Drip legs for Tankless W/H

[Mike Birenbaum]

I have been seeing more and more tankless water heaters in my area and am wondering if the gas drip leg standards still apply....Keep in mind it is rare to see a drip leg installation at all in So Calif....any input is greatly appreciated

[Vern Heiler]

I have been seeing more and more tankless water heaters in my area and am wondering if the gas drip leg standards still apply....Keep in mind it is rare to see a drip leg installation at all in So Calif....any input is greatly appreciated

Mike, keep in mind that "drip leg" and "dirt leg" look alike but are different in function.

My county does not enforce the installation of dirt legs because the local gas co. says there gas is clean. The problem I have is that most if not all mfg. installation instructions require a dirt leg. Without a dirt leg, if there is a fire caused by the appliance, the mfg. gets a "get out of jail card" free. So I write every one I see up in the report and explain why to the customer. It only cost a few dollars to install and keeps the mfg. from getting off free!

[Ted Menelly]

Mike, keep in mind that "drip leg" and "dirt leg" look alike but are different in function.

My county does not enforce the installation of dirt legs because the local gas co. says there gas is clean. The problem I have is that most if not all mfg. installation instructions require a dirt leg. Without a dirt leg, if there is a fire caused by the appliance, the mfg. gets a "get out of jail card" free. So I write every one I see up in the report and explain why to the customer. It only cost a few dollars to install and keeps the mfg. from getting off free!

Who cares if the "gas is clean"

How about everything that gets into the lines during installation to the property and thru the property and then through out the home to the appliance. Clean gas, dirty gas. I get a kick out of it every time I hear that.

That's like dry gas because they take the water out of it along the route to the home. I guess the colder weather regions still have drip legs installed if I am not mistaken.

[Bruce Ramsey]

Sediment traps are required for all gas appliances.

P2419.4 Sedimet Trap. Where a sediment trap is not incorporated as part of the gas utilization equipment, a sediment trap shall be installed downstream of the equipment shutoff valve as close to the inlet of the equipment as practical. The sediment trap shall be etiher a tee fitting with a capped nipple in the bottom opening of the run of the tee or other device approved as an effective sediment trap. Illuminated appliances, ranges, clothes dryers, and outdoor grills need not be so equipped.

Yes, a tankless water heater should have one.

[Gary Burnett]

Who cares if the "gas is clean"

How about everything that gets into the lines during installation to the property and thru the property and then through out the home to the appliance. Clean gas, dirty gas. I get a kick out of it every time I hear that.

That's like dry gas because they take the water out of it along the route to the home. I guess the colder weather regions still have drip legs installed if I am not mistaken.

Ted,
Just did new construction inspections in Allen and McKinney and they have drip legs installed (Dree's & DR Horton). I don't see them on the older homes and all the areas around here evidently don't require them.
I guess with all this crappy cold weather we are having around here we must qualify as a "colder weather region".

[Gunnar Alquist]

I would like to know when sediment traps became a requirement. I have looked in the UPC 1994 and earlier, and can find no sediment trap requirement. I do find it in the 2003 IRC. I realize that it is a requirement now and I still write them up, but I am curious. I have a gap in my UPC documentation. Does anyone know?

[chris mcintyre]

Ted,
Just did new construction inspections in Allen and McKinney and they have drip legs installed (Dree's & DR Horton). I don't see them on the older homes and all the areas around here evidently don't require them.
I guess with all this crappy cold weather we are having around here we must qualify as a "colder weather region".

Gary,
Are you sure they are drip legs and not sediment traps?

From Jerry Peck on another thread:


A sediment trap is to catch sediment and debris in the gas flow. It is installed just before each appliance, all appliances except what are referred to as "illuminating" appliances. A better name would be "attended" appliances.

The appliances which are exempt from sediment traps are ranges, cooktop, dryers, gas light, and the like, i.e., appliances which the operator 'turns on and operates' or which are visible, such as the burners on gas ranges and cooktops, gas lights, etc.

