concentric vent

Ryeguy12

Hi all

The deck that has been recently installed will make it so that i have to notch out decking due to the size of the cone on the concentric vent, the deck is above the pipes, but again the cone is the taller part ( horizontal out side of house). Can i take a 45 degree elbow and shift the cone down towards the ground? or shave a little off the the cone part that will potentially be sticking above decking? that remove maybe 20% of the area of the cone. Thanks for feedback and any other suggestions.

Ryan

Ironman

I assume that your talking about a concentric PVC vent for a gas appliance?

If that's the case, then understand that it's a pipe within a pipe. The inside pipe is the exhaust and the outer pipe is the fresh air intake.

According to code and the manufacturer's instructions, the vent kit cannot be modified except for changing its length before it's glued together.

Also, you cannot vent it under the deck: that's another code violation and it would cause condensate vapor to freeze on the deck creating a hazard.

The vent needs to be extended beyond the deck in accordance with the manufacturer's instructions.

HVACNUT

As Ironman said, what you want to do is against code. If you have the equipment manual, it will show all clearances and what to avoid (inside corners, windows, overhangs etc.)
If you don't have the manual, you can check the make and model number of the appliance and download it.

rbeck

You are right, cannot vent below deck, cannot change vent kit and must terminate 12" above grade or deck. This may even qualify for the 7' above the deck.

Steamhead

Won't have this problem with a chimney-vented cast-iron boiler.

ChrisJ

Steamhead said:

Won't have this problem with a chimney-vented cast-iron boiler.

Won't have this problem with proper planning either regardless of what is used.


What are some ideas to help the OP out?
Can the vent be extended to get past and clear of the deck?

Can the vent be moved to somewhere else on the building?

What code compliant options do they have?

hot_rod

The installation manuals have the most amount of pages dedicated to venting options, there should be a method that works.

I would not modify an assembly like that, for performance and liability issues.

Perhaps a separate vent and intake instead of the concentric kit? That way you could use a 45 to turn down. I'm not a big fan of concentric.

In some cases intake air can be from inside the space, so just one exhaust.

Jack

I have seen this a lot with Rinnai's concentric vents. The issue you will have if you do not extend the vent out past the edge of the deck is recirculation of exhaust gases. The clearances, and this pertains to Rinnai's concentric venting installation instructions only, are 36" to an overhang above the pipe. It is not a combustible issue but again, a recirc of gases problem which I can assure you, you do not want. Convenience of install is way down the list of priorities. IF, the vent is run our past the edge of deck or porch, it has to be graded properly and supported like a kid is going to swing off it...which they will. I recommend sleeving the vent pipe with 6" pvc in that application and hanging it so it cannot move. Also, if you do this, make sure you have the right make-in and properly attach the pipe sections according to the manuf instructions. When properly done and terminated, I am a big fan of concentric. The single hole and pipe exiting the house trims our much better. Not properly done, nothing works.

Jack

ChrisJ said:

Steamhead said:

Won't have this problem with a chimney-vented cast-iron boiler.

Won't have this problem with proper planning either regardless of what is used.


What are some ideas to help the OP out?
Can the vent be extended to get past and clear of the deck?

Can the vent be moved to somewhere else on the building?

What code compliant options do they have?

Chris, every install has to be evaluated by where the equipment is to be located number one, paying close attention to not perpetuating the mistakes of the original low cost bidder, and then that location has to be modified by "how the hell am I going to vent this thing" and sometimes the vent drives the location of the equipment.

Steamie, respectfully as I understand your system presences, if it is a factory built chimney and in good shape, then maybe. If it is a masonry chimney, show me one that meets NFPA 211 and can get past even a Level II inspection. They do not exist. Also, if it is a condensing appliance, which is where the market is going nationally then you are out of luck.

Steamhead

Jack said:

Steamie, respectfully as I understand your system presences, if it is a factory built chimney and in good shape, then maybe. If it is a masonry chimney, show me one that meets NFPA 211 and can get past even a Level II inspection. They do not exist. Also, if it is a condensing appliance, which is where the market is going nationally then you are out of luck.

According to the chimney contractor we use, a properly constructed and lined masonry chimney will meet 211. They routinely line chimneys with stainless steel for us- a method which gives you a flue with no joints to leak.

Once this is done, you have a venting device with zero moving parts. No moving parts means almost no chance of a breakdown. Speaking from the perspective of the guy who gets the after-hours no-heat calls, this is a huge advantage. I like to sleep at night. That's one reason I don't have a condensing boiler in my house.

We have several customers where previous owners abandoned chimneys and installed power venters. At least one of these breaks down every winter. So, by my standards, this was a very poor choice. We encourage these customers to switch back to chimney venting.

Also, condensing equipment is, by its very nature, more complicated and therefore has a greater chance of breaking down. Since the AFUE difference between a typical condensing unit and a good non-condensing unit is maybe 7% (92 vs. 87%) it's easy to see where the increased service the condensing unit needs, as well as its shorter expected life span, will overbalance the small AFUE increase (yes, I know AFUE is far from perfect, but it's all we have at the moment). Factor in the widely-held belief that gas equipment doesn't require regular service- which we all know is bogus- and the cast-iron, non-condensing unit starts to look a lot better.

There will always be those who just have to have the latest stuff, no matter what. But it's not always the best way to go.

Jack

Steamie, I think I would be shy of challenging your choices, knowledge and experience