Lets discuss gas fireplaces

[elkimmeg]

there are many catagories but does the general public know this some gas fireplaces are called

Decorative

Usually this catagory covers gas log sets but there are also gas fireplaces The decorative appliance is not government tested for effeciency Some of these fireplaces in the real world only rest just above 50 % effeciency meaning they use as much energy running and drafting and return a very small percentage of heat.

Heating Effeciency tested gas fire place heaters: Most of them test out in the 70's to low 80's in effeciency percentages. In reality about what a decent wood stove produces

I have often wondered there existances in modern homes equiped with high mid 90's effeciency central heating systems. People tell me the reason the install them is to provide heat to augment their heating system? Why would one run an appliance the is 20 % less effecient than there main system and tell me how much energy they are saving?.

Don't get me wrong there are some real good units that provide a decent amount of heat. But again I have to wonder by the time one is installed building the suround, the cost is fairly close to replacing an older furnace/ boiler and increasing the effeciency with the new boiler /furnace

I can see one going in an addition where it is the sole heat scouce. I can see ambience but do not try to justify them are being effecient. there are better ways to increase effeciencies and to produce heat using gas

Over at IB forum gas fire places are recomended I wonder if thy know the dirrerences between Decorative and heating and how they recomend an appliance that has little heating value?

So far I am discussing Vented gas appliances there is a whole other catagory of unvented ones with other issues I'm not a fan of breathing in their exhaust

 

[tradergordo]

They are worthless if you ask me. In THEORY they make a lot of sense - besides the ambiance factor, space heating in general is going to be more efficient than heating the whole house, even if you are using a slightly less efficient appliance, you also don't have the loss of efficiency from the ductwork. But the reality is that (and I know this from first hand experience because I have a direct vent gas fireplace) they can make your house much less efficient. First lets remind people that "vent free" models are dangerous, combustion appliances need ventilation, and vent free models are not intended for serious heating or long term use. Next you have the direct vent design, which is what I have. Due to stack effect, its nearly impossible to get a typical direct vent system to have positive draft when the gas fireplace isn't running - this means freezing cold air is pouring into your home 24/7 when the fireplace isnt' running. At least that was my experiece with the one I have, so I had little choice but to kill the gas to it, stuff some insulation over it, and board the thing up completely. I haven't used it in years and don't intend to ever use it again.

Oh, and the pilot lights on them also waste energy 24/7 whether you are using the gas fireplace or not.

 

[babalu87]

Ambiance PFFFFFT

Part of the Ambiance is the building of the fire , not flicking a switch

Man cut tree, man split tree , man stack wood, man get calloused hands, man build and maintain fire, man is sexy beast

 

[Highbeam]

I think there are applications where they make sense. My last house had an 80% efficienct natural gas furnace. The house was built in 1999. Every house in this area has a hearth and in a tight suburban neighborhood, that hearth is almost always equipped with a gas fireplace. So I have read, here even, that duct losses in HVAC can cause up to a 40% loss between the furnace and the heated space. Zone heating with a gas fireplace can also save over the whole house heater.

Your typical modern gas fireplace or stove that uses that funky double chimney which both takes in outside air and exhausts the exhaust would make a fine unit. Don't foregt that these things work fine in a power outage as well.

Is it better to simply upgrade the furnace? No way. That loud motor pumping air into the room inefficiently heating or the attractive and quiet fireplace with dancing flames and radiant heat which costs less to run.

When NG is really cheap, the gas fireplace (heater rated of course) offers many of the benefits of a wood burner. Oh, you simply shut off the pilot light when the heating season is over.

Maybe I'm missing something but I would love to have one if I lived in an urban setting.

 

[MountainStoveGuy]

any kind of zone heat is better then a forced air furnace. Sure a furnace can burn more efficient then a fireplace, but the transfer efficiency is lousy. Point source heat of gas is fantastic. If i had gas i would install it.
Pyro Ceram glass fireplaces will burn the hair of your arms if you get to close, and ember burners with fantastic log design is taking over the market. Next time your in a hearth shop take a look. The technology is changing every year.
you DONT want to turn the pilot off in the summer. It lets bugs get in just like your gas grill. They can foul orfices and venturies.

