water heater power vent won't stop running


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Old 08-26-08, 03:06 PM
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water heater power vent won't stop running

I have a Kenmore Power Miser 9 (model 153.335916) that is just about 5 yrs old. The power vent fan won't stop running unless i turn it off manually. Please help
 
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Old 08-26-08, 06:25 PM
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Has it always been like this or is it something new?
 
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Old 08-29-08, 06:31 AM
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It has functioned perfectly fine up until this point - I had it installed just about 5 yrs ago. I do not have any problems getting or obtaining hot water. After heating the tank, the gas returns to pilot mode, while the fan just runs & runs. The red light that is supposed to indicate that fumes are present to turn on the blower is not lit, but the fan runs anyway.
 
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Old 08-29-08, 07:16 AM
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OK, I just tried finding your water heater on Kenmore's web site and could not find your model.
Is the power venter attached to the water heater? Is it LP or Natural gas? What size tank is it? What is the warranty date? (most likely 9 yrs.)

I am thinking that on a call for heat, the power vent gets energized and goes through a pre-purge period. During this time, the if the venter is working properly, the pressure switch is activated and sends power to the gas valve, through a few safety swithches. Once the gas valve is energized, the pilot will light, thus sending a signal beack to open the gas. You will then begin to heat the water until the thermostat on the front of the water heater is satisfied, shutting off the gas, and causing the venter to go into a post purge. After about 30-60 seconds, the venter should shut down, unless anytime during this process, a sensor is tripped, shutting down the entire system until repaired.

So using what I have just explained to you, I would be looking at a possible bad pressure switch or the line going from the switch to the venter.
 
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Old 08-29-08, 01:25 PM
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go to sears.com, parts, & enter the model #153.335916, it comes right up. It's 50gal, natural gas, power vent is attached, 9-yr tank warranty, 4-yr parts.

http://www.searspartsdirect.com/part...5916&pop=flush
 
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Old 08-29-08, 01:55 PM
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Hi,

Thanks for that site. I just bookmarked it for future reference. I went in through Kenmore and could not find it.

It looks as though Kenmore wants you to buy a new blower assembly, But it may be as simple as moisture in the pressure switch line or dirt in the pressure switch. I could not tell if the pressure switch is user serviceable.
 
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Old 08-29-08, 02:07 PM
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yes that tube runs from the blower down into a black circular switch near the manual on/off switch for the blower. it's the only switch I can see, so I guess I'll replace that one & see what happens

thanks
 
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Old 08-29-08, 02:36 PM
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Try tapping on it a few times first. It could just be a piece of dirt. Also pull off the tube, blow through it, and check the ends where it connected with a paper clip for any debris.
 
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Old 08-29-08, 03:04 PM
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Originally Posted by mikeperu
yes that tube runs from the blower down into a black circular switch near the manual on/off switch for the blower. it's the only switch I can see, so I guess I'll replace that one & see what happens

thanks
Better yet, if you handy with a multimeter, check the terminals on that switch to see if you have voltage through it when there is no call for heat. Either that or unplug the water heater and check to see if there's continuity.

Edit: thinking about it, it isn't likely that. The pressure from the blower is what closes that switch. I'll have to check one of the water heaters at the shop to see how the blower energizes.
 
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Old 08-29-08, 03:24 PM
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The problem here is not engaging the blower, but dis-engaging the blower. If it is manually reset, the unit starts, but it never shuts off.

The only things could be the pressure switch, or what activates it, or possibly the post purge timer could be stuck

It starts up, fires, runs to temp, but never shuts down. It has to be one of the above.

If you disconnect the tube, leaving the other end connected to the pressure switch, you can blow or suck to check if the switch is manually working. It will make a clicking sound. Then you could ohm out the switch to check for continuity when close and negative continuity when open. If the switch is working properly, you want to check the post purge timer. It may be stuck in the on position and only de-energizing it will reset it.
 
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Old 08-30-08, 05:39 AM
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Originally Posted by plumbingods
The problem here is not engaging the blower, but dis-engaging the blower. If it is manually reset, the unit starts, but it never shuts off.
I understand what you are saying, however, in the sequence of firing, the blower starts up before the pressure switch closes. Once the pressure switch closes then the ignition process begins.

With that said, on a perfectly working water heater if you disconnect the tube on the pressure switch when the flame rectification is present the only thing that happens is the flame goes out. The blower will still remain energized. Agree?
 
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Old 09-01-08, 05:44 AM
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tapping & blowing through the tube was no help. I have noticed there's a manual reset button for the fan on the top that doesn't appear to function at all. I cannot press or toggle the button at all and disconnecting the 2 wires that attach to the leads of the switch has no effect at all.
 
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Old 09-01-08, 06:33 AM
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When blowing through the tube, did you hear a click? Did you try sucking on the hose, and if so was there a clicking noise?
For the pressure switch to be working properly, while placing positive or negative pressure to the switch, should activate the switch making a clicking sound. Some work on positive and some work on negative pressure. That is why I say to check both ways.
 
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Old 09-01-08, 06:42 AM
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Originally Posted by hankhill6018
I understand what you are saying, however, in the sequence of firing, the blower starts up before the pressure switch closes. Once the pressure switch closes then the ignition process begins.

With that said, on a perfectly working water heater if you disconnect the tube on the pressure switch when the flame rectification is present the only thing that happens is the flame goes out. The blower will still remain energized. Agree?
If the sequence of operation is correct as you state, then when the water heater calls for hot water, the blower is energized, then the air switch closes and allows the burner to fire, once satisfied, the burner stops and the post purge begins. after approx. 45 seconds the pressure switch should open allowing the blower to stop.

If we have a bad pressure switch that is stuck in the close position, you would not need the switch to prove and send power to the burner, so that will continue as normal. BUT after the burner shuts down and the blower goes into a post purge, the pressure switch never opens to shut off the blower.

Hence my reasoning for the problem to be the pressure switch.
 
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Old 10-24-08, 09:24 PM
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water heater power vent wont shut off

i had the same problem with my state H2O heater. I was cotinuously running down stairs and tapping on the switch that controlled the blower operation. It should be right infront of the gas valve. I put a piece of aluminum foil between the switch and the pole that the switch slides in on. I've cycled the heater 10 times and it seems to be working perfectly. I believe that the switch is not carrying the current effectively and the foil is helping the current transfer more effectively as there is a bit of a gap between the pole and the switch that slides over it. I will repost if this soloution fails after further testing.
 
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Old 11-08-12, 07:46 AM
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I had the same problem with my State Waterheater. The only thing that works is disconnecting the wiring harness that leads to a switch where the pilot line starts. I've been doing this for a year now. Good thing its loud enough that I can hear it running and now to do this. Its a 12 year old 75 Ga unit that I'm not replacing until it dies completely.
 
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Old 11-11-12, 07:18 AM
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Old thread. I am closing.
 
 

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