Gas Fireplace Inserts-Bigger Isn't "Always" Better

Dec 13, 2001 (Updated Feb 4, 2010)

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The Bottom Line The road to satisfaction from a new gas-fired insert is paved by doing a little bit of homework and asking informed questions before making that purchase. I hope this helps.

Having decided to clean up the look of your existing wood burning fireplace, by retrofitting a gas-fired insert, you have so many things to think about, you may want to forget the whole idea. Don't be daunted by the technical lingo, or taken in by the flashy advertisements. Read the fine print and ask informed questions.

If you've been using the wood fireplace extensively, it's always a good idea to have the chimney cleaned, just one more time, before the gas insert is installed. Some hearth stores offer that service at a reduced rate if you're buying a gas insert from them.


There are only a couple of types of gas inserts you may wish to consider. A conventionally vented and direct vented or sealed combustion type.

* Generally speaking the conventionally vented provide fewer performance problems. They are almost all equipped with a four inch aluminum flex vent from the unit to the top of the chimney. The four inch flex effectively resizes the chimney for the reduced volume of products of combustion produced by gas inserts as compared to the smoke, heat, dilution air and other products of combustion drawn into the chimney from a roaring wood fire.

Today the most common types of inserts are direct vented, which simply means they use two three inch diameter aluminum vent pipes.  One to exhaust products of combustion and the second provide air for combustion, down the old flue.  When generally means you need to understand the specifications for your home.

Since you are retrofitting a wood burning fireplace which used much more air than a gas insertl, it is unlikely that there is an air supply problem to the room it is going into. Natural infiltration around windows and under doors is usually sufficient to accomodate the amount of air required for complete combustion and dilution air through the draft divertor into the chimney.

A chimney liner with a rain cap is not an option with a gas insert, it is a requirement. In fact, the gas insert likely won't function without one. At least, it shouldn't, if it hasn't been tampered with and it has been designed properly.

* Direct vented inserts usually use two, three inch diameter aluminum flex vents from the unit to the top of the chimney. One vent is used for exhaust and the other for bringing in combustion air.

You may want to consider this type of insert if you are living in a tightly sealed home and you are concerned about availability of combustion air to the fireplace. In some municipalities, it may be worth a quick call to your gas supplier to check whether there are any new building codes regarding air quality.

Some of the problems reported by the manufacturers of these products include; ice build up on the vent cap at the top of the chimney, poor draft conditions causing the air supply to slow down and choke out the flames, (especially from a cold start, on a cold day which is presumably when you would be turning it on) and intermittent pilot outage.
Pilot failure occurs most frequently when the colder, heavier air in both vents, hasn't started to flow. Until the heat builds up, the cold air provides an effective wall against the escape of flue gases. If the exhaust side stalls out, the incoming air side has no suction, so the flame and the pilot lift off and extinguish.

This doesn't tend to be a problem with conventionally vented gas appliances, because they are drawing air from the room and will spill through the draft divertor until sufficient heat builds up in the chimney vent to establish a proper draft action.


Some people believe, an insert is an insert, built to national safety standards, there shouldn't be anything too different from one to another. Take a closer look at the specifications on the brochure. Some of the specifications you need to know, are not always there. Ask who the manufacturer is of the brand you are considering. There are a number of manufacturers who put out the same products under a variety of brand names so that their dealers appear to have different lines.

Don't ever assume that just because the manufacturer has a well recognized name, the product must carry a bigger price tag and that will ensure higher quality. Nothing could be further from the truth. Some of the smallest manufacturers in the gas hearth products industry, produce some of the best made appliances and offer them at substantially lower prices than the nationally recognized brands.

They may not advertise their products on the sides of buses, but, they are not passing on a percentage of their advertising budgets to you in their suggested retail prices either. I know a couple of small to medium sized manufacturers whose presidents walk the production lines every day of the week. They know the one thing they have to offer is quality and attention to details. That is rarely the case with the multi-national, mega brand name manufacturers, whose presidents can forget that they even have a fireplace division.

