How do I use a chimney plug in my flue, if my fireplace has 4 slanted walls?

How do I use a chimney plug in my flue, if my fireplace has 4 slanted walls?

Q:  I am trying to use a chimney plug to seal an 11 inch diameter circle damper situation with the rod handle, as you can see in the picture. My goal is to primarily seal the flue from insects and pests and second reason is energy efficiency.
Would you please let me know which chimney plug and size is best for my damper handle situation. Thanks! – Ibrahim

A: Hi Ibrahim, I would recommend you use the 12″ round Flueblocker above the flue damper. In order to install it, you will tuck the wool pad past the open damper without the handle attached. Then spear the Flueblocker handle into the wool pad clamp and tighten the handle by turning it to thread it into the hole on the clamp. One it is threaded you can use the leverage of the Flueblocker handle to push the wool pad into place above the chimney damper. It will look like the photo below. It will do a great job stopping bugs and drafts. – Jason R

Flueblocker installed in round chimney

Flueblocker installed above the damper



My Heatelator fireplace is very drafty and I would like to close it off to stop the draft.

My Heatelator fireplace is very drafty and I would like to close it off to stop the draft.

Q: Jason, Hi, I stumbled across your site today, and I am very interested in one of your Chimney Balloons. My fireplace is very drafty and I have a question. My chimney has a system to take cold air off the floor in front of the hearth, and draw it through some pipes that run through the flue. This warm air is then fan forced out above the fireplace. The question is whether your Chimney Balloon will go between these pipes and the damper, or squeeze through between the pipes, and be inflated above them. – CW

A: Dear CW, Most people refer to those systems as Heatilators (but that is a brand name.) A deflated Chimney Balloon needs a gap of 2″ to 2.5″ to fit through between the pipes. Once you are through these pipes you should be good to go. I would suggest using a folding carpenters ruler to measure the pipes so you can tell what size Chimney Balloon you need. You may need to consider a HEK  extender for your Chimney Balloon if you plan on reaching very far past the Heatilator pipes to inflate the Chimney Balloon. The Handle/valve Extender kit (HEK) will give you an extra 16″ of reach to your 8″ Chimney Balloon handle. – Jason

Will a Chimney Balloon fit a Bellfires retrofit fireplace with a locktop damper cable?

Will a Chimney Balloon fit a Bellfires retrofit fireplace with a locktop damper cable?

Q: Jason, It looks like your product would fit my application, but I already had to mail back another company’s product for a refund because I couldn’t get it to fit well.

Here is a little more information. I have a Bellfires retrofitted, concrete fireplace (, and I also had my old chimney flue replaced with the Solid/Flue product ( The horizontal cross-section of the firebox is roughly trapezoidal but has rounded corners. The smoke chamber zone is also concrete (fairly smooth) and has sloping surfaces with no corners to smoothly join the Bellfires fireplace with the 8″ round flue. The round flue begins at about 4 feet above the floor of the fireplace.

I have a lock-top type, cable operated damper at the chimney top and no damper right above the fireplace. Would my best bet be using the 9″ x 9″ Chimney Balloon in the flue itself? Would the square Chimney Balloon conform adequately to the round flue? The damper cable is pressed against the side of the flue at that point, so I don’t think the cable will be an obstacle. Would I need to order auxiliary parts to use the Chimney Balloon up that high?- JW

A: Jay, I understand the fireplace configuration you are describing and we have a solution that will fit that application. A 9X9 Chimney Balloon will fit your 8″ solid flue tube. The square corners of the Chimney Balloon are designed to conform to a circular flue as well as a square flue. When inflated the Chimney Balloon will also press your lock top cable to the side of the flue wall. We have had many customers with Lock-top dampers and Chimney Balloons in their chimney. It is a very effective combination. To accommodate the 4′ reach I would recommend a HEK Extender for your Chimney Balloon. – Jason

Customer followup email: Jason, Thank you for the information. I ordered the Chimney Balloon, it arrived in 3 days. It works great. Thanks – JW

Can the Chimney Balloon work with a fireplace Heatelator?

Can the Chimney Balloon work with a fireplace Heatelator?

