rotate the view ccw. Sorry, it displayed differently than what I thought. It shows a 4" drain, 3" cup, and a 2" condensate drain line out of the AHU. This detail prevents the need for curb heightening or traps in the floors below.