Replacing faulty valve on old gas furnace


  #1  
Old 09-16-22, 02:42 PM
Q
Member
Thread Starter
Join Date: Sep 2022
Posts: 7
Received 0 Votes on 0 Posts
Replacing faulty valve on old gas furnace

Hello:
Amateur plumber here with furnace repair problem. -Descriptions follow.
SITUATION:
  • Pilot light on old 1940 Bryant furnace doesn't stay on when lit.
TESTS DONE:
  • Cleaned thermocouple of any/all buildup with plain steel wool.
  • Pilot flame is strong and hitting thermocouple completely.
  • Volt meter reading indicates that thermocouple is functioning correctly.
CONCLUSIONS:
  • Solenoid (within gas valve) must be bad.
  • Need to replace gas valve.
  • Order same one, i.e. White Rogers Model 36C03 300, online..
INITIAL REPAIR STEPS (Photo 1):
  1. Turn off gas at large red handwheel.
  2. Remove gas valve via dissembling pipes around the valve unit.
QUESTIONS: (Photo 2)
  • Joint #1 & Joint #2 are very stiff and won't budge so far.
  • Would any special tools, besides crescent & pipe wrench, be required to loosen them?
  • Which joint should be worked on first -- J#1 or J#2?
  • Is it OK to use penetrating oil, WD-40, & hammer tapping to free them up?
-Thanks for any inputs.

Photo 1

Photo 2
 

Last edited by questioner; 09-16-22 at 03:47 PM.

Popular Reply

 
09-22-22, 04:19 AM
Geochurchi's Avatar
Geochurchi
Geochurchi is offline
Member
Join Date: Nov 2012
Posts: 5,583
Received 154 Votes on 140 Posts
Hi, I hate to say it, but I think it’s time you call a Pro, remember your messing with gas , that hand valve should probably be replaced also with a suitable replacement.
Geo🇺🇸
 
  #2  
Old 09-16-22, 03:24 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,583
Received 154 Votes on 140 Posts
Hi, I would leave joint 1 alone and unthread the valve from the pipe , as for #2 , are you sure that you are turning the nut in the right direction? forget the WD40 , possibly some PB Blaster could be used.
Geo🇺🇸
 
questioner voted this post useful.
  #3  
Old 09-16-22, 05:07 PM
Q
Member
Thread Starter
Join Date: Sep 2022
Posts: 7
Received 0 Votes on 0 Posts
Hello Geous:
Thanks for the reply and for your points which were much appreciated. You mentioned unthreading the valve from the pipe and I'm guessing that would be to grab valve, in hand, and attempt to turn it one way or the other. So, I'll incorporate that it into my work, Otherwise, about turning the nut in the right direction, I probably wasn't because Joint #2 confuses me -- it's like a large nut sticking up in the center surrounded by two smaller nuts, one on either side. So, I was still trying to figure out what's attached to what, exactly, and how these parts thread together. I'll be studying Joint #2 more closely before trying again, .
 
  #4  
Old 09-16-22, 05:31 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,108
Received 2,957 Votes on 2,668 Posts
A lubricant would probably not help.

That is called a union. It is three pieces. # 3 is the part that turns to open it.
You need two big pipe wrenches..... one on #1 and the other on #3.
The direction shown with the yellow arrow is tightening.


40 years old is very old for a heating appliance. Is that a furnace or a boiler ?
If it's a furnace and heats air... it MUST be routinely inspected for rust thru issues to keep CO out of the living quarters.

Volt meter reading indicates that thermocouple is functioning correctly.
As measured where ? What voltage did you see ?
Those gas valves rarely.... if ever... go bad.
Why don't I see the entire thermocouple line ?

 
questioner voted this post useful.
  #5  
Old 09-16-22, 06:05 PM
S
Member
Join Date: Oct 2013
Location: United States
Posts: 3,312
Received 99 Votes on 93 Posts
Q,
PJ has outlined the union for you. In your case you want to use at least 18" pipe wrenches or even a 24 and an 18". Use an 18 on the #1 nut closest to the burner using upward pressure to stabalize the union and then put your other wrench on #3 large nut which you will use downward pressure to unscrew towards the gas valve. That will seperate the pipes. From there you could put a wrench on the underside of the gas valve where the pipe goes in and you will lift upwards while holding the pipe between the valve and the gas shutoff with downward pressure so that pipe doesn't loosen.

