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Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience:  Experienced in all aspects of HVAC, both residential and commercial.
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I am interested in replacing a 50A51-507 rodgers

Customer Question

I am interested in replacing a 50A51-507 white rodgers
Submitted: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need. Did you need help in finding a new module or what? What is this going into? Make and model of the unit itself?

Customer: replied 1 year ago.
I have a Trave xv80 that will not start up. I checked the low pressure switch its ok, as are the thermal switches and limit switch. I replaced the pressure switch but same problem persists. I can get the furnace to start if I use a wire to jump the low pressure terminals. Furnace then starts with inducer motor, then 17 seconds later igniter glows and gas ignites. It will burn for 9 min and 45 seconds then stop. I have repeated this process a dozen times. No obstruction in flue, if I pull off vacuum tube when operating it shuts down - thus I have good vacuum. I'm thinking the board is bad - whote rodgers 50A51-507. I took it out and have it on my desk. I left small thermostat board in basement.
Customer: replied 1 year ago.
switches will get 24V when called. All thermal switches and limit switches have continuity when furnace is running
Expert:  Tim H. replied 1 year ago.

What LED flash code are you getting when furnace shuts down?

Customer: replied 1 year ago.
Thus I think switches are OK. I can hear board clicking every 30 seconds or so as the temp is below setting at thermo stat. I am getting a three flash LED which implies low pressure switch, but I checked that
Expert:  Tim H. replied 1 year ago.

So you let inducer come up to full speed, jump the pressure switch terminals and furnace still won't stay running??

Customer: replied 1 year ago.
inducer will not start until I jump the low pressure switch. As soon as I do the jump, the inducer motor starts to turn and creates vacuum, igniter then comes on about 15 seconds later and when hot enough it ignites the nat gas. I installed a brand new flame sensor as well.
Expert:  Tim H. replied 1 year ago.

The unit should never start with pressure switch terminals jumped. The board looks for an open pressure switch before it allows heat to work.

Customer: replied 1 year ago.
Maybe the board thinks the low pressure switch is open? As soon as I jump it, the inducer starts to create vacuum. I have to leave the jumper there for about 10 seconds I think it's creating up draft
Customer: replied 1 year ago.
It definitely will start if I jump the two terminals on the low switch ... I pull back the connectors enough and do the jump. I think when I jump it perhaps I am signaling the board that I have closed the switch?
Expert:  Tim H. replied 1 year ago.

If it's starting with the pressure switch terminals jumped, you need to replace the board as this should NEVER happen!

Customer: replied 1 year ago.
I could do it all day, but of course its not a good way to heat the house, sitting next to the furnace and jumping it every 10 min
Expert:  Tim H. replied 1 year ago.

The board does a check of pressure switch and looks for open pressure switch before allowing heat to start

Customer: replied 1 year ago.
I know it sounds odd but on the .17 WC switch, if I take a wire and touch both terminals the inducer starts, igniter does its thing, then the gas will ignite, and the blower will come on to blow the warm air into the ducts
Expert:  Tim H. replied 1 year ago.

Then you need to replace the control as this is not safe.

Customer: replied 1 year ago.
Maybe when I jump the switch I am toggling it? I can hear the board go click-click-click (three times) then the inducer starts
Expert:  Tim H. replied 1 year ago.

Pressure switch terminals should always be open until inducer comes up to full speed and the switch closes.

Customer: replied 1 year ago.
ok so I am willing to replace the board ... it seems there are some after market boards that are now used as replacement part number 21V51U-843 Emerson
Expert:  Tim H. replied 1 year ago.

If you give me the full model number, I can help you find the right part number for the new board.

Expert:  Tim H. replied 1 year ago.

Model of the furnace, that is.

Customer: replied 1 year ago.
I have a white rodgers 50A51-507 board and a Trane TUD140R9V5H furnace
Expert:  Tim H. replied 1 year ago.

