Older Mt. Vernon won't get going

[planetmf]

I've got an older Mt. Vernon (2005, pre "AE"). I'm hoping someone on here is knowledgeable on these and could provide me with some suggestions. My stove doesn't seem to want to light when it's stone cold. It will dump some pellets in the pot on startup and light them, but it's as if it's not dumping enough in or something. They will light and burn but it seems that the stove doesn't get hot enough to dump more in to get the stove fully going. When it does work, it's after it has been on and off already and maybe there is still some warmth inside, and even then it almost reaches the point of going out. It's an annoying problem because #1 the smoldering pellets stink like heck after the fans all go off and #2 I just know I'm going to go home to a freezing cold house one day with the "call light" on, in fact it happened yesterday.
This stove has a feed rod that you adjust the feed rate with, I wonder if something isn't wrong there either, it's done this with the feed rate jacked all the way up. Also, with the feed rate all the way up, the flame doesn't ever get really tall as I think it's supposed to. The stove seems to burn well once it's fully going with a regular active flame. I've tried a couple of new bags of pellets thinking the leftovers from last year may have had some moisture in them, but it's done it with the new ones too. I've had the feed rate all the way up. I've cleaned it well. I've cleaned the fines out of the hopper (can't or don't know how to clean the auger chute, hard to get to). I did remove the bottom of the burn pot at the end of last year to clean it, it was stuck. I do notice a small gap between it and the rest of the burn pot now (is a small gap normal?)
Any ideas or suggestions would be appreciated, this is a great site with helpful folks, Thanks!

 

[humpin iron]

Clean the hopper out, then stick the shop vac into to hopper and vac the auger-then put it to the drop tube above the burn pot and suck the rest of the auger clean.
I really suspect that the thermo couple is not getting hot enough, make sure that the thermo couple is seated all the way into the ceramic tube, if there is a slight air gap at the end it will throw off the temp readings.

Your stv works like this: call light comes on, the stv feeds for 1 min. then lights, within 2.5 min the thermo couple needs to feel 200 degrees. At that point the computer goes from start mode to safety mode. Within the next 3.5 mins the thermo couple needs to feel 600 degrees, at that point the comp. goes from safety mode to run mode.

If you have a clear computer box: when the unit starts it will be clear, when it hits 200 the box will glow green, at 600 the box will glow red.

If any of these temps are not met the unit will shut down on safety

Hope this helps good luck ck that thermo couple

 

[planetmf]

Thanks for the reply Mr. Iron. I did try to get the auger tube clean like you described the best I could, thanks for the suggestion on that. I did wonder about the thermo couple as well, as far as making sure it's all the way in, I will take a look at it when I can let the stove cool down, she's been running pretty heavy the last couple of days. A bit too early for that if you ask me. How can you tell if it's all the way at the end? I can remove and replace the ceramic cover, but that stops when it hits the mount I think. I've always been a little leary of messing with the thermo couple, thought it was sensitive. Anyway, thanks again for the response, and I will check it out!

 

[humpin iron]

you know its on all the way when it bottoms out and the t-couple is touching the end inside.

 

[planetmf]

Well, I thought it was cured, but I don't think so. I came home after a 60+ degree day, stove was off all day. Turned the thermostat and watched. The stove was cold from not being on all day, I had vacuumed it out the night before I think. Pellets dropped in, took a little while to light them, they burned (flame didn't get all that high), burned for 3-5 minutes I'll say and went out. I'm still thinking it's not putting enough in for the fire to get hot enough (the flames didn't really reach the thermo-couple). I don't know. I did adjust the feed rod back down, so I do have a tad I can turn it up, but I don't think it'll be enough, it was up all the way when my troubles started. Got any other ideas/things I can look at? Thanks in advance.

 

[humpin iron]

if you vaced the drop tube last nite you may have sucked out the pellets that would have been dropped for start up. Try it again and after the unit lights, hit the reset button and get it to feed again. You'll probably get a fairly large start up, but should produce enough btu's to make the t couple happy

 

[stoveguy13]

is it the clear control box or the grey one? make sure pot is clean and when was the last time you cleaned out the exhaust blower?

 

[jtp10181]

Sounds like it could be a weak thermocouple, it can be tested with a multimeter.

The bottom of the burn pot should seal up nice with the pot itself. A very small (1/16" or less) should be ok, anything bigger and you let in excess air.

Have you taken the baffles out of the inside and cleaned behind them? One of the Mt Vernon designs they are VERY frustrating to get off and then even worse to get back on again. I was ready to chuck it across the room and leave for one of them I worked on. Brute force is what got it back on in the end.

Keep this in mind, most problems with pellet stove is from lack of proper cleaning and many people who say its clean, don't even know how to take the baffles off

 

[planetmf]

Thanks for all of the replies. No, I didn't vacuum out any pellets from the chute when I cleaned it. I do have to push the reset button when it doesn't successfully light and then it is fine, plenty of pellets to get it heated up. One major reason I chose the pellet stove over wood was the control (auto start and stop), that's what's frustrating, the stove should light by itself. I can't recall how high the flames used to get on startup, seems they used to get higher on start up than they do now, a more robust fire on startup. Anyway, yes I've cleaned behind the baffles as I just had them all out to paint and such to get ready for the cold weather. They CAN be a pain to get back in, the back one especially, to get it around the chute. I will check the exhaust clean out box in the back though, although I suspect it's pretty clean too as there never is a ton of ash in it seems.
The gap on the bottom of the burn pot may be more that 1/16th, but not much more I don't think.
When an ignitor fails, does it die completely, or slowly weaken? Or can it do either?
I'm gonna start mixing corn in to because I hear nobody can get pellets now where I live, I want to make sure mine last me the winter. That means it'll be even harder to light at times, depending on how much corn gets dropped in too, no matter how well it's mixed.
I'd have to look and see what color control box I have, but I'm thinking it's the clear one for some reason.
The only time I think I'll have a problem is when the stove sits for a while (like when going to bed or leaving in the morning) and gets stone cold. It's just a little bit annoying.
Thanks again for all the suggestions people!

 

[jtp10181]

An ignitor either lights the pellets or doesn't. So if the fire starts the ignitor is fine. Pretty much it sounds like a thermocouple problem. Either its not into the porcelain sleeve all the way or its getting weak.

 

[stoveguy13]

I would agree that most likely cause is the thermocouple but i would also check that the box is fully seated it can strange things when the post are not all touching fully.

 

[jtp10181]

Yes good point, I have fixed a stove or two just by pulling the box out and putting it in again tight. Make sure you UNPLUG the stove first or you will fry the box.