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dtontarski

Direct Vent Furnace Venting Downhill

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I have never seen a direct vent furnace venting downhill like this. I reviewed the Ruud Installation Manual and didn't find where they specifically ruled this out, but in reviewing a few other direct vent appliance manuals, I saw wording such as "vent piping cannot under any circumstances be run downhill".

And oh yes..this is installed in a bedroom closet with louvered doors right next to a CAT 1 water heater and as vented the furnace is not obtaining all combustion air from the exterior.

Does anyone know if a downhill vent run like this is ever acceptable?

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You can't have a hot water heater in a bedroom closet.

The furnace seems to be getting it's combustion air from the outdoors by the looks of the piping.

I see you've looked through the installations instructions - on the job site or via the internet? If you've found them over the net do you have a link? I'd like to see them.

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Hi Terry -

Yes, I wrote up the water heater in the bedroom closet issue, and I found the manual online for this furnace. Like I said, Ruud didn't have a diagram that illustrated a downhill vent install, but then again, I did not find where they specifically spelled it out that is wasn't allowed like some of the other manufacturers.

Have you (anyone?) ever seen a downhill vent install on a direct vent appliance?

I've already recommended further evaluation by an HVAC professional on this entire set-up, I'm just trying to learn more about this.

Thanks.

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Have you (anyone?) ever seen a downhill vent install on a direct vent appliance?

I haven't. However the more I think things are standard the more I find out that they aren't

If you go to "new files" on this web site I u/l a Trane installation manual not to long ago. I tried to u/l the Carrier manual as well but it was over the u/l size limit.

Do you have a link for the manual?

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All Ruud installation instructions I have read, including the two I have here in a file state:

"All horizontal piping must slope upward a minimum of 1/4 inch per foot of run so that condensate drains toward the furnace".

In your pictured installation, I am assuming the vent that extends through the floor below the furnace will transition to horizontal before exiting a wall. That section of horizontal pipe can't possibly ensure "that condensate drains toward the furnace".

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Thanks - it appears that the 1/4" per ft. pitch upwards is pretty standard, and without any other mention of pitch, that if any section of the exhaust vent does not have that pitch...then I can justify calling it out.

I guess I just like having things spelled out, and because this was called out on another manufacturer's site, it made me wonder about it.

But like Terry says....the more you think (assume) things are standard, the more you find out that they are not.

Other: This vent did run horizontally within a crawlspace....the access to which was entirely obstructed by the current owner's stuff....I volunteered to come back and inspect the crawlspace once the bobcat cleared me a path.

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I had an issue a couple of years ago where a bedroom closet contained a gas fired water heater.

I called it out in the report, later got a call from my client who was told by the local code official (Wildwood NJ) that the water heater can be in the bedroom closet if it has a fan assisted direct vent out the side of the house.

The water heater had a double walled "concentric" type vent that pulled combustion air from the exterior.

Funny thing is they also said the closet door had to be louvered? Why, if combustion air is supplied from the exterior?

Nobody seemed to care however that the windows didn't meet egress requirements…go figure?

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I wouldn't worry about the vent going up or down, as long as it does one of the two and condensation doesn't discharge to an objectionable location. The manufacturers just don't want there to be a place in the vent where the condensate will collect.

- Reuben

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Funny thing is they also said the closet door had to be louvered? Why, if combustion air is supplied from the exterior?

Perhaps because of ventilation air requirements. Water heaters have both combustion air and ventilation air requirements.

Marc

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Good point Marc, I may have misspoke. Perhaps I met combustion air/dilution air. No air was "scavenged" from the utility room.

I personally love this type of venting, no conditioned air involved at all.

I'll look for some pictures...

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From the 2009 NJ IRC- M2005.2-

Fuel-fired water heaters shall not be installed in a room used as a storage closet. Water heaters located in a bedroom or bathroom shall be installed in a sealed enclosure so that combustion air will not be taken from the living space. Installation of a direct-vent water heater with in an enclosure is not required.

G2406.2- (Exception 5)

This basically states a direct vent appliance installed in a bedroom closet needs a solid, weather-stripped door with a self closer and all combustion air must be obtained from the outside..

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All good info. on the closet installation - I covered this in my report.