 

[Highbeam]

Bugs in the fireplace? I can see that on a BBQ qith exposed bits and pieces but the gas equipment inside the burn chamber of a sealed gas fireplace is only accessible by a bug that flies down the chimney. Is that what happens? I was actually more worried about corrosion when I shut the pilot light off every year for 5 years, never had bugs or rust and only a slight dusty smell when lighting it up in the fall.

It would be much cheaper to buy and operate a gas fireplace for heat than to buy and operate a pellet stove so long as NG costs don't rise like crazy. I am having a hard time seeing when these sealed units (isn't it called B-vent?) can ever be less efficient than a furnace.

 

[tradergordo]

Maybe technology has imporoved a lot since my '99 model, but mine never seemed to produce much room heat which is another reason I boarded it up. It had no fan, and was basically just glass sealed with nothing really to transfer heat into the room - seemed to me like it was basically just heating the outdoors. I have no idea what kind of efficiency rating it supposedly has, nor do I know how that industry measures efficiency, but my total guess estimate of efficiency based on actual heat delivered to the room would put mine in the 10-20% range probably.

How do the new designs transfer heat into the room?

 

[MountainStoveGuy]

Highbeam, it depends on the application, but i can tell you this. Our service comapany has made a small fortune pulling bugs out of burner orfices and mites out of pilot orfices. Mites and spiders are attracted to the additive that is in LP and NG, and they can find there way down. It doesnt happen all the time but it doens happen, and its a costly service call if your not savy to reconize the symptoms.
On the other note, DV or direct vents are the sealed units, B vents arent. And your absolutly correct, a proper zone heater sized correctly will be more efficient than a furnace. Once again, what kills the furnace is the transfer efficiency.

 

[MountainStoveGuy]

Maybe technology has imporoved a lot since my '99 model, but mine never seemed to produce much room heat which is another reason I boarded it up. It had no fan, and was basically just glass sealed with nothing really to transfer heat into the room - seemed to me like it was basically just heating the outdoors. I have no idea what kind of efficiency rating it supposedly has, nor do I know how that industry measures efficiency, but my total guess estimate of efficiency based on actual heat delivered to the room would put mine in the 10-20% range probably.

How do the new designs transfer heat into the room?

they make them inefficent by design, and they also make them efficient. There is a market for both (bedrooms and southern homes dont need heat, but they want a nice fireplace and not a cheap builder box) Logs look loads better today, as well as the burn pans in the firebox.
Efficient one have pyro cyram glass and can be upwads of 88% efficient. Decrotive ones have temperd glass and start at about 50%.
I dont know of a woodstove that burns 88% efficient. (thank god)

 

[elkimmeg]

AhRRRR gas spiders can stop a gas fired appliance cold
Part of this discussion is due to An Inspection I did today cold air pouring out the unit.
Improper chace/ bumpout construction is ususlly the culprit..

If installing a gas fireplace is due to ineffeciency of your heating system and poor tranmissiom losses ,then would money be better spent making improvements to your main heating system.
Might I remind some that froced hot water systems heat cleaner and more even They do not suffer leaks in their system but exposed basement pipes should be insulated.

the 40 % /35% Transmission losses do not apply to Forced hot water systems only to pooly installed hot air systems In a home with forced hot water the effeciency loss is not there and justifying a less effecient room area heater arguement is pointless.

In the real world heaters located in exterior bumpouts one has to factor the dremendeous cold air leak most have to improper preparation of the chace and bumpout..

By posting this info I wanted it to be discussed this is not wood vs gas this is a choice some make but lets get it right and not be looking at a decritive builders box the leaks cold air
and wonder where the heat is

 

[tradergordo]

Lots of unrelated thoughts...

