Vent Free vs Vent through wall heaters

[OlJarhead]

OK So I decided this might be something others were interested in.

What are the pros and cons of these two types of propane (or nat gas) heaters?

Vent free vs Vented?

I'll start:

Vent Free:  Cheaper, more options for placement (inside walls etc), appearance (many look like fireplaces).

Vented:  I don't know the pros but guess the venting reduces the chance of CO poisoning -- Cons however have me looking to vent free:  Cost.  Per BTU costs seem about 3 times higher than comparable vent free and placement is more restrictive as you must vent through a wall.

Pricing example:  10000BTU vent free heater for $140 with gas line and shutoff valve vs 8000BTU Vented heater for $440 with no valve or line.

Your pros and cons?

[MountainDon]

Non-vented: Con #1
25 ounces of water is produced for every gallon of propane burned. That stays inside


Non-vented: Con #2
The CO risk


Non-vented: Con #3
Non vented also means combustion air comes from the space being heated. O₂ depletion risk.


That explains my position.

[rick91351]

OK So I decided this might be something others were interested in.

What are the pros and cons of these two types of propane (or nat gas) heaters?

Vent free vs Vented?

I'll start:

Vent Free:  Cheaper, more options for placement (inside walls etc), appearance (many look like fireplaces).

Vented:  I don't know the pros but guess the venting reduces the chance of CO poisoning -- Cons however have me looking to vent free:  Cost.  Per BTU costs seem about 3 times higher than comparable vent free and placement is more restrictive as you must vent through a wall.

Pricing example:  10000BTU vent free heater for $140 with gas line and shutoff valve vs 8000BTU Vented heater for $440 with no valve or line.

Your pros and cons?

We are / were looking at a propane - walled mounted - vented - fux fireplace for the bed room of the new house.  Looks really good but I really did not like the price tag.  We will just have to see how it all budgets out.

     

[Erin]

I will NEVER have a ventless wall heater in my own home and it's primarily because of Don's reason #1.


You can have monitors for gas levels, but the water vapor will literally rot your house from the inside out.  We lived in a house that was doing exactly that from the two, ventless wall heaters.

[Squirl]

Code.

Ventless are not allowed to be a primary heat source in many states because of the reasons Don outlined.

I use ventless on my shed.  It has more airgaps than a sieve.  I wouldn't use on on my house for the reasons outlined. 

[OlJarhead]

Code.

Ventless are not allowed to be a primary heat source in many states because of the reasons Don outlined.

I use ventless on my shed.  It has more airgaps than a sieve.  I wouldn't use on on my house for the reasons outlined.

Not primary but what about secondary?

So what I see above is the the vented units eliminate the water, co and O2 depletion risk?  Seems the low O2 shutoff and CO monitors should negate that issue and if burning propane produces water vapor you get that with the vented also though I suspect most of the moisture must leave via the vent -- but a vent isn't for drawing air if it's for exhausting moisture etc -- which is it?

I'm not trying to start a fight here but the above posts seem pretty biased.

[OlJarhead]

Vent-free appliances feature an automatic safety shut-off device (Oxygen Detection System or ODS). The ODS turns off the gas in case of a malfunction. Since 1980, with 17 million units installed in the U.S. alone, the Consumer Product Safety Commission has stated that it is not aware of any documented incident in the CPSC In-Depth Investigation (IDI) database of fatal carbon monoxide poisoning associated with an ODS-equipped vent-free gas heating product. These appliances have earned an outstanding safety record.

http://www.ventfree.org/images/stories/files/VentFree_SafeEfficient_V06.pdf

I find it interesting that the more I read the more it seems the claims against ventfree heaters are unfounded.

[OlJarhead]

ARE THERE SAFETY REQUIREMENTS?

