We also have a fpl at our lakehouse, in NY, and that is about what the vent looks like. But for whatever reason, in my renovation here in CT, look at what I ended up with! And as I said, everyone tells me that it is due to code. The mfr, the vendor, the architect, the GC. As I told them, no one would expect that and someone should have known and let us know ahead of time. Not sure what can be done now. Thankfully it is in a part of the house where it is out of the way, but, still .... Yours may look like all the ones pictured, just saying I would ask first.

I wish someone would answer you, I was going to post something similar myself. We have a contract on a home and I had the chimney inspected today (realtor says I'm the only person in her entire career to have a chimney inspection, but you'll see why) Inspector told me the flue tiles needed to be replaced and the to reline a chimney was about $4K-$5K or could have the tiles that needed to be repaired which iwas about half that price - he wasn't positive on pricing as he does not do this type of work. He actually called me back and the low end pricing from the company gave him a guesstimate of $1500-$2500 depending on what I decided to actually have done. Originally, this was a wood burning chimney and now is gas. I know there was an issue with the damper not opening correctly and was having the owners clean it out before the inspection. Due to the issue above, he didn't do the cleaning - not until we decided what to do about the flue issue. Anyhow, I'm not putting out any more money on the home, it would be the owners who'd have to repair. My realtor called me back a little while later and said the listing agent spoke to the owners and came up with what they think would be a solution - a vent free gas fireplace. Since I'm a Floridian who's never had a fireplace in her life, I know nothing about any of this. I'm trying to find out if what they are proposing, how it differs from the gas fireplace that's there already. Will what they put in look the same as what's there now? They claim it's more energy efficient. I'm glad you are asking the questions you did above because I wouldn't have known to ask them, so I really hope someone knowledgable will answer. In the meantime, I was given the name of a guy who does gas fireplaces for a living. Will try to reach him and if I can , ask those questions and let you know what I may be able to find. If I go with the ventless, I'm still having them clean out the damper. With it not opening all the way, that means cool air is still coming in, and in summer, cool are is going out. Please let me know if you came across any info. THANKS!!!

Our house has a similar situation. It's 1900 sf, built in the 1890's, has some blown in insulation in the walls (we only know this because we gutted the bathroom and found it - this room will have regular batt insulation in the walls and ceilings), has the original windows but triple track storms. The old oil fired boiler is 199k BTU and our oil bills are completely heinous - we used about $650 worth of oil for the month of December. I can't imagine what our bills would have been for a house 50% larger. Just from a reality check standpoint, there is no way a house the size of ours requires the absolutely largest residential boiler available (there may be some slightly larger but in general, around 200k is as big as they get). Our old boiler does short cycle too, it's loud enough that you can hear it. Even in the dead of winter with single digits at night it cycles on and off. We are probably running somewhere in the 60-70% efficiency range also. Everyone who has quoted for us has universally said "WHOA that's a HUGE boiler for your house." After evaluating all of our options, we are going with a modulating/condensing boiler at about half the capacity (maximum) and putting zones into our house. Right now when it is 68 downstairs, it's about 80 degrees in our bedroom - so at a minimum breaking the house down into different zones for upstairs and downstairs should also help - DH works at home during the day and there is no reason to throw all of that extra heat upstairs when no one is there in order to keep downstairs comfortable. For various reasons we are actually going with more zones than that (the way our system was originally piped makes it extremely easy - labor wise it would be just as much to combine them back into one zone as leave them split - and there is a big temperature difference between the various parts of the house we are splitting off) but you might want to check into whether it is possible given your current piping to separate your 2nd floor from your first into separate zones. Between the zoning and the much more efficient boiler, we hope to slash our energy prices. It's NOT a cheap boiler (the cost of the boiler is more than the cost of your boiler + install) but with our old cast iron radiators with relatively cool return, the condensing part will work great, and with us zoning out our house, the modulating part should work great too (it operates at a much lower BTU if the demand isn't there). It also changes the temperature of the water sent out into the system based on the outside temperature, so if it's 50 degrees outside and we want to maintain say 70 inside, it's not necessarily moving 180-190 degree water through the system, so there is savings there too, especially in the shoulder months. We are switching from oil to gas (it would cost us thousands to replace our oil tanks, the real reason we are replacing the boiler - the oil tanks are not long for this world and because there is no longer outside access to the basement it would be a huge job to get the old ones out in pieces and multiple small new ones in and we decided to put that money into a more energy efficient boiler rather than use the same old boiler and just get new oil tanks) so it will be interesting to see the difference in our energy bills. Anyway it took a ton of research and a bunch of time looking at our system and figuring out what was going on to trace out the various loops we have, but I'm glad we put the time into it. We feel confident with the system we have chosen and hope our house will be far more comfortable and energy efficient for the years to come. Energy prices have nowhere to go but up, unfortunately. We are only planning to do this once so figured we'd do it right the first time. The first couple of contractors wanted to put in either a 200k btu boiler to replace the one we have or a 165kbtu boiler calculated by counting radiator fins. As I said before, some of our radiators have about 3x the capacity actually required for comfort in the room so it's kind of silly to oversize in this way because it's just easier to "replace in kind."

Actually in New York state you can have a ventless gas fireplace in your bedroom. (Its possible NYC has a different code) I was just reading the code yesterday. Up to 10,000 btus. Must have an oxygen sensor. There is a requirement based on the size of the room (air mass, you have to do a calc). So unless your bedroom is super tiny yes you can have a ventless gas in your bedroom. I just googled and found zero news stories on a ventless gas fireplace causing death unless it was a suicide. I don't think they are the best way to go but if you follow code and use common sense I don't see a problem. If we get one we only plan to use it occasionally on cold nights for about 15 min before bed. The room is large and opens to other rooms. Our house is dry to the little added moisture would be welcome. We are still researching as it is difficult to find one that is only 10,000 btus.