Vacuum Switch error, Quadrafire AE

[TexasBBQman]

I have a circa 2007 Quadrafire AE. It is failing with Vacuum Sw Errors. I removed the old rectangular switch and it would not close contacts when I sucked on the port. Pieces of glue fell out of it. I replaced it with the more modern round type. At the same time, I thoroughly cleaned the stove including the baffle plate and small holes under it with a small piece of tubing attached to the vacuum nozzle with tape. I blew out the vacuum switch hose and blew air into the port on the feeder tube. It was clear. I still get the errors often accompanied by Min Firepot Temp errors. I don’t understand the process cycles that the fireplace goes through and how the vacuum switch plays into the situation. Often when the Vacuum Switch error occurs, if you select retry, it will then function normally. Last night, after working fine for hours, I noticed that it would start up normally but at some point the flame would die down indicating that the auger was not dispensing pellets into the firebox. I checked the thermostat and there was a Vacuum Sw error displayed. It would not work after a retry. I turned the stove off of the evening and unplugged it.
Today, I removed the wires from the vacuum switch and placed a ohmmeter across the terminals. Using a hose, I sucked on the hose and the switch closed. I then used a tee and a vacuum gauge and the switch closed at about 1cmHg (very low vacuum pressure). Using the tee, I hooked up the pressure switch to the port on the feeder tube and left the vacuum gauge connected. I plugged in the stove and it ran a complete cycle from autoclean to a temperature rise of 3 degrees and shut down properly. No errors. I observed the vacuum gauge and at no time did the system pull a vacuum. Later, however it ran again and after running, it stopped feeding pellets and showed a Vacuum sw error. I was not watching the gauge at that time. I tried a retry and it resumed normal operation but did not pull a vacuum. Also, if the vacuum switch had actuated, I would have heard the click.
A vacuum in the fire box makes no sense to me. A vacuum indicates a lack of oxygen. At what point in the cycle and for what reason does the stove create a vacuum that actuates the vacuum switch? In my case I am getting a Vacuum switch error but the stove never pulls a vacuum on the switch that I can tell. My dealer does not return my calls and I would like to repair this stove.

 

[kappel15]

Hello and welcome to the forum. When wall control calls for heat, it starts the exhaust fan, which pulls air from firebox. This also pulls air from auger tube, that vac switch is attached to, thus closing the vac switch, which then sends power to the auger motor, so it can feed fuel to stove. If anything disrupts the vacuum created by the fan, bad door gasket, dirty vac hose or port, plugged exhaust path, which is thru stove and pipe, broken door glass, plugged oak. What number control board do you have? The older ones had an issue with a logistic error that would throw a vac switch error. kap

 

[TexasBBQman]

I took a picture of the board label. See attached. This should provide you with the control board part number and revision.
It would seem that if the board operated correctly for 12 years, the logic would not be suddenly wrong. Can the software be updated by an authorized serviceman using the laptop interface?

 

[kappel15]

That is an older revision board. Evidently the dealer never kept up with the updates. A dealer can put new fuel tables in the board, but can't update it. Is the pot floor fairly tight to bottom of pot? Are you sure the nipple the hose attaches to on the auger tube is clear? To be sure, I would poke a stiff wire or paper clip thru it. And just for giggles, jump the vac switch wires together and see how the stove runs. Do a few cycles. Let us know. kap

 

[TexasBBQman]

I think the pot floor is tight to the pot. See attached pictures. I had previously blown out the (new) hose and inserted a small screwdriver through the nipple. It was clear. I also blew air through it. I did jump the wires this morning. So far (it is early afternoon) the stove has worked fine, no errors. In addition, I rigged up a battery, resistor and LED to the contacts on the (new) vacuum switch. Despite what my gauge showed me, the contacts close early on as the exhaust blower comes on and stay closed throughout the heat cycle. If I pull the vacuum line from the switch, the LED goes off immediately. Given this, I don't understand why I was getting constant vacuum Switch errors. The switch is clearly working correctly. I will use it for another 24 hours before I take any further action.

