Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-20-2010, 07:29 PM   #1
Newbie
 
Join Date: Jan 2010
Location: california
Posts: 5
Rewards Points: 10
Question

blown transformer --> how to check/verify?


I didn't power off EAU at breaker when replacing Honeywell T8085D thermostat with Lux 1500 (possibly shorting the blue to the red wires). Now, I couldn't get the fan, A/C nor the heating started. I have a Comfortmaker furnace using a White Rodgers Main Control Board 50E47-130.

My questions are:

1. Power at the breaker is good, but couldn't measure power from the wirings. Is this confirmation that the transformer is fried?

2. Transformers are on the ones on the White Rodgers control board, correct?

3. What terminals to measure from the control board to verify the transformer is gone?

4. Do I need to replace with the exact same White Rodgers control board? Or, can I replace with another control board model (that is newer, better, cheaper?)

Thanks in advance.

samvee is offline   Reply With Quote
Old 01-20-2010, 07:55 PM   #2
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 1,000
Default

blown transformer --> how to check/verify?


1) what "wirings" are you checking.
2) most transformers are not built into the circuit board.
Check for a low voltage fuse or breaker first. Check the continuity across the line voltage side of the transformer to see if it's good.

Marty S. is offline   Reply With Quote
Old 01-21-2010, 07:34 PM   #3
Newbie
 
Join Date: Jan 2010
Location: california
Posts: 5
Rewards Points: 10
Default

blown transformer --> how to check/verify?


1) I measured across R & C wires (red and blue in this case) and there was no voltage reading.

2) The transformer below measures 22V across.



The controller board is as follow:

http://www.white-rodgers.com/wrdhom/...pg0278_281.pdf



When measuring across TH & TR of the control module, it does not have any voltage reading. L1 and TH measures about 125Vac.

Please advise where to go from here. Thanks.
samvee is offline   Reply With Quote
Old 01-21-2010, 07:46 PM   #4
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 1,000
Default

blown transformer --> how to check/verify?


Is that transformer in the furnace? Can't tell from the picture but it looks like a for a doorbell. Can you post a picture of the lower half of the furnace please.
Marty S. is offline   Reply With Quote
Old 01-23-2010, 05:45 PM   #5
Newbie
 
Join Date: Jan 2010
Location: california
Posts: 5
Rewards Points: 10
Default

blown transformer --> how to check/verify?


zoom out pictures of furnace are below:






samvee is offline   Reply With Quote
Old 01-23-2010, 06:39 PM   #6
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 1,000
Default

blown transformer --> how to check/verify?


Transformer should be in that metal box in front of the blower.
Marty S. is offline   Reply With Quote
Old 01-24-2010, 03:20 AM   #7
Newbie
 
Join Date: Jan 2010
Location: california
Posts: 5
Rewards Points: 10
Default

blown transformer --> how to check/verify?


I measured 24V across the transformer on the right side (with the cover switch pressed), but C and R terminal still has no voltage. With the transformer working, how come there's no reading across C and R?

What is the black box on the left side?





Where should I go from here?
samvee is offline   Reply With Quote
Old 01-25-2010, 05:09 AM   #8
Newbie
 
Join Date: Jan 2010
Location: california
Posts: 5
Rewards Points: 10
Default

blown transformer --> how to check/verify?


The secondary voltage measured zero from the transformer, so that is why I am not picking up power across R & C. I measured the wrong wire from the transformer the night before...

Will stop by local hardware store to get a replacement transformer to try.

In regards to air filter for the furnace, what is the best kind? I heard that electrostatic filter will stress the system too much. Any truth to that?

Thank you MARTY for your help!!
samvee is offline   Reply With Quote
Old 01-25-2010, 07:20 AM   #9
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 1,000
Default

blown transformer --> how to check/verify?


I like a simple pleated filter. None of that ultra allergen junk though.

Marty S. is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
transformer questions Steelhead Electrical 8 10-25-2009 09:39 PM
How to install Aprilaire transformer? Studly HVAC 9 09-18-2009 10:44 AM
Comfortmaker RPJ - Bad Transformer? olgranddad HVAC 2 12-26-2008 12:10 PM
Central Ac transformer question Rschrei518 HVAC 4 10-20-2008 09:21 PM
Different color wires on new doorbell transformer.... ConstantChange Electrical 31 11-22-2007 12:08 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.