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Proper furnace / water heater venting is an extremely important issue, which depends on the performance of the house chimney / chimney flue or other exhaust assemblies. The conditions explained in this post also apply to the wood burning appliances.
Consequences of improperly assembled vent pipes, problematic chimney flue, deteriorating chimney walls can be sometimes fatal – fire and Carbon Monoxide poisoning are topping the list.
Therefore, combustion products from your furnace, water heater, wood burning fireplace, and any other appliance that requires some kind of an exterior vent / chimney, have to be properly properly discharged to the exterior.
Certain requirements have to be met for the appliance chimney to draft properly. The most obvious one is unobstructed surroundings, in particular the roof itself. Depending on chimney placement / distance to the surrounding walls, there are different height rules.
For oil and wood burning appliances there is a very simple formula that regulates this chimney height requirement, it is called “3-foot, 2-foot, 10-foot rule”. What it means is that top of the chimney should be 3 feet above the roof surface through which it protrudes and 2 feet above anything within a 10′ radius measured horizontally (those are minimums) – look at the simple diagram of this rule application at FireplacesNow.
This chimney rule can be applied to wood burning fireplaces, heating stoves and any oil fueled appliances, but remember that manufacturer requirements have to be incorporated into it.
For gas venting appliances, the chimney / venting rules are more complex, simply because of the variety of products on the market. For a double wall type vent (required in cold climates) I’ve prepared a separate post – Gas appliance vent terminations.
Below are some requirements for the furnace / water heater single wall vent pipe / chimney (warm climate):
General rule - the chimney should not be outside a window or other house opening.
There’s several other requirements which apply to certain types of furnaces and water heaters venting. Always follow manufacturer guidelines, if you have any concerns about your chimney, call a heating contractor or other chimney specialist and have the chimney / heating system examined.
I’ll try to explain just a few basics that apply to most common types of appliances used in Illinois ((for more detailed information about gas appliance venting regulations in Illinois, go to this website: Illinois Peoples Gas and North Shore Gas , navigate to “Construction Guide“, fill-up simple form and download this free booklet – very helpful information), or contact me.
1. NEVER USE CHIMNEY FLUE TO VENT CLOTHES DRYER, KITCHEN / BATHROOM VENT
2. DO NOT USE SINGLE FLUE CHIMNEY TO VENT GAS AND SOLID FUEL (WOOD BURNING FIREPLACE OR HEATING STOVE) – you can have one chimney but multiple flues for different fuel types
3. READ MANUFACTURER INSTALLATION GUIDE and ask your licensed HVAC or plumbing contractor / installer if you have any concerns – installation guides are usually very clear, with simple diagrams explaining all required clearances, type of required materials, etc.
4. If you’re replacing an old water heater and a furnace (or any combination of those), with new appliances that also require regular chimney, make sure that your chimney flue is evaluated. Flue gases temperature in older, low efficiency furnaces (78% and less efficient), was sufficient to elevate chimney flue temperature to the point which guaranteed proper draft.
When connecting a new, regular type (known as category 1 type gas appliances) furnace /water heater, with efficiency slightly below 83%, old chimney flue size might need to be decreased with a new liner. This is extremely important, and serves various purposes – properly sized chimney flue:
5. If one appliance has been disconnected from the chimney previously serving 2 or more appliances, make sure that a professional re-evaluates your chimney flue. It may need to be down-sized to prevent flue gas condensation and to provide proper draft (typical condition when upgrading to a high efficiency furnace) – check this chimney flue sizing guide.
This video below explains in detail how to install a new liner inside the chimney. It is 8 minutes long, but you’ll get a good idea about the entire procedure – this is an extremely important and often necessary procedure.
6. If you’re replacing natural draft furnace (no motor assistance for exhaust gases removal), with an induced / forced draft motor equipped appliance, and your natural draft water heater remains connected to the same chimney flue pipe, make sure that water heater vent pipe connection is “Y”, and not “T” type.
“Y” type vent pipes connection is necessary to prevent exhaust gases from mechanical draft type appliance vent pipe, from being pushed back into the natural draft type vent pipe, and contaminate living space.
Possibility of such contamination is greater during the cold season and on taller, exposed chimney / for example – attached to the side wall of the house. Before the hot exhaust gases warm up the chimney flue and create proper draft, they often discharge through the water heater’s draft hood.
