Fireplaces, Heating Stoves, Flues and Chimneys - Heat loss through damper

Anyone use a chimney top alternative device to a damper?

I see advertisements for a product that claims that there is significant heat loss through a traditional cast iron closed damper during the winter, and they offer a product to address that.

They claim the damper does not give a good seal. They have an alternative that mounts at the top of the chimney (and squirrel proof), that gives a perfect seal, thus stopping heat loss up through the chimney when the fire is out. I guess it has a tough rubber like seal that can handle heat, but it is not as hot up at the top as it would be directly under a fire.
They claim they could save a person up to $200 a winter using this device over a leaky damper.

Any experienced users with thoughts?

I have two fireplaces, and although I don't have them, I have seen those chimney closers installed on Bob Vila's TV show.
Personally, I just use 6" insulation batts with vapor barrier down and cram them up over the dampers.
Good luck!
Mike

Yeah I would do the same thing, however I own a multifamily and I am renting out the first flr with the fireplace. They probably will use it over the winter and if so I cannot do it the inexpensive way.

On trouble calls on a home it is the fireplaces most of the time. People dont know how to fire them or use them, lets say. They all build to big of a fire in them and that is what messes up the damper to start with. In 99% of them they dont close all the way. Does it cost you ? You bet both when they are not burning and also when they are. just think where does it get all that air that has to go up the flue when it is burning??????When a fireplace has a ash dump door there .We put a bolt under it to stay open and on the outdoor clean out .Drill lots of small holes in the door. this lets the air in to the fire and not taked heated air you paid for in the home up and out the flue. In all new fireplaces we make duct work or pipe to let out side air come in and a register for it right in front of the glass doors

So yes that top on top of the chimney works very well. Also a plywood front to fit tight in the opening of the fireplace. Then the best one and I like and use them all the time is the glass doors. here you can control the draft to the fire. When you go to bed no sparks can jump out onto the rug.
In many many homes where they used the fireplace a lot. Then next year they didnt burn it the fuel cost went down in all of them.Also I would not have a fireplace if it didnt have a steel heatilator in it so I could get some heat out of it

My .02 cents ED ;)

Thanks Ed for taking the time to respond.

If I was living in this flr of the multifamily house, I would not be using the fireplace and would seal up that damper, but I have a tenant there, I am living on the third flr. They will use the fireplace and that is why I was thinking of one of these new fangled dampers at the top of the chimney so it seals when fireplace is not in use.

The fireplace chimney is sort of in the middle of the house. I would need to run some sort of pipe from the outside I guess to the ash dump. The fireplace has the glass doors.

Thank you for some great information...

I think these chimney top dampers are great, the serv many purposes. The best one being that instead of sealing the chimney at the bottom and the cold air is able to get to the inside of your chimney and keep it cooler than if it were sealed at the top, the room air will keep the chimney warm and start up will be much easier. The seal on the top of these are very good and can handle high temperatures. also taking out the damper lid can be benficial to the draft of the fireplace.