Gas Logs For Fireplaces

We have handled many brands of gas log burners (and even electric logs) over the years. We REALLY like Peterson logs. They're experienced; very realistic; prices are right; and NO customer complaints.

But we have supplied nearly a dozen different brands of gas logs at different times! In theory, we could get lots of kinds for you. In theory, because the savings we could provide you with our usual discounts, invariably gets MORE than eaten up by very high freight cost to get it to you because the log sets weigh so much! We have occasionally seen around $90 in freight costs to get the three separate boxes to a distant customer. Many decent quality, medium-sized gas log sets weigh around 80 pounds.

There are bound to be local fireplace shops near you that carry various brands of (quality) gas log sets. There are also mass merchandisers near you that sell really cheap gas log sets, too. Use your judgment regarding quality and your budget.


The following comments relate to using any of those gas log sets IN a JUCA woodburner, which converts it into a gas-burning fireplace or stove!

Nearly all homeowners desire the charm of a fireplace, whether it's a built-in unit or a free-standing one. We can help you with either. Our built-in F-9A Super-Fireplace has very flexible appearance with over 2,000 different brass door styles available, including:

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A JUCA F-9A has a sophisticated computer-designed heat exchanger that's built-in which can produce up to 140,000 Btu/hr of warm air which can be fed right into the house ducting system (in most cases) so that the owner can be heating the whole house while enjoying the fireplace.

Since most 24" gas log sets are rated at 90,000 Btu/hr (for natural gas), when a log set is combined with a JUCA F-9A, you get a gas burning fireplace which can totally heat the whole house!

Manual lighting, automatic safety-pilot lighting, wall-thermostat-controlled electronic ignition or even a remote-control "zapper" are available for any level of user convenience.

Our standard sized F-9A is the so-called 36"x28" popular size, but since we customize our products to specific applications, we have made thousands of special units, from huge 78" wide giants for restaurants, to double-, triple-, and even four-glass-sided units for dynamic living rooms. All of this customizing, economically.

After WE give you our liberal contractor discount, then many local gas companies give you THEIR $$$ REBATE FOR INSTALLING OUR GAS FIREPLACE OR GAS LOGS, and you're way ahead of the game. The house sells faster, with the advanced fireplace heating it.

Doors Opened or Doors Closed

A question sometimes comes up. Should the fireplace doors be opened or closed while burning gas logs.

Long ago, the directions that came with ALL gas logs indicated that they could be used either way. Then, (we think), the lawyers of those manufacturers got involved! We think they started worrying that if their gas logs were burned in a shallow (Rumford) fireplace (with doors closed), the fire might be too close to the glass panels and might cause them to shatter from the heat, spraying very hot glass chunks out into the room, onto people and carpeting and anything else.

The lawyers for the glass door manufacturers were clearly thinking along those same lines, because ALL current door sets come with instructions to ONLY operate a fireplace with the doors opened, whether wood or gas was being used! In their paranoia regarding potential lawsuits (maybe not paranoia, but reality!), they have overlooked the fact that tens of millions of fireplaces have been successfully used for decades, with the doors closed (to reduce heat loss up the chimney). Modern America, I guess!

We think the gas-log manufacturer lawyers also worried that if the gas logs were burned in a fireplace that had airtight doors installed on it (fairly unusual, even today), with the doors closed and the draft also closed, the fire might be able to use up all the oxygen inside the firebox. That could cause the fire to go out but the gas to keep filling the firebox for a while (or longer, if the safety control also failed at the same time). A firebox thus filled with gas, with hot logs all ready to ignite it, might therefore explode when the owner then opened the door (letting oxygen in) to see why the fire stopped.

Lawyers think like that! Each of these situations requires user negligence in combining incompatible products (Rumford and glass doors and gas logs / airtight doors and gas logs) and also pretty irresponsible action by the owner/user. But since manufacturers often get sued under such circumstances, their lawyers make sure their instructions eliminate every possibility of their company being sued. Ever see all the warning labels on a ladder?

So, you will definitely see a warning in the instructions of EVERY gas log set (and every glass door set( that it "must" only be used with the fireplace doors open!

For conventional fireplaces, that actually has a good aspect! It turns out that the standard glass used in fireplace door sets absorbs much of the INFRARED (heat) radiation. With the glass doors closed, the LIGHT gets through, so you see the fire, but only about 1/3 of the heat energy is able to pass through the glass out into the room. In order to get much more HEAT RADIATION out into the room, the doors need to be opened anyway! Of course, at the same time the opened doors allow the heat radiation to come out into the room, a good deal of (warm) room air is going through the opening to go up the chimney and be lost and wasted. So, operating any fireplace with glass doors OPEN, creates both extra heat GAIN for the room (the extra infrared heat radiation) and LOSS (the warm room air that is lost up the chimney).

In general, since the amount of infrared heat radiation goes as the FOURTH POWER of the effective temperature of the fire, people use fairly 'roaring' fires in a conventional fireplace. This situation makes it so the extra heat gained is greater than the heat lost as the room air is lost up the chimney. A conventional fireplace, with such an "ideal" roaring fire, can be around 11% efficient at best!

When people burn wood, as a fire starts to die down, that temperature drops, and there is a point where the heat gain and the heat loss are the same, and at that point, the doors should be closed. For dying fires, there is very little infrared heat energy being created but still a good deal of room air would be going up the chimney, and the overall efficiency of the fireplace actually becomes NEGATIVE! This is the main reason why people buy glass fireplace doors!

