1）二氧化碳容易进房间（不是厅）？ As long as the chimney is good, it vents most carbondioxide out. there will be some gets in the room but carbondioxide shall only cause less oxigen. It is not poinsonous like carbon monoxide.
2）会否容易damage 地毯？ less possible but it could if spark flys out of fireplace, put a screen in front of it, also wood burning is dusty.
3）另外就是有fireplace是否能租高点？ yes. especially in room fire place. but not too much. say $30 or so.
some people install gas log to keep it clean. but I would suggest not to be used in bedroom. It has too much liability issue.
If you have to use it, the remedy can be that on the lease, you add one more clause that using gas log is the responsibility of tenants. After you show tenants how to use it, it will entirely be tenants' responsibility for any health and life threatening events. You shall also suggest tenants to add carbon monoxide alarm. If you install it, you shall not responsible for no functioning of the alarm due to battery drain or unit failure. It is tenants' responsibility to test the alarm every month or more.
Hope that helps.
But watch out, JY will again 99% disagree. LOL
明白Fireplace增加house value，所以我只是考虑在出租期间封闭而不是拆除。
