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ionized_gw

temperature controller contacts

ionized_gw
11 years ago

I am looking at some Honeywell temperature controllers. I don't know what the abbreviations, AFL and ALR, mean. I am guessing Amps Locked Rotor, but I'm not coming up with anything for the first one and I can't afford to guess anyway! Can someone help me out?

Contact Ratings120 Vac-- 16.0 AFL, 96.0 ALR; 240 Vac-- 8.0 AFL, 48.0 ALR

Thanks for reading

Comments (12)

  • Ron Natalie
    11 years ago

    FL = Full Load

    If you have a 1HP motor the full load current is the amount it takes to run the motor with a 1 HP load attached

    The locked rotor amps is the amount it can consume when it is not turning. The major reason for this number is it's an upper bound on what the motor can consume briefly while starting (which will be higher than the full load rating).

  • ionized_gw
    Original Author
    11 years ago

    Thanks, just to be sure I understand, I can use that particular switch for a purely resistive load up to 16 A?

    I am looking for an economical replacement for a t-stat that controls some plumbing heat tapes. EBay, here I come!

  • brickeyee
    11 years ago

    Be careful because heating elements often pull more power until they reach operating temperature.

    Many an electrical engineer trying to control incandescent light bulbs has found this out the hard way.

    A 60 W bulb pulls more than 60 W until it heats up.

    Enough to blow solid state controls that cannot carry the brief surge.

  • ionized_gw
    Original Author
    11 years ago

    Thanks,

    The supply pipes in the crawlspace were all heat-taped and insulated. There is a Honeywell or similarly-styled t-stat hard-wired on the circuit supplying outlets under the house. Unfortunately, I really have to re-do all the heat tape and insulation as some of it is damaged/decayed. I can not rely on it so I don't even use it. Instead, I leave the water dripping which is a real pain. The thermostat does not operate either. IIRC, it is stuck in a closed position. I have not yet taken it apart.

    What I will have to do is determine what the load total is of the heat tapes while I am redoing the tape and insulation and see if it falls within the rating of switch (and the circuit breaker).

  • brickeyee
    11 years ago

    "The thermostat does not operate either. IIRC, it is stuck in a closed position."

    A common problem for switch contacts when the load is larger than they are rated for.

    They tend to overheat and weld closed.

  • ionized_gw
    Original Author
    11 years ago

    I played with the t-stat a little today. It was not ideal when installed since the lowest set temp is 35. There is a pilot light in the circuit (7W e26). It will break contact only intermittently if the dial is turned repeatedly. The t-stat is quite corroded outside so I bet it is pretty nasty on the inside as well.

    I have so much abandoned cable under the house, it is pathetic. I pulled out 35' of 10/2 today. It was connected to a 10-20 amp socket that was sitting where a gas wall heater was installed, no box, but wrapped round and round with electrical tape. I took out the wall heater a couple of years ago and never got around to pulling out the cable or the nat gas tube. Today was the day.

    While I was under the house, I saw another 10-20 outlet in a box wired with conduit and attached to a joist. It seems dead, but no time to investigate today. I can not begin to speculate what it might have been used for as it is a foot or two under the side of the house :-(

  • Ron Natalie
    11 years ago

    Sometimes people stick mechanicals in crawlspaces. The other thing to look for is the appearance of small holes chopped in the vicinity. Harry homeowner wants to put a dryer in. Rather than figuring out how to actually pull the wire into the room he just screws it the joist and drops the cord through a hole.
    I've seen more bizarre things than that.

  • doug_gb
    11 years ago

    Your other option is to use a contactor or relay - then you can use any low voltage thermostat.

  • ionized_gw
    Original Author
    11 years ago

    Thanks, I thought about that. It seems like the choices in LV t-tats is not as good as with line voltage. Keep in mind that I will want this to turn on at 28-30 F.

  • doug_gb
    11 years ago

    Check out commercial/industrial thermostats - Grainger has Honeywell and Ranco to name a few.

  • Ron Natalie
    11 years ago

    I had my airplane's block heater connected to a line voltage (think elecric baseboard heat) mechanical thermostat that I could dial down to 45.

  • ionized_gw
    Original Author
    11 years ago

    In my experience Grainger is a very pricy place to buy stuff, but I like the "showroom".

    I really don't want to be running this stuff above freezing temp. I'll look for an industrial-style control t-stat. Eventually, I will find one. My target completion date isn't until next fall anyway.

    I am finding the pipe heating cable/tape more complex than I thought I would. I only need a Watt/foot if I insulate. The most readily available are more. Then there is the decision to install cheap stuff or primo/costly/self-regulating stuff. I suppose I should start another thread for that, maybe in plumbing.