Must a condensate drain line have a low point, a trap?

 Express the Subject another way, in a Google search with AI:

may gravity-drain condensate lines loop with a low point?

Yes, a gravity-drain condensate line can include a loop with a low point, as long as the overall slope of the line still allows for proper drainage by gravity; the low point essentially acts as a "trap" to collect any debris or sediment that might otherwise clog the line further down. 

This result is correct. A trap may exist. It is not commanded or desirable. Condensate is acidic and foul, and over years unflushed, can plug the line. In usual PVC, the fouling is not visible.

Many HVAC mechanics think a trap is MANDATORY, and will glue-in this PVC trap. They will then plumb this to a transfer pump, even where a gravity drain was easily achievable..

This is the starting condition of a situation I have improved. See the undesirable PVC trap in the upper drain line of an air conditioning heat exchanger. The high-efficiency gas furnace condensate drain dumps directly to the pan of an ugly condensate pump. The pump pushes foul water up and over thirty feet to dump outside through a drilled hole in a rim joist.

There was never a need for the PVC trap.

All will be rearranged except the supply registers and their approaching in-wall ducts.

Now toss the PVC pipes and pump, and dump as trash. See a convenient plumbing drain that will accept gavity drain of condensate via a new P-trap.

With this arrangement of joining the two condensate paths, a trap exists in the furnace condensate line. I know it is nonsense that this could alter the dripping-down in  the exhaust pipes or affect furnace performance, I will eliminate the trap.

As the minimum required for all drain piping, and as limited by availble elevation change, I maintained a steady 1/4 inch per foot downward slope to disccharge atop a P-trap

I then swapped out the furnace-drain plastic 1/2"  MPT x 3/4" barb fitting for brass, to stop a flow pouring along the barbs.Unbelievably, the barbs are formed as spiral threads. I can't just return the fitting to Home Depot. I have reported a manufacturing error, homedepot.com, Feedback, asking a product recall. I believe the pipe threads also leak unavoidably from roundedness and inability to develop sealing pressure of engagement. Cast polypropylene may be always inappropriate for fluid hose pipe thread fittings.

This is the homedepot.com product image. Do you see the spiral threading of the barbs?Defective, for all of a batch.

4.5 stars in 56 reviews. There is no means of offering my own review. But, I have called the manufacturer.

Here are rival and contradicting Google AI search results:

Must a condensate line have a trap?

Yes, a condensate line must have a trap, especially if the drain is under negative pressure, as it prevents conditioned air from being blown back into the living space and is crucial for proper drainage and system efficiency; essentially, a trap is considered a necessity for a condensate line on most HVAC systems. 

This is an incorrect rule for HVAC condensate. The search demonstrates current Google AI bias to the affirmative of a question; the supporting of preconceived notions that makes a searcher feel good and click more.

Household drain piping is vented to atmosphere and can not be under negative pressure here. Pipe internal total pressure must be equal, atmospheric, at both sides of the trap.

Must a condensate line drain without looping?

A condensate line ideally should drain without looping, meaning it should have a consistent downward slope to ensure proper water flow and prevent potential clogs caused by water pooling in a loop; however, depending on the layout of your system, a small loop might be necessary, but it should be minimized and designed to avoid trapping water. 

This is more-correct, and it is what I practice.

And yet, know that permissiveness of a trap in a condensate line is a very positive thing. With stiff hose material sold in a coil. straight-running at modest slope may be hard to achieve. A complete loop for reach flexibility, is allowed. Do not prefer, opaque stiff and fragile PVC, for trap avoidance. Prefer serviceable connections without glue.

Here is another gravity-drain condensate lines example with an upflow high efficiency gas furnace:

In both examples, the found A/C heat exchanger condensate line has a P-trap, and the furnace heat exchanger condensate line does not. Why then, a trap, ever?

Here, PVC drain piping serves better than flexible hose.

Here see a rare example of better efficiency of heat transfer to air, with intermediate hot water, Lennox Complete Heat. It is hydronic home heating. Want to know more about this integration of domestic water heating, and home heating. Wonder why this was discontinued by Lennox. Wonder how this relates to electrification, in future fossil fuel bans. Tentatively find that the integration makes sense with geothermal heat pumps. See that this unit is serving reliably.

High-Ceiling Swedish Attic Ladder In A Busy Hardware Store

Wish that this comprehensive post shall be detected in a search of terms MidMade + attic ladder + customer reviews. At 12/28/2024, find two pages of results, with nothing in USA. Where are the USA customers and their sagging wood steps, unhappy with default very-steepness needlessly not-adjustable? Very much is written at this blog, and it is not detectable. Why?

