Ventless gas stove in basement

[Harley]

A co-worker of mine is looking to add some supplemental heat to the basement. It is a finished basement, approximately 1,000 sf (we'll assume it was insulated under the drywall). The heating for the main part of the house is forced hot air, fired by a natural gas furnace. The basement is heated (sometimes) by electric baseboard.

So the question is... would a natural gas fired (preferably ventless) stove make sense to add additional heat in this part of the house, so as to make it more livable in the winter? Also, any thoughts on the total costs of using this type of heater? The temperature of the basement, if the electric heat is not used, probably stays at about 56 degrees during the colder months.

 

[MountainStoveGuy]

i would never put anything that degrades air quality in place that already has poor air quality, like a basement.

 

[Harley]

Good point, MSG... what about a vented system.... then which would generally be better... the B-vent, or direct vent?

By the way... he grew up in South Jersey... so I'm not sure air quality is one of his biggest concerns... :sick:


Not trying to offend anyone from the Garden State... that was actually his comment, not mine :cheese:

 

[MountainStoveGuy]

Direct vent, it can vent horizontally, and wont spill carbon monoxide, b vents can back draft just like wood stoves in basements.

 

[BrotherBart]

A propane stove with a gas leak would smell like a refinery and make him home sick if he grew up down around Paulsboro.

As to B-Vent vs. Direct Vent I am going to pull up a six pack and watch the action. I have wondered for a long time why a bazillion natural vent wood stoves are great but natural venting a gas stove is not.

 

[Harley]

BB:

Actually still at work here, and now are doing the same thing (pulling up a six pack). The Paulsboro reference did get a chuckle out of him... never been to the area myself.

So... going back to the original question.... as far as saving cost for heating from electric, and making the living space more comfortable and usable, and having a source of natural gas pretty available.... does it make sense to use a gas stove?

The ventless was really a thought of mine.... knowing nothing about them myself.... thinking the installation would be easy and cheap. Both VC and Hearthstone make a ventless heater, and that was the direction I was going in. If it should be vented... I'll leave that up to him, and the stove shop and installer.

 

[Corie]

Direct vent.

My vote goes to direct vent because of the use of outside air for combustion. Especially in a basement, where I think fresh outside air is already at a minimum, it's best to not take the little bit of outside air coming in and burn it.



Vent Free RANT:

Remember that any room which holds occupants requires a certain amount of outdoor air. Generally this number is between 15-20 cfm per person. Basements, with limited windows allowing infiltration, and generally no stand-alone outdoor air supply system, are probably on the low end of this spectrum without a gas unit burning the limited supply of oxygen and then venting by-products back into the living space.

 

[BrotherBart]

Natural gas has a LOT of moisture in it. The moisture does not burn so it has to go somewhere. With a vent free it goes out into the living space. I don't know about his basement, but mine has about 30% more humidity than it needs already. The last thing in the world I would put down there is something to introduce more moisture into the air in my basement.

 

[BrotherBart]

Direct vent.

Why? Inquiring minds want to know.

 

[Corie]

I edited my post!


I know that humidity is a matter of personal preference, but just so ya know BB, ASHRAE tells us that a living space should be atleast 30% humidity in the winter and 50% in the summer.

 

[MountainStoveGuy]

A propane stove with a gas leak would smell like a refinery and make him home sick if he grew up down around Paulsboro.

As to B-Vent vs. Direct Vent I am going to pull up a six pack and watch the action. I have wondered for a long time why a bazillion natural vent wood stoves are great but natural venting a gas stove is not.

Basements are typically under negative pressure. When you have a wood stove in a basement, and it doenst draw properly, you dont use it much and you smell smoke. A gas one, you dont smell anything and carbon monoxide leaks into the living space, which should trip the spill switch, and shut downt the unit, making it unuseable. Basements and B vents mix about as well as woodstoves in basements. Sometimes they work somtimes they dont.
Vent frees and b vents are both illeagle in basements in my parts.

With direct vents you have tons of choices. Bvents are limited. Bvents need to go up like a chimney, direct vents dont. Why would any one want a b vent these days? there basicly exitinct.

 

[BrotherBart]

I am not quoting Corie's response because I am not arguing with Corie. What I just do not understand is why natural venting a wood stove or coal stove (want ya some deadly gases, there's a pup that'll give'em to ya) is fine and dandy but everybody always goes up in arms about not direct venting a gas stove. How many wood and coal stoves cussed and discussed here are in basements. A bunch'a them. And the only time outside air supplies are mentioned are when somebody has a draft problem. With natural vent gas stoves it is the first thing always pounced on. Even if the thing is going to be installed on the main floor of a house or in a shack out back.

