Navien NPE horizontal venting pitch?

[EIR]

I notice navien doesn't spec a specific direction if any to pitch the venting on a sidewall/horizontal installation. I know some other manufacturers do.

Is there a definitive answer?

If it doesn't matter, does position of any vertical rise in the horizontal run then matter? What if you need to snorkel after exiting the building envelope to meet distance above snow level?

They seem pretty vague with venting requirements for their condensing water heaters.

Are the venting requirements that lax where you can pretty much just do whatever as long as it meets the overall calculated length and elbow requirements?

I am used requirements for non condensing units, wood burning appliances, etc that require much more in order to be deemed safe and acceptable.

 

[Dana]

Since it's a forced draft appliance, it doesn't need the slope to guarantee the direction of draft the way atmospheric drafted burners do.

But slope can be important for managing flue condensate.

In cold/very cold areas you want it pitched to drain toward the unit, not toward the outdoors, or you can end up with ice/frost from frozen condensate blocking the vent during extended cold snaps. In more temperate eastern/coastal PA it doesn't matter as much as it does at higher elevation in the mountainous parts of the state.

You DEFINiTELY want it to terminate above the historical snow drift depths. In any installation where you have to snorkel up, the horizontals preceding it must drain toward the unit or you'll risk creating an unintended P-trap blocking the venting.

 

[Sponsor]

 

[EIR]

Since it's a forced draft appliance, it doesn't need the slope to guarantee the direction of draft the way atmospheric drafted burners do.

But slope can be important for managing flue condensate.

In cold/very cold areas you want it pitched to drain toward the unit, not toward the outdoors, or you can end up with ice/frost from frozen condensate blocking the vent during extended cold snaps. In more temperate eastern/coastal PA it doesn't matter as much as it does at higher elevation in the mountainous parts of the state.

You DEFINiTELY want it to terminate above the historical snow drift depths. In any installation where you have to snorkel up, the horizontals preceding it must drain toward the unit or you'll risk creating an unintended P-trap blocking the venting.

Thanks. I spoke with navien tech earlier today prior to seeing this. They confirmed the exhaust should pitch to the unit the standard 1/4" per foot. The tech said the intake didn't matter...I still find that odd.

I'm in NJ across the bridge from Philly. I can't seem to get a consensus on termination height. NJ code says 12" minimum above grade. Install manual says 12" above grade or heighest anticipated snow level.

Due to space constraints I could only mount my mini split's outdoor unit on the wall 18" above grade to the bottom of the unit. So I know when we get that occasional big snow event I'll have to keep it clear.
The intended vent location is similar at 18" above grade at the moment. I have read conflicting elevation recommendations for NJ. Some say average 6" typical snow level for a single storm. Personally even in my history I've seen the big storms dump over 24" not including drifts. Historic snow averages don't seem to give an accurate picture to antipated snow levels of a single event.

I'm going to call the building Dept tomorrow and ask. Seems like it's a grey area that is left to the whims and fancies of the AHJ.

The house is on a deep crawlspace (conditioned) and I'd really like to avoid abandoning the use of a low profile vent kit and snorkel up with exposed PVC.

If it was a boiler or furance I'd snorkel it way up just because I'd never want to wake up with no heat on in the house.
On demand hot water is less critical and the snow events in my area of significant accumulation seem to be once a decade.

I'll find out what the town wants but would prefer to keep some aesthetics even if it means me having to keep vigilant on that rare instance.

 

[Dana]

The intake doesn't matter because the number of times the dew point of the outdoor air would be above the temperature of the (room temp) intake vent would be pretty rare & brief. In short, there will (almost) never be condensation occurring on the intake vent, unlike the exhuast vent full of extremely H2O-rich natural gas exhaust that has a dew point well north of room temp, no matter how much condensation oocured on the heat exchangers.

Snow covering the vent won't instantly keep it from running, but it does raise the potential of pressurizing the vent to where exhaust leaks into the house. As long as 18" meets local code and you're religious about checking that it's clear after every storm it's fine.

 

[EIR]

I contacted the building department. No one answered during normal hours. I shot them an email.

 

[Jadnashua]

The orientation of the building, shrubs, and other things can radically affect how deep the snow will get right near the foundation that could vary significantly, mostly with wind direction. Even how well the foundation is insulated will make a huge difference.

FWIW, when my boiler was installed, they did not orient the exhaust properly and on a really cold spell, it iced over the intake and shut the system down (not nice on a really cold spell!). It was clearly shown the correct way in the installation manual, and they came back and fixed it for free, but it could have been really messy if I'd not been home and things all froze up before I could get home to notice!