OK, hang on a minute

Customer: replied 1 year ago.
OEM boards look different, my board has pins for a separate
thermostat board to press into
Customer: replied 1 year ago.
I have a termostat board that looks like this http://www.amazon.com/21C148501P01-American-Standard-Replacement-Furnace/dp/B00FZV0DCO
Customer: replied 1 year ago.
This appears to be replacement for main board https://www.patriot-supply.com/products/showitem.cfm/WHITE_RODGERS_21V51U_843
Customer: replied 1 year ago.
is the thermostat now integrated into the board?
Customer: replied 1 year ago.
I can easily enough wire the thermostat wires to a new board
Expert:  Tim H. replied 1 year ago.

Seems to be something missing from that model number. Can you recheck? Or give me the full serial number?

Customer: replied 1 year ago.
Trane *UD140R9V5H first letter is a "T" but could also be an "A" TUD140R9V5H or AUD140R9V5H
Expert:  Tim H. replied 1 year ago.

How about serial number, please?

Customer: replied 1 year ago.
Trane part number CNT2223 according to manualserial number is *****
Customer: replied 1 year ago.
I can double check s/n if it does not appear correct
Expert:  Tim H. replied 1 year ago.

Not correct. Nothing coming up

Customer: replied 1 year ago.
which one is incorrect?
I have the manual here ... Trane parts are
CNT2223 and CNT1537
Customer: replied 1 year ago.
can you click links if I send a link?
Expert:  Tim H. replied 1 year ago.

The serial number is ***** correct

Customer: replied 1 year ago.
Here is the CNT 1537
http://www.amazon.com/CNT1537-Trane-Replacement-Furnace-Control/dp/B00FZUB8OM
Expert:  Tim H. replied 1 year ago.

If I get exact serial number, I can see all parts for this furnace.

Customer: replied 1 year ago.
please hold while I go jot down serial number again
Customer: replied 1 year ago.
I just checked serial
N021Y4491G I don't know in follwing the N it is a zero or letter O
Customer: replied 1 year ago.
N021Y4491G
NO21Y4491Gthis is how it looks on sticker, cannot determine second character
Expert:  Tim H. replied 1 year ago.

This is your replacement board. CLICK HERE. I have to leave for an emergency, but will reconnect when I return.

Customer: replied 1 year ago.
when will you return?
Expert:  Tim H. replied 1 year ago.

what else did you need?

Expert:  Tim H. replied 1 year ago.

You have 2 boards in this unit?

Expert:  Tim H. replied 1 year ago.

Neither the model or serial numbers you gave me brought up anything on the Trane website.

Customer: replied 1 year ago.
there is a controller and a separate thermostat board
Customer: replied 1 year ago.
I have the manual here ... Trane parts are
CNT2223 and CNT1537
Expert:  Tim H. replied 1 year ago.

You don't want the thermostat board, that would not control the pressure switches. If you can send me a clear picture of the tag that has the model and serial numbers, I can look up. But that link I sent you is the replacement board for the part number, CNT2223

Customer: replied 1 year ago.
http://www.amazon.com/Emerson-21V51U-843-Universal-Integrated-Circulator/dp/B00BTLLLYS/ref=cm_cr_pr_product_top?ie=UTF8it appears this board works as a replacement
Expert:  Tim H. replied 1 year ago.

If you want to do that, that's up to you. I usually prefer the OEM board. Otherwise it may involve wiring changes that can get confusing to a laymen. I can look up the exact replacement if you can send me a clear picture of the tag that has the model and serial numbers, I can look up.

Customer: replied 1 year ago.
OK I will send a photo
Expert:  Tim H. replied 1 year ago.

OK, thanks

Customer: replied 1 year ago.
here is the sticker
Customer: replied 1 year ago.
I will be back in 20 minutes or so
Expert:  Tim H. replied 1 year ago.

OK, so that link I sent you is the OEM replacement control. CLICK HERE. If you want to try that other replacement control, that's totally up to you.

Customer: replied 1 year ago.
I am back
Expert:  Tim H. replied 1 year ago.

Did you check my last reply?

Expert:  Tim H. replied 1 year ago.

Let me know if you need additional help. Otherwise, good luck! Thanks for using Just Answer and please don't forget to rate my service as that's how experts get paid (thanks in advance for any bonus left). Otherwise experts work at their own time and expense. Feel free to post back with any additional questions.

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