I referred to uniform mechanical code 312.1

 

This is going to depend on your jurisdiction and their interpretation of the codes. It obviously has passed a final inspection and it can be an eye sore, but sometimes things are what they are and not worth causing a huge stir with a customer, a city inspector, and a site supervisor over something that is probably a minor code violation, but is nothing more than that. But who is to say and whose can of worms are you willing to open?

Usually most government and large commercial sites will demand in the mechanical plans that the system be trapped and piped using copper directly to a roof drain location. So you may want to go back to those plans and see if the installing contractor did not follow that direction, if so listed, and can go back on the original contractor?

But being in the industry as long as I have and walking a thousand roofs, and looking at a thousand condensate methods I would be happy with the fact that yours actually has something connected to the drain outlet, let alone it is trapped with a vent....rare to find in the least. One hell of a deep trap, but as long as it is drained prior to winter to prevent freezing and cracking it works...pretty sure it resembles the manufacturer's install manual drawing fairly closely.

But it's your call to further the case...your the one on site and have your finger on the pulse here.

 

That looks like a membrane roof, but most roofing companies don't like condensate keeping the roof wet all the time.

 

What are you gonna do about that in places that rain pretty much all the time?

 

That trap is not done correctly. Need at least 4 inch difference in height between inlet and outlet.

 

2 inch minimum. Not 4 . My bad.

 

No. There is no requirement that the weir be 4 inches lower.

The trap is a deep trap because of the high fan power.

It should not be assembled with solvent cement, so that when the trap water freezes in winter, it just pushes the trap apart without breaking it. Then you put it back together for AC startup, and break it down for easy cleaning.

The guys who cement these traps are resi guys who also do commercial.

 

Maybe there is a 2 inch requirement in Texas, but not anywhere else that I have seen. It does have to be lower than the inlet so the water can get out.

 

There is no inspection city or otherwise since it is federal property. Freezes are rare here in Houston. Thank everyone just trying to understand the "rules"

 

You might want to do a little research timebuilder.

 

This is from ashi reporter, regarding inspection of residential systems.


"Home inspectors should know that equipment makers often recommend a drop from the pan at a minimum of 2 inches and then a minimum of a 2-inch trap seal (see illustration above). Anything outside of these parameters, either excessively short or long, should cause a home inspector to look more closely for signs of moisture concerns in or around the equipment."

I would recommend that commercial techs not try to mimick the guidance given to residential techs who install fractional horsepower blowers.

You might want to do a little research timebuilder

 

see attachment

 

View attachment brusha[1].pdf

 

View attachment 518831

Never knew that was how you trapped a blow through unit. I have about 4 RTUs to re-trap now at my site. Good spring work.

 

I have seen this before. There is no need for that offset.

There is no purpose served by having the low pressure on startup draw water level down in the weir. This is a carry-over notion from that first pdf, which was around when my hair was still brown.

The important part is the depth of what they refer to as "h2," which is the weir depth. It has to be deep enough to have the water column meet or exceed the negative fan pressure.

As you can see from this discussion, these are suggestions and not code requirements. If you like to use up extra pipe, you can increase the depth of the first section, and make h2 half of that, and as long as h2 is deep enough to meet the power of the fan in the rtu, it will work just fine.

But, none of that is needed for the trap to function properly.

 

I disagree with your last sentence. It is needed for some to function properly.

 

In order for a trap on a draw-through RTU to function properly, all you need (aside from the aforementioned weir depth, which is a function of fan power) is for the outlet to be lower than the inlet, meaning the top of the weir must be lower than the edge of the PVC fitting that is screwed into the pan. This allows any water above that level in the pan to flow out of the unit whether it is running or not.

That is it's purpose: to get the water to flow out of the unit. And, it will.

I have seen that some local code authorities require copper traps, and some want them plumbed to the nearest roof drain. Others want PVC traps glued up like an indoor trap. That just means I will be replacing the trap in the spring after the water freezes in the trap and breaks it. In some extreme cases, I have seen copper traps damaged by freezing as well.

