Replies

1. 
   Mongo_ | Nov 14, 1999 10:17am | #1

   *
   I wouldn't advise using a ventless fireplace anytime, anyplace, anywhere.

   While combustion efficiencies have improved over the years, they still emit what I consider to be an excessive amount of indoor pollutants.

   Putting this in a basement, which, if a typical basement, has marginal fresh air flow to begin with, would only compound the pollutant issue.

   It's a nice idea that technology hasn't caught up to yet.

   I'm no HIV guru (that sounds bad, doesn't it? Let me rewrite...)

   I'm no Heating, Insulating, and Venting guru, but I'm familiar with the product and to date am not impressed.

   Regards, Mongo

1. 
   Rich_Beckman | Nov 15, 1999 02:27am | #2

   *This has been discussed before (an often used phrase here at Breaktime). If you do a search on "ventless" you will turn up some to the previous discussions (hiding among the attic ventilation entries that will also come up). You will find little good said about ventless heaters.Rich Beckman

1. 
   reinhard | Nov 24, 1999 10:29pm | #3

   *One of the shops I work in makes mantles for new construction, high end homes, almost everyone with a vented gas firelog firebox. The shop also builds mantles for a local distributor of vented and ventless units, which brings me to my point. I was delivering/installing a few units at the store and heard the salesmen make their pitch to many customers regarding safety.Part of the pitch was that ventless fireplaces give off as much carbon monoxide as a cigerette. After all customers were out of earshod, I asked the salesperson. "Isn't cigerette smoking harmful?" He didn't have an answer.

1. 
   Kevin_V._O'Neill | Oct 05, 2000 04:48am | #4

   *My only question is "How do you like living in a chimney??" If something goes wrong you can get very sick.Kevin

1. 
   Rob_Susz_ | Oct 05, 2000 06:06am | #5

   *They're a great way to heat the room, poison your family, rot your roof, cause ice damming, cause mold and mildew problems, cause headaches....-Rob

2. 
   Alan_Kim | Oct 06, 2000 05:02am | #6

   *I just don't get it.A gas log fireplace....Things have gone too far with that one.About as tacky as mall Santa photo booths with the upward blown cellophane flame fireplace.However, I do like the convenience of wood burning fireplaces that use natural gas to start fires.And I have seen a great outdoor BBQ island with natural gas burner for the hardwood that is used for cooking.

3. 
   Bob_Walker | Oct 06, 2000 12:15pm | #7

   *I agree with all of the above: don't do it (Kevin: great way to put it!)The best article on the web about them is at http://www.jlconline.com/jlc/archive/energy/vent/Everyone knows that at high levels, CO can kill you; few people know that chronic exposure at low levels can cause serious, sometimes irreversible adverse health effects. The added problem here is that Dr's usually misdiagnose CO poisoning.Bob

4. 
   Jeff_Maras | Oct 08, 2000 06:00am | #8

   *I think it's clear that the possibility of death, destruction, plague, war and pestilence are quite real, but with what I would guess would be large numbers of units installed are they causing more problems than the standard space heaters and furnaces that are out there now. My digital Nighthawk CO detector registers 0 near my 30,000 BUT Gas blue flame heater. This safety question could use some more hard data.

5. 
   Norm_Malcosky | Oct 09, 2000 05:06pm | #9

   *I have lived with a vent-free log set installed in my conventional wood burning fireplace for about 5 years. And yes, they do increase the level of indoor pollution - but my wife loves to use them on chilly evenings. On a wall adjacent to the fire place, a NightHawk digital detector monitors the level of CO with in the family room. During startup, the CO level rises to about 20 PPM and then falls to 0 PPM. Starting my car in the attached garage often will make the NithHawk go into "alarm state" for a few minutes - especially if there is a strong south wind.My current operating technique with the vent-free logs is to start the logs with the chimmney damper open. After an initial warmup, CO production by the logs apparently falls to very low levels. I have found I can avoid the 20 PPM CO "concentration spike" within the room by closing the chimney damper after about five minutes of operation. However, the NOx level within the room in unknown but probably increases the longer we operate the logs. Eye burn is noticable if the logs are operated on the higher heat settings. I would recommend following earlier suggestions of limiting the operation to less than 4 hours and using only the lowest heat setting. Unless of course, you or your guests enjoy the pretty yellow flames of the high output level. Then I would suggest you leave the flue open. We still get a "ton" of radient heat from the logs even with the chimney damper open and no fumes leaving the fire place cavity. There is no way I couldn't talk my wife out of using them now - she has enjoyed them too much to even consider going back to a real log fire. I just miss the cracking and popping noises. Perhaps I need a CD recording of a campfire. I agree that we need more information about indoor NOx levels produced by these logs. Perhaps we also need a NightHawk for NOx that can let us know how really "bad-off" we are - when enjoying the warm glow of the vent-free logs. Stay warm !!

