cost, energy issues B vent or direct vent fireplace

14 years ago

Hi Gardenweb friends-

We haven't posted for a while due to life issues. The longer you take to build a house, the more life changes. I've now been diagnosed with an autoimmune arthritis so we need to pull our master bedroom to the first floor. Not to mention the fact that my medical costs have eaten into our build budget. Such is life.

So, we're brainstorming new layouts (before we have a re-design meeting next week). We live in Wisconsin and a fireplace is a priority. We'd like something energy efficient, reasonably attractive, low maintenance, and relatively low cost. We read the recent post about direct vents with interest. Our favorite first floor layout has the fireplace in the center of the home, on an interior wall of the living room.

Direct vents seem to be most cost and energy efficient. Can they be put on an interior wall with a second story above and twenty feet to the nearest first floor exterior wall? Would this, in effect, be a B vent fireplace? Does putting a fireplace on an interior wall greatly increase the cost of installation? Does a roof vent mean building a chimney? Are roof leaks an issue?

Many thanks for any feedback. It seems like once we work out the fireplace location, other decisions will flow from there...

Liz

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Comments (9)

athensmomof3
14 years ago
I can't answer many of your questions but yes a b vent needs a chimney, but it can be a metal chimney (looks sort of like an attic vent). It would be something you would want on the back side of your house, but not particularly obtrusive. B vents vent vertically and can have a bend in them but I am not sure how far they can run horizontally, if you need them to do so to reach the back of your house.

A direct vent would vent out to the side of the house so it would not matter if you have a second story. I don't know how long the "run" to the outside can be, but I am sure someone else will chime in.

The big difference I have seen is that B vents function like a normal fireplace and don't have to have glass in front of them. Direct vents all have glass (although you can get clearview ones which don't have louvers on the front just glass inside the firebox).

The other thing to look at is whether they are zero clearance. These help them look more realistic too as they are sitting where a traditional fireplace would, rather than being raised up.
squarefour
Original Author
14 years ago
Thanks, athensmomof3. It sounds like a B vent could run straight up and out the roof of the second floor--but it would be best on the back side of the house.

I'd like to have glass in front of the fireplace to keep CO and any smoke particles (?) out of the house (two family members have asthma). Not the gorgeous look of a masonry wood burning fireplace, but we'd enjoy it.

Zero clearance is a very good point. I'll look for that.

Anyone else have an idea of cost?