Q: Jason, My fireplace was constructed with a 42″ metal heatelator box. The walls above the damper taper to a 16″x12″ opening about 28″ above to face. This seems to be the nearest location that has any ledge to grip. However, just above this metal, the ledge has an 18″x16″  dimension that tapers up to a 12″ square flue liner several feet above. Of the sizes you list, only the 15″x36″ would seem to be big enough at this location, but it’s disproportionately long for the 18″ width of that opening. Would maybe consider using a 15″x15″ and an extender, placing it higher up in the chimney? Suggestions, please. .DW

A: Dear DW, You may have a wood burning fireplace insert instead of a built-in Heatelator, but either way this would be my advice… Order a custom 18X18 Chimney Balloon and also get a HEK extender for the valve. This will allow you the reach to get to this higher height in the flue. That area above the metal ledge is where you want to install it as long as that metal edge does not have any dangerously sharp edges. A 18X18 Chimney Balloon with an extender will cost $64.99 including USPS shipping. Custom Chimney Balloons do take 14 days from your order to ship, due to building time. You can call the customer service line if you have any further questions about this particular application. – Jason

How long does a Chimney Balloon hold air? and is it for everyday use?

Q: Jason, I have several questions. My experience with inflatable devices is that they leak. Can one insert the Chimney Balloon and leave it in for months, or does it gradually leak air?

Can one use the Chimney Balloon in a fireplace that one uses almost daily? For example, inflate the Chimney Balloon in the morning and then remove it in the evening when one wants to build a fire? If this is done, does the Chimney Balloon get “messy” covered with soot etc? We have the fireplace cleaned yearly but use it a lot.What is the life expectancy of a Chimney Balloon if it is inserted and not removed for months (a fireplace that we don’t use) vs. one where we would remove it quite often. I wonder if the Chimney Balloon is to be used only in a fireplace that is not used often. Thanks! – JT

A: Dear JT, If you use a wood fireplace daily you are going to find a Chimney Balloon to be a hassle to take in and out every day, however, if you have an offseason that you don’t use your fireplace (like the summer), you will find it a keen energy saver during that offseason.

You have probably gotten pretty used to inflatable mattresses, beach toys, and rubber or latex stuff made with a variety of cheap inflation valves. It is very true that these items don’t hold air long term because it leaks out of the valve. They don’t even hold air for 24 hours.

However, If you put a Chimney Balloon in and leave it in, it will stay inflated for 6 months to 12 months, no problem. The difference is our valves and seams are made to be absolutely airtight, so the only pressure difference you experience is from the air pressure inside the Chimney Balloon due to temperature differences increasing and decreasing air volume. I would suggest once a year as the temperatures outside get cooler, top the Chimney Balloon off with air just to keep it at nice and snug.

On the wear-out question… There are a number of variables to this question, but I will try to answer it generally. If you are installing a Chimney Balloon and taking it out every day you could expect your Chimney Balloon to last a few months before it wears out. IF you put the Chimney Balloon in and leave it in, and once every year top it off with air, you can have your Chimney Balloon last 10-15 years before the top side of the balloon will start getting brittle from the acrid creosote fumes.

I tried to cover your questions as thoroughly as possible. Let me know if you want me to clarify anything. – Jason

Do I need to close my damper after I install a Chimney Balloon?

Do I need to close my damper after I install a Chimney Balloon?

Q: Do I close the chimney damper after installing the Chimney Balloon?- JJ

A: Dear JJ, There is no need to close the damper below your Chimney Balloon. The Chimney Balloon is doing the job of the damper and quite frankly it is doing a better job than the metal damper could anyway. So closing the damper after the Chimney balloon is installed is like closing a screen door on the inside of a submarine.

However, You can have the damper closed if you have the Chimney Balloon in there far enough to close it. There are a few things to keep in mind though if you do decide to close the damper. If you try to force the damper closed it may put upward pressure on the valve section of your Chimney Balloon. That is a little tough on your Chimney Balloon since it puts undue pressure on the valve and Chimney Balloon.

The other issue is if you close your damper you may forget you installed the Chimney Balloon and just open the damper and start a fire.

Personally, I leave my damper open and leave the inflation tube attached, so it dangles just above my head when I open the glass doors to the fireplace. With this solution, I still have no draft problem and I haven’t accidentally melted a Chimney Balloon yet. – Jason