Questions about my induced draft WH venting

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tollerplumbing

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I bought a 6 year old house with a State Select PR650XCVIT with a 2" vent, and have a few questions about the installation.

1) It say the termination must be a 2" T or a 3" 45 elbow. Mine comes out the wall, has a 45 elbow and a foot of 2" pipe. So it is not right, but it is hard to see why it matters. Does it?
2) It says to be a minimum of 3' from an inside corner. Mine is 4". Why does that matter?
3) I have 1' of 3" pipe, a 3" 90, a 3-2" reducer, 1 2" 90 elbow, 4 2" 45 elbows, and 20' of pipe. The maximum pipe is 35', each 2" 45 counts as 2.5', each 2" 90 counts as 5' and a 90 counts as 2.5'. So I figure it is 2.5' too long. 20+(7*2.5)
It seems to come out pretty vigorously; is it likely to be a problem?
4) Can I reduce the effective length by increasing some of the pipe from 3" to 2"? I can move the 3" to 2" reducer about 8' further down, and change a 90 and a 45 from 2" to 3". I can't change much more because it isn't very accessible.
5) On the outside there is a 2" 45 and 2' of pipe. It would be easy to put a 2-3" reducer there and change the pipe and the elbow to 3". Is that okay?
6) If #4 and/or #5 are okay, can I extend the outside pipe to get it beyond the inside corner? It says the termination must be as close to the house as possible, but can I make it longer if I insulate it?
 
Go with #4. Using more 3" will help reduce pressure loss in the vent piping. The reason on not putting the vent near an inside corner is related to winds and wind pressure reducing the vent capacity. It really depends on prevailing wind direction and it may not be a problem at your house. Ideally your winds should be about 90 degrees or more away from the corner....

I would NOT extend the vent further from the house. I would also leave the 2" vent termination alone. The 2" vent will have a higher velocity which helps overcome any pressure issues with the vent being in the inside corner.

If the prevailing winds are blowing to the inside corner (lets hope not), You might try using a Tee on the end. Otherwise put a 3" elbow and a few feet of pipe to get it away from the corner.
 
Beni said:
Go with #4. Using more 3" will help reduce pressure loss in the vent piping. The reason on not putting the vent near an inside corner is related to winds and wind pressure reducing the vent capacity. It really depends on prevailing wind direction and it may not be a problem at your house. Ideally your winds should be about 90 degrees or more away from the corner....
Click to expand...
The wind is almost alway from the west. The vent points south, coming out of a south wall. The inside corner is just east of the vent, so the wind would pretty well blow sideways on the vent. I hope that is clear.
I asked State about the wall and the refused to explain it.
I would NOT extend the vent further from the house. I would also leave the 2" vent termination alone. The 2" vent will have a higher velocity which helps overcome any pressure issues with the vent being in the inside corner.

If the prevailing winds are blowing to the inside corner (lets hope not), You might try using a Tee on the end. Otherwise put a 3" elbow and a few feet of pipe to get it away from the corner.
Click to expand...

I am confused here. You said not to extend the vent (which State told me also), but you also say to put on a 3" elbow and a few feet of pipe. Are you saying I should not extend 2" pipe, but putting some 3" after the 2" is okay?

I appreciate the help.
 
Sounds like the wind is blowing into the side wall from the west. Not so nice. I think the vent being 4" from the corner is not really going to work safely. The dynamic wind pressure near the side wall with high winds could exceed the exhaust gas pressure, which could allow exhaust gases to back up at the burner.

By extending, I mean extending away from the side wall along the house 3 feet. Using 3" pipe helps keep the total developed length within states blower static pressure limitations. Then put a 90 ell on the discharge pointing down. A tee would work too, actually better.

The danger of extending it out away from the house is that the fumes could be blown back into the house, via a window/ door. The intent is for the hot fumes to rise as quickly as possible. Though in thinking about it, if your only 4" from the corner, going straight out along the east wall and putting a tee in the line might be better. Need to make sure the vent is still away from windows / doors.
 
tollerplumbing said:
I bought a 6 year old house with a State Select PR650XCVIT with a 2" vent, and have a few questions about the installation.

1) It say the termination must be a 2" T or a 3" 45 elbow. Mine comes out the wall, has a 45 elbow and a foot of 2" pipe. So it is not right, but it is hard to see why it matters. Does it?
2) It says to be a minimum of 3' from an inside corner. Mine is 4". Why does that matter?
3) I have 1' of 3" pipe, a 3" 90, a 3-2" reducer, 1 2" 90 elbow, 4 2" 45 elbows, and 20' of pipe. The maximum pipe is 35', each 2" 45 counts as 2.5', each 2" 90 counts as 5' and a 90 counts as 2.5'. So I figure it is 2.5' too long. 20+(7*2.5)
It seems to come out pretty vigorously; is it likely to be a problem?
4) Can I reduce the effective length by increasing some of the pipe from 3" to 2"? I can move the 3" to 2" reducer about 8' further down, and change a 90 and a 45 from 2" to 3". I can't change much more because it isn't very accessible.
5) On the outside there is a 2" 45 and 2' of pipe. It would be easy to put a 2-3" reducer there and change the pipe and the elbow to 3". Is that okay?
6) If #4 and/or #5 are okay, can I extend the outside pipe to get it beyond the inside corner? It says the termination must be as close to the house as possible, but can I make it longer if I insulate it?
Click to expand...

By your numbers the venting is improperly installed . The reason manufacturer has installation instruction is for your safety and premature water heater failure. I would recommend having a professional plumber come out to inspect water heater & venting and correct anything that needs it. (carbon monoxide is a silent killer)
 
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