Thanks!
Liz
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macv - he was talking about using isokern for our other 5 fireplaces (2 in basement, one screened porch, one den, one keeping), not the fireplace in the small study, which is 12 x 12, where there is currently not one. I think he was talking about the depth difference between traditional masonry and isokern standard - he did say the fireplace was 2 feet (?), and the back to back isokern (in keeping and screened porch) is 4 feet. As one is on an interior wall and one is a back to back fireplace, we don't have the option of pushing the chimney outside, and our rooms are not very big so the 2 feet for the fireplace and 20 inches for the hearth make a difference I am finding! I think the plans are getting very close to being finalized and we were able to put two doors in the study (one from entrance hall and one connecting den and study with walk through butler's pantry like bar in the short hallway, which is a great place for the bar which we have been struggling with). I am going to have an interior designer look over the plans to be sure about room size as far as furniture placement, sight lines, flow, etc. and I will have her weigh in about the fireplace as well. How deep is a traditional b-vent? If we just have to find a foot for it that is less problematic. . . The hearth doesn't bother me as you can easily push an ottoman right up to the hearth (it will not be raised) if you need to. I still would like to have one but now that the room is not a dead end I feel much better about it not being necessary.
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Talked to my builder and the isokern was 4200 or something like that for the b vent and since we tacked the basement on after we started construction (we weren't going to finish it), we really have to watch the bottom line there! It is amazing how much this whole process costs. . . I look at what we have spent so far and we just have a bunch of wood with a few windows :) The problem I had with the ones I looked at is the proportion of them. The fact that they have a row of surround below the fireplace can be worked around by carving out the slab and repouring another one lower and recessing it (which my builder said is an option). The ones I saw today were all long and short. If I can get one which has a better proportion, the rest can be worked out. 36" or 42" by 24" looks squatty to me. . .
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First, DON'T install a ventless fireplace!!! Even though the MFG.s will tell you the exhaust fumes are OK, do you really want to breathe them? Many people end up with Major Headaches and chronic breathing issues. Does it sound like a good idea to breathe burnt exhaust gasses? B type flue(vent) pipes are dual thickness pipes. A pipe inside another pipe, suitable for use at 1" or more to flammable materials. Outer casing pipe is sealed and will not conduct air. D (Direct Vent) type flue(vent) pipes are also dual layers but they are capable of exhausting burnt gas through the inner pipe and importing exterior(outside) combustion air for burning. Think of a straw inside a larger straw. Inside straw blowing, outside straw sucking outside air for combustion. A fan is usually used to help exhaust the burnt gasses. Details below: B-Vent (Natural Vent) gas fireplaces are designed primarily for decorative use. Generally they produce a larger and more realistic yellow flame. B-vent fireplaces are sometimes available without a glass window, so many homeowners are attracted to this design because of the open, realistic flame effect; some models do have a glass window so the existence of a window on a fireplace does not define its product classification. Natural vent gas fireplaces use room air for combustion and vent fumes through a vent or chimney that must terminate vertically above the roof line. The key to determining whether a B-vent fireplace will meet your heating needs is to check the manufacturer's listed efficiency rating (gas consumed x efficiency = heat output). While efficient, heater-rated B-vent fireplaces do exist, many lower quality "builder grade" fireplaces have no efficiency rating and, therefore, will not supply substantial heat. In fact, this category of fireplace will often use the greatest amount of gas at the lowest range of efficiencies. If you live in a warmer climate where you want the aesthetics of a fire without much heat, this may be the appliance for you. Likewise, bedrooms and smaller rooms may be a good candidate for a b-vent fireplace, but please check building codes to see if this class of fireplace is approved in your locality or for installation in the room where you'd like to use it. Local/national codes in some areas prohibit the use of b-vent rated appliances, especially in colder climates. Be aware that very "air tight" houses can cause performance problems with b-vent rated appliances, so please consult an experienced fireplace installer who can advise you on the proper installation and use you are considering. Direct Vent Fireplaces offer the most features with respect to gas consumption, efficiency ratings and venting options. A direct vent fireplace will always have a glass window because these fireplaces are sealed systems using a double walled venting system. Combustion air enters the appliance via one section of pipe while fumes and moisture are vented through the other pipe. Most often, a double wall "pipe within a pipe" system is used. Subject to each model's requirements for distance and offsets, direct vent fireplace venting may be terminated either horizontally or vertically. Efficiency rating will average 65% to 84%, similar to ratings on gas furnaces. Keep in mind that these appliances must "waste" some of the heat produced to create a draft of rising warm air to evacuate the fumes produced without aid of a forced air exhaust system. Think of direct vent fireplaces as a decorative furnace: the beauty of a realistic flame with high efficiency. This appliance is great for primary or supplental heating and for emergency backup heating as most work without aid of electricity. Because this is a sealed system that uses outside air for combustion, direct vent fireplaces are usually the favored choice among those in the fireplace industry because of their greater efficiency and exceptionally reliable performance. Hope this info helps, I am a General Contractor. Renron
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oh oh oh....sounds a lot like my posts of 2012 doesn't it! I can't believe my system is 2 years old. The choices can make your head spin. I had a similar dilemma with my hwh. I eventually chose tankless and since we have a portable generator I don't worry about the power issues (which you will also have with a power vent). Have to say I LOVE the tankless. Sometimes we just seem to need a lot of hot water, with 4 adults in the house. I have a soaker tub that I love and when it's cold it is delightful to fill it and not worry about who might come home and complain I used all the hot water. I think they ripped me about $4k for that puppy. Perhaps you can sway them into a tankless for the price they quoted you. It is the slow season. I used a company starting with an H,here in south jersey, and I got them to drop about $1500 from the price they had quoted in June by waiting until this time of year. The other company would not budge. My oop was $2k, plus the 0% financed amount. I found the 0% to be very attractive as well so as not to spend cash that could be invested. I sometimes wish I'd gotten the next level up in my furnace, to variable speed from multi speed, because I had humidity issues the first summer. I think that was solved by choosing the correct speed setting as this year has been perfect and my heating has been fine as well, I did get 2-stage heat and ac. I just came up against my price limit and decided the luxury of the tankless was how I wanted to go (rather than up the heater another level) The guys here got VERY tired of me (sometimes rightly so!) Perhaps you can find the old threads (novels almost!) that I posted here about the NJ CLEAN ENERGY program. By the way, I did do some reading online and it can be true that if your house is well sealed that a conventional heater may not draft properly causing a risk of carbon monoxide buildup, which is why they talk you into a power vent or tankless. Good luck. Try not to overthink or get too wrapped up in it. Accept that you will save SOME $, but the contractor will get at least half your rebate $ in mark ups. Are you getting insulation added? I think that was a good thing that I wouldn't have done otherwise.
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athensmomof3
14 years ago
If you do opt for direct vent you can also get custom doors from http://www.stollfireplaceinc.com/direct_vent_fireplace_screens.asp. Lots of options in lots of finishes, in case the fireplace you end up with does not come with the doors you like (options are pretty limited)
macv
14 years ago
Yes, a direct vent gas fireplace can be put anywhere in the house if the vent lengths and turns meets the rules of the manufacturer which are shown in the form of charts & diagrams in the installation instructions. It can vent horizontally to an outside wall or vertically through the roof within those rules. The roof termination would be an exposed metal pipe. Fresh/combustion air is drawn into the outer wall of the vent and the center pipe acts as the exhaust for combustion byproducts.

