Newbie can't keep a substantial fire in her Harman SF 2500

Long story short..I grew up with coal but it's been years. My basement flooded destroying my oil furnace. My uncle sold me and helped install a Harman SF 2500 furnace. We have a barometric thingamajig on the ducts and a blower. I've had several fires started using firestarters/matchlight chsrcoal and wood I can get the coal burning using this method....but my fires tend to not want to last. We've had this going for a week now and my longest fire was 36 hours! I'm using the Santa bags of nut coal. Forgive me if I forgot any info...im exhausted staying up all night to make sure my house is warm enough for my toddler who won't wear nothing on his feet and working ridiculous hours. We're currently in the back half of our first major snow storm in the Northeast.

We had the same issue when we moved to a new house with a hand fed Harman boiler. My Harman SF-260 boiler would get ash bound within a few days of starting a new fire. Raking down each side and down the middle during each tending solved the issue and allowed the fire to stay lit for months (or until a big rock got stuck in the grates). We used a combination of a fireplace poker and a big 3 ft long pry bar. We called it the shake and rake or poke and stoke method...

1. Open ash door to get good, hot fire going
2. Shut ash door and Shake down like usual
3. Push 3 ft pry bar down to grates at front of stove and push all the way to the back on each side and middle
4. Add coal to top of fire bricks, heaping it up in middle
5. Open ash door until you get blue ladies (never, ever walk away from the stove with the ash door open)

If you live near Hazleton, you can have my two pokers. Have not used them since switching to the stoker...

Welcome!! Are you filling the firebox with coal? Once the coal fire is established have you closed off the load door spinners so all combustion air comes up through the grates? Those are the common things to correct. Then the art of ash clearing comes into play as mentioned above. Another common issue is to have too much air through the ash door burning through the coal too quickly. It may be helpful to have a manometer connected to adjust the baro damper and help keep too much heat from going up the chimney. Did your uncle give a hands on demo of how he ran it?

Stick with it and we'll get you to a long continuous fire until Spring!

Can you post some pictures...
How full is the coal bed...
Up to the top of the fire brick?...
Full manual control or some form of automation to control the fire...