Water heater trouble shooting

[JJ 109]

Woke up to a cold shower.  Haven't even looked at it yet.  Is there a troubleshooting guide I can use when I get home?

It is a high efficiency gas with PVC exhaust with fan.

[abaesemann]

Need a model number, we have no idea what you have to even start to help you.

[JJ 109]

Ill post up when I get home.  I figured the basics are the same, so I could have a place to start.

[BryanS]

Well does it have a pilot lit? If not my guess would be the flame arrestor needs cleaned.  Usually that's what I typically find wrong with them.  This info is for a more basic gas water heater though. I don't know about the high efficiency,  but if you get a brand and model I may have some info in my water heater paperwork

[JJ 109]

It is a Bradford White model number MITW50L6EN12

[BryanS]

Ok. I have an AO Smith book here on high efficiency water heaters.  They make a lot of models so it may be close.  SSequence of operations are:

1. Call for heat flashing on screen

2. Gas valve/tstat will do a relay check

3. Display will show temperature set point during the call for heat.

4. Draft blower is energized

5. System will verify pressure switch operation and start a 5 second pre-purge, then air intake fan will turn off

6. Ignitor will start a 12 second warm up period

7. Gas valve/ tsat will open for a 4 second trial for ignition and fan will turn on

8. Main burner flame is detected by flame sense rod. Air intake fan and main burner will continue to operate until water temperature inside the tank reaches temperature setpoint

9. Gas valve de-energized and air intake fan continues for a post purge time of approx.  5 minutes

10. Returns to standby.

 

This should be fairly close.  These are actually almost just like a gas furnace control wise.  Follow the sequence and report back what you find or where the sequence doesn't continue.

[BryanS]

[BryanS]

I'm not sure how well you can see that. I used a phone scanner app because my regular scanner doesn't seem to be working.

Edited February 10, 2016 by BryanS
I can't type

[JJ 109]

Thank you. While you were doing that, I went to check it out. I jumper'd the pressure switch and it fired off. The blower is not starting.  Upon further inspection it is also very hot, so appears to be stalling. 

Looks like time to replace blower. 

[BryanS]

Awesome. Yea if the switch works jumpered then you could have a faulty switch or a blocked exhaust, but in your case I'd say blower sounds like the issue.  If it doesn't read that pressure difference, then of course it won't fire up.

[JJ 109]

Verified the switch.  It's open then with I apply vacume it closes.

Now just need one of theses:

[BryanS]

Just a thought. You may want to take it off and inspect the wheel/exhaust pipe.  I know a lot of guys on gas furnaces find critters in the wheels

[JJ 109]

Will do , thanks again. 

[JJ 109]

Ok, now I'm having another issue. The igniter comes on, pilot light, burner ignites and then goes off a couple seconds later. Does this ~3 times then gives up.

flame sensor?  Is there a way to verify?

[BryanS]

http://heatingandaircooling.com/2012/11/16/how-to-test-flame-sensor/

 

See if that helps. Basically a microamp reading. The article suggests cleaning with a scotch brite pad.  I've heard using a dollar bill worka too. Basically,  if the flame sensor gets coated it will won't pull amperage when the flame is present.  Apparently,  microamps can vary by application.  Like I said these operate pretty closely to a gas furnace, so the same info should help.  Also you may want to jump out that pressure switch again to make sure that isn't giving you any issues still. 

[JJ 109]

I just cleaned it and it is still cycling off. I'm starting to think one one of the coils in the valve is bad?

[BryanS]

I'm not sure what else to say without checking microamps.   You need a meter capable of checking microamps.  If the amerage is there and valve isn't staying open then the valve may be your issue.  

[JJ 109]

?   Any othe thoughts on what would cause it to cycle on/off?  This is probably what caused the blower to fail. 

Im about to scrap this thing . Frustrated.....

[JJ 109]

11 hours ago, BryanS said:

I'm not sure what else to say without checking microamps.   You need a meter capable of checking microamps.  If the amerage is there and valve isn't staying open then the valve may be your issue.  

Can you explain where you want to check the current?

[JJ 109]

Please help stuck. 

 

Should i I just replace gas valve?

[JJ 109]

??

[JJ 109]

Ok, now I'm really frustrated. 

Replaced the gas valve, igniter, and flame sensor and it still keep cycling off. 

Im not sure what's left. 

Would really appreciate any help.

[JJ 109]

Here is a video of what's happening:

 

[Budget Appliance Repair]

First thing so that maybe someone else can give some help is your model number is wrong, you posted it as: MITW50L6EN12 the second character of the model number should be the number "1", not the letter "I".

Correct model# M1TW50L6EN12

This should be the service manual for your water heater www.bradfordwhite.com/sites/default/files/product_literature/238_39935_00.pdf

You say you have a bad fan motor, (draft inducer), but I don't see any place that you said you replaced it yet.

I only see you 

Quote

Replaced the gas valve, igniter, and flame sensor and it still keep cycling off. 

Are you bypassing the pressure switch to try and get it to work just to see if everything else is OK before replacing the draft inducer motor?  (That doesn't seem likely since you said you already replaced gas valve, ignitor and flame sensor).

But from you video, I don't hear any fan motor and your flame all falling down like it is doing tells me you don't have correct air flow out exhaust for flame to burn correctly and most likely shutting down on a heat/thermal sensor.

Does your gas valve have any kind of status/flashing led lights?   I don't think it does but if it does there is another manual that should have the codes.  I'm pretty sure yours is an older model without the smart valve that has the flashing status/error code led.

Here's that manual: http://www.bradfordwhite.com/sites/default/files/product_literature/45960A.pdf

Even if the above 45960A manual isn't for your valve type it has very good testing and disassembly instructions that should somewhat pertain to yours.

Edited February 15, 2016 by Budget Appliance Repair

[JJ 109]

Thank you for your response and the manual. It is an "I" not 1, even says MITW50 on manual. 

You are correct, I did not have the fan when I ran this test, I just had the pressure switch and high temp switch jumped.  

I was just trying to verify the fan was the problem.  I didn't see anyway it would know the difference.  

I have it now and will try in tonight with fan running