Check out the gauges of the materials used to fabricate the fireplace. The thickness of the steel is a good indicator of the quality of the product. That is not to say that the overall weight makes one better than another. However, a 16 gauge steel firebox is likely going to live longer than a 20 ga. steel firebox. Some manufacturers will go as thick as 14 ga. on the firebox. (The lower the gauge number the thicker the material.) 18 Gauge is fairly common and should have a reasonable life expectancy. However, that ultimately depends on design, quality of the welding, Btu input and the amount of expected useage.

All gas inserts come with a steel or an extruded, aluminum surround, to enclose the space around the fireplace opening. Check the gauges of the surrounds that come with the fireplace you are considering. Does it feel solid or tinny? Will it rattle when the fan comes on?

Ask the dealer what type of circulation fan comes with the unit and if they have had many service problems with them. They may be honest enough to tell the truth, it doesn't hurt to ask. Have them demonstrate the appliance in their showroom with the fan on high speed. If it rattles in their showroom, it will rattle in your living room.

Ask what the logs are fabricated from. The higher quality inserts today use ceramic fiber logs. Not only do they look more realistic than the concrete type, they heat up faster and glow better. Most come with a specific amount of glowing coals and embers to provide the effect of a glowing ember bed.

Bigger isn't always better. Higher Btu's per hour may cause short cycling and an uncomfortable room. It's hard on the unit and it is a less efficient way to operate it. Besides, you bought this appliance for both heat and aesthetics. You really want to be able to run your fireplace for long periods of time, without overheating the room and giving you the ambiance you were hoping for, to make romance happen on the bear skin rug. So, in this case, it isn't how big it is, but, how you make it last. *S*



Have you ever seen a hamburger come out of those little styrofoam boxes looking exactly like the picture? Of course not. At least,I never have. Almost all brochures look beautiful and that's their job, to hook you. The flames are regularly touched up and computer enhanced.

You need to go to a showroom. Either a local hearth products dealer or your local heating contractor. Many utilities also have burning displays. Seeing a burning display is a must before committing to purchase and even then, I hate to admit, there are specific questions to ask about the set up of the burning display.

Check the picture on the brochure and compare the effects flame with the display unit closely. Is it a reasonable facsimile? Ask the sales rep if the gas input rate of the display unit has been increased for showroom purposes. Ask them if this is the exact effects flame that you can expect from this unit, in your home. Be specific on that point. If you like it, based on what they have in the showroom, and you're impressed with the quality of the construction, the price is reasonable, you want it.

I don't know how many times I've heard people say, it doesn't look like the brochure I bought it from. Or, it doesn't look like the one in their showroom. Not all, but, many misguided hearth dealers and sales reps have been known to doctor their display units to be bigger, brighter flames. Overfiring a unit for display purposes may make a sale, but, generally produce unhappy consumers. Overfiring it in your home will cause you nothing but trouble with sooting and may even create a dangerous condition. It's an old trick to adjust the manifold gas pressure up for a temporary effect to make a sale or even to make a consumer happy after they bought it. However, it's a stupid trick.

The cost of your insert will vary from state to state, province to province, depending upon who your local dealers are. In larger areas you will have dozens to choose from and in small towns, perhaps only one or two local dealers. It's well worth a bit of driving time to see three or four hearth showrooms, even more if you have the time. Each time you look, take notes on the things you liked and didn't like, right on their brochures. (4958loes

As I said above, don't overlook the smaller manufacturers. If necessary, you may want to buy the insert from a wholesaler and arrange to have the installation done by a local contractor. Although, the contractor will usually charge a bit more for their labour, since they're not going to get any money from you on the equipment sale.

One small manufacturer I know, offers units wholesale to the public, fully loaded with, circulation fan, rheostat, gold plated doors and a wall thermostat, for a fixed price that is hundreds of dollars below some of the major manufacturers, and they still make a reasonable profit. So, the time spent shopping around can really pay for itself, in value and product satisfaction.


