Code requirements for double pipe side wall terminations

Toller

My furnace stopped working the other night because the inlet iced over.  Looking into it, I think I have a number of code violations that I want to be clear on. 



It is a Trane XP90 80,000 btu unit, 6 years old.  It is vented with 23' of 2" pipe with 4 elbows.  It is 8" under a deck, 11" from a side wall.  I have attached a photo of the termination.



There is a 2010 post by Tim McElwain in which he says typical requirements include:

·        Do not locate vent under decks.



·        Top of vent terminal must be at least 5 feet below eves, soffits, or overhangs. Maximum depth of overhang is 3 feet.



·        Vent terminal must be 6 feet from an inside corner.



Assuming that was code in 2006; I wonder if someone could give me actual citations for these.



I would be grateful for help on this.

Tim McElwain

There is no

specific code on venting high efficiency equipment. The requirements are according to manufacturers instructions. What I posted was a gathering of specs from different manufacturers which I felt were very good and would prevent venting problems with these side wall vents. I would check the Installation and Operations manual for your furnace as it will list venting requirements.

Toller

No code?

Okay, I guess I read something into it.



Trane's "installer's guide" gives a number of minimum-maximum specs, but on these issues  says "Clearance in accordance with local installation codes and the requirements of the gas supplier and the manufacturer's installation instructions"  It does not get more specific.



When you wrote "One of the most difficult and often troublesome aspects of the

new venting when venting out the side of buildings or even through the

roof is vent termination or vent location. When we go to the code books

it gets very detailed for example in the National Fuel gas Code ANSI

Z223.1/NFPA 54 section 12.3.5 for direct vent appliances and concerning

termination of direct vent section 12.9.3."  I thought I had found the code referred to.



This is all very frustrating.

But thanks anyhow



 

pipeking

WHY DO U THINK IT ICED OVER?

when penitrating under a deck i always extend the ca/e past the end of the deck,hanging it from the rafters. but more importantlly i alway point the exhaust straight out and the ca down so it won't back feed. another nono is that your ca/e is in an inside corner.

Tim McElwain

Toller, there are different

rules for termination of "Direct Vent" and "Mechanical Exhausting" for direct vent termination is related to the input of the equipment. For mechanical exhausting it is 4 feet from windows doors or opening etc these are in NFPA 54 National Fuel Gas Code. Your appliance is classified either a Category III or Category IV venting system which all venting is according to manufacturers instructions. I suggest you contact your local Trane rep or contact Trane factory tech services for rules specifically related to your situation.

Toller

I know why it iced over...

Being in a corner under a deck with inadequate separation between the pipes and the vent being inadequately long made it pretty much inevitable.  Really hard to believe it never happened to the previous owner.



I intend on have a chat with the contractor.   I can show him in the Trane installation instructions the minimum separation is 9" and he only did 8", the minimum vent length is 12" and he did 7".  Obviously his install ignored Trane's requirements and is negligent. 

While putting it under the deck and up against the corner is improper, I have nothing to point to.  He will just say that based on 20 years of experience he knows those practices are fine; and without a code or mfg requirement, it is just a judgement call.  He used what is obviously bad judgement, but that is not negligent, like ignoring Trane's requirements is.



I am doubtful Trane would even talk to me, but unless there was something in writing, it just gets back to everything being left to the contractors judgement.



He sent a man out today and increased the vent from 7" to 14".  So far there is no new ice, despite the cold; so it is better.   He also agreed to look into the possibility of extending the vent at least the end of the corner (getting it out completely from the deck would be pushing the allowed  length) but he is not sure if insulated pipe is available. 



Right now my big concern is corrosion.  Clearly exhaust was sucked in, and the heat exchanger isn't designed to accommodate that.  He did a cleaning and inspection 5 months ago as a condition of the sale, and said it was perfect.  Maybe it is and I have no problem; but at the moment I am skeptical.

So far he is being reasonable; but when I mention corrosion I expect to get major pullback.



I just want to be as prepared as possible before I talk to him.

