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Gas water heater installation question

10 years ago

Need to replace a leaking gas water heater. Lowes came out and refused to install saying it was too close to a moveable air source, meaning a clothes dryer. Here is the setup. This is in a townhouse that has a utility closet off the kitchen. In this closet are the water heater, stackable washer/dryer, and the furnace. There is a louvered vent in the outside wall and a grate in the floor (to a vented crawl space) for fresh air makeup. The water heater is probably 20" from the dryer. The current water heater was installed by sears maybe 11 years ago. Have the specs changed on these newer water heaters? There are probably 14 other units with the same floorplan as mine that also have the exact same setup. Safety is obviously #1 priority here. Lowes is suggesting I convert to electric which would require some costly electrical work to run a 220V line over. I'd just like to get some other opinions, I know I could probably get someone to install a new gas heater, I just want to make sure it will be safe. Thanks

Comments (20)

  • 10 years ago

    I am not a code expert, but I don't understand why the distance between two gas appliances would be a safety issue. The most important thing is it to have adequate combustion air. The vent to the crawl space should be sufficient, but should be checked. I would be more worried about that then anything else.

    Did the contractor say what is the minimum allowed distance?

    Call the code enforcement official in your municipality. They will tell you what is the required code.

  • 10 years ago

    Actually the dryer is electric. I think the concern was that it moves air. I think there is plenty of fresh air makeup. I will see if I can find out the local code

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  • 10 years ago

    Here is a quote fro the water heater manual, not local code. "Do not locate the water heater near an air-moving
    device. The operation of air-moving devices such as
    exhaust fans, ventilation systems, clothes dryers,
    fireplaces, etc., can affect the proper operation of
    the water heater. Special attention must be given to
    conditions these devices may create. Flow reversal of
    flue gases may cause an increase of carbon monoxide inside of the dwelling."

  • 10 years ago

    The fact the dryer is electric works in your favor. I assume the dryer has a vent that goes outside in order to exhaust the moisture and heat as the clothes dry. I don't see this an appliance that moves air. There is no exhaust fan and no flue gases.

    I would think think the gas furnace would be more of a problem. Gas hot water heaters and furnaces are installed in closets all the time.

    Do some more investigation, but so far it does not sound like a problem.

  • 10 years ago


    I think what you are reading is a CYA statement. Clearly you don't want a dryer sucking the air out of the room and causing the exhaust gasses to be pulled into the room. That said, if it's in the manual, you can't do it. Lowes wouldn't have discretion about that -- neither would most plumbing contractors.

    Here are some alternatives:
    1.) If you are very sure there's no problem with makeup air, find a gas heater that doesn't have that precaution in the manual.

    2.) Look at other types of gas heaters such as powervent or tankless that have an exhaust gas blower. Tankless units will even bring in air from the outside. A powervent would be the least expensive, least additional work.

    3.) consider a hybrid electric heat pump heater (still have the electrical work to do)

    You want to avoid going with an electric water heater if you can. They are the most expensive form of water heater to use.

    This post was edited by jakethewonderdog on Tue, May 27, 14 at 8:40

  • 10 years ago

    I find it strange that the hot water installation manual does not mention furnaces or air handlers. These are the biggest air moving appliances in a typical house.

  • 10 years ago

    I have another installer coming out tomorrow to install one. We'll see how it goes. I'm confident from a safety standpoint that I am ok because my current setup has been in place for 25 years. I will install a CO detector (should have one anyway) as a precaution as well.

  • 10 years ago


    The issue is creating a negative air pressure relative to the outside.

    A dryer pulls a large amount of air from the surrounding space and sends it outside - potentially creating a negative air pressure situation.

    A furnace will just pull the air it needs for combustion. Some furnaces even have outdoor combustion air intakes. As long as there's sufficient make-up combustion air venting for a utility room, a furnace shouldn't be a problem.

    This is also why a furnace has a safety switch on the blower door and you should never have the return air duct open to the furnace area.

    Just an FYI: I'm not a code expert either, but I know "Manufacturer's installation instructions" are often incorporated into code. Explicit installation instructions to do, or not do, something makes it not optional.

  • 10 years ago

    I wouldn't make a move until you first call the local code authority.


  • 10 years ago


    This isn't a DIY project - this is being done by a contractor who presumably will know the local code and be financially responsible for an approved installation. It shouldn't be the homeowner's job to parse code.

  • 10 years ago

    Disagree with post above. Your word choice of "presumably" is very apt.

    OP has a question that relates to a safety issue. Local Coding authority has the final say on these type matters. Many codes are simply ignored by installing dealers through ignorance or a cavalier "they know best" attitude.

    I don't believe I would rely solely on Lowes' opinion. What's the harm in a phone call?

    You and I will just have to agree to disagree on this issue.


  • 10 years ago


    I understand what you are saying: The point is that Lowes wouldn't do it - citing manufacture's instructions.

    Those instructions are very broad - probably overly so. The instructions would prevent the installation of the water heater in many situations including anywhere near a furnace (and specifically how near is near?). Both my furnace and dryer are in my basement... could I install this water heater?

    There are codes for combustion makeup air that apply - but even if the LCA green lighted it - Lowes wouldn't proceed because of the explicit instructions.

    The OP needs to be aware that the installation presents an issue with make-up air (he seems very aware) and that any installer needs to take that into consideration.
    The addition of the CO detector is good also.

    If this is now boilerplate instructions then the OP will need to consider alternatives.

  • 10 years ago


    You said:

    "A dryer pulls a large amount of air from the surrounding space and sends it outside - potentially creating a negative air pressure situation.

