Any Rheem modulating furnace techs out there? trouble with mine.
 

I have a 60,000 BTU Rheem modulating furnace which hasn't modulated for more than a day before it quites and only runs on single stage. I have the Rheem touch screen thermostat which I have thought has been the problem. I replaced it today and the furnace modulated for an hour then quit again.

This furnace was installed 9 months ago but the guy who installed it is now out of business.

Are there any Rheem HVAC experts out there in Pelican land?

Speedy:)

Is it firing on low or high fire?

Does your furnace have the sensors in the supply and return air ducts?

Can you see the led flashing on the circuit board?

If you can the codes are usually listed on the inside of one of the doors.

It could be an airflow issue. (dirty filter, blocked return air duct)

Try contacting Rheem, they should refer you to an authorized dealer that should honour the manufacturers warranty.

The problem is the warranty only covers parts and not labor. The nearest Tech is 40 miles away. I am upset that the furnace has not worked since installation and now since I am a broke college student I would rather put my money toward books than to pay somebody to fix a furnace which hasn't worked right from the very beginning. In my mind the installation is still not complete but since the guy went out of business I am stuck.

If I go into the installation configure mode in the thermostat I can manually modulate the furnace by changing the set-points anywhere from 35 to 95. This is telling me the furnace itself is able to operate correctly but the thermostat is not working in auto. In my last post I mentioned when I installed the new thermostat the furnace modulated for about an hour and then quit modulating. Is there something wrong with the system which could cause the thermostat to malfunction within an hour?

Speedy:)

I'm rusty when it comes to residential furnaces however if you replaced the thermostat and the same thing is happening the problem is somewhere else.

Did this problem just happen or has it been like this since day 1?

When you replaced the thermostat did you wire it the same way as the installer? If so maybe the installer wired it wrong.

If you can acess the circuit board there should be small Dip switches on the board that control the furnace. It's possible that it's set up for high fire only.

Did the installer leave a manual?

Sometimes there is a sticker on the inside of one of the doors that can help.

When I replace the thermostat it modulates for an hour then quites modulating. I wonder if something is blowing the thermostat.

The problem has been pretty much happenening since day one. When it was first installed the furnace modulated for a couple days then died.

The thermostat has been wired the same since day one and looks to be wired correctly.

I have the manuals for the furnace and the thermostat and pretty much have them memorized by now try to sort this out. All the DIP switches are set correctly per the manual for modulating.

I have sent the furnace through a calibration cycle where the furnace runs through a sequence of modulating steps. The furnace ran flawlessly through the calibration cycle.

The V signal wire from the thermostat is what controls the modulation of the funace and is controlled by pulse width similar to a fuel injector. How do I measure pulse width. Do I need an ociliscope?

Speedy:)

I remember seeing a Rheem furnace at a trade show 5 years ago ane the rep said there were sensors in the supply AND the return ducts. Did the installer forget to install the sensor or has the return sensor been eliminated by the manufacturer?

What would happen if you removed the supply sensor and try to cycle the furnace?

I'm wondering if the W1 and W2 wire are not reversed between the board and the t-stat.

I know I asked this before but aren't there any diagnostic LED's? I'm more familiar with Carrier 2 stage furnaces and they have 3 LED's on their board.

The sensors that I use in commercial set-ups (Tekmar Controls) measure ohms. I don't think you will need an ociliscope.

Hope this helps.

Speed: You may have better luck on a forum specific to your question. Here's one of a few.... http://www.hvacmechanic.com/forums/forums.htm

I found out what the problem was...
when I would adjust the temperature sensor calibration the thermostat locked up and wouldn't allow the furnace to modulate. The fix is the NOT calibrate the thermostat and then reset the thermostat by holding down the temp up, temp down and the system button for 5 seconds. This reverts the thermostat to factory settings. Boy it would of been nice if the manual would of had these instructions in it and 1 out of the 30 people I called with this problem had any idea what to do.

Rheem modulating furnace model number RGFD-06EMCKS 60,000 BTU

Speedy:)