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Timer for Gas hot water heater.....

Post in 'The Green Room' started by webbie, Jun 4, 2007.

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  1. webbie

    webbie Seasoned Moderator Staff Member

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    I have a newer high-efficiency gas hot water heater (tank type) that uses electric to operate the blower and contains no standing pilot.

    It is 120 volt and less than 12 amps.

    I have seen no information or suggestions about why I could not install a simply plug-in timer to turn this off overnight.

    It actually plugs into it's own outlet, so I would simply use a plug-in time like this:

    http://www.grainger.com/Grainger/items/5A688

    I don't expect a really big savings, but even 3-5% would make me happy.

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  2. Sandor

    Sandor Minister of Fire

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    I seriously doubt the blower would draw 12 amps. If it drew 10amps, that would be 1200 watts.

    The blower is needed to move the flue gases since It may not have enough heat to rise out of the stack. The high efficiency gas heater remove a lot of the heat.

    What you really need to do is to buy a Kill A Watt meter and see what it is actually drawing. I would guess its way less than 100 watts.

    High efficiency water heaters are usually insulated quite well and I would not expect it run much when not in use, like overnight.
  3. velvetfoot

    velvetfoot Minister of Fire

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    I found the power vented gas heater very annoying in our last house. It was quite noisy. It plugs in, right? I doubt the system is on without power, since it has an igniter and the gas valve is electric, etc. I bought a cheap digital timer at the Harbor Freight store that is powered by battery (apparently). It doesn't lose its programming after an outage and is quite flexible. Here is a link: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95205
  4. webbie

    webbie Seasoned Moderator Staff Member

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    The electrical info on it says "Less than 12 amps", which I assume means something.....although I also agree the max load is probably closer to 5 or 6.

    It does plug in 110v to it's own outlet. It is noisy and has multiple fans, including the exhaust and the power burner....plus the ignition modules, etc.

    Those spin timers would not lose their programming, but they would fail to keep up to time during a power failure. My main concern was the amperage. I'll take a look at that harbor freight thingy...don't see any amp rating on that, though.
  5. velvetfoot

    velvetfoot Minister of Fire

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    What is nice about the HF timer is that it does daily timing, so for me, Saturdays and Sundays are different for the TV.
  6. restorer

    restorer New Member

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    I may be wrong, but usually the amp rating is based on the maximum demand, as in all the motors starting at the same time. The actual use may be 1/3 the rating. It also may be that the rating is shown this way "less than..." to size the plug wire, small amps smaller wiring required. If you can use one of the draw meters like Kill-O-Watt, you can get an actual picture. Also, get your control timer and see what draw it takes. I had a timer that drew a constant 6 amps on outdoor lights that when on drew only 4 amps. I tossed the timer and left them on 24/7 a cheaper operation.
  7. begreen

    begreen Mooderator Staff Member

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    I'm not sure why it would state <12 amps, that sounds more like the plugin cord rating. For example - AO Smith's units are rated at "less than 3 amps".

    What's the make and model of the water heater? Typically these power vents use a 1/30th HP or less motor. It might have a startup surge of 1-3 amps, but I suspect goose is right, it's running probably at about 100 watts.
  8. Sandor

    Sandor Minister of Fire

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    Goose? He didn't even post in this thread!
  9. begreen

    begreen Mooderator Staff Member

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    :red:Whoopsie, got my goose mixed up with a gander! uh make that a Sandor :).
  10. restorer

    restorer New Member

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    BeGreen:

    DUCK!!!!!! Someone is not going to be pleased with that little ditty. Apologize now, before we have to pick you off the floor with a nice track of two wheeler tread up your back :coolsmile:
  11. titan

    titan Minister of Fire

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    Craig,just measure the amp draw of the unit @ a main wire feeding the heater with an amp-meter,then convert amps to watts.Watts=VoltagexAmperage.
  12. webbie

    webbie Seasoned Moderator Staff Member

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    The label must say that for a reason - AND, it plugs into a one-outlet box. Sure, the one motor is 2.5 amps (fan blower), but that does not include the burner motor or controls.

    I assume a printed electrical rating is something to pay attention to - in other words, it would be nice if the timer had the same rating.....or at least 10 amps.

    I'll dig up the make and model and look it up - but again, it does say 12 amps on the electrical schematic.
  13. begreen

    begreen Mooderator Staff Member

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    There's a burner motor on a gas hot water heater? We'll need brand and model to go further. This is intriguing.
  14. webbie

    webbie Seasoned Moderator Staff Member

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    Looking though the manufacturers lit, it seems as if it only uses slightly more than 3 amps - so I guess a timer that would handle 5 amps or so would be sufficient. Maybe I'll give that HF job a shot. Doesn't have a rating on the spec page, but we'll see- cheap enough that I can always use it for something else.
  15. Kenny1

    Kenny1 Feeling the Heat

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    Umm, not an expert in the field, but please keep in mind that electrical motors have surge start up currents (that is, when they start, they appear as nearly a short to the line).

    The label on the appliance should not be ignored IMHO. Anything you put in line should support the stated current as a minimum. The steady state draw of the heater may only be an amp or so, but depending on the motors, could easily draw many times that for startup. I would assume that the figures on lables are typically a worst case value with a bit of a fudge factor built in.

    My $0.02 would be to go (at a min) with the Grainger Air conditioner timer. For more money, a 15A timer can be had (check pool places like http://www.poolplaza.com/P-INT-30-831-T.html ). I know it is a jump in price, but it is rated for a full 15A and is designed for pumps (which also have a high surge factor).

    I'm a bit over cautious about electrical, and like to have devices operating with a bit of headroom.
  16. Jags

    Jags Moderate Moderator Staff Member

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    like Kenny, I will admit that I am not a pro on water heaters, but, if the ignition is like on a pilot free furnace....meaning it uses a heating element to ignite the gas, that may be where the additional amps are coming from. What type of ignition is on this thing?
  17. webbie

    webbie Seasoned Moderator Staff Member

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    Looking closer it says that it lights the pilot itself - which is unclear in some ways. I wonder if it has a standing pilot. I have unpluged it here and there, and never had to light the pilot, but at the same time it talks about a pilot light as opposed to a direct ignition. It is a Bradford White 75 gallon power vented unit.

    I'm going to dig up the manual, because it might be that turning the pilot on and off (if it is standing) is not a good idea - in that case, I will simply hook a timer to the thermostat wires, which would simulate turning that up and down.
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