1) To keep criters out during the off season - wouldn't it be better (save energy) to just put some bug proof cover over the burner instead of leaving the pilot on the whole time?

2) Elk - it costs a LOT of money to replace all the ductwork in your house, and that STILL doesn't eliminate the transfer efficiency loss although it can improve things tremendously. I think the payback time would be extreme (more than 10 years). But space heating makes sense in other ways - for example if you basically just use one room most of the time (like a family room) why heat the entire house when a space heater focused on that one room will due?

3) "In the real world heaters located in exterior bumpouts one has to factor the tremendeous cold air leak most have to improper preparation of the chace and bumpout.." YES, this was my main point. And it isn't really "improper preparation" per se, because there is no "proper" bump out chase or "out the side of the house" direct vent, they just don't work in practice, period. This has been discussed over an over again here. Stack effect. Cold air pouring into your room is no good. Basically you have to have the thing running 24/7 to prevent the cold air from pouring into the room, or you have to insulate and board it up.

AhRRRR gas spiders can stop a gas fired appliance cold
Part of this discussion is due to An Inspection I did today cold air pouring out the unit.
Improper chace/ bumpout construction is ususlly the culprit..

If installing a gas fireplace is due to ineffeciency of your heating system and poor tranmissiom losses ,then would money be better spent making improvements to your main heating system.
Might I remind some that froced hot water systems heat cleaner and more even They do not suffer leaks in their system but exposed basement pipes should be insulated.

the 40 % /35% Transmission losses do not apply to Forced hot water systems only to pooly installed hot air systems In a home with forced hot water the effeciency loss is not there and justifying a less effecient room area heater arguement is pointless.

In the real world heaters located in exterior bumpouts one has to factor the dremendeous cold air leak most have to improper preparation of the chace and bumpout..

By posting this info I wanted it to be discussed this is not wood vs gas this is a choice some make but lets get it right and not be looking at a decritive builders box the leaks cold air
and wonder where the heat is

 

[MountainStoveGuy]

there should be no air infiltration from the fireplace at all. NONE. The combustion chamber is sealed. the firebox penetrations in the bottom of the fireplace to the control should be gasketed and sealed. The direct vent fireplace has no place for air to come in the room whatsoever. The tightness of the install is completly determined by the quality of the bump out. I recommed bump in'. Then you only have one small hole to tighten up instead of a 42"x36" hole. Stack effect should have no part in the direct vent fireplace installation if done properly.
As far as bugs go.. if they can craw into a pilot orfice, then they can darn near crawl in a pore in your skin. A cover would have to be super tight, and the homeowner would have to do it every year. Its just easier running a 1500 btu piolt year round. Call it insurance that the fireplace is going to work next season. Its approx $46 to run a pilot for ayear at .07/therm.

 

[Highbeam]

You can have bad and leaky installs of any heater but that doesn't mean the heater is at fault or any less efficient. My last gas fireplace was a bump-in in the corner of the room. A TV cavity was built above it since the chimney stuck out horizontally through the exterior. I never had any black staining on the exterior light colored wall and really liked the TV mount. I agree with MSG, the appliance was sealed from the inside air, an outside source of combustion air and exhaust disposal through a single coaxial pipe. I suppose a creepy bug could make it down the chimney into the combustion chamber but I must have gotten lucky and they stayed away. Never had bugs in my BBQ orifices either, maybe it's a regional bug that likes the added scent of LPG and NG.

Assuming no moronic construction methods, a delivered btu is a delivered btu and the NG fireplace/stove can really deliver a lot of them to the living space in an efficient manner with almost zero consumer input. You think pellet stoves are nice with their thermostats and on/off controls, well a gas stove has almost no moving parts and needs never be fed with pellets. Gas bill is no higher than pellet bill unless you must use LPG and then it's pricey.

That said, I would rather sit around a nice heavy wood burning stove.

