DIY Home Improvement Forum banner

AO Smith GPSH water heater in System Lockout mode

83K views 32 replies 27 participants last post by  supers05 
#1 ·
I have a 5 year old AO Smith 'GPSH with Hot Surface Ignition' water heater that will not heat water. I will cycle the power and when it comes back on the fan will run for a less than a minute then kick off, then run for less then a minute and kick off, then it goes into System Lockout.

I checked the manual and it states these could be the issues

1. Gas supply is off or too low to operate - gas is on and working to stove and fireplace
2. Hot Surface ignitor not positioned correctly - ?
3. Low Voltage to the water heater - Don't know why this would all of a sudden happen
4. Electric Polarity to unit is incorrect- Don't know why this would all of a sudden happen


I am finishing my basement and have been cutting wood down there. I have tried to keep everything as clean as possible, could the dust have done something?

Thanks and any help would be appreciated. Ice Cold showers suck!
 
#5 ·
I found out what it was. It was a dirty Flame sensor. I guess it was thinking that there wasn't a flame \wasn't getting gas and kicking itself off. I unplugged the water heater, pulled the bottom plate off (1 screw, undid the gas line (turn off the gas first), and pulled out the burner assembly. I then took sand paper and cleaned the flame sensor, put everything back together and boom HOT WATER. It was less than 20 minutes and saved me at least $100. The flame sensor looks like this (on the right) if anyone finds this thread in the future.



Thanks for the help.
 
#23 ·
more appreciation

@abs777 - Had same problem. In the years since the original post my ignitor (now ceramic) / sensor looked like this (attached). I removed (two screws total one for access plate one for ignitor/sensor assembly --- did NOT have to disconnect gas lines), cleaned both (maybe a mistake with the ignitor) with 00 steel wool, reinserted and fired up. Hot water now.
 

Attachments

#26 · (Edited)
@abs777 - Had same problem. In the years since the original post my ignitor (now ceramic) / sensor looked like this (attached). I removed (two screws total one for access plate one for ignitor/sensor assembly --- did NOT have to disconnect gas lines), cleaned both (maybe a mistake with the ignitor) with 00 steel wool, reinserted and fired up. Hot water now.
I have the same ignitor/sensor as this one. I was in a foul mood because this hot water heater has been a pain for a few years.
I didn't remove the ignitor/sensor. I reached in with a small piece of 2000 grit sandpaper (what I had handy in my toolbox, I was too lazy to go looking for lower grit) and VERY lightly hit the top and bottom of that sensor. (I wasn't sure what I was supposed to sand so I very lightly did both). I only went 2-3 passes as I get nervous working with gas. (Electrical/Plumbing/Carpentry I can handle, but gas makes me nervous)
Put it back together, the unit fired up, ignited and stayed lit.

My question. Is this good? Or should I replace that ignitor/sensor assembly?
Also, I might sand it a bit more later on as I wasn't sure what I was supposed to sand and I went so lightly over both the ignitor and sensor that I can't imagine I did much.

BTW....THANKS!!!!! I was so peeved, and with the issues I've had with this unit, I was just going to bag it and have it replaced.
 
#4 · (Edited)
SOme of these newfangled heaters, particularly those with electronic control and motorized flues, also have an air filter for the combustion air and the filter could need cleaning.

If combustion air is from inside as opposed to a concentric intake/exhaust pipe to the outside, then your carpentry work down there could have made enough dust to clog the filter.
 
#11 ·
Thank-you ABS777

I too, had to register just to THANK-YOU!!

I am a female that has had nothing but bad luck lately:mad:..(sitting right now getting my air in my car fixed)...

Well not to change my luck I was taking a shower after mowing my 6acres and NO HOT WATER!!:furious:

My home is only 7 years old...warranty on hot water heater 6 years (haha).:(

Looked at the LED panel and seen I had a systems lockout problem.
googled it and found your solutions.:thumbup:

Printed off your solution along with your pic. :eek:

Called my son's dad (good think I never raised his child support payments when my son was young):whistling2: and with a little whinnning he came over and fixed it no problemo.

My finished walkout had flooded a few months ago and they just finished drywallying so the dust probably caused the issue.