7. When upgrading to, or having a high efficiency furnace installed, exhaust gases will be discharged through the PVC pipe, and not the chimney.
There are two types of venting associated with those furnaces – single pipe and two pipe systems.
Because high efficiency furnaces venting system must be air tight, PVC vent pipe connections should be monitored periodically during furnace operation for any moisture / condensation. If such occurs on PVC joints, you should have this condition evaluated by a licensed HVAC contractor – connection will have to be resealed.
PVC vent pipes should not be inserted into the chimney flue if it is still used for other appliances venting.
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salik alvi
1 month ago
I have a house that has a gas based water heater and the flue from the water heater is going into the chimney, I just removed the old forced air furnace and put in a new energy forced air furnace gas based, but I ran the PVC that takes the carbon monoxide out directly into the chimney is that ok?
admin checkthishouse.com
1 month ago
Unfortunately, such installation is not permitted. High efficiency / condensing type appliances cannot be vented through the same chimney as the regular type gas burning appliance. Condensation and exhaust gases temperature are the main issues. There are two things you should do – high efficiency furnace requires its own, dedicated (no sharing with anything else) PVC vent that discharges through the side wall or house roof to exterior. There should be a manual that came with a furnace explaining proper venting of your appliance. If not, check the manufacturers website. Second thing is to make sure that your chimney isn’t oversized to vent water heater only – you’d need to find out its interior dimensions and the water heater draft hood diameter. Let me know if you have any problems…
awmccready
1 year ago
My 20 year old natural gas WH’s (water heater’s)hot water is only enough for one person to shower, so I want to replace it before it leaks too. However, its 3″ vent pipe is “T”d into the 6″ double wall vent pipe that my new high-efficiency furnace no longer uses. The furnace and WH are side by side in the basement about 1′ from the wall. The 6″ pipe runs through the concrete block basement wall (5′ up) then under & parallel to an interior door to the garage and then up between the wall (contains the door) between the attached 2 car garage and the family room (no basement) into an attic then up through the roof above the garage and family room.
On the phone, the Borough engineer thought the existing 6″ metal vent pipe may be too big for just the WH, though one of the engineers inspected the new furnace installation about 7 years ago and didn’t mention it. Also, the code may have changed.
What are my options for venting a replacement WH other than switching to a power vent WH & venting through another basement wall, which has its own problems?
admin checkthishouse.com
1 year ago
Hi there, based on the Seven Times rule, the largest permissible chimney diameter for the water heater with a 3″ draft hood would be 7″ (49.455sq inch), so your 6″ almost completely concealed within the house structure (warm chimney) should be OK. But I’d highly recommend to use Gamma tables, where you can input BTU, vent pipe length and # of all connectors – http://icpindexing.mqgroup.com/documents/076416/gama%20vent%20tab.pdf Power-vent equipped water heater will cost you a few hundreds $$$ more than regular, savings per year are roughly $30.00 (based on energy guide), so you’ll need 10 years to get that extra money back. Also, it needs electricity to run the motor, and the motor runs a lot (before and after the burner stops). High efficiency water heater or tankless type will save you more money, but it costs much more. Tankless is probably the best choice, but it must be installed as close as possible to the faucets to give you biggest savings, it usually requires larger gas pipe diameter and special venting. If your current chimney will match the Gamma tables, getting another regular WH will be of course the cheapest way. Did it help?
John Hammond
1 year ago
Resent 2-2-09
I have an old pot belly wood/coal burning stove which I would like to use in my shop (a separate building from my house). It is a small stove made by King Stove and Range Co, model S-30, (flue outlet is oval with five-inch equivalent diameter).
Where can I find information to design and build an appropriate chimney flue system? I presume it has to vent out through the roof for best efficiency and maintenance, although I could put it through the end wall of the building.
John
P.S. I should have indicated preference for e-mail response. Thanks. John
admin checkthishouse.com
1 year ago
Hi John, Sorry it took that long but I hope you’ll find at least part of the answer by following this link Solid (Wood/Coal) Fuel-Burning Stove Chimney Venting. Good Luck with your project…
John
1 year ago
I had a high efficiecy gas furnace installed. Origianlly the contractor said he would run the vent through the old chimney but his installer just ran them out the side of the house because there is a bend in the chimney. The side vents are pretty obtrusive. Is it possible to use ABS pipe for venting since that would be flexible enough to get it around the jog in the chimney?