 

[thechimneysweep]

We sell heater-rated direct vent gas fireplaces rated at 80% delivered efficiency. Our customers might buy them for the ambiance of the cheery fire, but most end up using them to heat their homes. High-efficiency gas stoves, inserts and fireplaces are no harder to heat a home with than woodstoves, wood inserts or high-efficiency wood fireplaces: the heat transfer technique is the same. BTU production is more controllable with gas fireplaces, and gas fireplaces are less messy in the home than wood-burners, but of course the fuel is costlier. As to comparisons with gas furnaces, no furnace manufacturer can rate delivered efficiency, as no two delivery systems are the same: the rating on a furnace is for heat extraction efficiency. We have a couple of letters on the subject in our online Sweep's Library at (broken link removed to http://www.chimneysweeponline.com/hoinvsfu.htm)

 

[elkimmeg]

the common faults of the bumpouts air leak #1 the vent pipe is cut larger than the pipe onening that space needs to be caulked Coaxial pipe returns fresh combustion air in the outer section of the pipe. Heat is not a factor so common caulk can be used.

#2 chancces are fiberglass batt insulation is installed between stud bays and it is not always correctly fitted this creates leaks I also have found that only the wall are insulated and
for some mystery no insulation of the ceiling. Too many times this is the norm. Code compliant bump out requires to to be sheathed with 5/8" fire code sheet rock and to be taped ans seamed
When is the last time installers you saw one bump out 5/8" fire code sheetrocked and seamed?. I know the answer None? Then why do you install a stove in an improperly built bump out?.

Me I would like to avoid problems in the first place by doing it right the first time. It's a he)) of a lot easier when things are open up to do it then.

The DIY If you are getting too much transmission loss then time to adress that Every joint ans seam should be sealed in Duct mastic including elbows and take off flanges boots. After that is done all duct work should be insulated to R6.0 including floor joist pan return bays (Joist pan bays I hate them most are sloppilly installed very ;leaky ans they should be caulked and draft proofed then the exposed metal insulated . Thos is what I'm talking about most home owners can do this the pay back is instant a side benifit you just made you home quieter Money is better spen there correcting faults than ignoring them and purchasing a supplememtal heater

Again this is meant to be educational not one fuel is better than another To me,, doing things right the first time to allow your appliance to do what it is suposed to do

 

[MaineWoods]

Not a fireplace but gas related. I'm not trying to sell Rinnai heaters but I did buy one based partly on whats on this guys site. He is very biased but maybe for good reason.

http://www.alsheating.com/HeatingEfficiency.htm

 

[thechimneysweep]

All vented gas heaters need exhaust flow at a certain volume to clear the fire chamber of exhaust and draw in combustion air. In the case of direct vent heaters, there are two standard co-axial pipe sizes used: 4" exhaust and 5" exhaust. The reason Rinnai is able to get functional outflow with such tiny exhaust pipe is that their heaters have forced-air exhaust. For example, if you need an outflow of X cubic feet/minute to make your gas heater function, you can vent using whichever of the standard co-axial pipe sizes and venting configurations creates the natural outflow rate needed for the btu's being burned, or you can create the same outflow with a smaller exhaust pipe by putting an X cubic feet/minute forced air exhaust on your heater. Either way, the same amount of exhaust (and heat loss) will occur.

 

[Fire Bug]

If someone has a house with a open fireplace I would strongly recomend buying a good DV insert unit to put in the firebox.
As you probably now, open fireplaces are just as bad as leaving a window open in your house in the winter. All your heat goes right up the flue and you have to leave the damper open until the wood fire dies out and the coals cool.
At least with DV insert, you can get heat, the ambiance of a burning fire, and the ability to sit back in your favorite easy chair to enjoy it all instead the constant poking, and wood feeding of an open fireplace.
If your serious about wood heating and like the heat from wood,(who doesn't?), than a nice woodburner downstairs sounds very reasonable.
Unvented is not a option and when installed properly, the new DV inserts leak no air from the combustion chamber or anywhere else on the unit.(As noted previously).
John