Make sure you shut the gas off and remove the silver pilot line and the 2 wires from the gas valve before removing.

If it were me I would rplace the thermocouple first. Even though it's clean it still might have lost its properties to send a strong signal to keep the pilot lit.
The thermocoupe's job is to send an electrical signal to the main gas valve strong enough to keep the pilot on and let the MV know it's OK to open on a call for heat.
 
questioner voted this post useful.
  #6  
Old 09-17-22, 06:19 PM
Q
Member
Thread Starter
Join Date: Sep 2022
Posts: 7
Received 0 Votes on 0 Posts
Hello to commenters Pjmax, spott and, again, to Geochurchi:

I'm just now returning to DIY.com after a day's break from the furnace problem and must say that, on first read, these new inputs appear to be no less awesome than the first. I must make dinner, etc. now but will be returning ASAP to study and explore their details.

-Looking much forward to this and can't thank you enough for providing such informative posts.
 
  #7  
Old 09-18-22, 04:16 PM
Q
Member
Thread Starter
Join Date: Sep 2022
Posts: 7
Received 0 Votes on 0 Posts
Pj, S, Pete, Geo:
  • It's a boiler: Boiler # 6 W 253, Serial # 25 40 92
  • 82 yrs old via Google search as yr of Bryant furnace manufacture = 3rd & 4th digits of Serial #.
  • UNION...okay and Thanks!
  • Largest wrenches here are: pipe 14", crescent 12". -Could order new 18" & 24".
  • Regarding thermocouple & multimeter:
    1. This thermocouple was new replacement by professional service on 12/27/17.
    2. -Had moved thermocouple out of way in prior photos. Overall scene pic taken then:
    3. Just now retestedTC-- it went up to 30.8mv; then shot pic below at 22.8 mv.


Otherwise, thanks for reminders -- gas off, disconnect pilot line & 2 wires if valve removal necessary.

Next, I'll be further studying the descriptions of wrench placement and how/where to apply force.

-Much appreciation to you all for so generously sharing your knowledge!
 

Last edited by questioner; 09-18-22 at 04:37 PM.
  #8  
Old 09-19-22, 01:47 PM
S
Member
Join Date: Oct 2013
Location: United States
Posts: 3,312
Received 99 Votes on 93 Posts
If your only purpose for the larger wrenches is this job then a suggestion would be to put an extension pipe over the handles of your wrenches to get more leverage which is the same as a larger wrench as long as the jaws open wide enough for the part you're removing. Don't forget the pipe dope when reassembling.
 
questioner voted this post useful.
  #9  
Old 09-21-22, 07:39 PM
Q
Member
Thread Starter
Join Date: Sep 2022
Posts: 7
Received 0 Votes on 0 Posts
Replacing Valve Update

Hello again:
  • Extension pipe over wrench handle for leverage tip -- thanks, much appreciated.
  • Using some pieces of an old floor-to-ceiling metal bookcase for this purpose. (Photo 1)
  • Union nut #1 was moving but then handwheel and valve became offset. (Photo 2)
  • Placed jack under valve to stabalize it and prevent further movement. (Photo 2)
  • Handle #1, Union Nut 3: Downward force, clockwise, screw. (Photo 3)
  • Handle #2, Union Nut 1: Upward force, couter clockwise, unscrew. (Photo 3)
  • No pieces have come apart from each other, or are even moving freely, yet though.
  • 18" wrench to arrive tomorrow.


