St. Croix Prescott EXL - Is it working how it should?

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New Member
Jan 26, 2016
Milford, New Hampshire
Hi all,

I recently purchased a used St. Croix Prescott EXL on Craiglist. After getting it home and cleaning it out I realized that it was missing some parts. St. Croix helped me determine that it's an older model stove built in 2001 and I was able to locate replacement parts for the cera-bricks (using the after-market steel brick plates), heat exchange baffle, and the exhaust pipe gasket.

All venting in the room, including the vent adapter connection, was sealed with high-temp RTV silicone. The door gasket and window gasket were also in very rough shape and replaced.

This stove is installed in a walk-out finished basement area in place of a Harman Invincible that ran wonderfully for 4 years, until we moved it upstairs to heat the main living area of our house. The St. Croix was intended as its replacement. The venting has a roughly 6-ft interior rise before exiting through the thimble in an exterior wall to a vent hood about 2-fit off the ground. No vegetation around the vent.

Despite all this, I notice some odd things when running the stove. My only pellet stove experience is with the Harman, so I don't know if I'm doing something wrong or some of this is to be expected.

1. Smoky smell - It was a lot worse before I super-sealed the venting and replaced all those gaskets, but it's still there, especially on startup. My last time running it was for about 48 hours before I just couldn't take the smell anymore. I tried the dark room and flashlight trick, but I don't see any smoke.

2. Lots of soot on the window - I've tried running it with the air intake both closed and opened. Fully opened is better, the flame is nice and active, but I had to clean the glass 3 times in one day. Seems not quite right. Admittedly I have not experimented with different opening sizes yet. (BTW - I know everyone GLOWS about Harman, and maybe it's overstated, but I only have to clean the glass every 2 weeks in that stove. I've never had to adjust the air intake.)

3. Pellet feed rate seems high - Despite the feed rate being set at 1, it drops pellets about every 7 seconds. Even with the rate at 1 and the temp set as low as possible the distribution fan continuously blows hot air. Even with the cold weather we had the last few days it was too warm in my family room which is about 15 x 20 and 10-ft ceilings. My Harman could run at a very low setting for days, just enough to make it not freezing, then I could crank it up if we wanted to use the room for a while.

I'm debating whether to keep playing around with it by doing research on sites like this, or call in an "expert" from a stove shop. I'm hesitant to call for service because the stove is kind of old and I feel like it's hit or miss whether they would even know enough about my stove to help me. The newer model of this stove is very different than what I have.

Anything else I should try?
Used St Croix, assume its corked up with ash somewhere in long exhaust passages. Lots of tricks posted on this forum to try: leaf blower to suck ash out exh pipe with door open, clean behind firepot, behind exh doors, up back wall behind firebrick, etc.

My Prescott runs great with air damper barely open, many use standard pencil width gap to set damper gap to tube.

Shouldn't smell smoke when runnind so its either exh leak, or check heat exchanger tubes for rust through.

Its a very nice heat generator and efficient ince set up.

What is the auger on time divided by the period (on plus off time)? That duty cycle percentage will help diagnose low setting and why its so hot on low. I have ours set so #1 heat flame is barely visible.
My stove has a 13 1/2 second cycle time. Level one is on for 1.5 seconds, off for 12. (Each cycle totals 13 1/2 seconds.) Level 5 is 5 1/2 seconds on, level three is 3 1/2 seconds on. Yours may be similar. My control has a jumper on the board to change the cycle times. It is supposed to feed more pellets per level, but all the book says is to call the company before moving the jumper.

I can adjust the feed rate and fan speed for level 1 only. When the control is unplugged, it reverts to standard settings.

Agree with jzm2cc about the plugged passages, and the source of the smoke smell.
Thanks for all the good feeback folks!

When I first got it home I blasted every little nook I could see with a leaf blower. Soot was flying everywhere! But I will try getting deeper in there with my ash vac using a narrow hose attachment.

It came from the previous owner with the heat exchanger tubes completed caked with ash and creosote. The scraper was stuck. I have a feeling the stove came with their house and the owner had no clue how to maintain it. I don't see any rust, but will check again.

Next time I run it I'll time the on/off cycle of the auger and post a reply back. Based on what heat seeker is saying mine seems way too fast.
Can you post a video of the flame?
Hopefully you were blowing stove internals with stove outside! Typically pelletheads just hook up suction side of leaf blower on exhaust to suck ash out, but with this cruded up stove it may need scraping with clothes hanger in ports on either side of burn pot, bottle brush up ash traps to reach within back wall chamber, scraping between exchanger tubes with putty knife, and some even use compressed air and nozzle to blast hidden areas while leaf blower is pulling soot outside. Once clean i think you'll be impressed with its heating ability. Fine tuning can be done on control board plus air damper will probably need to be closed down quite a bit to keep heat from blowing out exhaust.
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