Thank-you soooo much!!!:thumbsup:
 
#13 ·
Wow! Christmas evening and no hot water. Been having this issue but I had been able to just reset the heater and it comes back on after 3 or 4 tries. That would not work tonight. Finally was going to call a tech tomorrow and decided to jump online. Thank god I did. Thank you all for the help. Took out the sensor like the people above and it worked like a charm. Hope I don't jinx it by posting this. God Bless and Merry Chrostmas!
 
#14 ·
Looks like a recurring problem with a fix you can do yourself

:) This worked for me too. The unit would start up, the igniter would glow, the flame would light and then the system would shut down. It recycled about 3 times, then lockout mode. Then maybe after 30-60 minutes it would "try" again.

"Pulling the burner/ignitor/sensor assembly is fairly easy. Turn off gas, unplug unit, loosen/disconnect the gas tube going to the burner (below electronic/thermostat/valve unit) and disconned the wire assembly plug (again located below electonic assembly) then take off 2 nuts located on a metal panel at base of unit thru which the gas tube/ignitor/sensor wires traverse a metal panel. You can now pull the entire unit out and clean it. I suspect care should be taken to not touch the ignitor as it ceramic & fragile. I cleaned the sensor with fine steel wool, vacuumed the burner unit and the chamber within which this whole assembly resides. Then reposition unit and reconnect gas tube and wires to the "electronic control/valve/thermostat. Obviously care should be taken that the gas tube is reconnected properly. Check for leaks (I use an electronic hand held gas leak detector that I got from one of the big box stores for about $30 (I check all gas equipment as a safety measure from time/time)) when the unit is now (hopefully) working. Note gas only goes thru that tube/connection when unit is running.
 
#15 ·
I'll add that I just had to do the same at a Takagi tankless water heater which would cycle on and then quit, displaying a "12" error on the installed auxiliary thermostat.
 
#19 ·
Just in time for Christmas...My A.O. Smith Pro Max High Recovery 50 gallon tank, built in March 2008, is not heating water. The pilot is not out. It seems to kick on and off. Water is a balmy (ha) 80 degrees at faucets. My heating contractor has been here and is ordering a gas limiter valve. It won't arrive until the 26th; five days. Would the above instructions work? The plastic dust covers at the bottom of the heater were not very dirty. I haven't pulled any other covers off. My three teenagers are getting ripe. Anyone?
 
#22 ·
Thank you!!!!

This worked like a charm! We've been fighting with having to reset the water heater for a week until today when it just wouldn't reset. Husband was online looking up new hot water heaters when I found your thread. I had him try it....it's working great. Except now he's mad he can't buy a tankless ;) Thanks for saving us some $$$
 
#24 ·
I came here for this exact problem! Wouldn't turn on and showed a lockout code. I turned it off and back on and it seems to be fine now.

We had a one minute power outage just before it happened, but that might have been a coincidence.

Should I clean it or leave it alone? (Assuming it stays better...)
If I clean it, with steel wool, sandpaper, vacuum?
 
#27 ·
I also had this EXACT SAME ISSUE!!! Registered just to say thank you and to hopefully help others!

My hotwater tank model = GPSH 50 200

The sequence worked like this...

1. Blower activated...
2. Heating element activated...
3. Gas valve turned on...
4. Flame produced...
5. Flame went out after a few seconds

Thus no hot water for me, my wife, and two little ones.

I figured there must be some type of sensor that was an issue. I'm an IT guy not a HVAC/Plumber so I'm no expert!

The posts above (especially the picture!) showed me where the sensor was.

He is what I did to fix it.

1. Turned off the gas
2. Turned off the blower motor (there is a toggle switch on it. Just flip it.).
3. Turned off the power to the blower at the breaker
4. Opened the door at the bottom of the tank. You just need to remove 1 screw.
5. Sandpapered the dickens out of that thing in the picture in the post above...
6. Unleashed the vacuum on it...
7. Sandpapered it again for good measure...
8. Unleashed the vacuum again...
9. Put the door back on
10. Turned on the gas
11. Turned on the power to the blower at the breaker
12. Turned on the blower motor

MANY THANKS AGAIN FOR POSTING!!!!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top