 
  #10  
Old 09-22-22, 04:19 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,583
Received 154 Votes on 140 Posts
Hi, I hate to say it, but I think it’s time you call a Pro, remember your messing with gas , that hand valve should probably be replaced also with a suitable replacement.
Geo🇺🇸
 
CircuitBreaker, questioner voted this post useful.
  #11  
Old 09-22-22, 02:29 PM
S
Member
Join Date: Oct 2013
Location: United States
Posts: 3,312
Received 99 Votes on 93 Posts
You have the wrenches going the wrong way.
The wrench on the center nut must be pulled UPWARD and NOT DOWNWARD.

The backup wrench must go on the other nut on the side of the ELBOW and must be connected so you are using DOWNWARD PRESSURE as backup.

When you look at your union one side of the large nut has a FLAT SIDE and the other side, in your case, the side facing the ELBOW is open wear it is being threaded onto the other nut.

Your gas valve is turning because you are tightening that pipe because of your wrench positions. You have plenty of wrench leverage with those just position properly and it will come apart.

The union in the pics that Pete has mark are being assembled and dismantled from the opposite side of the way you are working so you must allow for that.
 
questioner voted this post useful.
  #12  
Old 09-24-22, 02:52 AM
Q
Member
Thread Starter
Join Date: Sep 2022
Posts: 7
Received 0 Votes on 0 Posts
Hello again:
  • Appreciation to G for the word of “caution” and am taking this under advisement.
  • Phone call, yesterday, to my HVAC specialists revealed them to be currently out of commission, though, so need to look for an alternate.
  • I've just now, anyway, returned to DIY.com to discover the new message from S.explaining my errors. Many thanks for this and wish I'd found your post sooner. Turns out I'd come to a new understanding of the union, in the meantime, however, which enabled (1) separation of its parts and (2) return of handwheel to its prior position. (Photo 1)
  • Will, next, be examining how to remove the pilot valve.
  • -Likely need to replace union piece #2, as well, as it got pretty beat-up. (Photo 2)
    As for the hand valve it seems to be working okay. This was good thing to assess but will probably leave alone for now



-Further gratitude for the amazing support you've all provided!
 

Last edited by PJmax; 09-24-22 at 10:38 AM. Reason: labeled pic
  #13  
Old 09-24-22, 10:44 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,108
Received 2,957 Votes on 2,668 Posts
As long as the ground beveled flange on #2 has not been damaged.... don't replace the union.

Using those two wrenches.... put one on fitting A and pipe B.
Righty tighty - lefty loosey.
Removed B and C from A.
Put the valve carefully in a vise if you have one to remove pipes B and C.
If no vice... put flat on the bench. Hold the valve down and remove one pipe at a time.
Reinstall pipes on new valve using joint compound.
A to B will also require fresh joint compound.
 
questioner voted this post useful.
  #14  
Old 09-25-22, 09:49 PM
Q
Member
Thread Starter
Join Date: Sep 2022
Posts: 7
Received 0 Votes on 0 Posts
Hi there:
Thanks to P for the new post and progress has been made since I received it earlier. (Photos 1-3)
Photo 1: A, B & C

Photo 2: Removed segment [B, Valve, C] and transferred it to vice.
Photo 3: Union Part 2 gripping faces got flattened but beveled flange is probably still good.

Next, will be doing these things:
  • Reinstalling pipes on new valve using joint compound.
  • Reinstalling segment [B, Valve, C] at A and at union Part 3.

Question: In addition to joint compound, is it okay to use thread tape on any or all of these joints? (Photo 4)

Photo 4: Blue Monster PTFE -- Pipe Thread Sealant & Tape

That's all for now and thanks again!
 
  #15  
Old 09-26-22, 11:55 AM
S
Member
Join Date: Oct 2013
Location: United States
Posts: 3,312
Received 99 Votes on 93 Posts
q,
Tape not necessary but if you use it start winding at least 1-2 threads back so the tape doesn't break off and get stuck in the gas components and always thread clockwise so when winding in pipe the tape will not loosen.

As long as the bevel part of the union is unmarked it is fine.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: