Results 1 to 11 of 11
  1. #1
    Join Date
    Feb 2007
    Posts
    20

    7 1/2 ton reversing valve

    Any one have the amp draw for a Trane 24v solenoid on a reversing valve (specs)? We are in a discussion at our shop . Its a older valve and drawing .98 . Is this too high ?

  2. #2
    Join Date
    Dec 2006
    Location
    phoenix
    Posts
    106
    Most coils are 4-6 watts which would be .25-.5 amps. One watt is high even for an older valve IMO. Drawing one amp through the RV plus all the other 24V loads is a lot of juice through the TSTAT. Most thermostats will have real issues with that much current.
    Is the RV noisy? Excessive humming is indicative of worn RV slides which causes excessive amps.

  3. #3
    Join Date
    Feb 2007
    Posts
    20
    Thanks for the reply tunaguy . Its a very old Trane unit . ( Split system 1985) We are blowing the 5amp control fuse....Once a week or so . No Excessive humming . All components are original , Comp , contractors , and yes the reversing valve. With that said the unit is in very good shape to be its age. It is scheduled to be changed out this summer so we are just trying to make it last until then . High voltage is normal and with in range , 27.4 volts at the secondary side of the transformer. I energized the Reversing valve (cooling mode) for 6 hrs and I had my fluke amp meter on the Reversing Valve and thats when I saw .98 amp draw . The indoor fan runs 24/7 . I know theres a lot of different loads to check , I thought .98 amps was a little high and may heating up after a extended time being energized , But after 6 hrs I ruled it out ?

  4. #4
    Join Date
    Jul 2007
    Location
    Delta BC Canada
    Posts
    89
    What VA rating is the transformer? If you have a 40 va transformer the fuse should only be rated for 40/24= 1.5 amps.As tunaguy pointed out add all the other loads and you could have a problem.Also does the voltage drop from the transformer during start up when the contactor pulls in?

  5. #5
    Join Date
    Feb 2007
    Posts
    20
    75 va...The 5 amp fuse is the factory fuse Trane put in it . No voltage drop when Comp. contactor pulls in . Total amp draw 1.76 . This is the highest Ive seen it . It pops when no one is around ...Go figure. Years ago there was some in line fuses you could put on each load . I think they were call tattle tales ?? It was a one time deal. May look into something like that.

  6. #6
    Join Date
    Mar 2007
    Posts
    26

    Commercial Tech.

    Sounds to me you have a short of some sort. I would change out their control wires. The one going the indoor unit to the outdoor unit and the one going from your indoor unit to your thermostat. Try the outdoor one first since it is always the easiest. Good Luck.

  7. #7
    Join Date
    Dec 2006
    Location
    phoenix
    Posts
    106
    Quote Originally Posted by Blownfuse View Post
    75 va...The 5 amp fuse is the factory fuse Trane put in it . No voltage drop when Comp. contactor pulls in . Total amp draw 1.76 . This is the highest Ive seen it . It pops when no one is around ...Go figure. Years ago there was some in line fuses you could put on each load . I think they were call tattle tales ?? It was a one time deal. May look into something like that.
    Yes. The old fashioned Tattletales were used a long time ago, 20 years, with good success. The best ones were the old fashion instant camera light bulbs. However, they were used across safety contacts only. The light bulb would flash if the safety opened, before the lockout relay could energize. I don't like the newer Tattltales, IMO. Also, if the load "shorts" then the Tattletale won't work.

    I suggest adding in-line fuse holders with each load, fuses are in series. Fuses will be big enough to hold load but much smaller than the 5 amp fuse. Maybe 2 amp for the RV, .5 amp for the fan relay and contactor ?? The smaller fuse should blow before the 5 amp, provided they're both fast blow type fuses.

    Another possibility is that a load or control wiring is going to ground erratically. The 24V transformer would have to have a low voltage leg grounded, which is common on the newer units. If a tstat wire insulation is compromised and the wire rubs against metal then the fuse will blow in an instant.

    Regardless of blowing fuses, the RV amperage sure seems high. I hope this helps. Good Luck

  8. #8
    Join Date
    Aug 2009
    Location
    hazzard county md
    Posts
    173
    sounds like you got a short in one of your control wires. i have had that problem before. its almost like intermittently shorting.check your wiring at t-stat and then where it is run to ahu. good luck

  9. #9
    Join Date
    Jul 2007
    Location
    Delta BC Canada
    Posts
    89
    With Lennox heat pumps have had issue with the contactors. On defrost the steam would cover the entire electrical section and rust would form on the coil and on the internal components of the contactor this would cause the contactor to chatter and blow control fuses.

  10. #10
    Join Date
    Dec 2006
    Location
    phoenix
    Posts
    106
    Quote Originally Posted by DPinst View Post
    With Lennox heat pumps have had issue with the contactors. On defrost the steam would cover the entire electrical section and rust would form on the coil and on the internal components of the contactor this would cause the contactor to chatter and blow control fuses.
    I'm curious. We don't do residential but which models have this issue? Thanks

  11. #11
    Join Date
    Jul 2007
    Location
    Delta BC Canada
    Posts
    89
    This was more with the Chp-16 series package roof top heat pumps.This style of unit had the electrical section above the compressor /outdoor coil section. On defrost the water vapour would cover everything. The compartnment was never sealed up.would replace the contactors with sealed coil type rather than the more open type coil for the contactor .

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