AO Smith water heater pressure circuit switch remaining open


  #1  
Old 06-21-15, 06:49 PM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
AO Smith water heater pressure circuit switch remaining open

Monty, I'm having the same issues as you. What did you do to fix?


http://www.doityourself.com/forum/wa...ning-open.html

I tried the jumper method mentioned above, the fan didn't turn on but after about 5-10 seconds I heard the pilot attempt to light and then turn off a second or two later.

I'm sure my pressure switch sensor is dead as I put my multi meter on it and it doesn't show continuity. I thought the jumper would fix, but I'm still here with error code 3 instead of error code 4 and no lit pilot.

I don't have a condensate tube, I checked the square vent tube and it's perfect. The barb fitting is also clear. I sprayed air through both with no signs of blockage. The unit is 5 years old GPVH 50 100
 

Last edited by lawrosa; 06-23-15 at 04:54 PM.
  #2  
Old 06-21-15, 07:52 PM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Pressure Switch

Dead...unless I'm doing something wrong
 
  #3  
Old 06-23-15, 09:40 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
To update this thread, I swapped out the pressure switch and all is working. Not sure why the jumper didn't work
 
  #4  
Old 06-23-15, 04:57 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
Jumper dont work as I recall. Its a normally open switch. Jumping it does nothing. If it did all safety switches would be jumped and the safety feature would be bypassed...

Welcome to the forums................
 
  #5  
Old 06-24-15, 05:05 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Weird! I've been part of the forum for years, though admittedly mostly a reader

Ok, so the saga continues. I swapped the pressure switch Monday night. Everything was working perfectly fine. Wake up this Wednesday morning and ice cold water

Head downstairs and error code four is back. Unplug the new pressure switch, take a one last ditch effort at jumpering and it worked (I probably jumpered in the wrong order previously). Water heater is on and at work.

Went to test the new pressure switch for continuity and I get a reading. Can't tell if I should be or

So, what do we think my problem is now? As I mentioned before, the brass barb fitting is clear and clean, the square tube is clean and clear, fan and everything else seems to work just fine.

Only thing I can think of is possibly the new pressure switch being stuck closed and that's why I'm showing continuity
 

Last edited by LarryM13; 06-24-15 at 05:33 AM.
  #6  
Old 06-24-15, 06:57 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
Only thing I can think of is possibly the new pressure switch being stuck closed and that's why I'm showing continuity
What did you actually jumper?? You tied the two wires together? These are spade connectors and something would of had to be made..
 
  #7  
Old 06-24-15, 07:38 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
I used a short piece of 12G wire I had leftover when I added outlets and lights to my basement.

The 12G wire was jumped between the two spade connectors which were previously connected to the pressure switch.

Based on this service bulletin http://www.hotwater.com/lit/bulletin/tb-a023-06.pdf jumpering makes sense if following the appropriate sequence as described earlier, the user can temporarily by pass this feature. (I assume until the unit needs to re-heat the tank and the pressure switch needs to be tested again)

I think I know why I showed continuity after I had the unit jumped and running. Since I still had the square tube connected, the pressure switch was then "activated" because the diaphragm was depressed thus closing the contacts and showing continuity.

So....I'm lost again and don't know what my issue is
Don't really understand why the new pressure switch worked perfectly on Monday night and not this morning
 
  #8  
Old 06-24-15, 08:51 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
Many things..

What size pipe is the heater piped with? How many feet and how many ells?
Is this the intellivent gas valve?
Did you do a resistance test on the HSI?

What actual error code are you getting? ie: vac-B-C?
 
  #9  
Old 06-24-15, 09:02 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
ERROR CODE 4 - PRESSURE SWITCH CIRCUIT REMAINS OPEN
Vac / Red Arrow / C


Vent pipe is straight to the roof. Not sure how many feet or change of directions as the house is finished.

It is an Intellivent
Not sure what the HSI is?
 
  #10  
Old 06-24-15, 09:15 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
Hot surface igniter = HSI.

Even though thats the code it throws it may not be the issue.

I cant get to the AO smith doc page but I have the service manual. I was an AO smith rep.

Often the wire harness from fan assembly to gas valve gets an intermitted short. Thats a possibility too. If the vent goes up then no worries there... 3"???

