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| Venting Issues | Rate Topic |
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| Posted: Fri Sep 3rd, 2010 10:50 pm |
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1st Post |
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phx Member
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Hi all -- would appreciate your insights on the following issue. Bought an old house w/ water heater in the laundry room (washer/dryer are electric; dryer vents out exterior wall immediately next to it.) In the process of having some insulation work done, and the contractors noted (as did the home inspector several months ago) that the laundry room had no external combustion venting for the gas hot water heater. Now, the heater has an exhaust vent of course, and it seems to be in proper order -- few kinks, almost entirely vertical up into the attic and out of the roof. Nevertheless, the contractor stated that without external combustion venting, I'm at risk of CO backing up into the laundry room/house. I'm admittedly a novice at this stuff, but his recommendations are to either install a tankless system or to drop a new vent from the outside into the laundry room where the heater is, then build a platform for the water heater (it's currently on the floor) and then basically create an air-sealed closet for the heater. (Hoping I haven't lost you with the description.) Just wondering if anyone has thoughts on the situation and/or solutions offered by the contractor. I'd been leaning tankless due to the tax credits/local utility rebates + the fact that the solution re: building a platform, adding additional venting, etc. was only a few hundred dollars less than the tankless install estimate. After reading some of the info on tankless found on this site, though, I'm not so sure anymore about the tankless, not to mention unsure about whether the contractor's platform/venting solution is needed. Appreciate your patience reading this lengthy post. Again, any thoughts would be much appreciated. All best. --AM Last edited on Fri Sep 3rd, 2010 10:51 pm by phx |
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| Posted: Sat Sep 4th, 2010 02:12 am |
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2nd Post |
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eleent Member 
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Hello: I am a little fuzzy on the description, but some things are clear. The heater needs to vent up and out. It sounds like you're saying there is no vent pipe. That needs fixing now!  A tankless would need some sort of vent also, so I see no benefit there. A satndard atmospheric draft heater is best with a pipe going straight up out and out the roof.The question of a platform would make sense in a garage or some place where gasoline is stored, but only there. The new FVIR heaters should not need a platform in a garage, but codes have not caught up to what's really being installed these days. The room needs some air supply so the dryer doesn't compete for air the heater might want. Yours, Larry
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| Posted: Sat Sep 4th, 2010 05:21 am |
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3rd Post |
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phx Member
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Hi Larry -- Thanks for the reply. Let me clarify a few things I left hazy. First, the water heater DOES have a vent pipe in good working order. An important clarification indeed! (I had tried to briefly describe this vent below -- it begins with a slight angle in the vent, then proceeds vertically straight through the soffit/attic/then roof.) The contractor seemed concerned (dare I say alarmed) that there was a possibility of CO backing up into the room/house with the current set-up. Again, the heater has a fully functioning exhaust vent through the attic/roof. How would the addition of an additional air supply (as suggested by the contractor) affect this situation? Regarding the dryer, would it still potentially compete for air with the heater even though the dryer is electric? Forgive the extensive questions -- I'm much appreciative for all advice you've already given! All best. -- AM
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| Posted: Sat Sep 4th, 2010 07:08 am |
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4th Post |
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eleent Member
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Hello: Let's think for a minute, only about the air in the room. Air must come in to replace any air that leaves the room. If the room were air tight and the only two openings were the water heater and dryer vents, you see what would happen. When the heater alone was running, air would be pulled back through the dryer vent. If the dryer was running, air would be pulled down the heater's vent pipe. If both ran at the same time, the dryer would win as it has a fan and combustion byproducts from the water heater would be pulled into the room. The room is likely not air tight, but does it have provision for make-up air? This is needed so the room cannot be depressurized at all when the dryer comes on. Otherwise there is the risk of combustion stuff getting into the household air  A question becomes; Where do you want to get the make-up air from? Is it to be conditioned indoor air or from the great outdoors? That choice affects how you separate the room from the rest of the house.Source of heat has no effect if we're ony looking at the air, (unless it were an electric water heater). Also, a direct vent heater, which takes it's combustion air from outdoors would make this discussion moot. Yours, Larry
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| Posted: Sat Sep 4th, 2010 03:31 pm |
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5th Post |
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energyexpert Member
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I've seen a small room with a gas water heater which had a fresh air vent from outside near the ceiling and one down near the floor fed from inside the house. Natural gas (methane) is lighter than air. If you have a gas leak methane will rise to the ceiling. So a vent from outside near the ceiling will help minimize methane buildup. When WH or dryer is not operating (ie, no negative pressure in the room) methane can escape either by diffusion or convection. David
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| Posted: Mon Sep 6th, 2010 07:18 pm |
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6th Post |
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phx Member
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David and Larry -- Thanks for the thoughts. I think I now understand the issue of make-up air, esp. w/ a water heater and dryer in the same room. As of now, there's no dedicated source for make-up air -- the heater and dryer are just pulling air from the rest of the house through the laundry room door. The contractor had said one option was to create a closet in part of the laundry room solely for the water heater, install high (and maybe low too?) vents through the attic/roof, then air seal that closet from the rest of the laundry room. This is all part of a local program to air seal/weatherize homes, so I'm assuming he's concered with air sealing the new closet from the rest of the laundry room b/c he's concerned about air leaks/outside air being drawn into the HVAC system? (Perhaps a particular concern in a place like Phoenix, where outside air in the summer is blisteringly hot?) In any case, your help has been super helpful, guys -- thanks so much again. All best. -- AM
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