The manufactures dont offer warrenty, the dealer does. The manufacture warrenty is never direct, and its the responsibility of the dealer to take care of it. The dealer who services also covers labor warrenties. A "plumber" who does the work might not cover labor under a warrenty situation, and it would be up to you to diagnose the problem. Dealers wont install product bought of the internet because they dont want to be responsible for the warrenty. The only exception to this is a non servicing dealer subcontracts a installer. Then the installer will take care of the dealer who sends him the work. So thats truth what your hearing. Buy what you want, if its out of your service area your taking a risk on no support after the sale.

Ventless is a big mistake and in many place a code violation because it allows fumes to build up in the indoors and consumes indoor oxygen levels. They should be outlawed altogether, but the manufacturers' lobbyists have prevented that. If you enjoy a wood burning fireplace, that is certainly an acceptable alternative to ventless gas, and would probably be cheaper to put in place. Assuming the chimney is structurally sound, a new liner should run about $1K installed. That's just a guess. Get several estimates and ask around for recommendations because you need to make sure your installer is competent and honest.

Thanks, Will. Ten degrees several times during the winter sounds about right. Sometimes I forget just how cold it gets here. We are in the city itself. I keep the thermostat around 68 degrees. On a cold day outside when it's 68 in the front of the house, it's about 63 in the back (ie, the new addition). Thank you for framing it in terms of heat deficit vs. distribution. The ducts are basically vented to the front half of the house; partly because two were taken offline in the process of building the addition. And partly because it's awkward to run them to the furthest part of the new addition without getting in the way. (Thus the reason why we're in this predicament of considering a fireplace). We had a blower door test done - house is circulating 30% of its air each hour. And we did have a heat load calculation done - that's how we arrived at the 75K figure. But it would be great if the current furnace could handle the whole load. So all of this is to say, I'm still curious to know what size fireplace we might install. I'm guessing it wouldn't have to be very big. Anyone want to estimate what we would need?

I can handle the structure part. I can run my own gas line. I can install the new gas fireplace. My problem is how to continue the exhaust from the basement through the new gas fireplace. How big does the flue from the basement have to be? Can it possibly be run right next to the new fireplace on the main floor? Like if the new fireplace is 3 feet wide, maybe I can make a one foot cavity on both sides going floor to ceiling so it would still look symmetrical with one of the cavities containing the flue from the basement wood burning fireplace.