Help me out here.

BB (an arrested development product of natural vent floor furnaces in the fifties)

 

[BrotherBart]

I edited my post!


I know that humidity is a matter of personal preference, but just so ya know BB, ASHRAE tells us that a living space should be atleast 30% humidity in the winter and 50% in the summer.

I know. But the 60 - 70 in my basement office is killin me.

 

[BrotherBart]

Basements are typically under negative pressure. When you have a wood stove in a basement, and it doenst draw properly, you dont use it much and you smell smoke. A gas one, you dont smell anything and carbon monoxide leaks into the living space, which should trip the spill switch, and shut downt the unit, making it unuseable. Basements and B vents mix about as well as woodstoves in basements. Sometimes they work somtimes they dont.chimney, direct vents dont. Why would any one want a b vent these days? there basicly exitinct.

That makes sense. Thanks.

BB (who loves that little woodstove in his basement and must have a real leaky house)

PS: One reason they would want a B-Vent is because if they are venting into an existing flue it is a hell of a lot cheaper installation. Probably the reason their water heater isn't direct vent.

 

[MountainStoveGuy]

technology bb, thats all. And no more trouble shooting b vents installed in basements. Once again, direct vent dominates the market, there the same price as b vents, the venting looks more natural then 4" b vent, it takes outside air and pre heats it for combustion, whats not to like?

 

[elkimmeg]

You guys got your six packs ready There probably not one appliance working correctly in that basement. After 1000 sq ft of space is partitioned off and sheetrocked. Remember it takes 50 cubic ft of combustion air for every 1000 btus input Whats left a little boiler room with enought support air for a 2 minute burn? if that? The reason it is electric baseboard is probably due to the furnace not able to handle the aditional capacity to heat that room. A furnace not running too effecient now. If it were my house, Zone damper I would upgrade the furnace. Add zone dampers and pick up that room with a new zone. Chances are most new gas furnaces are far more effecient approaching 98% that over 5 years th and the added zone the effeciency factor would save money Add in it being able to qualify for the energy tax break it really is looking good

B vent is gas piping commonly used are you condfusing it with draft hood appliances.. Many attic furnaces are B vented this is a common practice. The real high effecient direct vented ones are so effecient in the summer they freeze and ice up. Common practice is to use 80/84% furnaces in attic locations venting them with b vent B Vent is nowhere near ad obsolete as some may have indicated.
I know and have seen a lot of gas hot water heaters b vented.. Btw those attic b vented appliances are not dumped into chimney's but vent directly up and out the roof

 

[Corie]

whoa, 50 cfm per 1000 btu's. Is that an ashrae number elk, I was looking but I couldn't find it. I don't have the books here, but I'm sure you've read over them.


That's a LOT of air being used.

 

[BrotherBart]

whoa, 50 cfm per 1000 btu's. Is that an ashrae number elk, I was looking but I couldn't find it. I don't have the books here, but I'm sure you've read over them.


That's a LOT of air being used.

The stuff I have seen says the room has to have fifty cubic feet of space per 1000 btu's. I think Elk may be talking about that.

 

[elkimmeg]

ashrae the internationam Mechanical codes and NFPA all codes are consistant with combustion air requirements 50 cubit feet for 1000 buts of free air space. Interpetation, ajoining rooms or spaces can be included in the vollume, if they comunicate with one another.
If the ajoining room has door it can not be included. One can use threw the wall high and low grills. Metal grills are factored for 75% of there area meaning a 10/10 shall account for 75 sq inches. IT takes 2 sq inches of communication area, to allow enough passage of vollume to support 1000 BTUS. Due to the thickness of wood louvers only 35% of wood louver area may be applied. For example a 30' by 6'6/' do louver door will allow the communication air vollume trasnsmission of about 200,000 Btus. However the air vollume must be added up in that space. Even if the louver door or grill support the transmission, there still has to be the vollume. Complicating this further all appliances are added for the final vollume space. Another example is 150K btu furance and 50K hotwater heater has a total combustion air requirement of 200k BTUS. Got a gas or electric dryer also into the mix common figure for the dryers are 150 cfms that too has to be factored. And one wonders why his basement stove does not preform well? Corie there are also codes that govern locations called proximity. You can"t expect two applainces firing at once to function correctly when the are both competing for the same air in close proximity. Then factor in a gas 40k or 50 k stove that too has to be added to the needed vollume