6. 
   Bob_Walker | Oct 09, 2000 07:27pm | #10

   *Be aware that under the current UL standards, CO detectors are not supposed to register at levels below 30ppm. (At least, that's what I've been told by experts.) There is a new AIM unit (which is not UL-standard for just that reason) which will read down to zero, but is very tough to find.Chronic exposure to low levels of CO can cause serious health problems.Bob

7. 
   Rob_Susz_ | Oct 10, 2000 05:16am | #11

   *Bob,The digital units will display any CO level, but alarm only above 30. The older units were more sensitive (effective).-Rob

8. 
   Bob_Walker | Oct 10, 2000 03:06pm | #12

   *I haven't seen the UL standards directly (they charge an arm and a leg for them) but based on discussions in a CO mail-list and seminars I've been to, the current UL standards provide that (i) the lowest level/time exposure for the alarm sounding is 7ppm over 4 hours (I've also heard 8 hours) and the lowest level for digital display allowed is 30ppm.Some advocates of CO safety argue that the standards were set "high" because too many alarms were going off but that the responders didn't know how to analyze a situation and were concluding they were "false" positives.The first big fiasco was the "Chicago" incident. Several years ago Chi passed an ordinace requiring CO alarms/detectors in some residences (I don't recall the exact requirement.)Come October's heating season, alarms start going off all over the place. The responders go out to checked armed with (i) Monoxor gas tube detectors (which have a threashhold of 100ppm - Not to be confused with the MonoxorII) or (ii) Tiff combustible gas detectors, which will detect CO at 1000 ppm (if I remmember correctly). They concluded that the alarms were "false positives" when their equipment was far less sensitive than the consumer alarms then being sold!Even where responders have better equipment, often times they don't know how to use it and come to erroneous conclusions.FWIW, AIM has introduced a "health monitor" which measures to zero, the AIM 935, but its very tough to find, no retail distribution yet that I'm aware of. I do know of some sources if anyone's interested.Bob

9. 
   The_Tennis_Court_Builder_...on_t | Oct 10, 2000 09:37pm | #13

   *i Any Thoughts on Ventless gas fireplaces in a basement ....I'd say, "A thought-less idea"...It may make the occupants "thought-less" too...my thoughts...near the stream of fresh air.,aj

10. 
    john_madison | Oct 16, 2000 12:02am | #14

    *>A customer of mine is concerned about the effect of heat from her gas fireplace on the wood mantle that is about 10" above the louvre vent above the glass doors. I ran the unit on high for about two to three hours and the mantle did get hot but I was able to hold my hand of the wood so I can't imagine the wood can combust, and there is no damage to the clear finish. How do we know this is safe?

11. 
    Andy_Engel_ | Oct 16, 2000 01:12am | #15

    *John, in my prior life as a carpenter, I built and installed dozens of mantles on zero-clearance fireplaces. The manufacturer's all had clearance requirements clearly illustrated in their installation manuals. Failing that, check the code books. CABO, for one, is pretty specific about mantle clearances.Andy

12. 
    Bob_Walker | Oct 16, 2000 08:12pm | #16

    *John, Keep in mind that as wood is repeatedly heated, its ignition point is lowered so that at some point what was once "safe" is now a fire hazard.In the early 80's I pulled some pine paneling (installed probably in the 50's) which had been about 12" from a small wood heater. I was able to ignite the wood which burned like a torch with a Zippo lighter.Bob

13. 
    Gene_Leger_ | Oct 20, 2000 07:06pm | #17

    *Wveloso. See the artice, "Vent-Free Gas Heaters--Hpw Safe?" in the Julyn 1997 issue of the Jpournal of Light Construction.GeneL.

2. 
   wveloso | Oct 20, 2000 07:06pm | #18

   *
   Heating, Insulating, & Venting gurus,

   I'm hoping for any advice on installing a ventless, 'zero clearance' gas fireplace in a basement on an interior wall. Any recommendations would be appreciated.

   Thanks