A sediment trap is required at any appliance which is automatic in operation is the logical way to think of it.

A drip leg is to collect condensation which accumulates in the gas line from "wet gas". Drip legs are required to be places at the lowest points in the gas piping without regard to being close to or anywhere near an appliance as the moisture which condenses in the gas line will run down the gas line piping and collect in the drip leg, hence it being called a "drip" leg. Few places have "wet" gas, so it is seldom you will find a drip leg, and if you find one at an appliance that would only be because the gas line was run to the appliance from above AND be using "wet" gas. You would also have a sediment trap at the appliance regardless of the type of gas being used.

Thus, there are SOME (however few that many be) installations in which the sediment trap is also a drip leg ... which is why the drawings and statements reflect the drip leg being one and the same as a sediment trap and at that location. In reality, there are very few drip legs at appliances but there should always (with a few exceptions) be sediment traps at appliances.

[Ted Menelly]

Ted,
Just did new construction inspections in Allen and McKinney and they have drip legs installed (Dree's & DR Horton). I don't see them on the older homes and all the areas around here evidently don't require them.
I guess with all this crappy cold weather we are having around here we must qualify as a "colder weather region".


They started North of Dallas in a few cities last year. On a rare occasion I see them elsewhere in DFW but not to often. What I have seen were sediment traps though. I think Neil and Rick had something to do with making the calls to city inspectors and talking to them.

[Rick Hurst]

Gary,

I'm seeing the "sediment traps" as you mentioned in all of the newer homes being built esp. in McKinney, Allen, Frisco and neighboring areas.

Now I believe Rockwall, Sachse, and Wylie have started requiring them also.

rick

[Gary Burnett]

Ted and Rick,
Yeah! What ya'll said........................er, sediment traps.

[Ted Menelly]

I care if my natural gas is clean...... The cleaning process removes many things, Hydrogen Sulfide, Chlorine, Water, Nitrogen Compounds, plus many others leaving a clean burning fuel which will not leave any deposits, metallic or otherwise in my equipment. Hydrogen Sulfide would create additional problems in case of a leak.

The drying of natural gas (while commonly thought of as only the removal of water) is the removal of hydrocarbons which can and will condense and "drip" out of the gas under certain conditions. If you have "wet" gas then the drip leg will help prevent the introduction of a liquid drop from entering an orfice.

The "who cares if the gas is cleaned was sarcastic.

The gas being cleaned of impurities is a necessary thing but the fact remains that all gas is clean now a days. The other fact is, and this where sarcasm came from, there is a lot that can get into the gas lines during the installation of the gas lines all along the supply system including the lines run to the home from the street and throughout the connected gas lines in the home.

As far as the wet gas they do remove the moisture from the lines in route to the homes around here but colder climates may still allow a lot of moisture to get into the lines.

Sediment traps and drip legs do help. Another fact is that I talk to folks installing, repairing and maintaining gas appliances all the time and *almost* never run into folks that say that the lack of sediment traps and drip legs have ever caused a problem with the operation of the units. These folks have been servicing units for decades. Now before you state the countless times there has been problems with out these items I did say that "almost never run into". A little different than never.

[Jerry Peck]

OK this is a good thread for a "WHATS WRONG WITH THIS PICTURE".

Note that the gas supply line is installed in the functioning position of a PTrap. As installed any sediment, debries, condensate, or etc will be trapped in the direct flow of the gas supply. At some point this will restrict the flow of gas and severly impair the operation of the supplied device causing failure. The device will probably fail before the line becomes completly blocked (unless a "plug" of condensate moves quickly into the trap. A drip leg will allow a larger amount condensate, debries, etc to collect in the line before impeding the flow.


Note that where a drip leg is required, the drip leg is required at the low point, and that where a drip leg is not required, the sediment trap is required to be close to the equipment, after its service shut off valve, and there are no requirements regarding "trapped" sections of gas piping where the gas is not considered a "wet" gas which would require drip legs.