If you pull the molex connector from the gas valve for the HSI there is a black resistor on the molex end.Check ohms between pins of that resistor.
 
  #11  
Old 06-24-15, 09:16 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
This was taken immediately after replacing the pressure switch

 
  #12  
Old 06-24-15, 09:20 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Yes, the vent goes up, looks like 3" to me. The video above gives a glimpse of the size. There is a small reducer above that, but nothing dramatic like going to a 1.5". Seemed minimal.
 
  #13  
Old 06-24-15, 09:24 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
Larry it can be lots of things..

Look in the air intake. Since the cumbustion chamber is sealed the air intake screen may be clogged with lint. Remove screen and look in there and up.. Is there a layer of lint? Unit may be overheating. Whats the flame look like?

Take pics...

Also fans loose their CFM over time. And especially if your at the length limit of the exhaust pipe run.. How I test this is I remove the PVC vent from the fan to test only. If the unit starts normal then the fan got weak and cant pull in the switch consistently..

Test only. You will be letting CO in the home which could cause death

Wiggle the wire harness while the unit is running. Espeacially where it enters and exits the heater..may have some type of short..
 
  #14  
Old 06-24-15, 09:38 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Wow!

Thanks, too much info
 
  #15  
Old 06-24-15, 09:41 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
I will delete when you repond.

Set who can see what in your pics settings.....

Just trying to help you protect yourself...
 
  #16  
Old 06-24-15, 09:44 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks, I'll try those recommendations out above.

I took the fan assembly off the other day, completely cleaned the fan and air intake. Overall pretty clean other than some dust.

One item I found interesting was the gasket between the fan assembly and tank wasn't in good condition. I wonder if this is critical and may be causing me to lose pressure??? Don't think so because if I recall correctly the fan section is sealed within
 
  #17  
Old 06-24-15, 09:49 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
Check the air intake at bottom of heater. Should have black screen. Remove that and look inside and up... Take a pic. You can post pics from your computer if needed and not photobucket...
 
  #18  
Old 06-24-15, 09:51 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Great! Will check that as well.

Really appreciate all your help
 
  #19  
Old 06-24-15, 10:37 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Oh my oh my oh my...

While cleaning the fan assembly Sunday night, I noticed the flue assembly was awkwardly positioned. First I had no clue what it was and second I thought it was set that way since I have never touched the unit before this.

Reading page 11 of this document http://www.hotwater.com/lit/training/320988-000.pdf indicates the various potential issues. The last bullet point mentions flue gas temperature as a possible cause.

Fast forward to page 19 of the same document and the second picture labeled "Flue Restrictor Dislodged" is exactly what mine looked like!

Hopefully this is the problem!
 
  #20  
Old 06-24-15, 12:05 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
keep us posted on your findings and outcome
 
  #21  
Old 06-25-15, 04:13 AM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Got home last night around 6:30
Spent about 45 minutes taking the fan off, fixing the flue baffle, cleaning out the black screen at the bottom, fiddling with intelli-vent wires (including unplugging and blowing on them), checked the square tube again for defects. After all that, fired her back up and all ran fine! Checked again last night and the unit sat idle, checked again this morning while the wife was showering and the unit was running again! So far so good. Fingers crossed.

Black screen at the bottom






Didn't do any further cleaning of the fan intake


Gasket on the bottom of the fan assembly






Venting


Reduced to 2"




Up the vent


Messed up Flue restrictor




Flue baffles
 
  #22  
Old 06-25-15, 08:34 AM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 15,993
Received 85 Upvotes on 77 Posts
That round disk in there should be vacuumed. You need yo make a tool of some sort to attach to a shop vac. I use a piece of 3/4 PVC with an elbow on it. Search corderite disk...




Did you pull the baffle out and check it? I have seen them broken and pieces sitting on top of burner...
 
  #23  
Old 06-25-15, 12:10 PM
L
Member
Thread Starter
Join Date: Oct 2011
Location: USA
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
I did vacuum in there a bit, but was not thorough. I can easily do that.

I pulled the baffle up about a foot. I'll have to pull it out and give it a look.
I do hear an odd clanking sound in the tank like a rock is banging around. I thought it might be sediment, but when I flush my heater, the water is pretty darn clear pretty quickly.
 
 

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