Troubleshooting intermittent operation of RHEEM RGRA-12ERAJS


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Old 02-14-13, 07:42 AM
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Troubleshooting intermittent operation of RHEEM RGRA-12ERAJS

‚ÄčThe current problem with the furnace is that it will try to start and will fail because of not being able to close the pressure switch. After a few attempts it goes into a lockout mode.

I would go and open the top compartment, disconnect the rubber hose from the inducer and I would see a little water in that port. So I would try to suck the water out, reconnect everything and the furnace would fire without any hesitation. And can run a day without issues or only a few cycles. In which case Iíll repeat the above procedure.

What Iíve checked and done:

  1. Pressure switch was replaced to rule it out.
  2. I disconnected rubber drain hoses and flushed them with water/bleach mixture. Water run freely through the hoses to the trap and down to little electrical pump
  3. With furnace running I went outside to observe intake and exhaust pipes. Iím not a pro, but it looked like the suction was good and the exhaust was blowing strong.
  4. Earlier this heating season I had a humidifier installed (Aprilaire 600). Can it cause an excessive humidity? It is installed on the return plenum as a bypass. So humidified air is going though the filter and up the supply.

Is there anything else I could check myself before calling a professional?
Since the problem is intermittent I donít want him to be on a wild goose chase and start replacing/fixing what is not broken.

I might have an access to a manometer. Should I just verify the suction the inducer creates? When the furnace fails to start, the motor feels warm to the touch. Maybe itís failing.

Thanks in advance.
 
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Old 02-14-13, 12:48 PM
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This is a condensing gas furnace.

Apparently you are finding water in the plastic tubing connecting the inducer motor housing with the pressure switch whenever the furnace fails to light --- is that right?

Removing the water reliably allows the furnace to operate for a while--- is that right?

How many plastic tubing connections are there to the pressure switch --- one of two would be the likely number.


How much water do you see in the plastic tubing? enough to block the tubing itself?
 
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Old 02-14-13, 01:04 PM
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Thanks for getting back to me.

Apparently you are finding water in the plastic tubing connecting the inducer motor housing with the pressure switch whenever the furnace fails to light --- is that right?
More like inside the plastic nipple on the blower itself where a rubber hose is connected.


Removing the water reliably allows the furnace to operate for a while--- is that right?
Correct

How many plastic tubing connections are there to the pressure switch --- one of two would be the likely number.
Pressure switch is with one rubber hose connection, 2 contacts. Two pressure switches total

How much water do you see in the plastic tubing? enough to block the tubing itself?
I wouldn't say so. But if I suck on the hose when it's connected to blower, i can feel little water in my mouth. But no more that a drop or so. Don't actually see water in the rubber hose itself.

 
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Old 02-14-13, 01:20 PM
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>


So you are finding a droplet of water inside the nipple of the inducer motor housing --- is that right?


There isn't a flow of air through the plastic tubing to the pressure switch. It's mostly just a static pressure transmitted to the pressure switch from the inducer motor housing by the plastic tubing.

You shouldn't be getting water there. That you do implies that the water drainage system of the furnace isw plugged up.

You should see a plastic water trap and hoses which drain water away from the furnace. The water trap in particular has a tendency to get plugged up with mold and dwebris which blocks the drainage of the furnace.

So I'd start by checking that trap and flushing it out with fresh water to clean it, and inspecting the rest of the tubing and drain lines for any blockage.
 
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Old 02-14-13, 01:29 PM
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As i mentioned in my post, I actually flushed the hoses connected to the trap with water/bleach solution and the water went through the trap down to electric water pump without any issues.
The trap itself is kind of glued to the PVC piping going to the electric pump, so I wasn't able to remove the trap and rinse it. I just don't want to brake anything and make it worse.
 
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Old 02-14-13, 03:11 PM
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Thw next step would be to remove and inspect the inducer motor fan. Usually the inducer motor, fan and some sheet metal bolt onto the furnace sheet metal, and the entire assembly can be unbolted and removed pretty easily.

Inspect the fan wheel for debris, damaged or missing blades. Check to see if the fan wheel turns easily or is stiff and hard to turn. Power up the inducer motor and see if it appears to start up easily and come up to what seems like a normal operating speed.

Examine what you can see of the heat exchanger for any debris, gunk or plugging. You should be able to pour water into the exposed heat exchanger and see if it drains out the furnace easily. You might be able to use a spray nozzle to see if debris or gunk is present and can be cleaned out, or whether the exposed heat exchanger is clean and free of debris.
 
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Old 02-14-13, 06:02 PM
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By inspecting the heat exchanger you mean I should look through the hole behind the inducer when I take it out. Correct?
Same goes to pouring water into the heat exchanger, through the opening behind the inducer.
I'll will do that tomorrow and report with the results.
Thanks for taking your time and helping me.
 
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Old 02-15-13, 03:22 PM
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Yes.

When you have the inducer assembly out, run a small drill bit by hand into the nipple on the housing that the plastic tubing connects to. Sometimes that can get plugged with crud and debris.
 
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Old 02-16-13, 01:19 PM
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A little update on the situation.

This friday morning when I had to restart the furnace, I didn't close the top section door all the way. I inserted the screws, but didn't tighten them. The furnace ran without a single fault till saturday 3 PM. That's the time when I decided to close the door all the way. The very next heating cycle the furnace failed as before (2 blinks for PS stuck open). At which time I measured the suction on the inducer motor. It showed 1.4 " WC. The rating on the PS is 0.8" WC.
This time I left the door slightly open to see how it will go.

From all the above, does it mean the air supply is not sufficient, or there is something else in play?

If it fails again, I'll remove the inducer for inspection.
 
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Old 01-25-14, 03:44 AM
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Dear Ubersl,

it has been about a year from your last post on this topic, but I was wondering if you ended up solving your problem. I have the same unit with the same issue, including the fact that everything works fine if I leave the door open. The vent is clean, but as soon as I close the door the pressure switch (which I replaced to make sure that it didn't go bad) opens and I get the double blinking green light. Do you have any advice? Thanks!
 
 

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