Gas furnace pressure switch code venting problems 

I was about to pay 5,000 for a new furnace untill I saw ur video. The miracle words were " start wave in there....it doesn't take much" went up on the roof Lo and behold, water. Lifted up the pipe, now the furnace is working. Thank you.

Thank you for the video. I ended up having two feet of snow clogging the pipe. Thanks for saving me a service call.

Very good information! When I was a younger tech we got call backs from things like this! It’s not always the pressure switch!! I’ve gotten birds out of draft inducer area many times on 80% furnaces too! If vent is hooked to a chimney you can guess a bird (dead afterwards of course) done flew in!! I had an older tech explain the pipers not slopped properly causing pressure switch problems! 90% furnaces are cool & great but honestly I like 80% better! More reliable to me in freezing temps! You don’t have drain issues in freezing weather with an 80%er ! When you get an emergency no heat on a 90% in below 32 degree temps you’ll understand what I mean!

THANK YOU I have been looking for this problem for 2 years

Here in New England I have seen them not just with some snow inside the vent pipe but actually buried in snow after a major snow storm or blizzard where you get 12"-24" on top of what ever else was on the ground. I have not seen it happen a lot but it does happen.

Good diagnostic video. I installed many trane 90+ with their bay vent concentric adapter. Made for a clean finished product and keeps birds and other critters out. I agree you would still have to check for other debris. Thanks.

Very effective troubleshooting steps 👍👌

I just love the words you used to describe problems like some"craps here"..... and more......👍😅. But you very honest and very good instructor..... thank for Sharing...... God bless you and your family 🙏 😇

This is Fantastic Sir. Thank you.

Thanks! My Carrier was flashing "3-1" decoding to "LPS failing to close." Pulled the hose off and sucked on it - LPS clicks and closes. Next step, opened up the intake port, right before the inducer blower and found not one, but 2 unlucky birds had somehow gotten into the intake.

I pulled 5 bats out of an American Standard furnace last year, they were all the way down at the screen in the burner box. I found another dead giveaway that there is a blockage, is a lot of times you will hear what I would call a "wheezing sound." Kind of like a pregnant womans breathing technique in Lamaze class. Where the furnace is trying to suck air through every nook and cranny of the burner compartment. And the sure fired method for diagnosing a blockage in the intake is to just remove the burner compartment cover and let it pull air in from around its location. If the furnace fires and runs, you know the blockage is in the intake.

thank you sir!!

Thank you !!

I have a question.. I only get the low pressure switch blinking light when I put my cover/filter back on (even with a new filter) Any Ideas? Thank you for Your time.

I saw that the venting had bushings in the 90's. This would most definitely hinder the return of the condensate water.

I like to use a cordless blower to check for pipe flow/obstruction and blow everything out.

good video thks again

Hello sir. I'm doing some D.I.Y. on my vents and could use a hand with a suggestion or two. A few years ago I got my first house and been doing renos. It's a 2 story and noticed the air flow (heating and cooling) was weird. Certain rooms got blasted with air and some got none. So I started tracing the vent lines in the basement (open ceiling) checking for dampers. In doing that, I found so many problems. It looks like someone in the 1980's did some D.I.Y. and it hasn't been touched sense. I'm talking holes in the venting, gaps on connections, multiple lines going nowhere (wall cavities)... and a layer of dust so thick it looked like a thin S.O.S pad. So I went to town, started cleaning the outside, vacuumed, washed, wiped. Then the gaps stated to show more. My vents honestly looked like a strainer. I cut a few square 'service holes' in the main line off the hood. To see inside, and get access to the branches from the inside. I've been removing the old connections (dead lines) and sealing the holes with a cut patch plate and that metal tape for vents. I started at the hood and air intake. Taping all connections, holes, every place that could leak air. Spent a few hours, making sure I got everything. The outside of my vent edges are shiny now. Just taping about 10 feet of the venting I've noticed a huge difference in air flow. So I'm planning to finish all I can reach. I've noticed in your video, you have a insulation wrap around your vents. Also your connections are taped. Really nice and clean looking. That's my goal also. What's that insulation wrap? I also want to wrap my heating vents after to reduce thermal exchange in the basement. I also don't like the idea of wires against the metal vents. I'd rather have an barrier between, I've seen some melting on the older wiring. I know that I'm bound to lose some percent of efficiency in the air. But if can get within 10% of maximum I'll be happy and saving on my bill.

thank you! i had maybe 3/4 cup of water, drained it and Viola!