 

[kappel15]

In the one pic, there is a gap on the side. I can't tell where that is in the pot. Where is it ? Is it on the left side of pot? If so, the pot floor is not closing all the way. Sometimes the cause of this is the auto-clean motor mounting bolt is loose. It happened to me once. Pull ashpan and it is on back wall on left. Easy to reach and tighten. kap

 

[TexasBBQman]

About the gap, if you face the stove, it is on your left. It looks like the gap is at the fold or at the bend in the pot bottom. I removed the ash tray and looked inside at the back wall and all I saw was a vertical aluminum plate. The mechanism was not visible. Given that the pot bottom has multiple holes (presumably to let in air for combustion) the gap would just be another hole. It looks like it is part of the design. When I pull up a picture of a replacement pot bottom, I don't see holes though. The features look like indentations in the metal.

I observed the LED through many cycles (wires to control board still jumpered). Usually, the switch activates very soon after the exhaust blower motor starts to spin up and remains on solid until shutdown is complete. With the jumper in place, I have not observed any error messages. However, I did observe the LED go off during the startup cycle after the pellets were ignited but it went back on within 10 seconds and the stove continued on normally. Once, mid cycle with a roaring fire and the convection blower on high speed, I observed the LED go off and back on several times and never repeated. Before jumpering the wires and installing the LED, these scenarios were times that I would see a vacuum sw error and the stove would shut down. Usually a repeat would clear the error.

A loss of vacuum seems likely but what would cause it? Certainly a pot issue as you suggest might cause an air leak as would a faulty door seal (which looks fine). But a contradictor to me is that the switch closes early on in the cycle when the exhaust fan is just barely started. I would think an air leak, even a small one, would delay or prevent switch closure at startup.

 

[kappel15]

If you look to the upper left at rear of ashpan, you can see the pivot arm of auto-clean. Right below it is a small bolt. That is the mounting bolt for the auto-clean motor. Something to try if that is not loose, is to lower temp so stove won't turn on, and unplug stove. Open door. Put a small magnet on door switch to make it think door is closed. Plug stove back in. This will cause stove to do an auto -clean. When pot floor is closing, use a small screwdriver or punch, and when door is getting near end, help it along with that tool in a hole. If it closes more then it was before, you have an issue. If bolt wasn't loose, other options are the auto-clean arm with the slot in it can be pushed open further, making it more oblong then just a slot. Set screw in pot floor arm. The auto-clean micro switch could be going. Motor could be getting weak. Loose connections on wires. In 1/11/07 they realized they had an issue with the auto-clean motor not having enough power on return stroke, and installed a new code to fix that. In 8/24/08, they came out with another new control board to fix a logistic problem with vac switch and auger man error codes. Access to auto-clean motor is behind panel on left of stove, to right of control board, that you have to take off to access it. But usually if pot floor is not closing all the way, you would get an ashpan error code. I would double check wire connections on vac switch and possibly a different vac switch? New doesn't always mean good. kap

 

[TexasBBQman]

If you look to the upper left at rear of ashpan, you can see the pivot arm of auto-clean. Right below it is a small bolt. That is the mounting bolt for the auto-clean motor. Something to try if that is not loose, is to lower temp so stove won't turn on, and unplug stove. Open door. Put a small magnet on door switch to make it think door is closed. Plug stove back in. This will cause stove to do an auto -clean. When pot floor is closing, use a small screwdriver or punch, and when door is getting near end, help it along with that tool in a hole. If it closes more then it was before, you have an issue. If bolt wasn't loose, other options are the auto-clean arm with the slot in it can be pushed open further, making it more oblong then just a slot. Set screw in pot floor arm. The auto-clean micro switch could be going. Motor could be getting weak. Loose connections on wires. In 1/11/07 they realized they had an issue with the auto-clean motor not having enough power on return stroke, and installed a new code to fix that. In 8/24/08, they came out with another new control board to fix a logistic problem with vac switch and auger man error codes. Access to auto-clean motor is behind panel on left of stove, to right of control board, that you have to take off to access it. But usually if pot floor is not closing all the way, you would get an ashpan error code. I would double check wire connections on vac switch and possibly a different vac switch? New doesn't always mean good. kap

