Water heater exhaust pipe question

Yesterday, to save the install charges, friend and I put in a water heater in the basement of my house. The new heater is 1 inch higher than the old one. Hooked it up okay, doesn't look like anything is leaking. Used the existing exhaust pipe that goes to the chimney. Instructions say the pipe needs to slant 1/4 inch per foot downward from the chimney to the water heater. Problem now is, since the new heater is taller, the pipe is just about on a level run from the heater to the chimney. Questions: Is it okay to have the pipe running level? What harm, if any will arise in either the operation of the system, or the environment of the house? Will the heat not rise efficiently? Etc. Thanks for your help, Bill
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It is NOT ok! The rise from heater to stack must be 1/4" to 1/2" per foot to ensurecombustion by-products are exhausted. Take it apart, get some tin snips and cut something, usually the pipe that goes to the roof. Don't delay! This is important.

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Put in a good Co detector, and fix the exaust pipe.
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The slope on the pipe is so the condensate (water vapor) that is contained in the flue gas from the heater will drain back toward the heater and not lay in the vent pipe and rust it out. You should use double wall type "B" vent pipe in any unconditioned space (un-heated) to minimize the condensation effect.

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Hi Dana, hope you are having a nice day
On 28-Sep-04 At About 13:08:19, Dana wrote to All Subject: Re: Water heater exhaust pipe question
D> The slope on the pipe is so the condensate (water vapor) that is D> contained in the flue gas from the heater will drain back toward the D> heater and not lay in the vent pipe and rust it out. You should D> use double wall type "B" vent pipe in any unconditioned space D> (un-heated) to minimize the condensation effect.
Actually the first answer was correct. it is to allow for proper venting. if you have condensate in the flue you have a major problem.
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I don't believe any slight slope such as 1/4" per foot in a horizontal flue ssection will have any detectable effect on the venting, certainly not in a short run. Draft is almost entirely a function of the vertical section(s) of the vent and the flue gas temperature rise. Flue condensate, particularly during startup in cold weather is not uncommon although definitely not present during continuing operation of a proper vent. Don Young

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Hi Don, hope you are having a nice day
On 28-Sep-04 At About 12:22:41, Don Young wrote to All Subject: Re: Water heater exhaust pipe question
DY> I don't believe any slight slope such as 1/4" per foot in a DY> horizontal flue ssection will have any detectable effect on the DY> venting, certainly not in a short run. Draft is almost entirely a DY> function of the vertical section(s) of the vent and the flue gas DY> temperature rise. Flue condensate, particularly during startup in DY> cold weather is not uncommon although definitely not present during DY> continuing operation of a proper vent. Don Young "HvacTech2"
Sorry but you are wrong here. the slope is to allow for venting and has nothing to do with condensation as there is none. without that slope the flue gases would enter the house as they would spill out of the diverter. the flue gases will not vent downhill and need that slope to allow them to vent up the chimney.
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Around here, the combustion products from natural gas always have moisture as a component. One of the ways I test for bad venting or back drafting is to hold my eye glasses near the draft hood. If they fog up, it's back washing and there may be a venting problem. Dana

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Most likely you need to shorten the pipe that rises. The sharper the rise the better the draw.
To test for proper venting. With the main burner burning stick a burning match at the edge of the draft hood and slowly move it under it. If you have a proper draft the match will continue to burn and draw toward the chimney. If it blows out, you have a serious problem that should be corrected immediately. CO kills. Do it right or call a pro.
best wishes
Colbyt
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The 1/4 inch per foot slope will not measureably change the venting. That is mainly a function of the vertical part of the pipe. It is important, however, to provide drainage to prevent accumulation of water from condensation or from rain finding its way into the pipe. Accumulated water will rust out the pipe very quickly. Fix it. Don Young

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