Every vent-free gas product marketed in the U.S. today, regardless of the size, shape, appearance, heat output, or price, has been approved by a recognized listing agency.  This involves testing to a rigorous safety standard, in this case ANSI Z21.11.2.  But what does that mean to the average consumer?  The American National Standards Institute (ANSI) oversees a process for the development and constant upgrades of safety standards for virtually every class of home appliance available in the marketplace.  Every manufacturer must submit their designs for testing to the applicable standard by an independent laboratory.

UL is often the agency testing electrical products whereas gas appliances are generally tested by CSA or ITS.  Whether we're talking about a furnace, water heater, toaster, barbeque grill...or vent-free gas product, the ANSI safety standards process applies and is the first line of safety defense for the consumer.  The ANSI standard for vent-free gas products is a document of 119 pages, and includes 33 separate tests that each product must successfully pass before approval to be marketed.

WHAT IS THE SAFETY RECORD?

Once appliances are in the U.S. marketplace, the U.S. Consumer Product Safety Commission (CPSC) is the primary safety "watchdog", accumulating product safety data from numerous sources, and investigating and reporting the safety record of various product categories.  What does CPSC data reveal about vent-free gas appliances? The U.S. Consumer Product Safety Commission (CPSC) has stated that it is not aware of any documented incident in the CPSC In-Depth Investigation (IDI) database of fatal CO poisoning associated with an ODS-equipped vent-free gas heating product. These appliances have earned an outstanding safety record.

In 1980, the ANSI standard for these products was revised to require each unit to be equipped with an oxygen detection safety sensor (ODS).  The ODS is remarkably equivalent in function/reliability to what a circuit breaker is to electrical current.  The ODS automatically shuts off the unit in the unlikely situation that carbon monoxide is elevating and there is oxygen depleting in the vicinity of the unit (regardless of the CO source).  The ODS is tamper resistant!  If there is any attempt to override, modify, or tamper with the unit, the ODS will shut off the gas supply and disarm the ignition system and the appliance cannot be operated.

WHAT ABOUT INDOOR AIR QUALITY?

Among informed sources, the concern for CO poisoning has essentially been "off the table" for many years for vent-free gas products, but even well intentioned critics have legitimately asked whether there are other possible harmful effects associated with use and exposure to emissions from vent-free gas products.  To address this question, in 1996 the Vent-Free Gas Products Alliance, members of GAMA, an Association of Appliance and Equipment Manufacturers, commissioned an independent research project to be conducted by the American Gas Association Research Division (AGAR).  The objective was to measure the primary by-products of gas combustion from vent-free gas products against the most relevant indoor air quality standards and/or guidelines.

The contributors to indoor air quality that were tested were oxygen, carbon monoxide, carbon dioxide, nitrogen dioxide, and water vapor (humidity).  The researchers took into consideration the climate in the five Department of Energy heating regions in the U.S., various types of housing construction, and varied volumes of space to be heated.  After running hundreds of thousands of computer based scenarios, the results were confirmed by the American Gas Association test house which was modified for all factors.

The researchers concluded that "vent-free gas heating products performed well within nationally recognized guidelines for indoor air quality.  This research proves that vent-free gas heating products meet applicable emissions requirements even when used over extended time periods, among sensitive populations, and with units whose maximum heat output exceeds the requirements of the space." Only in region V, (primarily the northern U.S. tier) if the appliance is used in a confined space (a room not able to communicate air exchange with other parts of the residence) there should be a limitation on the Btu/hr input of the heater.  This landmark research has been extensively peer reviewed and has served as the basis for acceptance of vent-free gas products by national code groups and state regulatory agencies.

WHAT ABOUT EXCESS HUMIDITY?

During the last five years increasing attention has been drawn to the general environmental issue of sustained high humidity/moisture from many sources and the potential negative outcome of mold growth.  Some parties began asking whether vent-free gas heating products generate enough water vapor to raise indoor relative humidity levels high enough to foster mold growth.  Again the industry commissioned independent research to answer this question.  In December 2002 the rigorous and comprehensive study was completed by risksciences, LLC, an independent scientific consulting firm nationally recognized for its expertise in human exposure modeling in residential environments.