    A furnace will just pull the air it needs for combustion. Some furnaces even have outdoor combustion air intakes. As long as there's sufficient make-up combustion air venting for a utility room, a furnace shouldn't be a problem."

    I don't follow this. How does an electric dry pull a lot of air? There is no combustion and there is no fan inside the dry.

    The furnace needs combustion air plus it has a blower pulling air to push through the vents. You know there is always some duct leakage that could cause negative pressure.

    What am I missing?

    I would not trust any contractor to know the local code especially where a mistake could cause a big safety issue.

  • 10 years ago

    "I don't follow this. How does an electric dry pull a lot of air? There is no combustion and there is no fan inside the dry"

    An electric dryer does exhaust air - put your hand over the exhaust vent and you'll feel a quite strong air flow. Frequently warm, moist, and 'linty.'

  • 10 years ago

    I would have to agree both electric and gas dryers exhaust air. But is it more of a problem than a furnace or air handler?

  • 10 years ago

    A furnace or air handler has a great big return duct(s) for a source of air and ideally does not exhaust air outside of the envelope.... a dryer uses surrounding (ambient) air as a source and exhausts that air outside that space.

    Mike, I have no idea either what the relative import is of this difference is.

  • 10 years ago

    "How does an electric dry pull a lot of air?"

    Mike: Of course there's a fan inside the dryer. All clothes dryers, electric or gas, pull a lot of air from the surrounding area, run it past the heater (gas or electric) to heat it, through the drum of wet clothes and out the dryer vent.

    Regarding the furnace: Anything other than very minor leaks in the return air system on a furnace (which are usually canceled out by minor leaks on supply plenum) are a problem. You can have back drafting of the furnace - far worse than back drafting of the water heater because it's more CO (more btu/hr input) and because that means it's pulling the CO into the return air and circulating it in the house.

    "I would not trust any contractor to know the local code especially where a mistake could cause a big safety issue"... umm ok. To begin with that's not really the issue - since as I said, the issue is that Lowe's WON'T do the job.

    But that's really an absurd statement because virtually every job, be it electric, HVAC, Plumbing or even many carpentry jobs depend on the contractor knowing code to do a safe installation. If we can't start with that assumption the building trades would come to a screeching halt.

    I'm not naive... I do know people make mistakes and/or are unqualified. But the people who do this for a living and have their work regularly inspected by local authorities and who's livelihood is dependent on being able to be licensed, bonded and insured are in a pretty good position to know local code. Besides, killing your customers is a big civil liability, potentially a criminal liability and really bad for business. It's far more likely that the average DIY installer would make a serious safety error.

    The OP is very aware of the makeup air issue. He's going to point that out to the contractor so it's not overlooked. As far as we know, this has been an acceptable situation up to this point with makeup air grills in the outside wall and floor. Nothing has significantly changed since the original design. A contractor is going to confirm the makeup air situation meets code and then install the heater. He may even inspect the current heater for evidence of backdraft.

    The real issue is a broad warning in the manufacture's installation instructions that, while is important to bring to installer's attention, is too broad. (again, how near is "near"? Is that 24"? is that in the same room? is that in the same dwelling unit?) Lowe's had no choice about following this prohibition because explicit manufacturers instructions are binding if not counter to local codes. If the instructions said not to install the heater in a room that was painted white, it would be just as binding.

  • 9 years ago

    Lowes is not doing the job. It is a subcontractor hired by Lowes. It is good that this contractor has concerns, but that does not mean he is correct. I have encountered very experienced contractors not know what is code and what is not. If this contractor knew what was required he should have told the amount of make air required in order to install the how water heater.

    It does not matter what is our opinion. The final authority is the local code official. A phone call is all it takes to get the answer.

    In my township you have to apply for a permit to replace a hot water heater. As a matter a fact you to apply for a permit to do just about anything.

  • 9 years ago


    I understand what you are saying. The complicating factor is that, as far as we know, the contractor from Lowe's didn't refuse to do the job because of concerns about not meeting local code for make-up air. If that was his concern he could have clarified the number of square inches of open venting required or got an opinion on that from the local code authority. The installer probably has a handy contact for that very purpose.

    The problem is the manufacturer's installation instructions expressly prohibited it. After hashing it out, I think we can all say we understand the rationale behind the instructions, but that puts the code authority and the installer in a very tricky place -- even if the code authority were to approve it, it would still leave the installer in a bad place that many wouldn't agree to be in.

    Part of my reason for saying this is to impress on people that manufacturer's installation instructions aren't merely a suggestion - Code authorities recognize that the manufacturer engineered the product, and although they can't contradict local code, the installation instructions carry a lot of weight.

    If the OP can find a standard water heater that doesn't have these specific limitations in the instructions, then the concern is simply make-up air and local code. I feel confident that the OP will follow up on that issue with the installer.

    If he can't find one without those specific limitations because it's become boilerplate, he would have to find an installer that would be willing to do that with the blessing of the Code Authority... which may be very difficult. Or he can look at some of the other options - some of which I outlined earlier.

  • 9 years ago


    Attached is a link to see if the current hot water heater has a back draft problem.

    As a test turn on the furnace, the dryer, and raise the temperature on the hot water heater so that it fires. If possible close the door to the closet if it does not have louvers. Check the air flow at the hot water heater vent hood. Air should be flowing in not out.

    For a more safety margin keep the closet door partially opened whenever you use the dryer. Put up a big sign so no one forgets.

    Here is a link that might be useful: Water Heating Backdrafting