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Old 03-04-2011, 11:02 PM   #1
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Old rheem hvac problem


I have a Rheem 3.5 ton HVAC unit. Someone took the model identification off of both my units. The house was built in 1978 and they are both 4 burner units. My home is approximately 2000 sq ft.

I called out a repairman and after we spent $500 to replace four tube burners he suggested I may have to replace the Pilot Relite because It appeared the unit was getting a “weak spark”.

I've cleaned the terminals, and sanded the points, and all contacts with emery paper. For a while the unit cycled on and off and worked good. Then for a while the unit would only start after a couple of hours.

I replaced the Pilot Relite White Rogers 5059-22 with a 5059-23,which is the replacement item suggested.

Still the unit would only start after a couple of hours. Now after one cycle it will not start again, unless I trip the breaker in the unit, and then it is only good for one cycle.

I realize this is an old unit but I am this far along and believe that if I can fix something I should. I want to avoid spending an outrageous amount of money for a more “efficient” shiny new unit. I think the new units have things on them that will break more often. Also we are retired on a fixed income.

What would be the next item to replace and where would a circuit board be on one of these old units?

I hope this is enough information for someone to help. I appreciate your time and effort. Thank you for your reply.


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Old 03-05-2011, 11:11 AM   #2
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Old rheem hvac problem


New units don't break down anymore then old did/do.

Your unit is probably locking out on a temp or flame sense issue. it also burns a whole lot more gas then a new unit would. Sounds like you have 2-80,000 or 100,000 VTU units. And that is extremely over sized for 2,000 sq ft, unless you have no insulation at all, and lots and lots of windows, and leave the windows cracked open all day long.

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Old 03-05-2011, 11:49 AM   #3
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Thank you for your comments about the new units. I may have to purchase one at some point. Are any good ones made in the US? I want to start purchasing items made here if I can from now on.

Another responder on another forum suggested I probably have a 10,000 BTU unit. The insulation up there needs to be augmented. We changed out all of our windows to double pane about three years ago, which made an enormous difference. So the house was bleeding energy pretty bad.

I would pull out the tray where the burners and flame sensors are but I will have to disassemble all of the gas lines and unless I have the correct part to replace what is wrong, and I am confident that I know what I am doing, I hesitate to do that. I am competent to disassemble and reassemble the gas lines but do I need to buy a new flame sensor or just clean the old one?

The person who installed the new burners said he cleaned the sensor, but he also said he cleaned the terminals, etc. which he didn't so I don't know what was actually accomplished. I am certain he just wants to come out on another call and it costs us $100 each time just to come out. Although I respect the expertise of HVAC technicians, if it is possible I would like to do as much myself as I can.
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Old 03-05-2011, 07:41 PM   #4
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Old rheem hvac problem


See this YouTube video for cleaning sensor/thermocouple:

http://www.youtube.com/watch?v=I86jo...eature=related

Relatively easy to clean once you see it. Other parts should not have to be removed. Experts on this site advise wearing gloves and not using sandpaper.
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Old 03-05-2011, 11:05 PM   #5
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Thank you for your comments. I did see the video.
I'll go up tomorrow and see if I can get to the thermocouple. It may be, though, that the thermocouple on this unit is back where I can barely touch it.
I'm not very good with the termonology but there is a long wire connected to the igniter that goes back there, and there seems to be the flame detector (?) right next to it. something back there has a ceramic stem on it. Would that be a thermocoupler?

It was sure interesting to read the comments about the video!
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Old 03-06-2011, 03:13 AM   #6
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Quote:
Originally Posted by Daulton View Post
Thank you for your comments about the new units. I may have to purchase one at some point. Are any good ones made in the US? I want to start purchasing items made here if I can from now on.

All the common brand names are made in the USA. usually with parts made in other countries.

Another responder on another forum suggested I probably have a 10,000 BTU unit. Probably closer to 100,000.

The insulation up there needs to be augmented. We changed out all of our windows to double pane about three years ago, which made an enormous difference. So the house was bleeding energy pretty bad.


I would pull out the tray where the burners and flame sensors are but I will have to disassemble all of the gas lines and unless I have the correct part to replace what is wrong, and I am confident that I know what I am doing, I hesitate to do that. I am competent to disassemble and reassemble the gas lines but do I need to buy a new flame sensor or just clean the old one?