This ladder for 25" x 64" rough opening gave access for perhaps thirty years, to vast storage space over a hardware store. It is a Louisville industrial attic ladder, typical of USA construction, with flimsy 1/4" plywood door and operating hardware of far less durability than the worthy step sections; now to be scrapped. The rivets of 1x4 structure over the door panel are broken away. When standing at the opening end of the door, there is little rotational rigidity of the aluminum steps. There is an awful feeling that the ladder is not safe.

A bit unusual for a hardware store, the ceiling is up more than eleven feet (135").

A long metal pole, hook-tipped, has allowed operation from the floor. The slam-close door has no latch. Just pull it down. Use the same pole to hook and walk-out the step sections to the floor. The step section pull is also a high reach, nearer hinges, the better to resist toppling.

How could these flimsy arms without elbow locks, do much to restrain door rotation when the very tentative door rigidity is lost?

See the typical USA-ladder unstable offset of the spring pull from the upper pivot. The next failure mode, usually the killer of these unfortunate ladders, is in bending-back of the spring pull offset, perhaps when snagged by some object or personal clothing. Once bent there is no stability of the arm shape. Bending often begins with failure of the rivet attachment of the arms upper pivot due to large rotation of the ladder frame where installers don't know to drive long screws through two of the four holes in the square pivot plate, obviously for that purpose.

See failure here to install the upper pivot bonding to rough framing, so very common. The 1x4 ladder frame is not rigid.

In passing, look for an alternative available to anyone.  This might be among offerings of Rainbow Attic Stair, imported by SP Partners LLC , focusing on F-series, a very pretty industrial ladder rated to carry 570 pounds, with a 1/2" thickness plywood door, not fire-rated. These ladders are offered only with three step sections.

Powder-coated white, with very many clever features for user-friendliness and safety.

Here is a video description:

https://youtu.be/9pCDxq2tf80 

Offered Model F22/60-11 at in excess of $2000, will not reach 11' 3". There is no adjustment flexibility in the rigid welded-steel assembly. Rainbow will build to suit a project, but that was not offered, in a phone call.

A Rainbow ladder that will serve at 11' 3" is Model Prestige:

Also not fire-rated. I find this uninteresting. I installed three of these between 2006 and 2007, and find them wobbly and not "industrial." Dented tubing unpredictably loses strength; I have seen one ugly failure of this ladder.

• 350 lb. weight capacity
• 7′-4″ to 11′-6″ (Varies by model – see specifications for details)
• Self adjusting stair rise
• All powder coated steel stair components.
• Strong 3/4″ melamine finish MDF frame
• Built-in 2″ steel trim – No ceiling molding needed
• 2″ Styrofoam insulated door – melamine finished on both sides
• Weather stripping to reduce drafts and air leaks
• Specialized steel hangers to simplify installation
• All steel, telescoping handrail (reversible)
• All steel grab handles at top of stair
• Protective floor bumpers
• Pole and hook for operating stair

A Swedish MidMade LEX that is fire-rated, would exceed "professional" status of any other usable ladder, at large cost savings; but the fire-rated model is not imported to USA..

MidMade ladders are imported to USA exclusively by Conservation Technology , in Baltimore MD. Attic ladders and access doors are a secondary opportunity to sales of superior European building gaskets and much more. The only ladder imported is the LEX 70, in frame sizes 56 cm x 118 cm and 56 cm x 136 cm, not fire-rated.. The measured maximum reach of the default larger MidMade ladder is 118.5". I, alone perhaps, am not constrained by factory limits.

And here is the installed ladder, with many inventions:

In this drawing, see employment of new machined part, Step Sections Joining Plate:

When this is bolted to a step section already drilled. this acts as a drill guide for a new step structure. Offered new step structures include a locally-built Top Step, an additional step section rigidly applied to another, and  simple 1x4 stick extension of stile to floor contact. You get the idea in the hardware store as-built drawing. Trimming to reach the floor is done accurately, progressively with a chop saw. Saw new sticks if there is an error.

Routinely offer Leveler Legs for fine adjustment of floor contact. The polyvinyl base is soft and is sticky to smooth wood, tile or concrete floors. Traction is helpful in resisting attic ladder kick-out, a common and very scary situation where in leaning forward upon the upper section, the lowest section snaps to an upright condition. 

Ladder deployment is with the same hook-tipped large pole used for the Louisville ladder.

