St. Croix Revolution Furnace died - I'm done for the year

I've been fighting vacuum errors with this St. Croix Revolution furnace for the last two months. I clean it religiously, and pulled the combustion blower about a month ago - not much crap on it, but I cleaned what was there out. It got to the point where I had to sweep out the whole venting system at least once a week to keep it going, never that much came out (maybe enough to fill a beer can) but that would get it back up and going for a few more days. I could hear that the convection blower was getting very noisy, but it's a major teardown to get it out and I was hoping I could make it through to the spring. The furnace died altogether last night - now when I plug it in the power light comes on for maybe a second and immediately dies. So the main fuse isn't blown, but something in there is obviously drawing heavy current. I'm frankly seriously tired of dicking with it, and I have most of the half a tank of oil I bought at the beginning of the season left, so I'm gonna burn expensive dino juice for a couple of weeks and hope it gets me through. My main suspect is the combustion blower, although it seemed to spin freely when I had it out. Hate to think it's the control board.

Question: can I just pull the wire to the hot side of the combustion blower (and after that the convection blower, if that doesn't work) and see if that's what's causing it to not power up at all? Or does the circuitry expect to see a load? I can make up a patch cord to test the blowers separately, but am wondering if this would be an acceptable quick check.

hossthehermit said:

Think about it. You say you plug it in, the light comes on for a second and goes out immediately. Which light are you talking about? Does it come on when you plug it in, or when you hit the on/off button? Is the selector switch set to man., tstat, or smartstat? Convection blower may be getting bad as you say, but the convection blower isn't supposed to come on when you plug it in or turn it on, anyway.
Startup sequence is as follows; Turn it on, combustion fan comes on, runs for 30 seconds or so, checking for a vacuum. If it gets that, the burnpot does it's quarter turn cleaning cycle, auger starts up from the small hopper, ignitor comes on, should have fire within 4-5 minutes, tops.
If you follow thru with your plan to burn oil for the rest of the year, it's your call, but when you do get around to trouble shooting it, feel free to PM me or whatever, more than happy to offer any help I might be able to.

Click to expand...

Hoss-

It's the green "Power" LED that comes on as soon as I plug it in. It lasts about a second, then I hear a relay click and it dies. It was last running on Tstat when it died, but it doesn't matter which position the switch is in now. I know the convection blower doesn't come on as soon as it's plugged in, I thought I remembered that maybe the combustion fan did spin up (which is why that's my first suspect). I've had the jammed burnpot syndrome before, and this isn't it. The pot has ash in it, because it was burning when it died and the current pot just burned away, but the microswitch is in a proper groove - it just can't rotate the spent ash out without power. Actually, thinking about it that motor might have croaked, too.

Hoss-

When I did what you suggest the night it died and again the next morning, there was no response to the power button whatsoever. Just dead. But it's been unplugged for a couple of days, I went down to try it after reading your message this morning and it fired up. It's been running for a couple of hours now, we'll see if it lasts.

I have had vacuum dropouts (shut down with blinking #2) for months now. It started only when the weather was very cold (teens), it would drop out overnight. In recent weeks it doesn't matter the outdoor temps, after a few days running (mostly at prog4 heat1 on the stat) they can come on at any time. If I run a brush through the venting the errors will go away for a while, even though it seems like not much comes out. I am fairly sure my venting is too long overall, has too much horizontal run, and the 3' rise outside is too much. But allowable venting length/EVL is not specified by Even-Temp, there are only vague hints in the manual. I suspect I have problems both with the exhaust gasses cooling in the outside vertical run, and with downdraft in general. But there's no other way to route the venting that I can think of. At some point I'm going to get a gauge myself or find someone who has one and see just how bad it is on various days. I'm hoping my problems might be at least partially alleviated with some better anti-wind capping, maybe something with an impeller to assist the draft, if I can find it. Another guy in Upstate New York with a brand new furnace reported similar problems here, but he hasn't been back in a while. I think you saw that thread, because we were talking about how the vacuum switch on both of ours had an extra reference hose coming out of the side of the furnace, and yours didn't. I did clean the combustion blower thoroughly about a month ago (again, it didn't have that much crud on it) and replaced the gasket when I installed it.

Thanks for your help, Hoss!

Hoss-

Sorry for delay, I was away for a bit. The furnace limped (not ran) through Sunday, dumping out with vacuum errors every couple of hours until I gave up. Away yesterday, this morning I cleaned everything stem to stern including another sweep through the pipes, which as usual dislodged about a half a beer can (not a full one as I said above) of sooty black ash. Restarted an hour ago at prog4 level1, so far so good but it's also warm out without too much wind. I replaced the room air filter in the fall and again in mid-late January, it was dirty but not clogged. You can see a picture of my inside venting in post #3 of this thread

https://www.hearth.com/econtent/index.php/forums/viewthread/90975/

and the outside portion is below.

Damper is closed onto a pencil right now with the OAK hooked up (When it's having vacuum trouble it sometimes lasts longer if I pull it off). I've had it closed more before, but that sometimes leads to smoke at the exhaust (which is clear right now). The flame is active, but changes often from yellow to white at the base. Fire occasionally licks the baffle at this level.

Dexter-

My flame looks about as active as this, a little smaller since right now it's at level 1, but definitely being blown from below, sparks jump out of the box as pellets hit, etc. I doubt that there's a hopper gasket - it doesn't show on the exploded diagram, I've never seen a significant difference when the hopper is closed or open, and as far as I can tell the only path into the airspace of the firebox is through the auger. There's no interlock on the hopper door, like some stoves have. The small hopper is entirely contained inside the large one. I could pull a dollar bill out of the front door, but it wasn't easy and the gasket there visually looks good.

What concerns me most is that if I sit there and watch it I can see the flame change character from more to less whitish from yellowish and back and forth over the course of a few minutes, especially if it's windy out. That's why I think the length and configuration of the venting is at the heart of the issue. If I'm feeding it too much air, I think back pressure on the vent is causing it to lose specified vacuum and dump out. I can tell when it's coming on on an especially cold day, because the control board will go unresponsive (it's designed to do that for a minute or so at a time when it goes into an alarm state, before it actually gives up). Which is why I'm thinking I need some kind of better wind cap or a draft enhancer at the termination to take the downdraft out of the equation.

Hoss-

I wanted to start in manual this run so I could keep my eye on it. Maybe at this time of year I could get away with Program1 or 2, but it's so underpowered for my space that for most of the winter that level is next to useless to me. I have a stat, and for most of the winter ran in Prog 3 or 4 and level 4 or 5. It made it through the night, so I manually inched it up to 3 and put it back on the stat this morning. I started on Program 4 because I'd have to shut it down for an hour or so to change it later. From past experience, on Program 1 I'd be burning more pellets but due to the various heat losses in the building and ducts I wouldn't actually be getting any more heat.