This is because the sediment flows with the gas and is knocked out of the gas stream by the 90 degree turn of the gas line, allowing for the sediment to drop out of the gas stream and fall into the sediment trap, and, if there is condensation in that piping ... then the gas is "wet" gas and drip legs are required - at all low points in the gas piping system, which means special attention is needed to install the gas piping such that the gas piping will be sloped to drain to those low points and the required drip legs located there.

[Matt Bezanson]

'Course ya gotta have a drip leg!
That's so Bubba has a place to connect the 1/4" soft copper tube to run through the basement wall, under the grass and up to the grille! :D

[Vern Heiler]

OK this is a good thread for a "WHATS WRONG WITH THIS PICTURE".

Note that the gas supply line is installed in the functioning position of a PTrap. As installed any sediment, debries, condensate, or etc will be trapped in the direct flow of the gas supply. At some point this will restrict the flow of gas and severly impair the operation of the supplied device causing failure. The device will probably fail before the line becomes completly blocked (unless a "plug" of condensate moves quickly into the trap. A drip leg will allow a larger amount condensate, debries, etc to collect in the line before impeding the flow.

Note that the water supply lines are installed such that they are flattened and as such will impede the flow of water threough the heater.


James,

In reading your post, it appears your concern is in restricted flow of gas. The more critical problem is debris caught in the regulator valve. With restricted flow, you can call an HVAC tech and have it fixed. With a stuck valve, you might be calling the fire department or coroner. I did see you addressed moisture getting into an orfice in a latter post, so I am sure you are aware of the real problems. My point is that if your post is part of a boiler-plate you use in reports, you may want to re-word it a little to reflect the larger concerns.

JMHO

[Bob Harper]

So, gas piping aside, how about that 800+lbs of water and tanks on those joists? B-vent connector no draft hood connector? Where do those TPR drains go and terminate?PVC? Drip pans tight? Drain where? Seismic straps? Why two WHs? Is this NG or LP?

As for sed. traps, they are required whether enforced locally or not.

Target rich environment....

[Vern Heiler]

James, I suspected you knew the subject well but didn't want anyone reading to get the wrong idea. I think it is important to give good explanations to the customer as it reduces those aggravated calls wanting to know why you wrote it up. I actually think the P'trap was by accident on the plumbers part. As for the settings on gas heaters, the only things I check, regarding settings, are that it makes hot water and its not over 120. The settings are too easy for anyone to change on gas heaters so I have been staying away from that in the report. Maybe I shouldn't?

[Chuck Lambert]

I have been seeing more and more tankless water heaters in my area and am wondering if the gas drip leg standards still apply....Keep in mind it is rare to see a drip leg installation at all in So Calif....any input is greatly appreciated

You also have to check the gas line size as most tankless heaters require a 3/4 inch gas line (very few alow 1/2 inch)..the one in the picture has been reduced down...not good.

Chuck

[Dave Hahn]

Bruce....

Curious where you got the "P2419.4" reference?
(OK, I see a G2418.4 in the IRC, but NC deletes this entire chapter and follows the IFGC w/NC Amendments)

The 2006 North Carolina Fuel Gas Code (don't yet have the 2009 version) states under 408.4 (my capitalization is reflecting NC specific changes to the IRC): "Sediment Trap. Where a sediment trap is not incorporated as part of the gas utilization equipment, a sediment trap, IF REQUIRED BY THE MANUFACTURER'S INSTALLATION INSTRUCTIONS, shall be installed as close to the inlet of the equipment as practical. The sediment trap shall be etiher a tee fitting with a capped nipple in the bottom opening of the run of the tee or other device approved as an effective sediment trap. Illuminating appliances, ranges, clothes dryers, GAS LOGS, LOG LIGHTERS and outdoor grills need not be so equipped."

[Gary Burnett]

So, gas piping aside, how about that 800+lbs of water and tanks on those joists? B-vent connector no draft hood connector? Where do those TPR drains go and terminate?PVC? Drip pans tight? Drain where? Seismic straps? Why two WHs? Is this NG or LP?

