The fireplace guys came out Monday. They cut a hole in the drywall in the master bath in order to get access to the side of the fireplace where the outside air combustion duct connects.
The objective was to determine if the damper that feeds outside air is opperating correctly and doesn't have a shipping screw interfering. They did find a screw but it was not interfering with the damper. So I guess that means that I'm not screwed! Actually, I was hoping I was screwed because that sounded like a simple fix.
The next thing done was to inspect the ACC (automatic combustion control) to make sure that it was letting air properly into the firebox. The beauty plate in the front of the fireplace was removed by unscrewing 5 screws. Then an access panel was removed in order to see the ACC control mechanism.
My wife placed a mirror below the ACC control in order to get a good view of the mechanism. The mirror in the picture has a blue plastic frame around it.
The fireplace guys were not familiar with this fireplace but have a lot of experience with Northstar fireplaces that are made by the same company that makes our Quadrafire 7100 fireplace. The workers said that the hole that feeds air to our firebox looked small to them. They took a picture of the hole and said they would send it to Quadrafire and ask them if the hole was supposed to be that small.
The mirror shows the ACC control as if you were lying down and looking up to see underneath the front of the fireplace. You can see the oblong shaped hole centered in the mirror. That hole feeds combustion air into the fireplace. The ACC control is partially covering the hole. In the picture, the ACC control is fully open but appears to be covering half of the combustion air hole.
I carefully read the manual. It states the ACC setting is on "Low" if the ACC control is positioned fully to the left. The "Medium" setting is with the ACC control positioned between 1/8" and 1/2" from the left. "Medium High" is between 1/2" and 1 1/2" from the left. "High" is all the way over to the right.
I took out a tape measure and positioned the ACC control at each of the settings so I could see how much of the hole was covered at each setting. When the control was on Low, the hole was fully covered. When the control was on Medium, the hole was still fully covered even though the control knob was moved 1/2" from the left. It was not until the control was slid more than 1/2" inches that the hole started being uncovered.
The control made no difference when set between Low and Medium!
I am now questioning whether or not the combustion hole was cut in the right place at the factory. I cannot understand why sliding the control from "Low" to "Medium" does not change how much the hole is uncovered. In fact the hole is fully covered in both positions. It is not until the control starts moving into the Medium High setting that the hole that feeds combustion air to firebox starts getting uncovered and lets air into the firebox. I wonder if the fireplace, as it was manufactured, is really operating on "Medium" when the ACC control is opened as far as it can be opened. If so, that would explain why we seem to have difficulty getting the fireplace to burn really hot with the glass doors closed.
The only way I can think of to verify whether we have a manufacturing defect is to see another Quadrafire 7100 and inspect its ACC control and compare it to ours. We don't think our fireplace store has installed any other 7100's. We did talk to a fireplace store 90 minutes away who has installed one in a house that is currently in new construction. We are going to see if that company would be willing to let us inspect that fireplace and compare it with ours. Otherwise, we just have to wonder whether or not our FP is working as it should.
