What does a power vent WH do for me?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by rick.a, Jan 29, 2007.

  1. rick.a

    rick.a New Member

    Jan 11, 2007
    Palmer, Massachusetts
    My new place has a 40 gal Reem PowerVent HWH. What are the pros and cons of a PV? Is there anything that I should know about living with it? If I shut off the gas because I will be gone for a week will it freak out? And what's the little vacuum tube on top doing? Is there any maintainence other than to check for leaks periodically and maybe pull the TP switch every now and then to be sure that it still works (I am aware of the chance of crud sticking it open but gamble with this to just feel safer living with the potential "rocket").

    Is the PV REQUIRED since it vents out the side wall?

  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    A power vent water heater means you do not have to have a chimney to vent through the roof of your home. The venting is done through PVC or ABS pipe that can exit the house at ground level. The word "power" simply refers to the fact that it uses a fan on top of the heater to push the hot air out. I think the small tube is what tell the fan to activate. You treat a power vent heater exactly the same as any other type of water heater. If you shut the gas off, it will not heat water until you turn the gas back on. They use an ignitor plate rather than a standing pilot light.
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    The vacuum sensor tells the gas valve that thefan is running and it is safe to start the burner; i.e., it won't fire unless it senses the fan is on.

    The next step up from this type is one that uses closed combustion - it draws combustion air in from outside rather than inside. Whenever you burn fuel, you must replenish that air from somewhere. This means that any air leak in the house will be bringing in outside air to make up for that lost out the flue. It is much more efficient to not waste or dilute the air you paid to condition with outside air.

    You can simulate this with an air vent in the room where the heater is, but then you've got a colder room which increases the standby losses from the water heater - the surrounding air is colder, therefore more heat is lost.
  5. dubldare

    dubldare Plumber/Gasfitter

    Sep 14, 2005

    The little vacuum tube connects to a fan proving switch, which tells the ignition control if the fan is operating and whether or not the vent is blocked.

    As far as when going on vacation: simply turn off the switch to the unit. This is either at the top near the blower, or on the box on the lower part of the unit. There is no need to turn off the gas supply to the unit, as there is no pilot.

    Additionally, only turning off the gas will cause the blower to run as long as there is a call for heat. Which, in the case of a week away from home, would probably be 5-6 days straight.

    Yes, a powervented system is required when venting horizontally. Essentially, excess air (from within your dwelling) is mixed with the hot combustion products of the water heater at the draft hood of the heater. This excess air cools the burnt gasses sufficiently enough to be vented through plastic piping.
  6. rick.a

    rick.a New Member

    Jan 11, 2007
    Palmer, Massachusetts
    OK, now I get it. Thanks for the replies.

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