A B-vent gas fireplace can only vent to the roof and draws combustion air from the room (or through a separate outside air duct). It can have a glass face or bi-fold doors.

Either unit might have heat recirculating louvers or not.

If you find the roof termination unattractive you can add a fake masonry or wood surround.

Roof leaks shouldn't be an issue if the roofer knows how to flash a roof penetration. Be sure to use Ice & Water Shield self-adhering flexible flashing in addition to the factory metal flashing.

Click on one of the direct vent gas fireplace installation manuals and see if the vent tables will work for your installation. It's a lot of design work if the vent travels horizontally and vertically.

Here is a link that might be useful: installation manuals
macv
14 years ago
Zero clearance refers to a factory manufactured metal fire place that can be as close as 1 inch to combustible materials.
squarefour
Original Author
14 years ago
macv, thank you for the detailed information and the link to direct vent installation manuals. I'll look through them tonight. The idea of a fake masonry or wood surround on the roof sounds more promising than an exposed metal pipe. I've saved your information about Ice & Water Shield too. Thanks also for the clarification on the term "zero clearance". It is wonderful to get this kind of information so quickly. All the best, Liz
macv
14 years ago
Here is a fake stone chimney hiding a large chimney from a zero clearance wood burning fireplace.

Here are two gas fireplace direct vent terminations.
squarefour
Original Author
14 years ago
macv--what a difference! I know the direct vent box on the side of the house is not attractive, but I'd say the metal pipes on the roof are worse. The fake chimney is an improvement. I'm not a fan of fake, but sometimes it is better than the alternative. Many thanks. Liz
macv
14 years ago
Everyone has a different opinion about such things. I would tolerate almost anything on a roof in order to avoid disturbing the face of a building especially near the ground where you can see it up close. The metal terminations are not intended to be painted (usually galvanized or stainless steel) but it can be done. Black hides them against the roof and grey hides them against the sky.

The chimney hidden in the fake stone enclosure looked great on an ocean front house so we left that one exposed.

The slope of the roof makes a big difference in how much of a chimney you can see when standing close to your house.

cost, energy issues B vent or direct vent fireplace

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cost, energy issues B vent or direct vent fireplace

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