As for sed. traps, they are required whether enforced locally or not.

Target rich environment....

Bob,
The joists are engineered for the water heaters. Both B vents have draft hoods and are properly installed. The TPR drains go to the outside of the home right next to the pan drain lines and terminate about 8" above the ground. (4 separate terminations although sometimes they tie the drains to one large 1" line) The drains are CPVC and not PVC. Siesmic Straps are not always used in Frisco, Tx. We don't get many hurricanes or earthquakes and if a tornado hits the straps just become additional flying debris. Two water heaters for big 4 & 5 bedroom homes with a bunch of nasty kids and dirty laundry. Clean, scrubbed and dry Natural gas.
This is a pretty common site in the North Texas area. We have great big garages that would certainly accommodate the water heaters but that wouldn't be any fun for the plumbers or homeowners if the bottom falls out!

[David Bell]

The original pic shows the water heater,,where is the pic of the gas main outside? It could have a trap on the main that make everything else moot.

[David Bell]

I will take flack for the wrong term,,not a trap but a leg, whether sediment or drip it is the same design for a different issue. This forum somtimes reminds me of the high school debate team,(I kicked your asses back then too)

[Jerry Peck]

whether sediment or drip it is the same design for a different issue.


Not always.

Now, I hope you don't bounce too far on your arse (which was just kicked quite thoroughly). :D

One could have a drip leg which consists of a trap which looks like like a squared off 'Y' (a 'U' with a bottom tail) and it would work well for a drip leg but not work well for a sediment trap. :p

[Bruce Allen]

2009 International Fuel Gas Code

408.2 Drips. Where wet gas exists, a drip shall be provided at any point in the line of pipe where condensate could collect. A drip shall also be provided at the outlet of the meter and shall be installed so as to constitute a trap wherein an accumulation of condensate will shut off the flow of gas before the condensate will run back into the meter.

408.4 Sediment trap. Where a sediment trap is not incorporated as part of the appliance, a sediment trap shall be installed downstream of the appliance shutoff valve as close to the inlet of the appliance as practical. The sediment trap shall be either a tee fitting having a capped nipple of any length installed vertically in the bottommost opening of the tee or other device approved as an effective sediment trap. Illuminating appliances,
ranges, clothes dryers and outdoor grills need not be so equipped.

[David Bell]

I have cleaned many drip legs,,(traps) that were loaded with sediment,, a drip leg is inherently a sediment trap

[David Bell]

Quite honestly I can't remember the last time I saw any moister in natural or lp gas. The sediment found these days is rust from aging systems that can't support the load that they need to.

[Bruce Ramsey]

Bruce....

Curious where you got the "P2419.4" reference?
(OK, I see a G2418.4 in the IRC, but NC deletes this entire chapter and follows the IFGC w/NC Amendments)

The 2006 North Carolina Fuel Gas Code (don't yet have the 2009 version) states under 408.4 (my capitalization is reflecting NC specific changes to the IRC): "Sediment Trap. Where a sediment trap is not incorporated as part of the gas utilization equipment, a sediment trap, IF REQUIRED BY THE MANUFACTURER'S INSTALLATION INSTRUCTIONS, shall be installed as close to the inlet of the equipment as practical. The sediment trap shall be etiher a tee fitting with a capped nipple in the bottom opening of the run of the tee or other device approved as an effective sediment trap. Illuminating appliances, ranges, clothes dryers, GAS LOGS, LOG LIGHTERS and outdoor grills need not be so equipped."

The original poster is in California, not NC. The reference is from the IRC.

[Michael Chambers]

The original pic shows the water heater,,where is the pic of the gas main outside? It could have a trap on the main that make everything else moot.
I could be misunderstanding what you're saying here, but wouldn't the possibility of dirt, metal chips, etc. already being in, or being generated in the piping inside the house as it's all being assembled make a sediment trap at the appliance a good idea as well, regardless of whether or not there is one on the main?