Summary:

if you want to make the weir 2" below the inlet height, it will work as long as the weir itself is sufficiently deep for the fan power. BUT, that 2" is not a requirement for it to function properly.

 

I am sure that roofers warranties are "CYA". YOU know that the condensate won't hurt the roof. And I know that too, but roofers don't because they heard about "this one time" where condensate ruined the roof. It was probably something like a boiler condensate drain/blowoff and, of course, that is a very different animal so they exclude everything without knowing what it is.

As for the argument of whether or not the trap was built properly, I see that TB and Timber are arguing technical details while using general terms...be very specific in everything guys.

Also, do we know if it is a blow through or draw through system? I didn't see that in the OPs post.

 

just saying that I have had to modify traps that were built like the OP posted in the picture. This involved creating a height difference between inlet and outlet. More of trial and error deal .
Problem is caused by the negative pressure on the water column.

Nothing to do with code, blah blah blah.

 

Ok , if you cannot make the weir deep enough because of roof height limitations, then the offsets come into play

 

An offset will not help at all. It is the weir, the second part of the trap, that controls the height of the water column. If it is too shallow, then the seal will break when the fan starts. An offset only makes the weir more shallow.

 

If manufacture has a picture of what they want, that trumps building codes. I'm pretty sure.

Currently repairing leaky drains because R and B roof company will not honor warranty because of condesate.

 

I don't do enough rooftop units that it's a real issue for me but I do have to say I would much rather work on a unit that has the condensate piped away so I don't have to stand or kneel in condensate water {rain can't be helped} to work on it.

 

Absolutely

 

Leave it on the roof, it wont hurt a thing, in fact you can get some evaporative cooling.
Years ago Mc donalds designed some of their stores to hold a few inches of water for that very purpose.

Why would you possible care if there is water on the roof in Texas?
Here in califruty every drain is piped with a absolutely useless vent after the trap, then they all run downstairs to a common drain, lots of problems with plugged up drain lines.

 

Califruty....That's funny.

 

In Wisconsin and Minnesota, its very common to just have the water drain onto the roof.

Even in municipalities that have very anal-retentive inspectors, they don't seem to care about draining water on the roof.

For what its worth, I prefer just having a trap that drains on the roof. There is less chance of clogging, and if it does clog its very easy to clean out. There is also less risk of frost damage, and if it does freeze and break its very easy and inexpensive to repair.

 

Our AHJ requires us to pipe the drains to a storm drain. Its a waste of time, money and causes clogged drain service calls. The wind also blows them around and breaks them and sometimes they get repaired after they cause a leak in the membrane roof. Im all for piping it a few feet away from the unit so i don't have to stand in it but 20, 30, 50, 100+ feet is ridiculous and just asking for problems. i usually cut the "extra" pipe off after inspection so it doesn't cause me any grief later.

 

Roofers get mad because they seem to never pitch the roof in all locations leading to the storm drain. Condensate revealing a poor roof job.. You start getting plants growing on the roof. It begins to break down.

 

To the typical roofer, pitching the roof properly, installing crickets, etc, is an extra-level of work that is not in the scope of their contract. Most will just spread out some sheathing and roll out the material, such as EPDM rubber membrane or white PVC. It's a lowest bidder situation for many landlords, and the skill of the crew and desire to make the roof work correctly is largely an economic consideration, and the landlord is in control of that dynamic.

I was on a roof yesterday that was a problem for many years, an EPDM with a lot of leaks due to UV breakdown. The roofer told the store he would be done with the project in two weeks. That was mid August. He just finished in early October. I met with him in early September on a PM visit, and I can't tell you how he communicated with his crew (he did not speak any Spanish while we talked) or how he got the other guys back to the jail from work release.

In other words, 20 men, one roofer.

The plant life typically grows in the pipe hub connection around the flood drain (the one where the pipe sticks up higher than the other drains) so that's just a matter of dirt settling out of the air and a few spores or seeds.