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    cthomsen's Avatar
    cthomsen Posts: 3, Reputation: 1
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    #1

    Mar 26, 2008, 04:15 PM
    Beach furnace conversion to mac limit switch
    We have a Beach furnace which is very old (installed in 1973). The limit switch connected to the temperature on the Beach needed replacing and we were told that a switch for a Mac/MGH furnace would work. The problem that we encountered is that there are more wires coming into the Mac limit swith over the old Beach switch and we can not get it to kick the fan on properly in auto and the heater does not kick out automatically either. We are having issues going from the old beach diagrams to the ones sent with the new replacement fan/ limit switch. We have phoned a few electricians and they don't even want to try and look at the problem. Is there anyone out there who can help?
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #2

    Mar 26, 2008, 08:35 PM
    (((electricians and they don't even want to try and look at the problem.))0

    Electricians have no idea about this kind of thing anyway.

    Here is what you need to do.

    Look at the old switch assembly.
    There will be temperature numbers on it as required by law.
    Post those numbers here. Might look like (limit 180 degrees or 140 ETC)) Also how many wires the old switch has.

    I will look in my old Miller furnace catalogue and see if I can find one that is a close match. Also post a picture if you can but if not describe the switch. Like the size of a quarter with two mounting tabs or??
    T-Top's Avatar
    T-Top Posts: 1,871, Reputation: 100
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    #3

    Mar 27, 2008, 07:15 PM
    How many wires are going to the switch. 3, 4 or 6? Not to many options. If its 6 you have a built in heater in the fan limit control to keep the blower from short cycling with cooler return air temps.
    Handyman2007's Avatar
    Handyman2007 Posts: 988, Reputation: 73
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    #4

    Mar 27, 2008, 11:54 PM
    [QUOTE=hvac1000](((electricians and they don't even want to try and look at the problem.))0

    Electricians have no idea about this kind of thing anyway.

    A well trained electrician WILL know how to install this or any other electrical device. Ask Me-- I am an electrician.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #5

    Mar 28, 2008, 12:03 AM
    ((A well trained electrician WILL know how to install this or any other electrical device. Ask Me-- I am an electrician))

    That's great because in the state certified electric safety class I teach there is never a mention of electricians doing HVAC work. I would appreciate it if you would help and answer this question for this person since he has a old beach furnace that the parts have not been available for years and I am sure with you expertise you can tell him exactly the part number of another brand to use and exactly how to hook it up. Thank you for all your help.
    cthomsen's Avatar
    cthomsen Posts: 3, Reputation: 1
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    #6

    Mar 29, 2008, 08:51 PM
    Sorry, but I don't have any pictures but the original limit switch had a sensor that went inside of the furnace and two wires coming from it. It then had two prongs to hook wires up from there. The new switch has six wires coming from it. It has two blue, two yellow and two red. We kind of have it figured out but we can not get the gas blower to shut off when when the sensor gets too hot. We have asked our electrical friends and they can not help us (they do oilfield electrical work) The other electrians are to busy to help. If one of you can help via diagrams or something that would be great. The mac switch is made by nordyne for model mg (-) -75 and -100 gas atmospheric furnaces or a mac 1175 furnace. Part no 902909. Sorry but I don't have any more information I just need to know to wire this switch in if someone can please help it would be great.


    Carmen
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #7

    Mar 29, 2008, 09:45 PM
    Quote Originally Posted by cthomsen
    Sorry, but i don't have any pictures but the original limit switch had a sensor that went inside of the furnace and two wires coming from it. It then had two prongs to hook wires up from there. the new switch has six wires coming from it. It has two blue, two yellow and two red. we kinda have it figured out but we can not get the gas blower to shut off when when the sensor gets too hot. We have asked our electrical friends and they can not help us (they do oilfield electrical work) The other electrians are to busy to help. If one of you can help via diagrams or something that would be great. The mac switch is made by nordyne for model mg (-) -75 and -100 gas atmospheric furnaces or a mac 1175 furnace. Part no 902909. Sorry but I don't have any more information I just need to know to wire this switch in if someone can please help it would be great.


    Carmen


    Is this what you have (see pic below)




    The air blower motor is not supposedd to shut off when the unit is to hot. Staying on is a safety part of the control just in case the burner control locks on so no damage will come to the furnace.
    cthomsen's Avatar
    cthomsen Posts: 3, Reputation: 1
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    #8

    Mar 29, 2008, 09:50 PM
    Yes that is the current switch that we have now
    Beach m70-0's Avatar
    Beach m70-0 Posts: 1, Reputation: 1
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    #9

    Nov 20, 2008, 09:42 AM
    I too am having issues with a Beach Furnace, would it be possible for you to resubmit the picture of the switch it isn't displaying in my web browser.
    c holloway's Avatar
    c holloway Posts: 1, Reputation: 1
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    #10

    May 20, 2009, 10:54 AM
    If your still having problems email me at [email protected] I have a beach furnace and have changed that switch.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #11

    May 20, 2009, 11:00 AM
    Replacement part for this unit is here

    furnaceparts.com: 902909 fan timer upgrade kit
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