A C Timer questions


  #1  
Old 07-23-11, 06:24 AM
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A C Timer questions

I have a 5K ,115 vac,15amp, room A C Air conditioner that i
would like to put on a timer.

The timer plugs into a A C outlet,and the Air Conditioner plugs into the timer. Timer is rated 115VAC,15 Amps,1820 resistive.

Is this a doable? Thanks
 
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Old 07-23-11, 09:49 AM
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would like to see some more amps on that timer rating...the compressor is the major load and if the timer goes to open to shut the unit its not a major draw going off, but if the unit calling and is waitng on the timer to close that is the LOCKED ROTOR draw on start compressor and fan for a millionth of a second...right thru the timer worst is the contacts within the timer wears out sooner(timer closes shows run but AC sits) .then say it was just a ceiling fan or table top oscellating fan....next time at HD check hefftier rated timers..just in case if you ever pull the casing check the rating on the thermostat that does the same load as your timer if its 15 amps rated your good to goNo Beer 4U
 
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Old 07-23-11, 09:56 AM
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One thing...
Is this a newer A/C with electronic controls or knobs for cooling and temp setting? Most electronic units will reset to the off mode when power is removed in my experience, so timer won't do anything except turn it off after a certain time. If thats what you want...shouldn't be an issue.
 
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Old 07-23-11, 10:54 AM
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Thanks all.

I'll check this out more
 
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Old 07-23-11, 05:59 PM
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The timer you posted is rated for a resistive load, and may not be suitable for an inductive load. You need a timer rated for an inductive load.
 
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Old 07-23-11, 11:12 PM
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First, he's not going to find a 15A plug-in timer rated higher than that. 1800W is 15A, so the only way to get a higher rating is one that's hardwired and rated for 20A or a plug-in with a 20A plug. No way is his 5kbtu AC drawing 1800W. It's probably going to be more along the lines of 500-600W, with a starting surge 2-3x that. OP, don't go by the plug, go by the nameplate. It'll tell you exactly what it draws.

Second, a plug-in timer rated at 15A/1800W would be considered 'heavy duty', and will most likely have motors listed as suggested/recommended applications. The timer they got will work just fine. Even if it isn't designed for inductive load, it won't cause any issues anytime soon. Inductive load arcing happens on the break, when it is at the lower 'running load amps'. The startup surge happens on the make, where the arcing is minimal. It'd take thousands of make/breaks to burn the contacts. I've always heard you derate 20-50% for an inductive load on resistive rated contacts, which would still be fine for this unit. But like I said, I'd bet anything this timer is inductive load rated.
 
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Old 07-24-11, 06:22 AM
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I'd have to agree with JerseyMatt on this one. There is no way the 5000 BTU window unit will draw 15 running amps and starting amps is not the same as Locked Rotor Amps (LRA) either. I suspect the OP has a timer similar to this resistive rated plug-in timer by Intermatic which is also rated for motor or air conditioner load of 12 amps.
Heavy-Duty Grounded Timer TN311C | Intermatic, Inc.

If I were specifying a plug-in timer for air conditioning use, however, I'd probably prefer using this one.
Air Conditioner & Appliance Timer HB113C | Intermatic, Inc.
 
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Old 07-24-11, 06:54 AM
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Originally Posted by CasualJoe
If I were specifying a plug-in timer for air conditioning use, however, I'd probably prefer using this one.
Air Conditioner & Appliance Timer HB113C | Intermatic, Inc.
FYI, this one requires a 20A receptacle. It has a T-slot receptacle to accept a 15 or 20A plug, but it has a NEMA 5-20 plug, so it would require changing out the receptacle (and that's assuming the circuit is 20A).
 
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Old 07-24-11, 07:54 AM
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If I were specifying a plug-in timer for air conditioning use, however, I'd probably prefer using this one.
Air Conditioner & Appliance Timer HB113C | Intermatic, Inc.
Sorry to be off topic, but do they make an outdoor version of this?
 
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Old 07-24-11, 01:09 PM
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Sorry to be off topic, but do they make an outdoor version of this?
Not that I am aware of. They make two 240 volt versions as well, but they appear to all be for indoor use.
 
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Old 07-25-11, 01:08 PM
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I found a outside timer rated "heavy duty",115VAC,15 amps resistive.

Manufacture,sorry ,i forgot the name,listed Pool,outside lighting,etc.
what caught my eye was the "pool" claim.
The Air Conditioner is about 10+ years old with knobs to set functions.
 
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Old 07-25-11, 02:23 PM
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If its marked pool, it means the pool pump motor, which is an inductive load. This timer will work with the a/c.
 
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Old 07-25-11, 03:02 PM
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Does it have a horsepower (HP) rating?
 
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Old 07-27-11, 07:54 AM
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No H.P. rating I may wait a bit on this.
 
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Old 07-27-11, 08:36 AM
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It's ok, I don't think you'll have any problem with it anytime soon. As Justin said, if 'pool' was one of the suggested applications, it meant the pool pump, which is the same type of load as an air conditioner.
 
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Old 07-29-11, 08:39 AM
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Thanks everyone . As usual, you all are very helpful.
 
 

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