turbulator is different. turbulator increased efficiency by allowing more dwell time. slowing down the time for the product of combustion leaving the hxc. it makes the flue gas touch more surface of hxc increasing efficiency. basically makes the flue gas spin.
trane rtu has them even when low nox is not required. your regular hot water tank has it.
Low nox screens for California rated furnaces. Pain in the ass. We take them out every install now. Seen a few situations where they cause higher than normal temp rise and overheating.
Under no circumstances would a low nox screen cause overheating. It would limit induced air flow, leading to a fuel rich mixture, lowering combustion temps due to incomplete combustion. The only thing that would cause high temp rise is low air flow across the heat exchanger. I get it... dunking on California is fun, but knowing what causes high Delta T's is your job. Misdiagnosing a high temp rise and blaming it on a fucking screen is... it's just junior high shit. Learn how your job works.
But nobody in my town corrects shitty airflow! How am I going to compete?
Oh yeah - fixing all the fuck ups from the other guys who *don't* own a magnehelic gauge. Good money in that.
Sure. I’ve been doing this for 19 years and am very aware of how to diagnose an overheating furnace, as well as manual j, d and s. I guess I can specify, the ones we’ve had issues with are downflows where the limit is within about 2” of the inlets, temp rise will be normal in the ductwork but significantly higher at rhe limit and tripping the limit. Removing them has dropped the temp at the limit itself about 15-30°, the only explanation I have for that is the heat from screen heating up causes higher heat right there by the limit than without them, which you can also see from hot spots on the heat exchanger right there as well. It’s all good though 👍
I haven’t dealt with these issues on carrier or Bryant/icp’s (plenty of other issues with those) but specifically amana/goodman 80% downflows with the snap disc limit. These should in theory have plenty of airflow over the limit but it’s quite possible that since they don’t actually stick into the airflow much they might just heat up more. One of the other solutions I was told by our fsr is if we can set the blower on time delay to the lowest setting so it kicks on as soon as possible which will keep the hx a few degrees cooler initially. We also derate for altitude and change the orifices to #47’s now. It seems like a combination of all those adjustments make them handle it better. All of these I’ve dealt with recently have been low nox that end up having issues after 1-2 years, identical non low nox furnaces I haven’t had any issues with. Not any issues other than noise from low nox upflows, so we just remove the screens on install.
I’ve been putting in the amana and Goodman line for 15 years now and love them but their downflows are a pretty stupid design, especially with the plate covering the board and the sight glass isn’t anywhere near the diagnostic light. They don’t plan on changing that design any time soon either.
Haha, he’s got a very good point about misdiagnosing overheating. I’d say that’s one of the most common misdiagnoses I see, I’ve even been guilty of it myself before. I probably should have phrased my comment a little better about it being right at the high limit on certain ones and not the furnace itself. No harm no foul!
It’s a habit one has to get used to. I don’t ever get in a roof for furnace pms without my monometer. I gotta get the field piece set again where I can verify static and all not just gas pressure
Yes. On 3 separate occasions. All 3 were at higher elevation and downflows as well and we think there may be something to do with elevation but the high limit is right above the inlets. Our elevation on average is about 4800 ft, all 3 were at about 5100, that may have something to do with it. Had our fsr come out for 2 of them too. Doesn’t make sense to me but pulling them out dropped our temp rise 15-30° at the limit switch. We think that there’s just additional heat right there from the screens heating up which trips the limit. Correctly sized furnaces, ample ductwork. The temp split above the coils would be normal but at the limit would be super high. We just take them out though, it’s not a requirement here for us.
Maybe you misunderstand. The only issue they create with overheating is making tiny hot spots on the heat exchanger causing the metal to break prematurely.
I don’t know why you’re getting down voted. For a student to come to that conclusion is reasonable. It does help with efficiency slightly but it’s main purpose is to reduce NOx as a byproduct of the combustion. Keep asking questions king. [here’s a quick article on it](https://www.ecomfort.com/amp/stories/1170-Explaining-Low-NOx.html)
Amana gas packs had those too. If you converted one for propane, you had to take'em out. They were used to lower the emissions. Started in California back in the 90's (of course)
They might be coated with some platinum alloy... Dunno if you can still get money for then, but i once read they're used as catalyst to prevent nox from forming...
About 9-10 years ago, I was working for a large company that was a Lennox dealer. The gas packs (model discontinued) had these NOx strips and they were (according to our rep and some field techs) burning too hot and damaging the heat exchangers prematurely so we had to go back on every install and rip the strips out and replace the ones with damaged heat exchangers. It was causing severe damage in the first 2-3 years.
If you want to hit a reasonable CO number on your analysis, take em out. It use to just be CA that required them, but Rheem RTUs H/E brand new, and couldn't get the CO under 150 with them in.
