Chimney Questions

TIA:
My circa 1949 rental house an 18 year old furnace with a flue chimney which appears to be asbestos. It's gray and hard and flat about 3" x 15" and fits inside a wall. At some time it was moved, but not the whole thing, just the segment between the attic and the basement, to accomodate a wall move on the ground (only) floor. I guess they didn't want to re-do the roof so there's a "Z" in the attic, about 2' of horizontal run of same material, with glue and sheet metal at the two 90 joints. I think they also cut that horizontal piece out of the entire run of chimney, as it hangs from joists in the crawl space, and is flush with the roof deck on top.
1. Tentant smelled gas in the room where the chimney runs up the wall. 2. Gas Company measured some CO in the crawl space and made me shut off the furnace, saying "there might be a crack in the heat exchange" 3. HVAC guy wants to sell me a new furnace, since "there might be a crack in the heat exchange" (Didn't verify any crack) 4. Where the furnace vent tied into the asbestos was very loose, there was a " gap all around it, looked like a good place for CO to get out. I sealed it real good at that point. 5. Gas Company came back and measured 0 PPM CO in crawl space. (NONE!) but then they measured 10 PPM in the house, and turned off the furnace. 6. I went on the roof to see if the chimney was clogged, and at 2' I hit something hard 7. I went in the attic and found the 2 right angles, and decided to go get drunk. (Just kidding about that last part.)
(furnace is 18 years old but works)
Asbestos and age aside;
1. Is it conventional or kosher to have a horizontal run in the flue vent for the furnace/water heater? 2. Where the chimney is flush with the roof, it's not sealed, should the chimney extend above the roof line? 3. Is there any kosher way to run the flue inside a wall nowadays? 4. I know I can vent a 90% or better furnace out the side with PVC, can I vent the water heater out the side, legally? 5. What am I forgetting?
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Maybe Yes Not really, you probably need to box it in somewhere following appropriate code. Yes, there are hot water heaters that can be side vented.
If you go with high efficiency furnace and hot water heater they can both be vented out the side. They will be more expensive equipment but depending on the location you may make up the difference in the savings on having a new flue run to the roof. Plus there will be a 10% or so gas savings. If your tenant is paying for the gas then maybe you don't care so much about that. Otherwise look for a closet that you can box a corner in that's close to where the equipment is and run a new metal flue to the roof. You are allowed some horizontal run in teh basement but it will need to be in the vicinity. You will probably need to just go straight out the roof with the new flue and patch the original hole in the roof. If the house is single story with a basement then that might not be so bad.
Don't let anyone try to talk you into removing that asbestos stuff. There are lots of specialized procedures for remove asbestos these days and it is usually pricey. Closing it off and leaving it in place is in most cases perfectly legal. It's only when you start messing with it that all the new handling rules kick in.

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Ooops, I forgot. You could also switch to electric for the hot water heater if the house has 200 amp service. If it's still a 100 amp service that might not be an option.

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A chimney should not be flush with the roof or it may not draw, an uncovered chimney could have dead animals and junk in it that can block the draft and leak combustion gasses back in
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ransley wrote:

The flue is required under the UMC to be 2 feet [24"] higher than any roof peak or obstruction closer than 10' around the flue vent. Check the GAMA tables for newer rules with reguards to a newer furnace installation.
If you do choose to run a horizontal run, the UMC requires the flue vent horizontal to be no more than 75 % of the total vertical run.
If you choose to install a new metal vent, you also must not have more than one 90 degree ell under the UMC. You can however have several 45 degree turns. Anything more than 45 degrees is considered a 90 degree ell under the UMC.
As another HVAC Tech posted, you may run any direct vent appliance horizontally [following the Mfg's instructions], but it MUST be a direct vent appliance approved for that type of installation.
And I don't like cross posting.
--
Zyp



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I measure the current draw for my water heater at right around 16 amps. I don't have any problems with my 100 amp service..... but my house isn't that big.
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If you have 100 amps. service you should not have any problem dedicating 20 or 30 amps. for you hot water heater even if you have heat pump drawing 30 amps. Tony

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