Sorry I haven't performed all actions that you requested, life got in the way. I did remove the ashpan and inspect the pivot arm and the small bolt. It is tight. I noticed that in response to my issues with the vacuum switch errors, you honed in on the firepot. I would like to understand where you are headed. Do you believe that the gap that we see in one picture is a result of the bottom not closing properly and letting too much air in? Further, too much air in equals lower vacuum in the firebox? I guess that I have learned enough to know that all air for combustion comes in through the pot bottom. Is that right?

 

[kappel15]

No. All air comes in thru pot holes. Ones in floor and ones in wall of pot. kap

 

[Ssyko]

the vacuum switch you replaced, was it an OEM switch or an aftermarket? i ask because each stove is set up for a certain amount of vacuum and the switches are designed or selected for those parameters. so do the switches have the same spec's?

 

[TexasBBQman]

the vacuum switch you replaced, was it an OEM switch or an aftermarket? i ask because each stove is set up for a certain amount of vacuum and the switches are designed or selected for those parameters. so do the switches have the same spec's?

As I understand, the original rectangular vacuum switch is obsolete. The new one is the same part number as the old one (7000-166) and seems to be the same style everywhere. I purchased it from a reputable source. It is a aftermarket switch but is specified for the Quadrafire AE. I believe the switch itself is acting properly because at startup, when the combustion blower just begins to speed up so slowly that you can barely hear it, the switch closes. What seems to happen is that it opens mid cycle with a roaring fire and that generates a vacuum switch error.

 

[TexasBBQman]

Sorry I haven't performed all actions that you requested, life got in the way. I did remove the ashpan and inspect the pivot arm and the small bolt. It is tight. I noticed that in response to my issues with the vacuum switch errors, you honed in on the firepot. I would like to understand where you are headed. Do you believe that the gap that we see in one picture is a result of the bottom not closing properly and letting too much air in? Further, too much air in equals lower vacuum in the firebox? I guess that I have learned enough to know that all air for combustion comes in through the pot bottom. Is that right?

Replying to kappel 15: Today I took the pot out and cleaned and inspected it. I wire brushed the interior surfaces and cleaned out the holes. All surfaces that mate with the bottom seem intact and smooth. I also wire brushed these surfaces. I think I saved the gasket OK. I then removed the bottom. While the underlying metal seemed to be intact and solid, there was a lot of buildup on the surface and even the surface where it makes contact with the pot itself. One hole was plugged. I used a 1/4 inch round wire brush to clean out all holes. I then used a wire brush and putty knife to clean all surfaces paying attention to those that mate to the pot. I then re-assembled the bottom and pot itself. I did as you suggested and used a magnet to fool the stove into thinking that the door was closed and plugged it in and it ran an autoclean cycle. The bottom opened smoothly and closed smoothly. After closure, it seemed to be closed correctly, no gaps. I then was able to move the bottom left about 1/8 inch using a small screwdriver but that did not result in an improved seal and in fact that appears to be natural slop in the mechanism. I will observe the stove for a day or so and report back.

 

[TexasBBQman]

After 24 hours and multiple cycles, the vacuum switch errors have not re-appeared. So it looks like the cleaning and re-work of the pot and pot bottom has resolved the vacuum Switch error issue. Initially, I did have a defective vacuum switch. So kap was right in his suspicions about the bottom not closing and sealing properly. I am going to obtain some gaskets so that I can do this maintenance annually. It was not difficult. After 12 years of use, the pot and bottom (after re-work) are still in good shape. Thanks for the helpful suggestions.

 

[kappel15]

Glad you were able to clean the pot and check things out to such a degree. I don't think the 1/8" you closed it after the fact is an issue. It was getting rid of the small opening that mattered. Routine maintenance on these stoves is a must, and spare parts are essential to keep the stove up and running. I try and steer clear of after market as lots of folks have had bad results with them, but I also hate paying the expensive price for OEM parts too. Stay warm. kap