The research study concluded that, "for the vast majority of homes in the U.S. (99%), vent-free gas heating products DO NOT generate enough water vapor to raise indoor humidity levels high enough to foster mold growth". Furthermore, the findings indicated that greater emphasis should be placed on other factors that can cause humidity levels to exceed mold formation thresholds such as aging homes, outdated construction, poorly sealed or leaky windows, wall insulation, insufficient ventilation and maintenance of air conditioning systems.  However, if a home is showing any signs of excess moisture, a vent-free gas heating product should not be installed until the excess moisture problems re eliminated.  We are all aware that many homeowners use humidifiers during winter months and in most all cases the limited humidity produced by the vent-free gas product adds comfort to the otherwise "healthy home".
- See more at: http://www.ventfree.org/content/view/42/18/#sthash.GtNct9br.dpuf

http://www.ventfree.org/content/view/42/18/

OK, that pretty much tells me what I suspected:  the cost of the vented heaters isn't justified by anything I've seen yet.

Thanks all for sharing, it's forced me to do my own research

Now, on a side note, it is likely I WILL be getting a vent through the wall heater for the composter despite the cost difference.  This is because the room is MUCH smaller and as such doesn't have the air volume to support a ventfree heater based on their calculations.

[MountainDon]

....but a vent isn't for drawing air if it's for exhausting moisture etc -- which is it?

The so-called direct vent heaters, like the Housewarmer from Northern Tool, utilize a concentric arrangement of two ducts. A smaller one within a larger one. The inside duct is the exhaust. The larger tube that surrounds the exhaust vent is the fresh air intake. Incoming cool air insulates the hot exhaust pipe from combustibles to a large degree. The moisture produced when propane combusts exits the closed combustion chamber via the exhaust vent along with any other products of combustion.

You can get around the CO and the O₂ issues with meters, alarms and automatic ODS devices. The moisture from combustion has no easy workaround. BTW, do meters, alarms and automatic ODS devices require batteries or electrical hookups?  My neighbors who almost died from CO poisoning never checked the battery in the CO alarm. The battery was as dead as they almost were.

Reading testimonials about the safety of non vented heaters on a site with an obvious vested interest (ventfree.org) is akin to relying on RJ Reynolds for information on potential health risks associated with tobacco use.  Of course why listen to a guy who believes he should be wearing his chaps before starting the chainsaw; and wears ear protection around noisy machinery and eye protection too where suitable, uses push sticks on the table saw, and so on.

[Erin]

Not primary but what about secondary?

That's all ours were.

No WAY would I do it.

25 ounces of water is produced for every gallon of propane burned.

This is very basic science.  There are natural by-products produced with the burning of propane and natural gas fuels.  Water vapor is one... I didn't know it was 25 ounces, but if MtDon says that's what it is, I'm going to bet he's probably right.

In which case, 25 ounces is a cup shy of a full quart; for a single gallon of fuel.  That is a significant amount of water vapor. 

Where are you planning on it going?

[OlJarhead]

The so-called direct vent heaters, like the Housewarmer from Northern Tool, utilize a concentric arrangement of two ducts. A smaller one within a larger one. The inside duct is the exhaust. The larger tube that surrounds the exhaust vent is the fresh air intake. Incoming cool air insulates the hot exhaust pipe from combustibles to a large degree. The moisture produced when propane combusts exits the closed combustion chamber via the exhaust vent along with any other products of combustion.

You can get around the CO and the O₂ issues with meters, alarms and automatic ODS devices. The moisture from combustion has no easy workaround. BTW, do meters, alarms and automatic ODS devices require batteries or electrical hookups?  My neighbors who almost died from CO poisoning never checked the battery in the CO alarm. The battery was as dead as they almost were.

