Venting for cat I gas appliances

This one covers sizing the vent for 80% gas furnaces that vent with metal pipe.

[@Cloakedpyro]

You are THE MAN! this video is exactly what i needed. These charts can be so confusing without outside clarification. So thanks for your detailed examples and thorough knowledge!

[@grayfurnaceman]

Cloakedpyro Welcome GFM

[@joshp7469]

I am writing my gas examination in less than a week, this was a super helpful visual review to follow along too ! thanks so much

[@grayfurnaceman]

Welcome GFM

[@57Buss]

you always do a good job on you videos. Great for reviewing, I don't do it very often

[@grayfurnaceman]

Thanks for the support. Happy new year. GFM

[@jenniferthompsonriinivbghh8871]

Thank you for your videos. It helped me pass my boiler test. I recommend them to my coworkers that have to take the test as well.

[@dkszz]

I write my test tomorrow and this helped me alot, thanks!

[@solaj22]

Thank you Thank you for this video and all the other ones! Getting ready to take my master plumbing test and this is on the test.

[@grayfurnaceman]

Glad I could help. GFM

[@MisterGreenGuy]

@@grayfurnaceman Same here, this video helped so much thanks gray furnace man!

[@darylholdsworth301]

I just passed master gas fitter test in Maryland WSSC a very hard test. This video helped me greatly to accomplish that.

[@grayfurnaceman]

Glad I could help. GFM

[@jasonclements4607]

Thank you! the connect direct to vent had me off. I appreciate your help. Liked and subscribed sir!

[@jorgecedillos3815]

Does a direct pvc pipe direct vent get hot?

[@RayRay-nb7tn]

Thats a great explanation of this. This helped me alot. Thank you. I have the 1996 edution. I need to get the 2018 edition.

[@grayfurnaceman]

Glad it helped. GFM

[@georgeEPC]

Another great video Gary...wish you had done more examples with natural draft and two appliances into a chimney

[@3beltwesty]

Very Nice Video; Double wall vent pipe is called Type B. The reason it is used is for safety ( 2 walls) and so the hot flue gases DO Not cool off too much so the flue gas rises. I mention all this because it might not be obvious and heck I did not know this too at one time. I heard the safety 2 wall feature along time before I heard the inner pipe purposely kept warm story. The double wall has an air gap between the sides and thus is insulation. The inner pipe heats up quickly and is not sinking ie passing heat much to the outer wall. One wants the flue gas to exit before the water in it condenses very much too, thus a warm inner pipe keeps the "draw" going to pass the flue gas out of the building. In a house here with a furnace in the attic installed in 1994 it has I think a 3" type B pipe and the installer just stuck it inside the old 3 feet of 6" single wall pipe below the roof deck that exits the building. They added no coupler and just had one pipe inside another with an overlap. The flue gas would condense and dripped down the angled 4" type B pipe and ruined the sheetrock in the ceiling below. Thus a hokey poor vent system besides being a fire and Carbon Monoxide risk can just be basic water causing mystery leak that ruins a house and causes a water source for ants and termites. Sadly the HVAC installer always though it was a leaking pan under Freon A coil and thus the odd rare problem never really got fixed for over a decade plus. kzbin.info/www/bejne/bqiQopuui61gecU

[@williamkennard6080]

Thanks for going above and beyond.

[@hvactech4567]

Great video, especially helpful for the people taking the ICC ( International Code Council) test

[@grayfurnaceman]

Climate Control It was originally made as a prep for the test for my students. Thanks for the thoughts. GFM

[@chuckd89]

Is there any other videos you found helpful for the ICC test? I will be taking it soon.

[@MrEbutts]

very clear and helpful.

[@Masterzlolgaming]

Super helpful info, thanks for doing Gods work

[@grayfurnaceman]

Welcome GFM

[@jerryleejohnsonjr1377]

Great video, thank you sir!

[@geojor]

thank you for this...