Question: Would it have been the responsibility of the furnace installer (2009) to address these issues when he installed the furnace? (same guy installed the CAT I water heater in 2002)

Other: I'm still looking for more opinions regarding the downhill vertical run of the exhaust vent. Does anyone have any documentation spelling out that this is not allowed? I've only seen this specifically spelled out as not allowed in a direct vent water heater installation manual.

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G2406.2- (Exception 5)

This basically states a direct vent appliance installed in a bedroom closet needs a solid, weather-stripped door with a self closer and all combustion air must be obtained from the outside..

I don't have the 2009 IRC, but in the 2006 IRC it says you can have an appliance located in one of those prohibited locations if the installation complies with one of the following, and then goes on to list the exceptions.

The first exception listed is a direct vent appliance. This means that if you have a direct vent appliance, you don't need to do anything special. You can put it wherever you want, and you don't need to mess around with weather stripped doors and all that. Those requirements are only for non-direct vent appliances.

Did they change this in the 2009 version?

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Question: Would it have been the responsibility of the furnace installer (2009) to address these issues when he installed the furnace? (same guy installed the CAT I water heater in 2002)

IMO, no. If the furnace guy is being hired to install the furnace, let him install the furnace. He's not there to fix every other defect at the house, even if the defect is very closely related to what he's doing.

Ultimately, it would be up to the AHJ to decide. The AHJ needs to have a bit of a balance in what they decide to make contractors do; while it would be nice for the safety of the occupants for the AHJ to require correction of all installation defects they see that relate to the trade they're inspecting for, they're overstepping their bounds if they do this.

When AHJs start making contractors fix other stuff that isn't directly related to the work that's being performed, contractors will start becoming reluctant to pull permits. A good AHJ will recognize this and not overstep their boundaries.

- Reuben

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Other: I'm still looking for more opinions regarding the downhill vertical run of the exhaust vent. Does anyone have any documentation spelling out that this is not allowed? I've only seen this specifically spelled out as not allowed in a direct vent water heater installation manual.

If you read the installation instructions and this wasn't prohibited, why are you worried? I don't think anyone's opinion here makes any difference if the manufacturer doesn't prohibit the installation. Are you thinking the furnace is going to malfunction or create an unsafe condition? If so, call Ruud and ask 'em.

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From the 2009 NJ IRC- M2005.2-

Fuel-fired water heaters shall not be installed in a room used as a storage closet. Water heaters located in a bedroom or bathroom shall be installed in a sealed enclosure so that combustion air will not be taken from the living space. Installation of a direct-vent water heater with in an enclosure is not required.

G2406.2- (Exception 5)

This basically states a direct vent appliance installed in a bedroom or bathroom needs a solid, weather-stripped door with a self closer and all combustion air must be obtained from the outside..

That's not how I interpret that particular cite. You need a solid, weather stripped door for a natural draft WH installed in a bedroom closet. You don't need it for a direct vent WH in the same location. Can't put either in a storage closet.

Marc

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Marc;

I agree; I was writing about a natural draft WH and thinking about a direct vent system.

See that above attached NJ IRC sections.

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That's not how I interpret that particular cite. You need a solid, weather stripped door for a natural draft WH installed in a bedroom closet. You don't need it for a direct vent WH in the same location. Can't put either in a storage closet.

Marc

There are natural draft water heaters that have thru-floor ducting-all combustion air is drawn from outside. Closet locations are closed with a panel, sans weather stripping. Of course I'm referring to HUD Code country.

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That's not how I interpret that particular cite. You need a solid, weather stripped door for a natural draft WH installed in a bedroom closet. You don't need it for a direct vent WH in the same location. Can't put either in a storage closet.

Marc

There are natural draft water heaters that have thru-floor ducting-all combustion air is drawn from outside. Closet locations are closed with a panel, sans weather stripping. Of course I'm referring to HUD Code country.

If it takes all of it's combustion air from the exterior, it's a direct vent water heater.

- Reuben

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My post got off track, but I guess that was my fault for providing too much information in my original post. (good dialogue though)

Here's an update:

Ruud was no help, but I was able to speak to someone at Rheem (Arkansas), and he verified that this was wrong and cited their 1/4" per ft. pitch upwards rule for all horizontal pipes as the documentation for citing this as disallowed. (Like Bill Kibbel pointed out)

And.....he requested photos of the install, and had already spoken to someone else in the organization about this.

Perhaps someday soon we might see the Ruud/Rheem install manuals call this out more clearly, as some other manufacturers of direct vent appliances are currently doing.