Reading testimonials about the safety of non vented heaters on a site with an obvious vested interest (ventfree.org) is akin to relying on RJ Reynolds for information on potential health risks associated with tobacco use.  Of course why listen to a guy who believes he should be wearing his chaps before starting the chainsaw; and wears ear protection around noisy machinery and eye protection too where suitable, uses push sticks on the table saw, and so on.

For the most part I agree but then it comes down to the same conundrum in AGW arguments.  One side is benefited by one outcome, the other, another.  What I found interesting is that there was an independent study done which indicated no issues at all and as my intent is to use the unit as a backup heater for when I'm NOT at the cabin the cons begin to have less effect.  Sure, it might be used once in a while when I am there but then I'm used a Kero heater when I'm there and haven't had an issue.

I liken using this heater to using my propane cook stove with the broiler.

[Erin]

I work at the local salebarn.  We have sales one day a week that last maybe four hours. 

In the rest rooms we have ventless, propane wall heaters. 
Keeping in mind, these things run a total of 6 hours per week (lighting them before the sale and a little after), and just enough to keep the chill off a single room, both bathrooms have light mold growth in the corners.  Now, it's possible it could be coming from some other source, but I'm not sure what that would be...

I would not go ventless just to save a few bucks. This might be a place for field research rather than written.  Maybe see if you can find some homes that have had them for 10+ years and see what you find.  Or even 5+ years will be showing the effects. 

And AGW?
I can definitely see where ventless heater folks have an agenda, but people like me who just have experience to share?  What is my agenda?


If cost is the big motivator here, why not just go with one of those little electric blower wall heaters. 

[Squirl]

Not primary but what about secondary?

So what I see above is the the vented units eliminate the water, co and O2 depletion risk?  Seems the low O2 shutoff and CO monitors should negate that issue and if burning propane produces water vapor you get that with the vented also though I suspect most of the moisture must leave via the vent -- but a vent isn't for drawing air if it's for exhausting moisture etc -- which is it?

I'm not trying to start a fight here but the above posts seem pretty biased.

I'm not as negative on the product as others.  I might consider it as a secondary heater.  I would treat it as I would a propane stove, even though the stove is not catalytic.  I would only use it when I was awake, monitoring it, and not as the majority BTUs for my house.  Then again, IIRC you have a wood stove for that.

I am trying to build a super tight house.  I even blocked and sealed all sheathing.  With the reasons stated above, it just wasn't worth it for me.  I was going to need a primary heater, and ventless wasn't it.  I got two Empire DV-210 heaters for $150 each off craigslist. (I had to do the uninstallation)

http://www.ventfree.org/content/view/36/53/

[OlJarhead]

I guess I look at it like a wood stove.  In some, perhaps many, states it is no longer to use a wood stove without fresh air intake (outside air) and/or low particulate system (catalytic etc).

In the case of venting it is to prevent people from being killed by the stoves (though as a Libertarian I feel it is their right to do so and not the Governments to protect them from themselves) however in some states it is not illegal to use those stoves (Oregon for example still sells high particulate non-vented stoves in stores).

So, do you make the same arguments about those wood stoves as you do ventfree propane heaters?  If so then at least it's consistent right?  If not, then it's inconsistent.

Anyway, I didn't mean to stir up a hornets nest, it's just that it seems there are some strong feelings there which may or may not be warranted depending on who you are asking.

[MountainDon]

No further comments about vented vs non vented propane heaters from me.

(Oregon for example still sells high particulate non-vented stoves in stores).