admin checkthishouse.com
1 year ago
Hi John, some of the ABS pipes are approved for the high efficiency furnace venting. You can find details here High Efficiency Furnace Plastic Vent Pipe Types. But I’m not sure if it will be possible to make it through the chimney offset. The problem is, that ABS, CPVC and PVC pipes crack easily when under stress and in cold temperatures. If you force it into the chimney offset, it might just fall apart during the winter. Also, just in case you’re still using that chimney for some other appliance venting, you can’t put any plastic pipe there. Some jurisdictions and / or manufacturers might permit it only if the plastic pipe is within the stainless steel pipe – check your local code and manufacturers requirement. You can also consider using Bayvent200 or Bayiar30aventa exterior plate for your furnace venting purposes – it doesn’t look bad on a side wall and it will be much cheaper / easier to install it (if your particular furnace brand and local code allows it)
Jim Keller
1 year ago
I have a furnace venting into a 6″ metal vent, a water heater with a 3″ vent “T”ed into the same 6″ vent and I want to add a second 3″ water heater vent into it. Can I replace the 3″ T with a 6×4 “Y” and run the two 3″ water heaters into the 4″.
admin checkthishouse.com
1 year ago
Hi Jim, I’d need a picture of your setup(if you can take one – upload it at “Virtual Help”). Calculate total BTU of your 3 appliances and use tables from this guide Sizing guide for proper sizing of the vent flue pipe (I don’t know if you’re using single /double wall, vent pipes lengths, positioning of your appliances around the chimney, type of a furnace-natural/induced draft, BTU ratings, etc.). Are you planning to use a manifold for those two WH, and connect it to the “Y” 4″ leg? This guide shows something that looks close to your description – WH venting (2nd page)
Dennis Darling
1 year ago
How, or Would Schedule 80 PVC compare to that of Sch. 40 in venting a furnace? I’m installing a 90+ furnace and need to run a new Vent and Air pipe system over a heated room with a suspended ceiling. Would I still need to Armaflex the pipe? Would the thicker schedule 80 PVC encroach on the maximum allowable length of 2″ pipe? I am planning on using the Sch. 80 due to the availability of the pipe. (Shhh… don’t tell work). Thanks Derak.
admin checkthishouse.com
1 year ago
Hi Dennis, both PVC vent pipe types (Sch40&80) have been certified by the American Gas Association, you can compare markings on your pipe using this table High Efficiency Furnace Plastic Vent Pipe Types . I’ve never seen a PVC furnace vent pipe insulated, it does expand slightly during furnace operation but in a heated room it shouldn’t be a problem (unless your local code requires it). Make sure that you have a proper support (min every 3′), vent pipe slope towards the furnace for proper drainage (at least 1/4″ per foot), and length / diameter / quantity and type of bends properly calculated – never exceed max allowable length. PVC vent pipe wall thickness – not a factor, not even mentioned in installation manual for American Standard and Trane HE furnaces.
Any time
b-man
1 year ago
Hey I have a trane xe-70 unit in a house that I just bought and the unit does not have a vent pipe on it. Can I use pvc or do I have to use the regular pipe on it. It is a 1990 model. thanks
admin checkthishouse.com
1 year ago
Hi, not much info on this furnace, except for a lot of questions
. There’s a recall on this particular model (for attic installations / horizontal furnaces) – http://www.seay-inspections.com/Consolidated%20heaters.htm. From the pictures in this link and some other websites, it looks like this furnace model uses regular chimney for venting purposes. If it has a label, check BTU input and output to get efficiency – for AFUE 90% and up you’d most likely need a PVC vent. Also, there might be furnace category listed on the label – Category I and III venting will typically use metal pipe, Category II and IV typically uses PVC pipe for venting. Before working on furnace venting, get a heating contractor to check heat exchanger – many people complain about cracks in this particular model and year.
admin checkthishouse.com
1 year ago
I’m not sure exactly what do you mean by “leaking” – is the chimney flue section separated in attic area, corroded, leaking at roof penetration? Whatever it is, chimney flue is repairable. Is the house worth buying? – I wouldn’t judge it based on the chimney condition, just add the repair cost to the total of this transaction and if this is the only problem with the property, you should ask your inspector for help with a final decision. Unfortunately, I didn’t see it…
Heather
1 year ago
Hello, I am buying a house that is 8 years old and during the inspection the it was found that the furnace flue vent needs to be replaced from the attic up. It is leaking and I am wondering if this is dangerous or if it is fixed if it is not a big deal? Curious as to whether or not the house is worth it or to move on?