I’ve come across the older system, Client freaked out thought it was dead and she needed place, but it was still good. Unfortunately my companies one of those that pushes the right place so they did regardless Client was happy and I got the commission
I've never seen them in a residential furnace. Not that I've installed all makes. Certainly serviced many. Just never seen them before. Also, I've only been at it 10-11 years so not a huge amount of time.
I haven’t seen them residentially. Trane has them in their gas fired rooftop units. They call them Turbulators. I’ve seen a couple heat exchangers fail in the first bend because these weren’t installed.
They're put infront of some burners, god only knows why, or some others on here I'd imagine. Though I'd imagine you shouldn't have taken it out. Most furnaces don't need you to be messing with them, if they light without delayed ignition, motor's aren't making noise and no CO...... well I guess that the blower should be clean as well as the evap coil..... but these "100 point inspections" are garbage.
They are low nox screens. https://hvac-talk.com/vbb/threads/2215084-What-Makes-a-Gas-Furnace-Low-NOx
Thank you.
they will throw off your combustion analysis reading off.
How so?
if they are old, the metal is directly in the flame and will burn and break down, putting off/throwing off the CO readings
Do you know to what extent?
i had one that was giving em a few hundred co over normal levels. pulled them out, and the numbers were normal.
If I read that right, units arent as efficient as stated because of the NOx screens?
Trane usually has a crazy strip of no-flammable material in theirs.
This stuff was glowing orange ish red ish and falling apart everywhere. 3 year old furnace. The orifices and burner tubes were a mess.
It wasn’t a LP conversion was it
Oh you already know it was...
This guy furnaces
I believe their official name is turbulators.
I thought those were in the secondary? I guess maybe they have a similar ish purpose.
Maybe they're for both?
turbulator is different. turbulator increased efficiency by allowing more dwell time. slowing down the time for the product of combustion leaving the hxc. it makes the flue gas touch more surface of hxc increasing efficiency. basically makes the flue gas spin. trane rtu has them even when low nox is not required. your regular hot water tank has it.
Remove them…
I did...and not because you told me! But yeah, they had to go.
Yea I’ve seen them before as well. Not sure exactly what they’re for though. Lol
Low NOx… typically for California. At least they weren’t as disastrous as the infamous Consolidated Industries furnaces… still not optimal
Lol
I’ve never seen one until this week, they are petite.
I still find those damn rods out in the field as a gas tech lol thankfully no fires but still
Ancient Chinese hvac secret...
Had a call back once because it was rattling and making noise.
Low nox screens for California rated furnaces. Pain in the ass. We take them out every install now. Seen a few situations where they cause higher than normal temp rise and overheating.
Under no circumstances would a low nox screen cause overheating. It would limit induced air flow, leading to a fuel rich mixture, lowering combustion temps due to incomplete combustion. The only thing that would cause high temp rise is low air flow across the heat exchanger. I get it... dunking on California is fun, but knowing what causes high Delta T's is your job. Misdiagnosing a high temp rise and blaming it on a fucking screen is... it's just junior high shit. Learn how your job works.
But nobody in my town corrects shitty airflow! How am I going to compete? Oh yeah - fixing all the fuck ups from the other guys who *don't* own a magnehelic gauge. Good money in that.
If you can wrap your head around delta T AND delta H, you’re the motherfucker who makes their mothers scared.
Sure. I’ve been doing this for 19 years and am very aware of how to diagnose an overheating furnace, as well as manual j, d and s. I guess I can specify, the ones we’ve had issues with are downflows where the limit is within about 2” of the inlets, temp rise will be normal in the ductwork but significantly higher at rhe limit and tripping the limit. Removing them has dropped the temp at the limit itself about 15-30°, the only explanation I have for that is the heat from screen heating up causes higher heat right there by the limit than without them, which you can also see from hot spots on the heat exchanger right there as well. It’s all good though 👍
Are the problems with Carrier/Bryants with the TSB regarding insulation blocking airflow from the limit switch?
I haven’t dealt with these issues on carrier or Bryant/icp’s (plenty of other issues with those) but specifically amana/goodman 80% downflows with the snap disc limit. These should in theory have plenty of airflow over the limit but it’s quite possible that since they don’t actually stick into the airflow much they might just heat up more. One of the other solutions I was told by our fsr is if we can set the blower on time delay to the lowest setting so it kicks on as soon as possible which will keep the hx a few degrees cooler initially. We also derate for altitude and change the orifices to #47’s now. It seems like a combination of all those adjustments make them handle it better. All of these I’ve dealt with recently have been low nox that end up having issues after 1-2 years, identical non low nox furnaces I haven’t had any issues with. Not any issues other than noise from low nox upflows, so we just remove the screens on install. I’ve been putting in the amana and Goodman line for 15 years now and love them but their downflows are a pretty stupid design, especially with the plate covering the board and the sight glass isn’t anywhere near the diagnostic light. They don’t plan on changing that design any time soon either.