Whoa! Wrong state I think. Oregon has one of the strictest  set of laws regarding wood burning stoves in the country. 
Not only are non approved wood stoves not to be sold new, they are not supposed to be sold as used.
AND, if your home in OR has a non-approved wood stove in it the offending stove must be removed in order to sell the home. Removed and then certified as destroyed. Exceptions are made for fireplaces, antiques, cooking stoves and a few others. But the run of the mill non-approved stove has to be yanked. No selling them on craigslist or wherever; at least not legally.

http://www.deq.state.or.us/aq/burning/woodstoves/heatsmart.htm
~~~~~
Oregon law requires you to remove an uncertified woodstove or fireplace insert if you are selling your home. If the stove or insert is certified there is no need to remove the stove. The 2009 Oregon Legislature passed this law helps protect people from unnecessary woodsmoke pollution.

It is against the law to sell, offer to sell, or advertise any uncertified woodstove or fireplace insert. It is also against the law to install an uncertified woodstove in your home.

http://www.deq.state.or.us/aq/burning/woodstoves/questions.htm
~~~~~

How well all that is enforced I do not know.

[Erin]

So, do you make the same arguments about those wood stoves as you do ventfree propane heaters?

Nope.
Wood stoves don't produce even a fraction of the water vapor that ventfree propane heaters do.  And, as mentioned in all of my posts, that's my biggest objection to ventless. 

Again, basic science.  That water vapor has to go somewhere... 
Personally, I'm trying to design for elimination of vapor already created, I certainly don't want to make more!



So, you asked for opinions, people gave them. 
You're free to do whatever you'd like with the information given.   : )

[OlJarhead]

No further comments about vented vs non vented propane heaters from me.


Whoa! Wrong state I think. Oregon has one of the strictest  set of laws regarding wood burning stoves in the country. 
Not only are non approved wood stoves not to be sold new, they are not supposed to be sold as used.
AND, if your home in OR has a non-approved wood stove in it the offending stove must be removed in order to sell the home. Removed and then certified as destroyed. Exceptions are made for fireplaces, antiques, cooking stoves and a few others. But the run of the mill non-approved stove has to be yanked. No selling them on craigslist or wherever; at least not legally.

http://www.deq.state.or.us/aq/burning/woodstoves/heatsmart.htm
~~~~~
Oregon law requires you to remove an uncertified woodstove or fireplace insert if you are selling your home. If the stove or insert is certified there is no need to remove the stove. The 2009 Oregon Legislature passed this law helps protect people from unnecessary woodsmoke pollution.

It is against the law to sell, offer to sell, or advertise any uncertified woodstove or fireplace insert. It is also against the law to install an uncertified woodstove in your home.

http://www.deq.state.or.us/aq/burning/woodstoves/questions.htm
~~~~~

How well all that is enforced I do not know.

I've seen the 'boxwood' stoves at sale in a few Big R's.  Not sure how they manage it but they do.

[OlJarhead]

Nope.
Wood stoves don't produce even a fraction of the water vapor that ventfree propane heaters do.  And, as mentioned in all of my posts, that's my biggest objection to ventless. 

Again, basic science.  That water vapor has to go somewhere... 
Personally, I'm trying to design for elimination of vapor already created, I certainly don't want to make more!



So, you asked for opinions, people gave them. 
You're free to do whatever you'd like with the information given.   : )

Excellent point.

The independent study noted above (albeit paid for by the manufacturers) claims that isn't an issue.

In the end I don't have a problem if someone wants to use vented and I for one agree they are undoubtedly better.  I'm just not convinced that the vent free heaters as much of a problem as some appear to feel they are.  Guess I'm just being thick headed    but as a secondary heat source for those periods of time when I am away or in the off chance the wood stove goes out on a specially cold night and the cabin temp actually drops below 50 degrees I'd think the ventfree heater ought to be fine.

Perhaps I'm wrong (and if so I'll pay for it).

[Redoverfarm]

Eric I personally have 4 ventless heaters at Dogtrot.  Although mine might be used in a different fashion than you are going to use them.  They are not considered my primary heat source.  I only use a couple to get the initial temperature up in the cabin on cold days until the wood cookstove and fireplace get going good.  Then I shut them off.  I have not noticed any great amount of moisture problems but generally there are only 1 or 2 going at one time.  I do not heat the cabin in the winter but when I have at extremely cold periods a couple at low seem to work fine.  I do have two on exterior walls and if I would see there would be a problems they could be swapped out for vented at that location using a wall flue adapter. 