admin checkthishouse.com
1 year ago
I’m assuming that you have a high efficiency furnace installed – if the pipes have frozen, you have to remove the ice blocking the inlet / outlet. The reason for ice buildup is usually improper installation of the PVC pipes:
1. exhaust must be sloped at least 1/4″ per foot towards the furnace
2. positioning / spacing of the exhaust and intake on the exterior wall is also very important – if you could upload the pictures at my Virtual Help (top navigation bar), I might be able to give you some more info
John Andrews
1 year ago
The heat went out while my wife was in our new home we had built in Norther Wisconsin. The Heating contractor did not answer his phone or call back. Someone else came to check out the system to get it relit and after many attempts, found that the flue where exhaust gases vent to the outside was right next to the air intake of the furnace and that had iced up because of the intake of the moist exhaust from the flue.
What should we do?
admin checkthishouse.com
1 year ago
Some jurisdictions permit sharing of a single chimney flue with multiple appliances or fireplaces, so I would start asking at your local building department. If approved, you have to compare the fireplace manufacturer venting requirements (type of a pipe, min height, size, combustion air requirements) with your current WH vent flue pipe. Every time you connect more than one appliance into the same chimney flue, you’re increasing your chances for back-drafting, so going with properly installed separate flues (of course more expensive) would be safer and easier to control. Another option is to use a direct vent fireplace (venting through the side wall of your property), or even ventless, but all of the options should be checked first with your local jurisdiction.
Casey
1 year ago
I have a natural gas water heater on the first floor that is vented up through the roof. I want to add a vented gas fireplace to the first floor. Is it safe to vent it to the water heaters vent?
admin checkthishouse.com
1 year ago
Hi Craig,
The chimney guys are correct, you need a new, proper size liner for the chimney. It appears that your current flue is oversized, and cooler exhaust gases from the new 80% furnace condensate on the chimney interior walls. No, you can not vent through the sill plate unless it’s a direct vent type furnace, or 90+ condensing type.
Craig
1 year ago
In the last mo I have replaced a 30 y/o furnace w/a 80% furnace. Everything seems to be perfect except I am now getting water puddles at the base of my flue in my basement which I never had before. I have talked to 2 chimney cont. Both told me the added efficency in the old flue is creating a condesate problem for my old flue. I am told I need a insert for my flue from top to bottom. Nothing else is vented in flue, elec water heater. Can I just vent directly from furnace through sill plate like clothes dryer, and what material to use?
admin checkthishouse.com
1 year ago
There are different PVC pipes designed for different types of applications. But in general it is the same PVC pipe used in plumbing and HVAC. With the condensing type furnace exhaust gases temperature being usually under 130F, PVC pipe temp rating around 150F is sufficient. However, as always in such situations, you should follow manufacturer requirements for your furnace or local if it supersedes the above (some might require CPVC with 200F+rating). The following are general requirements – Vent system and combustion air supply components of the high efficiency furnace must be constructed of schedule 40 PVC, PVC-DWV, SDR26, SDR 21 or ABS plastic pipe, fittings, sealants, and installation procedures that conform to the following ANSI/ASTM standards:
PVC ASTM D-1785
SDR26, SDR21 ASTM D-2241
PVC-DWV ASTM D-2665
PVC-DWV Cellular Core ASTM F-891
PVC Primer And Solvent Cement ASTM D-2564
ABS Pipe And Fittings ASTM D-2235
Procedure For Cementing Joints ASTM D-2855
Steve
1 year ago
What is the difference between the PVC piping used in high efficiency furnace flues and that used for plumbing? Would it be o.k. to replace a faulty 2″ PVC furnace flue in a 92 AFUE sealed combusion furnace (Ruud achiever) with 2″ schedule 40 PVC designated for plumbing? The ASTM ratings are different, but I don’t know what that means. Thanks.
admin checkthishouse.com
1 year ago
Hi Phil,
There are two types of vent pipes used for natural draft water heaters – single and double wall. Both of them require 1/4″ per foot pitch between the WH and a chimney flue connection (always going up towards the chimney). For the single wall pipe you need at lest 6″ clearance from framing and other combustibles, and max horizontal run must be smaller or equal to 75% of total vertical height. All joints fastened with screws and properly supported. Double wall pipe (B-vent) requires 1″ clearance, and you can run it horizontally up to 100% of your vertical pipe – don’t use screws on this one except for the draft hood connection (it has special locks at each end) – if it is concealed inside the wall / ceiling – you have to use double wall type vent. Keep the number of offsets and bends (S-bend?) to minimum because each one lowers capacity of your chimney. Other option is going through the side wall with an induced draft / PVC vent water heater.