[@jordanelyea4396]

I'm taking this in trades school right now. Definetly interested

[@grayfurnaceman]

Jordan Elyea This video was what I used for training my students for the fuel gas code test. GFM

[@whitesheatingairappliancer7101]

Nice video thank you

[@grayfurnaceman]

Welcome GFM

[@tedlahm5740]

Clear concise information. Meaning of double wall vent? Insulated?

[@grayfurnaceman]

It is called Type B vent. GFM

[@WilliamJoseph2015]

Very informative video. Thanks for sharing. Do you have any videos for a positive pressure vent Cat IV. I haven't been able to find a table in the IMC 2012 that will tell me the size for a 90% Efficiency. Im trying to see if I can do a common vent for a 60,000 BTU 96% furnace and a 199,000 BTU Tankless Rheem. Need to know the size for pvc vent.

[@grayfurnaceman]

There is no table I know of. These are manufacturer instructions design. Also, you cannot vent 2 positive pressure appliances together. GFM

[@WilliamJoseph2015]

I was thinking the same thing. However Navien's Tankless water heater website has a common venting guide for multiple cascading tankless units all using a common vent. I question that method but can't find anything in the codes IMC and IFGC2012 that says you can't vent 2 positive pressure appliances together. Maybe i overlooked it. Do you have the code chapter number prohibiting common vents for positive pressure appliances and why would it be a problem??? Thanks again for your knowledge.

[@grayfurnaceman]

If the Naivien heater is 80% it can be common vented. I am not sure where the prohibition of common venting is. The reason for the prohibition of multiple appliances on one vent is if one appliance is on, with the other off, the positive pressure can cause the vent gasses of the one appliance to enter the off appliance and enter the structure. GFM

[@WilliamJoseph2015]

That makes perfect sense to me. I was thinking that since it was a closed system the CO wouldn't enter the structure. But I needed a professional to confirm that so I thank you again for your time and help. out of curiosity I will look into Navien's tankless heaters to see what efficiency. Thought all tankless was at 90+% It might be possible that Navien expects all the units using the common vent to be running simultaneously to force the gasses out.

[@WilliamJoseph2015]

just a follow up I called both Navien, and Rheem technical support and they confirmed what you said about gasses entering the unit and structure. I then asked them why would they have a manual online showing multiple units sharing a common vent. No one could answer that so I called Rinnai who has a common vent manual as well. Rinnai confirm my thoughts. The customer support said it's because they are all working in unison to fulfill the high demand for restaurant and hotels etc (Cascading). So therefore the gasses won't come through because they are all on pushing the gasses out at the same time.

[@craignehring]

It would look as if heat retention has something to do with exhaust flow rate in a given sized venting situation? Is this why the type B "seems" to be more desirable in some installs? Good stuff, thanks

[@grayfurnaceman]

Craig Nehring Correct. The newer fan assisted furnaces have lower vent temps, so single wall pipe losses more heat than B-vent. This reduces the ability of the gasses to rise and often causes condensation in the pipe or chimney. Thanks for the thoughts. GFM

[@mechacc2000]

If the furnace is located in an unconditioned, ie. heated, area B Vent should be installed from the furnace connector to the vent cap. Have seen single wall installed and it will rust out in a matter of just a few years.

[@grayfurnaceman]

Gary Reecher On newer furnaces even in a conditioned space, B-vent is a good idea. According to the IFGC, all vent pipe must be B-vent if in an unconditioned space.GFM

[@codyvalliere499]

good video i just have a question because the paper im working on has everything that you went over but there is another line that asks for the "vent Capacity" so for example its 15'H 2'L BTU INPUT of 163,000: and it asks for the "vent size" and the "Vent capacity" I know that the vent size is 6" but im just not sure on what its asking for with the "vent Capacity"

[@grayfurnaceman]

Vent capacity is the number of BTUs the vent is capable of handling. GFM

[@deanmartin1966]

Good info

[@grayfurnaceman]

deanmartin1966 Thanks for the support GFM

[@lukeysandra]

On the 25' example you would want to go down to 20' because of stack effect. A 30' chimney will vent better than a 25'.