Fergit about it. Very few inserts ever achieve the published efficiencies shown on the brochures. The published efficiency is achieved under ideal lab conditions, usually with an engineer tuning it and a couple of lab technicians tweeking it. Efficiencies are a numbers game and mean few little in the bigger scheme of things. Plus or minus 5% in an average gas insert is the equivalent of about the amount of heat a Bic lighter produces.

73 To 78% steady state efficiency is average. I'm not sure I would want an insert that was 80 to 85% efficient. Too much efficiency can lead to condensing in the chimney. You actually need to waste a bit of heat in order to keep the vent working properly and to keep it dry.

If you want this product to produce heat, have a contractor or sales rep from a hearth shop, visit your home for free and conduct a heat loss/gain calculation on the room it is going into. Then you can select the Btu/h input rate you require. If the contractor or the hearth dealer can't or won't come out to your home to pre-qualify the installation conditions, look for one that will. They can't sell heating products blindly and hope to satisfy their customers.


There's nothing wrong with wanting to jazz up your insert with a little gold trim, a gold plated door, a bay window or clip on cottage style doors. Ask the sales person if the unit on the showroom floor is equipped with accessories that you are getting or if they are added costs. Quite often the showroom models are decked out with all the gizmo's and accessories, but, the base unit price is shown less these neat tricks.

I don't recommend brass louvres or brass trim around doors, they tarnish too quickly. Real 24K gold plated doors, if done properly, will retain their lustre for years. Gold plating is not as expensive as many people think. So don't pay three or four hundreds of dollars, for an optional gold plated door. Negotiate the purchase price to include one or two optional accessories. They have room to move on their listed prices.


I know I'm repeating myself, but, it comes with age. Do not hire the local gas fitter just because he's handy with a wrench and a member of your bowling team. Check out their qualifications. Make sure they have installed gas inserts before. Ask how long they've been installing gas appliances, most are only too happy to brag about that. Ask them if they own a combustion analyzer and if they can conduct a combustion test after the unit is installed to ensure it is set up according to the manufacturers specifications.

Ask them to check the input rate after the installation is complete. Ask them to ensure that the primary air setting on the burner is set according to the specifications in the installation manual. Ask them to double check the manilfold gas pressure and supply pressures with the appliance running.

Before they leave with your cheque, make certain they have checked their gas lines for leaks.

If you're buying this product from a hearth dealer, ask them if they have their own trained installation crews or if they subcontract out the work to local contractors. This is important, if they subcontract it out, it is their responsibility to know much more about the contractors they hire on your behalf. If they're employees, ask how long the team doing your home has been doing it and how many they install per week. It's always nice to have a referral if possible.

Ask the sales rep if they check the condition of the chimney, before lining and capping it.

I know it sounds as though I'm suggesting you ask a lot of questions and expect your contractor to do so much extra work. However, most of what I'm advising here, are things that all contractors are supposed to do after every installation. The problem is that most get a little lazy and want to get on down the road to the next job. This is a gas appliance that you are going to be living with for quite some time. You need to be assured that the unit is set up right the first time and you won't be cursing me for suggesting a gas insert.

Properly installed and set up, you really shouldn't need to clean the glass more than once a year. A special cream is available for the special, high temperature ceramic glass, that all gas inserts are required to have. It only costs between $5 and $10 a bottle and one bottle will last for many years. If you find soot accumulates more often, there is something wrong with the set up of the unit. Gas does not burn dirty, naturally.

Frankly, if I was running a showroom and you asked me all kinds of questions about display units,the construction of the unit, and the competence of my installers, I would be impressed. So few ever do ask those questions. They just kick the tires and buy the car.

Hopefully, armed with some of the above, you can go into any hearth showroom and make a few sales reps sweat a little. Good luck, and feel free to ask me if you have a question not answered here. There's so much ground to cover and so little time.

Best regards,
The Gasman

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