The un-tented ladder drops to-hand , and is comfortably walked-out to land on the floor. This is more intuitive and safe than toppling a three-section ladder that demands a longer door. Smaller ladder openings are safer. A much greater reach to the floor is possible for a given ladder frame length. Look for new understanding of the expression attic ladder tented stowage .  In an internet search now, find such foolishness as this as the concept of "tenting.":

Dumb!   . As an air block (perhaps) when zipped and before soon being ruined as a fragile and dangerous obstacle, there is false notion of an insulating effect. With the ladder closed, the flimsy has no insulation value. A sense when lowering the ladder that covered space above is warm,  is mainly from a sudden flood of room air. For best value. no attic ladder need have more gasketing and insulation value than a USA R5, European U 1.0 best exterior door.

The tenting we all should learn  to like and demand, is central to a comprehensive proposal submitted to MidMade, for better design of all of their attic ladders. It may be said that MidMade in Sweden  invented attic ladder tenting, but they have yet to deliver its wonderful best possibilities.Where this commercial opportunity is to a ceiling with two layers of good drywall, 5/8" first, 1/2" below, there is seeming intent of much resistance to propagation of fire. The drywall is  completion of 2x12@24 box beam super-flooring, where top webbing is 1x8 excellent shiplap. But, fire safety concern is real. Where ever did we get a notion that any attic ladder may be not-fire-rated? So, I did what what was possible. Someday at my prompt, MidMade might build all attic ladders as fire-rated, and I have promised swap-out of the frame and door then at very little cost. 

Here are views of the completed installation:

Stowed

Deployed

Here is a YouTube video of the deployment and stowage of this MidMade ladder:

https://youtu.be/7nnhbayjgk0 

Call the story: Someone forgot to turn off the attic lights.

Report To MidMade in Sweden

Now, admit discovered and now-repaired defects of this MidMade ladder as-shipped by the manufacturer, midmade.se . This report, readily translated to Swedish, adds substance to a large new-product proposal  in this Google Doc  The sum of this will exceed a second-hand appeal to MidMade achievable by the USA importer, Conservation Technology. We understand that there is new leadership at MidMade, and I hope this leadership is inspired to a new surge of product excellence.

A competent installer may serve customer needs, not achievable with the factory-produced ladder. Begin with shop setup of decision-based placements, not just arbitrary. Test everything with computer graphics ensuring no interferences in deployment.

Better Arrangement of the Ladder Elements

Many installer adjustments are wanted and are very necessary. Beyond unobstructed deployment, the ladder must have proper setting of springs that balance swinging weight. The door with stowed steps must move with ease over full stroke both in lowering and in raising. The balancing springs on these MidMade ladders are of ideal dimensions and stiffness for their purpose, and this is with setup preload of stowed-ladder spring tension that is not achievable except with leverage. Absent that leverage, the steps crash down dangerously, and that is not provided-for in manufacturer instructions.

Compare red vectors of spring tension in the as-built and default setups to see that at 60° steps angle and with lowered upper pivots, there is a large moment from the springs as the door fully closes, to seal door gaskets even without operating the quarter-turn door latch. At more than eleven feet reach from the floor, a push-pull latch could serve, but not the factory-installed quarter-turn latch. Observe the spring tension that operates here. By test, learn the spring characterisatic:

T = 13 + 4.5 * Stretch, cm.

At 6/13/2024 departure from Sandy Ace Hardware, good balancing was with door-down coil length 58.5 and 58.0 cm. Average stretch is 30.3 cm. Tension is 149 pounds. It is poor design that such tension could bend-over an upper pull. And, at 6/18/2024, with final upper pulls, door-down Lc (at left) is 60.2 cm Stretch 32.3 cm, tension is 158 pounds. With 15 cm less stretch, door closed, spring tension is 90 pounds,modest, but too much to connect without parachute cord leverage..Lose more than 50 pounds tension in non-leveraged connection, and the door drops down hard if not restrained, lifting a load of more than fifty pounds.

Learn that MidMade factory-supplied springs are useful for all MidMade ladders, and perhaps all wood ladders with intelligently-placed simple limit arms. Just pull the needed preload tension to achieve balancing.

Here is a lot of information about balancing springs for wood attic ladders, allowing comparison of excellent MidMade springs with other springs I have experienced. The purpose of so much disclosure is to assure MidMade designers of their good place in this industry. See much Fakro error in employing springs far too beefy. Anyone may see that the tension that destroyed a factory-installed MidMade spring upper pull, is modest. The pull is of poor design.

At described spring tension values, the factory-installed spring upper pulls are of dangerous poor design.