Hey Gary, I have a question. Is it safe to put my furnace blower for HEAT to LOW? like the AC? I have a Rheem 16 SEER 2.5 Ton AC and according to the instructions on the condenser, the indoor CFM should at or close to 1000 CFM. This means we had to the Furnace blower to LOW because the charts shows 818 CFM-1208 CFM. LOW MED was 1012-1363 CFM. We can have the HEAT, COOL, and FAN on separate blower speeds OR there is a tap to put the HEAT and COOL on the same speed. I think the AC Company installed a furnace that's way oversize. My AC/Heat square footage is 1047 and they installed a 80% 75K Furnace... In South Florida. Having it on LOW MED to MED is way to much. When I had the HEAT on low, I checked the outgoing temp of the air. The incoming was 70 and out going was 135-145 degrees. According the manual, there should be a 25-55 differential or a maximum outlet temp of 155 degrees. Here is a link resource.gemaire.com/is/content/Watscocom/Gemaire/rheem_r801ta075417msa_article_1403974088948_en_ss.pdf?fmt=pdf to the specification sheet. My model is Rheem R801TA075417MSA. Thank you for your help.

Great video. I'm experiencing a red-3 blk, pause 3 blk pause..ect. I got up a 4 am and the furnace had stopped. I saw the 3 blk, pause pattern. I pulled some hoses off, sucked some sir, put them back on and turned the switch back on that sits on the furnace vent. Now, it's been working right for the last 8 hrs. However, this has been going on for quite some time. It works fine for wks, or longer, and then all of a sudden it stops. Most times it can be fixed just by turning the switch off and turning it back on again but I know it's only a matter of time before it goes out again...what do you think ? Thanks so much !

had a pressure lamp flash code . the exhaust venting. had water twice . the pipe in the attic travels about 8 feet horizontally . i’m going to increase the angle toward the furness so water can’t get trapped in low spot .

For the BTU of my furnace and number of 90 elbows I had to use 3" PVC (manual said 30' run and max of 2 90 elbows for 2" PVC or it might trip pressure switch ) I ended up needing 3x90s and 1x45, though only 10' of actual pipe, but still went 3" to be on the safe side. No issues with pressure switch but it was also recommended to reduce to 2" just beforing going through the wall... Do you know why that is and whywouldn't that affect the pressure switch reducing down?

Thanks for the video. I was curious if both vent pipes need to slope toward the furnace? If one drains outside, in my case the intake does, is it a problem?

Great video sir, Question i have a Lennox Pulse 21 80,000 BTU and replaced it with a Carrier 2 stage Furnace 96% 80,000 BTU, can i use the pulse concentric 2 inch vent kit that's 2-inch pipe from furnace to concentric, mufflers are removed, or should i replace concentric with 3inch vent kit and 3 inch pipe, thks

@grayfurnaceman I have a trane xv80 and it's had a mind of its own. I have replaced the pressure switch and board in the matter of 2 years. It's randomly throwing this pressure switch code. It happens on cold nights and randomly whenever it does. I'm not sure where to look now. I've checked the flue, the top of chamber, wiring, etc. The replaced part stated are original trane parts. If you may have an idea where to look, I would greatly appreciate it sir.

You know how many birds I have found stuck head first inside of the venter outlet? Why do they all crawl to the end of the pipe that has no freedom, only 💀? LOL 😆

I would have thought if the vent chart called for 2.5 in pipe as this install has. I would want as much of the 2.5in pipe as close to the furnace before adding the bushings or reducer if example it was 3in pipe

Please make a video on DOWNWARD venting a 90%+ Furnace.