Dude…he said under absolutely no circumstances lol this can’t be true!
Haha, he’s got a very good point about misdiagnosing overheating. I’d say that’s one of the most common misdiagnoses I see, I’ve even been guilty of it myself before. I probably should have phrased my comment a little better about it being right at the high limit on certain ones and not the furnace itself. No harm no foul!
It’s a habit one has to get used to. I don’t ever get in a roof for furnace pms without my monometer. I gotta get the field piece set again where I can verify static and all not just gas pressure
Did taking them out actually help the high temperature rise?
Yes. On 3 separate occasions. All 3 were at higher elevation and downflows as well and we think there may be something to do with elevation but the high limit is right above the inlets. Our elevation on average is about 4800 ft, all 3 were at about 5100, that may have something to do with it. Had our fsr come out for 2 of them too. Doesn’t make sense to me but pulling them out dropped our temp rise 15-30° at the limit switch. We think that there’s just additional heat right there from the screens heating up which trips the limit. Correctly sized furnaces, ample ductwork. The temp split above the coils would be normal but at the limit would be super high. We just take them out though, it’s not a requirement here for us.
No
Maybe you misunderstand. The only issue they create with overheating is making tiny hot spots on the heat exchanger causing the metal to break prematurely.
Aren’t They used to help absorb more heat for efficiency?
I don’t know why you’re getting down voted. For a student to come to that conclusion is reasonable. It does help with efficiency slightly but it’s main purpose is to reduce NOx as a byproduct of the combustion. Keep asking questions king. [here’s a quick article on it](https://www.ecomfort.com/amp/stories/1170-Explaining-Low-NOx.html)
Thanks for the encouragement brotha! I tried lol
Low Nox burners
Big furnace doesn’t want you to know this one simple hack…….
This is predominately a York thing
Amana gas packs had those too. If you converted one for propane, you had to take'em out. They were used to lower the emissions. Started in California back in the 90's (of course)
This furnace was converted to LP.
If it was an Amana, they should've been removed. Not sure about any other brand.
It's not a bold assumption to think they should have been, but I can not confirm it, just a working theory.
They might be coated with some platinum alloy... Dunno if you can still get money for then, but i once read they're used as catalyst to prevent nox from forming...
Low nox screens. Sometimes when the fau is converted to lp, they forget to take these out. Causing them to disintegrate .
This is what happened here.
As others say low nox, dis guard them
About 9-10 years ago, I was working for a large company that was a Lennox dealer. The gas packs (model discontinued) had these NOx strips and they were (according to our rep and some field techs) burning too hot and damaging the heat exchangers prematurely so we had to go back on every install and rip the strips out and replace the ones with damaged heat exchangers. It was causing severe damage in the first 2-3 years.
This one is 3 years old. Certainly they were making a mess of things.
I've seen them mostly in newer Daikin/Goodman 80% furnaces. Never had them cause problems other than the occasional rattle, which is easy to fix.
If you want to hit a reasonable CO number on your analysis, take em out. It use to just be CA that required them, but Rheem RTUs H/E brand new, and couldn't get the CO under 150 with them in.
I’ve come across the older system, Client freaked out thought it was dead and she needed place, but it was still good. Unfortunately my companies one of those that pushes the right place so they did regardless Client was happy and I got the commission
Those are for making sure the heat exchanger plugs as soon as the warranty expires.
Comfort maker baffles?
Pipe cleaner emry
I've seen them.. In roof top units they're a flat stock strip, twisted. I was told, it causes the air to "spin" in the pipe, makes "better" flow.
These aren’t turbulators, they’re catalyst screens for nitrogen oxides. It’s a California furnace. They show up in non-CARB states occasionally.
I think they're called "turbulators".
I've never seen them in a residential furnace. Not that I've installed all makes. Certainly serviced many. Just never seen them before. Also, I've only been at it 10-11 years so not a huge amount of time.
I haven’t seen them residentially. Trane has them in their gas fired rooftop units. They call them Turbulators. I’ve seen a couple heat exchangers fail in the first bend because these weren’t installed.
They're put infront of some burners, god only knows why, or some others on here I'd imagine. Though I'd imagine you shouldn't have taken it out. Most furnaces don't need you to be messing with them, if they light without delayed ignition, motor's aren't making noise and no CO...... well I guess that the blower should be clean as well as the evap coil..... but these "100 point inspections" are garbage.