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Decroative Appliance Gas Log Sets:

icesailor Member Posts: 7,265
This is a question for Tim McIlwaine or anyone else who wants to comment.

I have a question about Decorative gas appliances. I get conflicting answers. I have a job where last year, a customer wanted three of them to vent into three fireplaces with dampers. I have installed a few of these. I have one in my own house. There are two types. One that just dumps raw gas into same and it smokes like heck to give you "A real woods like feeling". They smoke up the fireplace and make a mess. I don't ever install these. They are limited by the manufacturer to 65,000 BTU's. The other kind uses a Bunsen flame and mixes air into the gas before it comes through a grate, covered with pellets and goes up through logs. They are limited to 36,000 BTU's. Less than a good gas stove. The manufacturer says they must be vented into a working fireplace. No mention of a lined chinmey flue because they don't get hot or cold enough to condense. As I have done. I never get any CO in mine, ever. With a CO detector right over it.

I bailed on the install last year and made arrangements for the LP supplier to do the gas piping for a stove and the logs. The owner decided to wait on the logs. I had all the fireplaces repaired with new dampers and an inspection. They all passed. The owner wanted me to do the logs again this spring. I ran out of time and there is some detail about getting the sets. I told the customer to get the sets from the LP supplier and have then install them. They called another plumber who has told the owner that all the chimneys must be re-lined or they can't be used. The gas supplier defers to the plumber. I asked the AHJ, Plumbing/Gas inspector and he agreed with me saying that it is a decorative fireplace and it goes on what the manufacturer says. It is allowable but can't be used in bedrooms. It isn't.

I've gone through the entire NFPA-54 and the Mass CMR 248 addendum's and I can't find anything to the contrary. It is a non condensing appliance.

What say you?


  • Tim McElwain
    Tim McElwain Member Posts: 4,593
    There is an ANSI Standard for

    decorative fireplaces as they would not be able to be installed without a standard for testing and installation. It is Z21.11.2 and can be purchased from ANSI for $1,074  it is 174 pages long. That would give you exactly what the requirements are.

    In most cases manufacturers instructions are going to follow ANSI standards to the letter. In that case they prevail.

    Most of the fireplace inserts I have seen do not require relining the chimney. In RI however there must be a chimney inspection by a licensed chimney sweep.
  • icesailor
    icesailor Member Posts: 7,265
    Gas Logs:

    As usual, the manufacturers instructions rule the install. They are installed all over the country and Canada too.

    This is another case of low information professionals giving out wrong information and while the AHJ is saying this potential install is OK and has no problem with it, others with no information and jurisdiction are saying something contrary.

    "When someone calls you on the phone, they want to spend money."

    I give a good job that I can't do at the moment, AFTER I gave someone a job to inspect a six flue chimney and install dampers, and give someone else a job to install the log sets, and the gas piping is done, all you need to do is drill the hearths and connect the gas piping below, send the bill and get paid. But, "NO", you need to line the chimney, when you don't.

    I guess this is all a plus. I now have the time. I'll sell the sets AND sell them glass fireplace screens. Custom made and fit.

    This isn't some expensive and involved stove, it's just a AGA approved gas burner where the flame is run through stuff like vermiculite and through ceramic logs and look like you have a fire in a fireplace. They don't give off much heat. It's decorative. It's not a heating appliance.

    I have to wonder.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840

    In Denver, you MUST provide a separate source of outside combustion air to the fire box, AND you MUST remove or otherwise disable the damper assembly to avoid the possibility of someone firing one up with the dampers closed...

    These things are a carbon monoxide generator, and in my professional opinion can NOT be made to operate safely. I know the logs can be arranged such that CO production is held to a lesser value, but who wants to lay on the floor staring at the burner in their oven... In order to look "real" they have to have yellow flickering tipping flames, which are full of CO.

    Even with the premix of air and fuel, the flame impinges on a cool surface, causing CO production. And without premix, well common sense tells you that it HAS to produce CO.

    Never liked them, never will.


    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Tim McElwain
    Tim McElwain Member Posts: 4,593
    I agree Mark

    I have never actually installed one of these or any unvented units and never will. I have shut off quite a few for high CO. AGA approval does not make them entirely safe just tested. I tested a floor furnace once in the gas company lab which was approved by AGA. I felt it was a fire hazard so we would not allow it on our line. One yer later in New Hampshire that very floor furnace burned down a log cabin with two people in it.
  • icesailor
    icesailor Member Posts: 7,265
    Log Sets

    Think/say what you want.

    I am asked to install a high end 30" gas range. It doesn't require a hood but should and will have one. The combined total of the top burners on LPG are 64,000 BTU's not counting the bottom because they don't list it in the install instructions. I guess I have to get it from the unit when it comes. They switched to a GE high end range. That one is 45,000 on LP and 58,000 on nat. gas.

    The log appliance is 35,000. The other kind that is a CO generator is up to 65,000+. It's for looks, ambiance. Not heat in any way. The house has 3 zones of FHW heat.

    I get more CO flying to work on a cold day when the aircraft heater is running than I get out of my own log set. The ones I am talking about are fully adjustable with an air shutter. The ones you are talking about are completely unadjustable.  
  • Jack
    Jack Member Posts: 1,046
    Think/say what you want!

    Then why ask?

    You would do well to follow Mark's, Colorado specs. Pinned damper, for everyones safety, including yours and a source of outside air.

    After installing them this summer. please interview the customer in June '12 and ask him to report on fuel consumption changes and whether they are happy with the operation. Please, let us know how that goes.
  • meplumber
    meplumber Member Posts: 678
    Disabled Damper is code up here too.

    I won't do them either.  Did one once.  Couldn't get comfortable with the install.  Disabled the appliance and told them to call the fuel supplier.