Back to the original post if 1000 sq ft have been taken out of the equasion for make up combustion air in a sealed off finished room
without louver doors or grills or the addition of outside air feeds, then chances are the burner hot water heater are stuffed into an 8/8 room with no chance of ever satisfying combustion air requirements. Neither function correctly or effeciently. They probably back draft one another. It would be like driving your car with a severly clogged air filter it starts and runs. but it runs poorly. Eventually if you continue running your car that way, you will end up with a very exensive repair

Corie I am very impressed with your fresh air requiremement 15 cfm pre occupant but there is more to that code requirement.
That is the requirement for bedroom occupancy. The area has to be divided into sq ft to establish the occupant load x sq ft per occupant. There there are codes governing The air. IT has to be tempered to no less thar 10 degrees. Meaning that 0 outside has to be tempered to 60 inside before it can be introduced to 70 degree living space. Does Villanova need a building inspector to teach its clases?

 

[Corie]

oh come on elk, I knew that of course

Actually, I'm only in week 4 of my Environmental Engineering course (HVAC), so I have a lot to learn. But I have learned everything you said in the last paragraph! See, my college edumication is good fer sumthin

 

[elkimmeg]

Sorry to hyjack the post but.... Corie I hope the HVAC class is teaching that ceiling returns are not the way to go for heating. It is my contention that dual hvac systems should have high low returns with atleast mechanical dampers. Open the low position to draw out and return the cool air drawing down the warmer air above and close the lower ones and open the top locations for air conditioning.

Today most Mac Mantions have a central ceiling return in the hall way in the upper bedroom area. Many do not have returns inside the bedrooms and the ones that do have ceiling returns. We are addicted to oil or energy, then why not address design and do as I recomend. Unfortunately code only goes as far as supply equals returns and does not address location. Attic locations of exchangers and furnaces is the worst possible location, as much as 35% of heat is lost in transmission. The burner or exchanger and duct work should be located within the insulation envelope. I hope the next generations are taught this. To compensate for these defeciencies systems are over sized cooling tonage is notoriously oversized. Not only energy wasted but short cycling compounds the waste.

Back when I built my house, I did everything I could to make my home as energy effecient as possible My exterior walls are r- rated
27 2/6 R 19 and one inch styrofoam sheathing then plywood and real hand split shake shingles 30 years later and r-13 is touted as effecient. Do me a favor ask you professor. Is the air space under the bedroom door a satisfactory return and if so please explain how cooler heavier air accends into that hall return.
Corie apply what we expound here. about ribbed flexible duct substituting hard piped roung ducting the drag and friction coeffecients? Why is it that most trunk lines are rectangular and almost all duct take offs are flexible ducts? Ask him to comment where the flexible duct is used for the 90 degree transition it oblongs and reduces the flow are almost 40% why I can tell you in real world applications, HVAC has been bastardized with flexible duct work to the point I'm amazed it even works. then one should witness the leakage and the crap burners or exchangers the leak profusly called builders specials these units gaskets do not fit right and do they leak. How come there is no complaints he solution is to oversize them. You will not learn this ina class room this is the norm everyday doing inspections. and I am helpless there are no codes that address location or flexible duct usage. or abuse I can correct the runs to an extent but... 99% of all HVAC systems suffer from what I see.

 

[thechimneysweep]

Back to the original topic:

Before your friend decides to install a vent-free, he should read the letters from vent-free owners posted on our website at http://www.chimneysweeponline.com/hovflett.htm, and follow the links at the bottom of the page. He should also read the operating instructions for any vent-frees he's considering, and decide if burning a vent-free in his basement for a limited time of 2-3 hours per day with a window open, as most manufacturers recommend, will accomplish what he's after, heat-wise.

When choosing between vented heaters, I'd recommend a direct vent over a b-vent heater, for these reasons:

1) Direct vent heaters are more efficient. The coaxial vent pipe used for direct venting is designed with a specific inflow opening to match the outflow opening, so the outflow of the exhaust gas causes the ideal combustion air intake for balanced combustion in the firebox. Further, as mentioned above, the incoming combustion air is preheated by the hot exhaust pipe, which aids in combustion efficiency.

2) B-vent heaters draw their combustion air from the room and direct vent heaters don't. In a confined basement, this can be a big advantage for the direct vent heaters.

3) Direct vent heaters are easier, and in most cases less expensive, to install. Even if there's an unused masonry flue that extends to the basement, chances are it will be too large for 4" b-vent exhaust, and need to be relined.