The person who installed the new burners said he cleaned the sensor, but he also said he cleaned the terminals, etc. which he didn't so I don't know what was actually accomplished. I am certain he just wants to come out on another call and it costs us $100 each time just to come out. Although I respect the expertise of HVAC technicians, if it is possible I would like to do as much myself as I can.
The flame sensor can be removed and cleaned without pulling the burner. Not always easy though.
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Old 03-08-2011, 04:25 PM   #7
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Day before yesterday I went to the roof and checked the furnace. I would definitely have to take apart the plumbing to get to the pilot and thermo-coupler. I used a latex glove and stuck my hand back in there and cleaned the thermo-coupler and pilot opening with steel wool.
Unit worked great until this morning again when it would not, (did not), ignite. It seems that when it's cold it hesitates but when the weather is warm it works great.
This morning I could smell propane after turning on the thermostat but no fire.
We'll see tonight what happens again.
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Old 03-09-2011, 01:17 PM   #8
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Last night I went home and switched on the heater. After about 30 min it went on and worked fine until I turned it off after several hours.

Do I have to take out the flame sensor to clean it? What I did with the steel wool seems to have helped. Do flame sensors wear out? Should I replace this or the thermocoupler, or both?

Our propane level is low right now. Would that affect the performance of the heater?


Thanks for your tolerance your wisdom and your reply
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Old 03-09-2011, 03:44 PM   #9
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Old rheem hvac problem


If you have a flame sensor, you don't have a thermocouple.

Could be the flame sensor is still dirty. Or the burners are dirty.
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Old 03-09-2011, 04:03 PM   #10
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Old rheem hvac problem


How low is low on your propane level indicator. It is possible that you can't vaporize enough propane in the colder weather to make the unit run properly, but can once it heats up outside. Usually you would want to be at 25% or more to maintain enough of a boiling surface area to provide you with enough vapor for cold weather. Just a thought.
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Old 03-19-2011, 07:10 PM   #11
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I was down to 5% propane. Now that the tank is full the unit has been starting within 30 minutes. This morning it wouldn't start until I left the house. I turned it on at 8ish and left about noon. During that time I had reset the thermostat, switched the power off and on..a couple of times.

I'm beginning to think the unit just doesn't like me.

Maybe you're right and the flame sensor is still dirty, or is just too old.

Thank you for letting me know that I don't have a thermocoupler. I think I will try to find out what type of flame sensor I have and replace it.

I did take my camera up there and I took photos of the flame sensor and of the electrical compartment.

Thanks for sharing your knowledge and for your help.
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Old 03-19-2011, 07:27 PM   #12
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Old rheem hvac problem


Does the unit have a proper and securely connected ground wire run to it? Through the flame to the cabinet there is electrical current to ground that affects the flames sensor's ability to sense flame/operate. No secure ground on unit and badda bing badda bang, no furnace only when it wants.

I think that's right anyways.
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Old 03-19-2011, 08:18 PM   #13
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Well, that's an issue I've thought about and when I cleaned all the connections in the "power box" on top, I re clamped the ground wire for the 220 line coming into the box.
Would that be the ground we are talking about? I also made sure the igniter was well grounded when I replaced it.

I've attemped to attach a photo of what I have..
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Old 03-19-2011, 08:22 PM   #14
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You're welcome Daulton. That specific grounding is measured in micro amps and will not be able to be read via a meter without that specific micro amp capability.

Never ever ever ever ground anything to a gas line or anywhere else, always make certain the ground wire is in tact all the way back to and connected in the ground bar in the home's electrical panel. From there that entire ground bar (with all ground wires from all circuits in the home) is grounded to earth via a wire to the ground bar buried in the Earth.

No tying neutrals together or anything else anywhere along the way. And that is electrical NEC code.

Good luck and let us know.
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Old 03-19-2011, 08:29 PM   #15
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Quote:
Originally Posted by Daulton View Post
Well, that's an issue I've thought about and when I cleaned all the connections in the "power box" on top, I re clamped the ground wire for the 220 line coming into the box.
Would that be the ground we are talking about? I also made sure the igniter was well grounded when I replaced it.

I've attemped to attach a photo of what I have..
You don't have a 220 line, you have two legs of 110 coming from A and B phase together to make up 220. 220 powered anything does not require a neutral wire but EVERYTHING electrical always needs a ground wire. The ground wire is green.

In your case I'm guessing you have romex with a white and a black and a green. The black and the white are your two individual legs of 110. The white is not a neutral, it is a hot, if you have romex which is residential electrical wire.

That ground wire needs to be checked (for continuity meaning it is not broken) to make sure it is making it all the way back to the panel. Sometimes the ground will drop off in a junction box along the way so even though you may see it in the panel and at the unit connected, it won't be connected in a junction box along the way so in fact there is no ground.

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