Hi Samantha. I'm a newbee at the forum and am from NW NJ. I had issues with my Vigilant II model 2310 but worked them out. I'll try to speak to my six years working with this stove. If you have the old Vigilant with the hopper insert for coal burning, this might not apply. I've never opperated the old unit but knew two who did without much luck or heat like you are experiencing. The insert hopper would leak and therefore not heat with coal as expected.
You stated that it's in a fireplace. A good point made as to where the heat is going if there's a lot a of masonry absorbing the radiant heat. It might take a while to heat all that mass up before it returns the stored heat in radiant form. Are all four sides of the stove exposed to the room or is it tucked into the fireplace?
Check the inside for the three clean-out plates. Found one of the three clean out plates missing right after dealer installed it. I couldn't get heat out with this situation; stove top temps <350 F, but the fire did keep. If they aren't in place, the fire will be robbed of some air ... and heating ability too.The design of the stove is essentially a box within a box to rerout and thus transfer more heat when the internal damper is closed. Big difference in heating between the two positions. Fly ash builds in there but wouldn't expect to find much unless you've burned it a lot or shake the fire down with the internal damper closed (handle down/vertical). Only shake the grates with the handle horizontal allowing the fly ash to stay out of the stove and fall onto the smoke shelf. I remove the plates to gain access to the inner space and vacuum out once about mid (after ~2 tons) season and at the end.
The outside of the stove is the remaining design of the original wood burner design - the Vigilant II is internally redesigned eliminating the hopper insert for coal burning. There is a small pie pan casting on the left side of the stove that rotates to cover a ~ 1inch hole. It's for secondary air for wood burning and maybe bituminous burning which I have no experience with. Keep this closed when burning anthracite or you'll loose draft there and keep the fire from getting to its potential. Nice to know there's supposed to be a gasket for the cast internal damper ... never had one on mine and won't bother as all seems okay. Checking only stovetop vs. external pipe temperature, it runs at ~ 75% heat exchange. No problem at all keeping stovetop near 700F with the air inlet rod straight up.
I have never used a baro damper with either of my Vermont Casting stoves. That's not to say it wouldn't help, but the wife doesn't like the look. The little rod in the back is attached to a bimetallic coil that acts as a thermostat. It will close off the air slowly reducing the amount of air/draft that the fire receives in response to stove temperature. Essentially, if everything is sealed, it cuts the draft but never shuts it off. Works really well for me. I have confirmed this with a draft meter on my Defiant installation in a masonry chimney but not the Vigilant that has a better drafting straight SS chimney.
I initially tried several tons of both nut and pea from a Scranton mine. Even tried to mix the two. I've found that pea is best for me from same source. I've heated my 3,100 sq. ft. well insulated house with it for six years. 9 ft ceilings on the first floor, stove is in a 30 x 27 ft room w/9 ft ceiling. Happy family! Can heat with the Vigilant II when it's 10 F outside and hold mid sixties in the far end of the house some 50 feet and three rooms away from the stove. I keep the bedrooms cool, low 60s and like it! It's pushing the stove to do this so I don't try to maintain it when is this cold, letting the oil burner make up the difference when the nights are in the high teens. Nice to know it can be done without electricity and I could also fire up the wood fireplace if needed.
Sorry for the long post everyone! Hope Samantha can glean something from all of it.