I appreciate the help.

Steve Whitbeck

vent termination

The intake pipe can stay as it is. The exhaust pipe MUST terminate beyond the deck. It must be insulated, and can not terminate under the deck. In very cold weather the exhaust gasses turn to snow and get sucked into the intake and freeze to the inside of the pipe, this builds up untill the pipe is blocked.

You will damage the furnace by sucking up the wet exhaust gasses if You don't fix it.

Henry

Code lets

Gas code lets one terminate under a deck if it is open on three side. The manufacturers instructions will not permit you to extend the vent. But you can extend the combustion air from under the deck to its ledge to be free of icing. Just keep it a foot above normal snow. There is nothing preventing one from extending combustion air inlets along walls or balconies!

Steve Whitbeck

Henry

The inspectors here will NOT let the vent terminate under a deck. And You can extend the vent pipe as long as it doesn't exceed the max length and it must be insulated where it is exposed to freezing temps.

Toller

Can you give me an actual citation for that?

Gas code lets one terminate under a deck if it is open on three side

Can you tell me where that code requirement is?  That would help me a great deal.

The installation instructions for the vent is 12" to 14', however it says that if it must pass through an unheated space the vent must be insulated with armaflex.  They say 1/2", but 1" is available.  Extending the vent from it's current 14" to 36" would get to where the deck is open on three sides.   It would also be within the 50' allowed.  What is wrong with that if it were insulated?  (I am not disagreeing with you, just asking for an explanation.)

Charlie from wmass

Toller you need to pull up your local code

If you let us know where you are maybe we can give you a link to the code that covers your area.

Toller

Local Code

"If you let us know where you are maybe we can give you a link to the code that covers your area"



Ontario County, NYS

While a local code would be best; a link to any code would be helpful.  If one area forbids within 36" of an inside corner, and I am 8", it pretty clearly is inadequate.  It would then be up to the contractor to show that local code is 6" and he is in compliance.

Steve Whitbeck

install manuall

Find the install manual for your furnace - The install manual should show you what the clearances are. manual supersedes the codes. If the manual says you can do something and the codes say no - the install manual is the correct method for that piece of equipment. If the code says you can do something and the manual says no - You can't do it.

Had a venting problem here where the code said I could vent it with so much clearance to the inside corner but the install manual said no - I had to go through the roof. ( high eff. boiler for in floor heat )

The guy installing the furnace used the corner since he could. The install manual and the codes allowed him to be much closer to the corner than my install manual allowed.

Toller

Manual says to observe local code

There are 4 problems:

1) Vent too short per manual

2) Vent and inlet too close per manual

3) Vent and inlet too close to deck

4) Vent and inlet too close to inside corner



For 3&4 the manual says to observe local code.  I am reasonably sure 4" and 10" are too close, but I don't know that. 

How do i find out local code?  The local building inspector is a nice guy, but I am sure he won't know this stuff. (or he would have picked it up originally; it is pretty conspicuous)  Nor do I want to get the installer into any trouble at this time, as I hope to work out an amicable solution.

VictoriaEnergy

... just fix it

"Nor do I want to get the installer into any trouble at this time ,(edit: emphasis added)as I hope to work out an amicable solution."



In my view this is a relatively minor mistake.  5 yards and repeat the 2nd down. No need to call your lawyer or the head of the inspection dept.  Just get it fixed.  Lots of installations meet code and the manufacturer's certified instructions and still don't work. 



All that's needed is to increase the separation of the inlet and exhaust vent to reduce the amount of exhaust getting dragged into the fresh air vent.  My first choice would be to extend the exhaust straight out 12" so the vent extends out from the edge of the deck.  Insulate the extended vent with Armaflex closed cell insulation to keep it from icing. 



The manufacturers don't want too much separation between the vents for more stable and constant flow through the vent system, they do expect a small amount of exhaust recirculation, and it won't harm the furnace.



Make sure the vent is not terminating directly above a sidewalk or driveway as these vents do drip condensate and that can freeze & make a nasty slip hazard.