(kind of like McDonalds having to tell people their coffee is hot, but who knows it might actually prevent a mishap someday)

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That's not how I interpret that particular cite. You need a solid, weather stripped door for a natural draft WH installed in a bedroom closet. You don't need it for a direct vent WH in the same location. Can't put either in a storage closet.

Marc

There are natural draft water heaters that have thru-floor ducting-all combustion air is drawn from outside. Closet locations are closed with a panel, sans weather stripping. Of course I'm referring to HUD Code country.

If it takes all of it's combustion air from the exterior, it's a direct vent water heater.

- Reuben

No, that's not accurate at all and it's liable to confuse some rookies. You can have an inner room containing appliances with air ducted to that room from the outside; however, unless the appliance is a direct-vent type, even though those appliances get all of their combustion air from the outside via those ducts, it does not make those "direct-vent" appliances.

A "direct" vent appliance is one where the internal components of the appliance, not the room, are sealed off from the air of the space around the appliance. A direct vent appliance either has a separate intake and exhaust vent that both extend from the collar of the appliance all the way to the outside; or it uses a combination intake/exhaust vent. Sometimes you'll see a two pipe that changes to a combi-vent just before it passes out through the sidewall of the building and sometimes the combi-vent extends all the way to the collar of the appliance such as the way Rinnai's PVC exhaust vents are configured for their internal tankless water heaters.

A power-vented water heater, for instance, is not a direct vent appliance unless it gets it's combustion air from outside via an integral intake pipe built into it and its combustion chamber is completely sealed away from the space around it. Some power-vented appliances are configured with integral intake pipes, some aren't.

You can install a Category IV furnace configured as a direct vent appliance in a bedroom; however, if you remove the intake pipe and get your combustion air from the interior, as is allowed by some manufacturers, it is no longer a "direct vent" appliance and is disallowed. In that case, it needs to be moved to an enclosure that's sealed off from the interior and air has to be brought into that room through an exterior wall, from the attic or crawlspace or via ducts that end within 12-inches of the floor or ceiling.

The easiest way to remember when an appliance is a "direct-vent" is to look at how the appliance is configured and ask yourself whether the interior of that appliance uses any of the air from the space around it; if it does, whether that air comes into that space from a vent through an exterior wall or is ducted into that area, it is not a direct-vent appliance.

ONE TEAM - ONE FIGHT!!!

Mike

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That's not how I interpret that particular cite. You need a solid, weather stripped door for a natural draft WH installed in a bedroom closet. You don't need it for a direct vent WH in the same location. Can't put either in a storage closet.

Marc

There are natural draft water heaters that have thru-floor ducting-all combustion air is drawn from outside. Closet locations are closed with a panel, sans weather stripping. Of course I'm referring to HUD Code country.

If it takes all of it's combustion air from the exterior, it's a direct vent water heater.

- Reuben

No, that's not accurate at all and it's liable to confuse some rookies. You can have an inner room containing appliances with air ducted to that room from the outside; however, unless the appliance is a direct-vent type, even though those appliances get all of their combustion air from the outside via those ducts, it does not make those "direct-vent" appliances.

In the situation you're describing, the appliance isn't getting all of it's combustion air from the outside; it's getting it's combustion air from the room it's in.

The definition of a direct-vent appliance, from the 2006 IRC is:

A fuel-burning appliance with a sealed combustion system that draws all air for combustion from the outside atmosphere and discharges all flue gases to the outside atmosphere.

I wrote "If it takes all of it's combustion air from the exterior, it's a direct vent water heater."

How is this not accurate at all?

- Reuben

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Because you can "take all combustion air from outside" via ducts, via holes through an exterior wall, etc., and still not be a direct vent appliance. The key to that definition isn't "takes all air from outside" but "sealed combustion chamber that draws all air for combustion from outside." That's not what you said; you might have meant that, but that's not what you said.

ONE TEAM - ONE FIGHT!!!

Mike

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Because you can "take all combustion air from outside" via ducts, via holes through an exterior wall, etc., and still not be a direct vent appliance. The key to that definition isn't "takes all air from outside" but "sealed combustion chamber that draws all air for combustion from outside." That's not what you said; you might have meant that, but that's not what you said.

Ok... I'll try to choose my words a little more carefully.

- Reuben

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