Phil
1 year ago
I have a gas water heater located in a corner of my basement in Georgia. The vent goes out the top of the WH into a short S bend (8″)and then up through the first and second floors and out the roof. The WH is badly located for room renovations and I would like to move it about 15 feet into another section/corner of the basement. Utilizing the same vent is it permitted to run a horizontal(slightly elevated along the distance) vent tube along the ceiling rafters in the basement over to the existing vent port?
v/r
Phil
admin checkthishouse.com
1 year ago
I don’t think it would, but it might become and issue if such installation is not permitted in your area (flue inside the flue used by other appliance), and you offer your house for sale. Also, does your chimney flue has an offset? Single flexible liner could partially block the flue in such design, and two liners will provide dedicated path for the exhaust gases. Just a thought.
Alan
1 year ago
Thanks for your comments,
It would seem to me that the size of the duct leaving the fuel oil furnace technically would be the minimum flue size required going up the chimney. Is that poor logic? If my logic is correct, then I have plenty of capacity for two flues in my existing.
Good point on the sulfuric acids from the fuel oil furnace. My goal is to virtually eliminate the use of my fuel oil furnace….only using that for an emergency (or long-weekend-away) back-up. If that is the case, and I’m only using the fuel-oil furnace the equivalence of a couple days per year, is that going to be enough to deteriorate the new flex flue?
Again, I thank you for your help!!
Alan
admin checkthishouse.com
1 year ago
Thanks for stopping by,
. Good luck!
A couple of things I would consider: by inserting a flexible duct into the oil furnace flue you’re downsizing it. If it was designed for venting your oil furnace only, eliminating several inches of its cross-section will compromise proper draft. It would definitely make sense to properly calculate your chimney flue dimensions requirement for both appliances, try http://www.csia.org to get a professional. If it is too small for 2 appliances, you’ll need an external chimney for one of them. If it’s big enough to vent both appliances – install two separate stainless steel flues (unless otherwise specified by the manufacturer) in that one large flue. With new boiler flue only, you’re exposing its exterior surface to sulpheric acids contained in oil furnace exhaust. Also… your local code enforcement division may have some different opinions
Alan
1 year ago
I’m glad I stumbled upon this website. I have an older home with a fairly large chimney. The chimney has two clay-tile-lined flues. One flue was for the fireplace in the kitchen and the other is ventilating my fuel oil furnace. I am considering installing a wood gasification boiler in the basement. It would be very easy for me to connect the flue from my wood boiler into the flue that the oil furnace uses. I’ve read, and been reminded on this site that the same flue shouldn’t be used for disimilar appliances. This flue however is big enough that I could drop a flexible duct down through the top and connect directly to my boiler. Is it “legal” then to still allow my fuel oil furnace to use the flue that my new flue is encased by, or do I need to have an insert installed for both appliances in the same flue? Thanks so much!!
admin checkthishouse.com
1 year ago
Hi Johnny,
I wouldn’t do anything without contacting a local Certified Chimney Sweep (www.csia.org), just to make sure that your other two flues are in a good shape, and to ensure that whatever you’re doing complies with a local code. Since you can vent multiple appliances into the same chimney for as long as different types of fuel haven’t been mixed / you’re using separate flues for wood burning, oil and gas, relining of the original firepalce chimney (your new insert would most likely require class “A” chimney which are designed to withstand a 2100 degree chimney fire for 10 minutes) might be possible. The height of all flues might need to changed so the house negative pressure will not pull the smoke from one flue down into another located right next to it – please let me know how this ended,
Thanks
Johnny
1 year ago
Hi. I have a chimney with multiple flue pipes running through it. There is one from a forced air oil furnace and one flue from a natural gas water heater. I want to know if it is safe to run a third separate flue pipe for a wood stove fireplace insert in the same chimney. Ive heard this can be a fire hazard because of potentially combustible gases in the exhaust of the natural gas water heater and the oil furnace. Does anyone know anything about this. I would very much like to use the woodstove this winter as it is a cheap source of heat. Thanks.