When using gas logs (fully on), with its fixed amount of flame, there is positive efficiency with the glass doors open, but it is still never much above the 11% level. If the gas valve is turned down, the efficiency becomes less, and rather small gas fires can also have ZERO or NEGATIVE efficiency!


All of the above discussion is about conventional fireplaces, where the ONLY heat that can get out into the room is by infrared heat radiation. Long ago (30 years?), people were disappointed in a MAXIMUM of about 11% efficiency. [Note: Actually, there has long been a very shallow type of fireplace, designed by Count Rumford in the 1800s, where the fire is nearly out into the room. The Rumford fireplace is therefore able to radiate more infrared heat into the room (because of geometry) and its overall efficiency is often higher, and can be as high as about 18%. But a Rumford fireplace is so extremely shallow as to not really permit the use of standard glass doors, a negative!] CIRCULATING fireplaces were developed to solve this. By having hollow chambers around the back sides of the fire (usually, in a metal structure) the infrared radiation going in those directions, which heats those walls, which then heat the air in those chambers, is able to be blown out into the room (with an electrical blower or by natural thermosiphon convection).

Such designs, without a blower, increased the overall efficiency up to about 25%, and, WITH a (little) blower, up to around 35%. This made "circulating fireplaces" extremely popular, and many millions of them got installed in houses. Usually, you can tell if a fireplace is one of these convection units by its having either grilles in the brickwork near the fireplace opening, or more commonly, having (black) metal areas around a smaller fireplace opening, and various holes or slots in those metal areas. In this last case, "standard" fireplace door sets (like we carry) generally cannot be used, because they would interfere with the airflow through those chambers, possibly making the inerior areas too hot, and potentially unsafe.

Actually, the JUCA designs are very sophisticated improvements on the general concept of circulating fireplaces. With extreme focus on gaining heat from those various interior surfaces of the firebox, JUCA found it necessary to use much larger/stronger blowers and much larger/more advanced air passageways inside those (hidden) chambers, to achieve its 65% to 70% overall efficiency (for F-9A units) and its 80% to 82% overall efficiency (for its B-3B, B-3A, B-3D and B-3C units). Nothing really 'magical' about it, just modern engineering principles of thermodynamics and aerodynamics being used where no one else had seemed to have done before!

Another note: People sometimes come to realize from this JUCA web-site, that a large blower is central to the JUCA excellent performance, and they decide that they want to attach a giant blower to some existing circulating fireplace. Sorry! It would certainly have minimal benefit (but it would have some!) Those competing circulating fireplaces were MADE for their little (optional) blowers, and their air pathways are very narrow and unsophisticated. Even a giant blower could not move much more air through the skinny passageways in them!

OK! We're FINALLY getting to the point! Since 'circulator' fireplaces, and especially JUCAs, collect much of the heat from heat exchange structures in those back walls of the firebox, the amount of total heat getting out into the room is FAR less dependent on the amount of infrared heat energy coming out through the doorway. This means that they supply the room with a good amount of heat, whether the doors are opened or closed! For 'performance' reasons, they could be operated either way!

Regarding 'circulator' fireplaces, since the unit could therefore be used with the doors closed, the two earlier concerns should be considered. If a firebox is very shallow, where the gas (or even wood) flames were closer than about 7" to the glass doors, that could cause the glass to de-temper and shatter, a bad thing! We are not aware of ANY circulator fireplace that has ever had airtight doors, so the other safety concern has probably never applied.

This logic implies that, for use in 'circulator' fireplaces (including JUCAs), WITHOUT airtight doors, and WITH reasonably deep fireboxes, a set of gas logs COULD be used with the doors closed, even though those lawyer-inspired warnings with the gas log set say otherwise. Our JUCA F-9A units have a 23.5" deep firebox, plenty deep for such safety.

Actually, as mentioned above, the lawyers for the glass door manufacturers have ALSO gotten into the picture, and most fireplace glass door sets now include warnings that even a wood fire requires that the doors always be opened! Many years ago, before countless lawsuits, there was no such warning, and many millions of people have successfully and safely have operated their fireplaces with closed glass doors for years!

Since we're on this tangent anyway, JUCAs actually have two advantages in this area. (1) The JUCA's firebox is rather deep, a little over 23", so the fire, whether gas or wood, is MORE than 7" from the glass door panels. [Many competing fireplaces are only around 16" to 18" deep] (2) Because of the very high efficiency of the JUCA design, a rather smaller fire is actually necessary to produce the desired heat for the room/house, so there's far less infrared radiation being absorbed by the glass panels, so they are less likely to get overheated.

SO, 'circulator' fireplaces, with their higher efficiencies due to the hidden heat exchange chambers, CAN generally be safely used with the glass doors closed (if they have deep enough fireboxes). By greatly reducing the amount of warm room air being lost up the chimney, that substantially improves the overall efficiency. This is a wonderful benefit of doing so! But always remember the warnings of all those lawyers! If you have airtight doors on your fireplace (even a JUCA) or if your fireplace is extremely shallow, then give serious thought to the safety matters mentioned here regarding burning gas logs with the glass doors closed. But, otherwise, millions of previous owners have established that it is very safe to do so!


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The JUCA Home Page is at: juca