The fireplace is not an efficent heat source but given the limited amount of use it works OK.  I may in the future put a decent insert in and increase the BTU output.  I guess I was after the ambience first.

[rick91351]

.....................................snip..................................................................................
Anyway, I didn't mean to stir up a hornets nest, it's just that it seems there are some strong feelings there which may or may not be warranted depending on who you are asking.

Got to hand to too you OJ you found another hot topic.

To vent and or not to vent that is the question.  Whether it be nobler to vent is to pay the price.  Yet hark should I scrimp and try and save some of my hard earned coin.  NO NO Tis greater than that.  I shall try and prove a point.....  Almost as bad as the nails vs screws thread.  House wrap vs Builders felt and weight. 

Then there is life stuff.......

Pro Choice - Pro Life

Pro Obama Care - Anti Obama Care

Right to Work - Closed Union Shops

Then there is my hot topic..... Jeff Gordon - NASCAR's  still darling - they will do anything to get him back into the 'Chase'.     Yep! we all got those hot button issues.....

[Squirl]

I like that rick.

I may have been the one to interject this, but there has been some comparison of wood stoves to ventless heaters.  Woodstoves can use interior air for the combustion and do pose a carbon monoxide risk, but they are still vented (chimney).

I don't have strong feelings either way.

[MountainDon]

I've seen the 'boxwood' stoves at sale in a few Big R's.  Not sure how they manage it but they do.

For that matter I wonder how those are still sold anywhere as according to EPA they should not be sold anywhere because they do not have an approval. 

[Erin]

And the only reason I have such strong feelings about ventless heaters is because I've lived in three rental houses that had them. 
The first couple I thought were really handy, for all of the reasons already mentioned.  But the last was in an older house so the insulation level allowed us to really see what was going on.  And it wasn't pretty!

I've also noticed a trend over the years--

In my area, electric heat is *very* common (the same REA subsidies that brought center pivot irrigation from diesel motors to electric, are also applied to home electrical systems).  But if you've ever dealt with electric baseboard type heaters, you know that they can be pretty slow to warm up and slow to cool off.  So this time of year you really don't want to use them.  Turn them on in the morning and the house will be over-heated all day.

When ventless propane heaters started getting popular (late 90s?), they were an immediate hit.  An all-electric house doesn't have much for ducting anyway, so ventED would have been a real hassle.  Ventless was the perfect solution. 
Until people started having moisture issues, that is.

All of the local lumber yards can get them in for you, if you want, but they all caution against them.   For me, that's a pretty clear indicator...

BTW, here's a brief article on the subject over at Green Building Advisor: http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/avoid-unvented-gas-heaters

[OlJarhead]

Eric I personally have 4 ventless heaters at Dogtrot.  Although mine might be used in a different fashion than you are going to use them.  They are not considered my primary heat source.  I only use a couple to get the initial temperature up in the cabin on cold days until the wood cookstove and fireplace get going good.  Then I shut them off.  I have not noticed any great amount of moisture problems but generally there are only 1 or 2 going at one time.  I do not heat the cabin in the winter but when I have at extremely cold periods a couple at low seem to work fine.  I do have two on exterior walls and if I would see there would be a problems they could be swapped out for vented at that location using a wall flue adapter. 

The fireplace is not an efficent heat source but given the limited amount of use it works OK.  I may in the future put a decent insert in and increase the BTU output.  I guess I was after the ambience first.

You're using yours the way I'd use mine pretty much.  My wood stove does all the heating I need even in he coldest temps but it can't do that when I'm not there over a long weekend

[Erin]

well at least make sure you follow the manufacturer's instructions and leave a window open.