admin checkthishouse.com
1 year ago
Hi William, I’d like to help, but would need a little more information. If that stain is under or next to the PVC flues, it might have nothing to do with a leaking water pipe. I’m not sure if those PVC flues are from the furnace or the water heater you’re talking about, but PVC flues sections are jointed together with PVC cement, which has a tendency to deteriorate when exposed to acidic liquid condensate / acidic exhaust gases that are produced during high efficiency furnace or water heater operation. The acid just leaks through the joint and might be dripping onto your drywall sheet. If the stain looks dark, there’s a chance that you already have some mold growing on the other side of the drywall. Other possibility is an exterior wall or roof flashing around those PVC flues … rain water might be just running along the pipe exterior if there are some gaps around penetration. So first check exterior (those PVC flues should be sloped towards the appliance at at least 1/4″ per foot) for any gaps around penetrations, and than I would open the drywall, to ensure that you don’t already have some mold colony growing, and if it is leaking joint on the PVC pipe, it should be re-glued, or more likely replaced with a new one (silicone or applying PVC cement on surface will not work) … or it might be a leaking water pipe
you can go to Virtual Help and send me some pictures
William copperleafacres.com
1 year ago
Hi,I have a gas heater that was added at some point into our 100+ year old farm house. I’ve noticed that there is a spot where water is leaking down through the drywall where the two PCV flues travel. My guess is this indicates a leak in the pipe? It’s only a little moister but is leaving a black spot on the drywall.
admin checkthishouse.com
1 year ago
Hello David, as long as you have two separate and properly sized / installed flues (make sure that you use proper type of material, especially for the wood burning stove flue, which would most likely be a stainless steel pipe ) within the same chimney cavity, you should have not problem. Building and safety codes only forbid venting different fuel type appliances into the same flue. You also have to remember that for the wood burning stove your chimney should extend 2 feet above anything within 10 feet or 3 feet above roof peak (regular furnace chimney might be sometimes shorter). Running both of the appliances at the same time (since the wood stove would produce much more heat) will most likely improve the furnace flue draft, but with a properly sized furnace flue, there’s no such need / don’t burn wood just to increase the flue temperature. Re-venting through the side wall (I understand that you currently have a natural draft furnace) assuming that your jurisdiction has nothing against it, could be done. Your furnace (like you mentioned) would have to be retrofitted with a proper size / type induced draft motor, and this is critical for your own safety. I would start from calling the furnace manufacturer and if they and locals approve it, hire a licensed HVAC contractor to do it. In Illinois this is much easier – it’s simply not permitted …
David
1 year ago
I have a 78% gas furnace in my basement venting up my existing chimney. I would like to use the chimney to also vent (on a seperate vent line) a wood stove insert. Both flues would occupy the same chimney cavity. Would the heat from the wood stove negatively effect the draft from the gas furnace? If anything would it not keep them hotter and insure up flow?I am going to consult a local professional, i’m just curious as to if it even is feasible. Secondly if i need to re-vent my furnace, is it possible to side vent a 78% gas furnace with a blower connected to the furnace switch?
admin checkthishouse.com
2 years ago
Hi Corry, it’s slightly beyond house maintenance advice
There are some basic requirements that apply to some high efficiency appliances utilizing exterior intake and exhaust (there are still various types and brands that allow air combustion from interior of the house … and the following would not apply). Those requirements are pretty much based on fundamental laws of physics – because hot air is less dense than cold air, it rises naturally (that’s rather visual explanation … actually cold air replaces warm air …), anyway, exhaust should never be located lower than intake and its opening should be within 12″-24″ from the intake opening (those numbers might slightly vary between the manufacturers). Not less than 12″ because exhaust gases are not suitable for being reused as combustion air and could be sucked back in, and not more than 24″ because it would be out of so called atmospheric pressure zone (area within 12″-24″) – flue gases discharged through the exhaust pipe create this zone, and help admit combustion air into the intake pipe. As far as terminations being the same length, I’m not sure if I understand … the vent and intake systems should have the same number of elbows, and approximately the same length of straight sections, but exterior terminations of both, as long as within the zone and within other manufacturer requirements (distance from the wall, from the ground, openings, etc.) don’t have to be the same length – is that from a particular manufacturer?
corry
2 years ago
So why do high efficency appliances need to have the intake and exhaust vents installed so the terminations are the same length and so close to one another? I have not had this question answered yet and am curious. Please advise…Cor