[@grayfurnaceman]

Luke Johnson This video follows the IFGC guide and is meant to show how to do according to code. Thanks for the thoughts.GFM

[@lukeysandra]

Thanks for your videos. They are a great resource. Keep up the good work!

[@grayfurnaceman]

Luke Johnson Thanks for the support.GFM

[@shawnfleming4511]

Hey Sir, Your lessons are truly inspiring and valuable. Do u still teach? and if so how do I enroll.

[@grayfurnaceman]

Sorry, I am retired. GFM

[@shawnfleming4511]

Thank you!

[@ebox008]

Good day, I have a question. I purchase a 35,000 btu single wall heater/furnace, if the length of the ventilation pipe is 10 foot. How big/ wide should the pipe be?. 3, 4 or 5 inches.

[@grayfurnaceman]

The minimum size should be the size of the vent connector on the furnace. Probably, with a 10 foot vent, that size will suffice. GFM

[@ebox008]

@@grayfurnaceman OK 4 inches. Thank you

[@1rewd133]

As someone who has been doing home improvements for 40 years, but never HVAC, I'm curious as to how this applies to flexible chimney liners. It just so happens I'm looking at a situation where I have a draft induced furnace currently installed with a 12 foot Bvent lateral directly into a 8x8 tile lined 32 foot chimney where there is now damage. I'm looking at redoing the vent and lining the chimney using insulated flex.

[@grayfurnaceman]

The chimney may have been damaged because it was not lined. The 2 methods I have used are B vent in the chimney and "Z-flex". I have not seen insulated flex. However, if the chimney has any surfaces that are outside, the space in the chimney will need to be insulated. GFM

[@1rewd133]

@@grayfurnaceman I'm pretty sure the damage is due to the furnace exhaust, it's a pretty common failure on old houses in my area (WV). I was just curious as to how one might figure for proper sizing when utilizing two different vent types, B for lateral and single wall Z-flex for the chimney itself. I've seen flex kits that come with insulating sleeves. Thanks, R

[@dcrams16]

What is the liner is 8 inch but doing the calculation correctly lets say needs only 6 or 7 inchss could I still use the 8 inch liner since it is already in there

[@grayfurnaceman]

+Dave C The 8 inch will probably work. Limitations are does the vent go thru an unconditioned space before exiting? Does it go to a masonry chimney? The best solution if the vent is all Bvent and goes directly thru the roof, is to put the proper size inside the old vent. Hope this helps. GFM

[@dcrams16]

+grayfurnaceman yeah its all 8 inch liner it use to be and still is oil want to covert to gas which is not a problem just as far as sizing chimney and vents i slack little Knowledge it will be for a water heater and 100,000 btu its definitely bigger than what i need and was curious to see if possible can get away with it ive heard people say they use induced draft to help push the flue gases better would this be a case for it I completely understand you cant see chimney and job in front of you I appreciate your reply back i am 6 yr tech i enjoy your videos a lot and have always learned something from your videos whether its something simple or complicated your experience and knowledge is awesome thanx again and happy new year

[@grayfurnaceman]

+Dave C Happy new year to you. GFM

[@raganoheatingacinc.4643]

On the first two cases would you reduce the outlet of furnace from 6"on furnace to 4" B vent?

[@RAVNEETBAL]

thanks lot of again and again your help sir , if you ever came vegas , call me , I wana take you any good place you like for diner

[@grayfurnaceman]

+Ravneet Singh It could happen. GFM

[@travisbarker4725]

good stuff.... sounds like you're eating though... kind of hard to listen too

[@chrissadler7775]

Jeeezuuus, no kidding. I had to turn it off!

[@dirktucker77]

The lip smaking... i couldn't even make it to halfway..

[@tonyblankenship1883]

J