Water Heaters - A.O. Smith Sealed Shot 50 Gal Gas W.H.
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DUNBAR PLUMBER
11-19-04, 09:03 PM
I was going to PM you Sharp, but I thought this one would be good for everyone to see.
I wanted to know if this is a common problem with the new sealed combustion chambers on water heaters with a sealed fresh air intake, along with sealed combustion vent piping.
A.O. Smith Sealed Shot 50 gallon Gas Water Heater (http://img.photobucket.com/albums/v70/DUNBAR/P1070005.jpg)
I can't say this is a problem but here is what happens:
Thermostat signals to blower to start
Heater initiates igniter startup
7 second warm up stage for igniter
In the second 7 second series, gas valve opens and allows gas to enter combustion chamber.
This water heater ignites, but when it does, WHHHHHHHHHHOOOOOOOOOOOOOOOOOOOOOOOSHHHHHHHHHHH!!!
The amount of unburned gas ignites and you hear this big combustion inside the unit, knowing that with a sealed chamber in the bottom, the flames have nowhere to go but up through the flue chase. The situation is very quick, but is startling to anyone not expecting it.
To clarify a bit, it's not the sound of explosion, it is the sound you hear if you throw gas on a burning fire, that huge sound of air movement that is drawn by the flames.
Everything is correctly installed, nothing changed. I contacted A.O. Smith and the exact words from the rep,
The ignition stage is 7 seconds from the time the gas valve opens once it completes all the safety features to reach ignition.
He also stated that if the ignitor is too close or too far away, the water heater absolutely will not operate. I explained the situation is grave detail, and the attitude from the guy was.......well, if there is nothing wrong with it, I have to charge you for the trip charge.
That led me to think this is a normal occurrence with the sealed shot models, even though he didn't flat out admit it.
The homeowner also stated that if you are on the deck in the back, you can hear this wooooooooosh from the 2 PVC pipes that serve as the fresh air intake and the exhaust.
To me personally, I don't like it, I didn't purchase it so I cannot be responsible for the operation of the unit, just the insurance that I installed to per say code, which I did.
The water heater has been installed 7 days coming this Saturday, heater cycles out properly, temperature is matching presets on the thermostat, and no vaccum leaks on the outgoing or incoming PVC pipes.
To me I think the time sequence (7 seconds) is too long of a time frame between the gas valve opening and the actual ignition of gas.
Opinions are welcome on anyone wanting to chime in on this one, this water heater is not malfunctioning to present a lockout on the thermostat, so I am trying to make sure that this is normal for the sealed combustion models in this product line.
Monday, I plan on going over the top of this rep and contacting A.O. Smith directly and inquire through tech support if this is a isolated situation or not.
This rep just recently replaced the former rep, and this guy seems to be uninterested in my situation.
Safety is my concern regarding this 'supposed' problem I am experiencing.
I wanted to know if this is a common problem with the new sealed combustion chambers on water heaters with a sealed fresh air intake, along with sealed combustion vent piping.
A.O. Smith Sealed Shot 50 gallon Gas Water Heater (http://img.photobucket.com/albums/v70/DUNBAR/P1070005.jpg)
I can't say this is a problem but here is what happens:
Thermostat signals to blower to start
Heater initiates igniter startup
7 second warm up stage for igniter
In the second 7 second series, gas valve opens and allows gas to enter combustion chamber.
This water heater ignites, but when it does, WHHHHHHHHHHOOOOOOOOOOOOOOOOOOOOOOOSHHHHHHHHHHH!!!
The amount of unburned gas ignites and you hear this big combustion inside the unit, knowing that with a sealed chamber in the bottom, the flames have nowhere to go but up through the flue chase. The situation is very quick, but is startling to anyone not expecting it.
To clarify a bit, it's not the sound of explosion, it is the sound you hear if you throw gas on a burning fire, that huge sound of air movement that is drawn by the flames.
Everything is correctly installed, nothing changed. I contacted A.O. Smith and the exact words from the rep,
The ignition stage is 7 seconds from the time the gas valve opens once it completes all the safety features to reach ignition.
He also stated that if the ignitor is too close or too far away, the water heater absolutely will not operate. I explained the situation is grave detail, and the attitude from the guy was.......well, if there is nothing wrong with it, I have to charge you for the trip charge.
That led me to think this is a normal occurrence with the sealed shot models, even though he didn't flat out admit it.
The homeowner also stated that if you are on the deck in the back, you can hear this wooooooooosh from the 2 PVC pipes that serve as the fresh air intake and the exhaust.
To me personally, I don't like it, I didn't purchase it so I cannot be responsible for the operation of the unit, just the insurance that I installed to per say code, which I did.
The water heater has been installed 7 days coming this Saturday, heater cycles out properly, temperature is matching presets on the thermostat, and no vaccum leaks on the outgoing or incoming PVC pipes.
To me I think the time sequence (7 seconds) is too long of a time frame between the gas valve opening and the actual ignition of gas.
Opinions are welcome on anyone wanting to chime in on this one, this water heater is not malfunctioning to present a lockout on the thermostat, so I am trying to make sure that this is normal for the sealed combustion models in this product line.
Monday, I plan on going over the top of this rep and contacting A.O. Smith directly and inquire through tech support if this is a isolated situation or not.
This rep just recently replaced the former rep, and this guy seems to be uninterested in my situation.
Safety is my concern regarding this 'supposed' problem I am experiencing.
rav12
11-21-04, 11:31 PM
Maybe I can be the first to chip in my 2c.
I also agree that it sounds a bit dubious that the gas valve opens 7 secs in advance of the ignitor being ready to cause combusiton. I would have thought the logical sequnce would be to open the valve when the ignitor has reached operating temp. I presume this is a hot surface ignitor.
If the ignitor is a spark type, then I think it is quite reasonable to open the valve at the same time as the first spark attempt. If the ignition is spark and it is taking several secs to ignite there may be a problem.
The installation manual may confirm that this is the correct sequnce of operation. Does it give any clues.
I also agree that it sounds a bit dubious that the gas valve opens 7 secs in advance of the ignitor being ready to cause combusiton. I would have thought the logical sequnce would be to open the valve when the ignitor has reached operating temp. I presume this is a hot surface ignitor.
If the ignitor is a spark type, then I think it is quite reasonable to open the valve at the same time as the first spark attempt. If the ignition is spark and it is taking several secs to ignite there may be a problem.
The installation manual may confirm that this is the correct sequnce of operation. Does it give any clues.