condensate drain discharge for fan coil units 2

[mechanical3010]

If the drain line from the fan coil unit condensate discharge is equipped with a P-Trap to prevent sewer gases from entering the occupied space, why is it still objectionable to discharge the condensate in the vent pipe of a lavotory that is part of the DWV system?

 

[Drazen]

That is issue of plumbing code, which you need to check for your teritory, possibilities of using vent pipes as discharge verticals are strictly prescribed.

Another issue is that you should actually need wet trap or double used trap, as in witner time water seal can perspire.

 

[mechanical3010]

We have ten fan coil units with a common pipe to drain the condensate. So according to reply from Drazen, would it be technically feasible to provide a P trap with a trap primer at the end of the line just before it discharges into the lavatory vent?

 

[PEDARRIN2]

When you connect directly with the plumbing system, you are now requiring all your condensate drain pipes to be required to comply with the plumbing code.

If you connect it indirectly - dripping into a mop basin or floor drain/sink - you will not have this problem.

In jurisdictions of the International Plumbing Code, what you are describing is a waste stack venting system, which by the nature of having 10 drains to the common pipe automatically rules you in conflict with the code.

To comply, each of the drains would have to be separately trappped and connected separately to the vertical vent of the lavatory. Thney would also need to be within a maximum distance from the vertical pipe - depending on the drainage pipe size.

The piping from the connection of your condensate drains to the connection of the lavatory must have no offsets - it must be vertically straight.

There are also limits to how much can be discharged into the vertical pipe. If it is a lavatory vent, it is most likely 1.5" which per the IPC, would be limited to 1 dfu, which would be approximately 2 gpm - so you have to determine if the condensate would exceed that flow.

 

[Drazen]

Pedarrin is specialist for plumbing and he will certainly give you valid information.

When you connect one-two fain coils to the closest floor drain or install wet trap nearby, that will likely easily comply with code.

When you have 10 fan coils with common drainage, you need to look at it as "full-scale" drainage installation.

If you have chance, it is best that you "redistribute" such piping to plumbing designer if you are not familiar with plumbing design.

Plumbing is my secondary domain, but when I work on larger project, I almost allways bring that to the dedicated plumbing guy (if I did not contract plumbing design).

 

[mauricestoker]

I was curious as to why you would send condensate to sewer instead of storm. If you are not using indirect, then you may want to think about including a clean-out in case the drain gets clogged and needs jetted or vacuumed. Seems to happen most in hot, humid weather, about when the vent gas will smell good when you break the line to remove a clog.

 

[DRWeig]

mauricestoker,

In my county the local code prohibits condensate to storm drain, gotta be sewer...

I don't know if a national code that requires it though!

Good on ya,

Goober Dave

 

[cry22]

Weird code Doc, never heard of code requiring discharge to sewer, to a combined sewer/storm yes.
Normally, condensate is not metered water,and the utility does not like to see un-metered water to the sewer system. Reason it connects to storm system.
Imagine all the cooling towers blow-down in summer connecting to the sewer system, it will oevwhelm it.

 

[mauricestoker]

In my county, it's the opposite. As the area falls within the Chesapeake Bay Initiative, we get pressed to reduce the sewer discharge to the greatest extent possible. The municipal and county treatment plants are getting hit with tens of millions in compliance requirements (reduce nitrogen, phosphorus, silt, the EPA has already been out to share the bad news) so I figure it's only a matter of time before the costs get passed on. Our sewer bill is higher than our water bill so sending anything to sewer that can go to storm costs money.

The county also requires Low Impact Development for SWMP/MS4, and recommends including condensate as part of rain water harvesting, rain garden, reducing irrigation water use, and building storm system disconnects.

 

[DRWeig]

I agree it's weird...

Seems like it changed to sewer-only about maybe 10 years back. We used to pipe 'em to rain gutters, or if small, to drip in a grassy area.

Even cooling tower blowdown as cry22 mentioned. Not sure about boiler blowdown, but I bet it's the same.

Interestingly, I put a new process control system in one of the two large wastewater treatment plants here, back in the 1980s. The sewer and storm drains are supposed to be separate, right? Well, whenever it rained, the plant inflow would rise from maybe 80 million gallons a day to upwards of 150 million. Saw it hit 320 million one day after mucho rain in the spring. It was cool because the plant could only handle about 250 million a day hydraulically. There was a sewage geyser about 20 feet high.

Good on y'all,

Goober Dave

 

[AnotherEllis]

Down here in SoFL, each municipality/ county writes its own rules on condensate disposal. It keeps us on our toes.

BTW- on cooling tower blowdown: that is technically metered water used for makeup to the tower basin. Most water used evaporates, but any blowdown water would have originated from a makeup source.

http://www.ellisconsultingengineers.com

 

[Drazen]

Yes, that is why I avoided to mention any specific detail but just referred to local compliance as a such - I have the same situation where each municipality company has its own rules about many aspects of drainage, I even strongly believe they do that to artificially bring more importance to local administrations...

 

[bimr]

Typical code requirements. Heaters are not plumbing fixtures.

"Plumbing Fixture": Approved, installed receptacles, devices or appliances which are supplied with water or which receive or discharge liquid or liquid-borne waste, with or without discharge of such waste into the drainage system to which they may be directly or indirectly connected. Generally an installed appurtenance to the potable water supply system which makes available intended potable water, or a receptor which receives and discharges liquids or liquid-borne waste either directly or indirectly into the drainage system. A permanent appendage usually designed as a receptacle and intended to receive and/or discharge liquid or liquid-borne
waste to a drainage system. Industrial or commercial tanks, vats, and similar processing equipment are not plumbing fixtures, but they may be connected to, or discharged into, approved traps or plumbing fixtures.

"Indirect Waste": A pipe that does not connect directly with the drainage system but conveys liquid waste by discharging through an air gap into the drainage system.

Installation. Receptors serving indirect waste pipes shall be trapped and vented and shall not be installed in any concealed, inaccessible or unventilated space, and shall be sized to prevent overflow.

Maximum Length. The maximum developed length of the indirect waste of any sanitary waste line shall not exceed five (5) 5 feet.

Clear Water Wastes. Water lifts, expansion tanks, cooling jackets, sprinkler systems, drip or overflow pans, or similar devices which discharge clear water only shall discharge indirectly into a building storm drain, building drain or building sewer, located on the same floor.

Cleaning. Indirect waste piping shall be so installed as to permit access for flushing and cleaning