This failure at modest 150 pounds spring tension, door down, was with audible sound at high pitch, rolling down in about one second, spring still attached. A tossed spring could be deadly.

Here is the safe setup of spring upper pulls.

A step-off well, encourages thought about placement of both feet before moving on or off of the attic floor. Here there were 10" extra length in the found floor opening, best filled at the walk-off end.

Seen with door down.

Another S-hook to the eye screw and another to the spring end or to a far link of the chain, allow loops of 1/8"  parachute cord for setting leverage, with the door closed.

Be happy then that this MidMade LEX 70, customized, has well-considered balancing springs, working in a way that will surprise many, to be self-closing,.with limit arms of rugged and simple design. Know that we might be happier if this ladder yet had a door latch operable from long distance, of push and pull operation with a hook, without the very serious difficulty of engaging and operating a very long quarter-turn key.

Using Installer Options of Steps Placement Upon the Door

This default placement of the upper step section is far too arbitrary. There will be reasons for different locations of all support elements, the crossbars attachment to the door,  and the steps relative to the ladder frame.

The steel factory upper section support brackets are attached to crossbars with too-small screws. Relocating steps upon them is needlessly very difficult. The steps are not readily blocked a desired distance from the door. New bolt holes through the wood upper section will almost never align with the tightly-toleranced  bracket holes. Field drilling will have challenging obstacles, but may prove to be necessary..

Begin without drilling-in the holes through the upper step section. 

Fit the steps assembly made rigid with Joining Plates. Only one bolt is needed at each of the four holes drilled through the Upper Step Section.

Crossbar and Upper Section Mounting Assembly Cross Section at Side Edge.

Now talk about recovery from very poor design of the bolting of step section hinges.

Better Bolting of Step Section Hinges

This is the default factory mounting of step section hinges with tee nuts. See large wood voids due to foolish countersink provision of tee nuts. Tee nuts will have much space for relocation under twist loading. Then expect an angle offset of up to 2° at each hinge.

Do better, thus:

Ladder hinge bolting should never fail to employ locknuts.

Fill in the wood void with Digi-Key Item RPC6485-ND? 

?12SWS1075? SHOULDER WASHER, NATURAL, NYLON, Qty 100 

 Find better bolts:

  1-1/4 Inch Long Stainless Steel Hurricane Sidewalk Bolts 18-8 (100) 

 

These innovations still do not restore the hinge stiffness that would exist if bolt holes were for M6 bolts, and lbound with locknuts, as achieved with all newly-drilled hinge bolt holes. Add to the repair a stuffing of wet flexible grout as the Digi-Key washers are installed.

The grout is identical in function to Custom Fusion Pro tile grout. Flood the area to be coated. Easy water cleanup, for awhile. Not rock hard.

With factory-default hinges drilling, expect ugly curves of the steps alignment. Eliminate tee nuts  at the factory, and the problem is resolved.

With the hinge misalignments, the bottom section needs to reach a bit further. Stresses at rotated hinge bolts may be damaging to soft wood. Tee nuts surely lose their grip upon bolts. One lost bolt breaks the ladder.

All of this is embarrassing at the least.

Handles matter very much to me in proceeding as a weatherization contractor, perhaps what the ladder installation was all about. Batt insulation must be pushed up as a dense and clumsy bag, dragging heavily in the opening of a 22" ladder frame. Cradling upon a pair of handles at the constriction, is necessary and is crucial to my safety. I want these handles to be offered by MidMade, powder coated in Safety Yellow color.

I want all ladders to be fire-rated at least thirty minutes, as good as the ceiling drywall. Here note that my installation method uniquely avoids safety compromise at usual poorly sealed gaps about the ladder frame merely hidden by wood or plastic trim. I fit the frame tightly to the ladder and need no trim. This installation is extraordinary in fitting a 22"x54" ladder in place of a 25"x64" ladder. I brought the new ladder into the attic and assembled 2x4 fill-in to the sides.

This is an extraordinarily fire-resistant ceiling, with a first layer of 5/8" drywall, and a covering layer of 1/2" drywall. There is unacceptable compromise in not finding a suitable fire-rated attic ladder.

As stated in my comprehensive proposal to MidMade, I want USA distribution to be via many local hubs where steps assemblies are custom-packaged for each customer, based upon computer-graphics analysis of each situation. Over time, planning will become simple informed selection via catalog. All customer ladder step assemblies will be assembled from common parts that are independent of the ladder frame and door assembly size. Factory-shipping and inventory economy is passed along as affording fire resistance, and better value for same cost.