    Never again.
  • Tim McElwain
    Tim McElwain Member Posts: 4,593
    Having worked for a gas

    utility for 28 years that was a stickler for safety I would not take a chance putting one of these in. Everyone I have ever seen are neglected by the homeowner and are making CO in the range of over 400PPM. Maximum allowed on these is 200 PPM air free.

    As for gas ranges and ovens most of them which are standard residential require no vent hood per there instructions. It is typically recommended however. A top burner on these is 10,000 BTU's so four of them would be 40,000 BTU's. The oven is typically 20,000 to 25,000 so that is a total of 65,000 BTU's. Here is the catch for 65,000 BTU's code will allow that in a 20 x 20 x 8 room which is 3200 cubic feet, at 50 BTU's per cubic foot that is 64,000 BTU's. Anything less than 20 x 20 x 8 is a confined space and will need dedicated air from outdoors and opening 12" from the ceiling and one 12" from the floor. Now that does not make sense so it would mandate a vent hood.

    If a customer decides to put a commercial range in a residential kitchen they have to have a vent hood interlocked with the range and also capable of providing make up air.

    It is not the best comparison to compare a cooking stove with a gas log insert. But to illustrate a point if you are connecting gas ranges without a hood and the kitchen is less than 20 x 20 x 8 then a vent hood is required with provision for make up air.

    Hey do you want to talk about gas dryers which require a 100 square inch opening into the room they are located in for just plain make up air.

    Before folks make comparisons they need to get educated on codes and get some proper training not fly by the seat of their pants.
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    edited July 2011
    Opinion: Log sets are soon to be obsolete

    Decorative gas log sets are likely on their way out, this will leave gas insets (complete appliances with vent lining systems that fit into the fireplace) as the only choice for retrofitting into an existing fireplaces.

    Gas log sets can be divided into 2 sub categories; vented and unvented (branded "vent free")

    The vented units all burn dirty, that is the exhaust usually has a yellow flame burner with a lot of CO in it.  They typically have a simple milivolt gas valve with only flame failure safety.  They don't have any form of vent proving switch or spill switch to shut the unit off in the event of some or all of the exhaust spills into the house.  Inspection authorities have responded by requiring combustion air and locking the dampers open.  On the plus side, they look great when they burn and make little change in the look of the fireplace when its not in use.  (the LPG versions tend to soot way more than nat gas)

    Unvented units typically have: lower BTU ratings, dump all the exhaust into the house, clean(er) burning burners, and oxygen depletion type pilot generators.  These are supposed to have the pilot flame lift off the thermocouple and shut the appliance off in the event the oxygen content in the combustion air starts to drop.

    As we start looking at a house as a system we need to consider things like:1) The amount of depressurisation from high capacity range hoods, bath fans, and cloths dryers can create a large enough negative pressure to overcome the draft in a chimney. 2) Measures like insulating,draft proofing, and window replacements; effectively reduce the available amount of make up air.

    Home owners can and often do make the above changes to their house subsequent to a log set installation oblivious to possible hazards they could be creating.

    Gas inserts are complete appliances that install within the fireplace that incorporate a vent lining system.  They generally have either a vent safety switch in B-vent units that draw comb air from the room, or, are sealed combustion type that have separate liners for comb air and the exhaust making them immune to the above mentioned depressurisation issues.


    The EPA has vented and unvented log sets in their cross hairs.  Further; they intend to introduce minimum efficiency standards for all gas fireplaces as they are, more than ever, being installed as supplemental heat sources.  Can't happen soon enough as far as I'm concerned.

    Log sets can and have worked fine for years, but I think the inherently safer alternatives are the only way to go.
    Home Owners Please Note:

    You are receiving advice from some very skilled pros completely free of charge. One of the reasons I participate is to sharpen my own troubleshooting skills. So; did we get it right? I would be grateful if you extend this courtesy back by posting the final outcome of the issue you are inquiring about. Thanks
  • icesailor
    icesailor Member Posts: 7,265
    Log Sets:

    Did you read what I wrote?

    I said that there are two types. One just uses raw gas and makes lots of CO. The other is a Bunsen flame. As efficient as the burner on a stove. It has an air shutter adjustment. This isn't to heat a house, the house has three zones of FHW heat. It's for looks and will probably never be used once the new is worn off.

    In MA, you must block the damper and must have hard wired CO detectors.

    The kind I am writing about, you can connect the gas, not install the "stuff" that the gas comes through and have a blue flame through the burner grate like on a gas stove. The kind you are writing about, if you connect the gas to the burner, and the burner tube with the .010" slit in it isn't covered with the "stuff", and it is LP, it will run out on the floor and not ignite. It makes copious amounts of CO, no matter what you do. It makes black smoke and soot's. Like they advertise, "Real Deep Woods Fire Look".

    I have the former in my fireplace with glass doors. My wife wanted one. Once the new wore off, the last time it was used was during a winter storm two years ago and the power went out. I never got a reading with my CO detector. And I know it works because the other day, before I replaced the exhaust on a Heatmaker that had a broken inside plastic vent, it read over 1000 PPM of CO. The highest I have ever seen. When I repaired it, it went down to 35 at the outside outlet.

    Understand, this isn't a "heating" appliance, it is a decorative appliance. Looks only.
  • Jack
    Jack Member Posts: 1,046
    I am told that the MA language on the damper is...

    that it must be "removed or welded open". You can install glass doors on them as you note. A provision that came up recently in MA on a NG log was that there is a provision in the Fire Code since '88 that a NG appliance has to have spark ignition. Apparently, gas and fire officials are starting to enforce that provision, although most gas inspectors, I am told, are unaware of it as it is in the Fire Code. I know your install is LP so you don't have to worry about that.
This discussion has been closed.