Thank you nice video or the drain is clogged

Will switching from 2inch exhaust vent pvc pipes to 3inch exhaust pvc pipes help with pressure switch nuisance codes on the pressure switch. Tech has changed inducer motor, pressure switch, control board and made sure it was draining properly, also check the slope of the exhaust vent...said it was sloped properly. Still getting this stupid code 31 pressure switch tripped code.

Sir, let me ask you. I have a 95% furnace and the flue exhaust collar is black. I'm thinking it's ABS. So am I supposed to use red RTV silicone to bond the PVC pipe to the collar?

Hi thanks for the video. I was wondering if you can help me. I have someone wanting to sell me something I don't think I need. Earlier this year I extended my 2 inch id gas heater exhaust pipe out to 35 feet it was 25 feet. I did this to vent the fumes away from where we sit on the deck. I made a mistake when extending it because I did not use enough support straps and it developed a low spot in the pvc pipe which resulted in condensation that got stuck in that low spot and it probably froze or had water built up, causing my furnace to overheat. I fixed the slope , no low spots the water drained out right now and the slope is right. I think I am good, but the Hvac company told me that my 2 inch intake and output should not be placed under deck. In addittion, they told me that I needed to increase 2 inch Id pipe to a 3d ID pipe. . Do you know if they are telling me the truth when they say it should not be under the deck and that I need a 3 inch pipe to go 35 feet. I think since I fixed the slope issue that I might be good with the 2 inch id ran 35 feet?

Mine did that too.. had a relative try and fix it and he either blew a fuse or the transformer as now even the digital thermostat won't read ANYTHING.. blank screen and it is wired. furnace does NOTHING now.. not even a BUZZ noise as it was doing off and on but never igniting. so sitting in the COLD as we don't have the Income to pay a repair person. I'd do it myself if I knew what I was doing.. I know how they work but thats it. thanks for Posting and any ideas ?

how far should pvc exhaust pipe be from basement window... or any window on a residential property

If they are sagging due to improper installation, is the installing company responsible & have to fix it?

My fresh air intake doesn’t go to the outside I have 9 foot ceilings in my basement unfinished by 58 feet long is that a problem Oh and also there is a 4 inch radon pipe to goes up through the roof maybe that would help with Fresh air

Whats up with short radius elbows?? Thats a no no right?

What you didn’t use long sweep Ellis.

I thought code says for vent pipe that the purple primer is supposed to be used at all connections. I didn't notice any. Also all i saw were cheap 90°elbows in both lines instead of long sweep 90's. Lastly the opening for combustion air intake is supposed to be 12" above anticipated snow level. There's no way in hell that install would ever pass code.

I'd change out those terrible 90's for some long turn elbows.

I’m in Texas but I still have a venting problem. That or the inducer is bad (it’s motor runs constantly). I changed pressure switch and nothing happened.

Should have used long turn ells on the venting

I had a call once for no heat on a high efficient furnace on a pretty cold day. Show up and the inducer is running and coding on ignition failure I believe? I check the venting and the pressure switch tubes. All good. Checked the drainage too and it was fine. I jumpered out the switch after inducer startup and she lights. I say ok, ill go get you a switch. I put it back together before I went to get a new Pswitch, and just out of curiosity I tried to fire it and it relit and after about a dozen resets it kept firing with no issues and I haven't heard from them since. Would this have been a case of possible water in the Pswitch tubing that I didn't see or maybe the Pswitch diaphragm was stuck?

A 90% furnace deserves a good filter access & better than standard filter!! Install pleated media or good washable type!!! These furnaces have a recuperating coil off of the heat exchangers!!!! Poor filtering can cause the heat coil to clog up(evaporate coil too!). Not fun cleaning those off either!!! If owners properly changed their filters they could have fewer professional visits!? Drain lines & cracked heat exchangers a different story!!! So don’t blame HVAC companies when these problems arise & you haven’t had yearly inspections!!! Jus saying! Nothing’s perfect it’s all man made & maintained!

also i cut the existing pipe just above the furness and the furness ran . so the water block in attic caused problem