I have checked through messages and am still not certain of which way to go…
I have Gas Dryer in interior laundry room on 2nd floor. Venting options are:
1. Up through roof, about a 10ft vertical run with 90 degree elbow at dryer. 4″ galv. pipe through insulated space above plaster ceiling (no attic). Have seen roof vent from Inovate Technologies, but not sure how well it would work (says recommended for flat roofs and this roof is standard pitched). Damper would I assume work like standard damper and open under pressure from exhaust air. a. Any issue for snow blocking vent? (in MA and sometimes heavy snow) b. Lint on asphalt shingles? c. Proper Flashing would be issue just like any other hole in roof d. What about moisture in a vertical vent and increased risk of lint accumulating at 90 degree elbow at dryer?
2. Vertical 8ft and then horizontal 15ft through sidewall and require numerous elbows. Distance is over limits and would require booster fan & switch ($), plus not be optimal from visual perspective. In other words, option 1 is my preference, but I dont’ want to risk mistake if it has too many problems. Advice? Thanks, Adam
Replies
I think I'm following you, through the roof w/only 10' of vent run should not be a
problem w/3 elboes. One elboe at the back of the dryer to transition to vertical and
instead of this "Inovate Technologies" roof cap use 2 elboes hooked together to
form a n (shepards hook)at the end of the pipe termination above the roof(high
enough
to clear any snow accumalation). For the penetration through the roof , you can get
a 4" roof flashing to run your pipe through the roof. I wouldn't use no damper,
because it will be a constant maintanece problem accumalating lint and staying
blocked open.
And as far as the lint on the roof if the rain doesn't wash it of you could always wash
it away with a hose.
Also use the silver vent tape(not duct tape) and if you use any mechanical
connections use rivets instead of screws.
Thanks for the advice. I am now looking at the air inflow for interior laundry room/make-up air. Can that be just a grill above doorway 12x12 leading into main hallway/staircase area and right next to return grill for 2nd floor air handler? I had read somewhere on site where someone recommended putting in a dedicated line to outside for make up air, but I don't want to punch any more holes in roof and wouldn't that just make my laundry room very cold in winter? Also, having just insulated walls for soundproofing, it seems like I am just opening another avenue for sound to travel out into main house?
thanks to you and anyone else who can shed some light on this.
Adam
I would use a grate into the laundry room rather than make another peneration in the building envelope. Consider the following if you don't want that grate to transmit the sound of the washer and dryer:
Instead of going straight through with a grate on each side, put a grate high on one side and low on the other. Use the stud bay as a silencer of sorts. If you force the sound to bounce off of multiple surfaces, you can reduce the transmission.
Note that no penetration should open the framing to a fire hazard. Sheetrock or block with wood the air passage from the rest of the stud bay. Check with the inspector, but at most, you'd have to put 5/8" rock on the sides of the studs and fire blocking (2x4s) high and low.
Once fire blocking is done, you are free to consider acoustical panel or accoustical foam inside the bay to further block sound. But sound leakage through and under an interior door is probably the bigger source once you've offset the grates.David Thomas Overlooking Cook Inlet in Kenai, Alaska
sad would cutting 1/2" off the bottom of your laundry room door be a solution?
we are a busy family of four and we hang dry just about everything but sheets & towels on wood drying racks during the day the room is usually open but at night we close it as it will be one of the last to be insulated -- we use two of those dry z air units ( electrical app 15" diameter) as drying agents say each one uses the energy of a 40 watt bulb ciao John
As far as make up air is concerned I wouldn't want to punch any more holes in the
building envelope either. To bad they don't make (as far as I know) an automatic
opening and closing cap that would only open when the dryer is running. i'd ck. with
local building authorities regarding using make-up air from the house instead of
bringing in outside air. It wouldn't seem to big of a deal with one gas appliance.
Several manufactors make roof jacks or vents just for dryers of exhaust fan.If I am not mistaken I think GAF even makes them to gowith their roof systems
Doc,I'd be interested to see what your talking about. Do you have any links or more
info. Inquiring minds want to know. Butch
In response to your request try http://www.gaf.com/content/document/20502.pdf or simply http://www.gaf.com you will find more than one product that can be used for your installtion.
Reading some of the posts I really think that b pipe is overkill.The straight up and out is about best way to deal with it,I used to take care of a condo complex that had long vertical runs installed through the garage attic space,they used to plug up with lint and then cause condisation to form on the outside of the pipe,was the roof leak that only happened when the dryer was on
sad,
If you are talking venting the cumbustion fumes (as I think you are) and not the lint, I would think you would have to use B-vent, not just sheet metal vent. It is also known as MetalBestos. It is a double walled vent to reduce the outer metal temperature.
This would not have a damper on it unless it was electrically opened with a safety device to prevent combustion if the damper fails. After it exits the roof it takes a special b-vent cap to help prevent downdraft. You should not use the box type vent intended for bathroom exhaust fans!
The two safety issues that this system addresses are CO fumes and flue temperature (sp.FIRE!) These should not be taken lightly. Make sure your system is safe and to code if you are determined to do it yourself!
I'm not trying to pass myself off as an expert in gas dryers (I have never installed one) but I have installed many other types of gas and wood funaces,stoves and fireplaces and I do know not a winter goes by that I don't hear of fires and deaths resulting from improperly vented gas appliances.
"venting the cumbustion fumes (as I think you are) and not the lint"
But all natural-gas fired clothes dryer vents combustion fumes (N2, O2, CO2, Ar and CO in order by %) with excess air and whatever lint the dryer didn't catch, right? I have never seen a separate lint vent.
In most of the combustion equipment in a house (HWH, furnace, boiler), the flue gases are (should be) the combustion products of an slightly lean mixture - a few percent O2 and very low CO. Equipment can be out of adjustment, poorly tuned and discharge higher than average CO, for sure.
But the excess air used in a clothes dryer keeps the temperatures much lower than a HWH, boiler, etc. Hence, things like plastic anti-critter screens are rountinely installed on dryer vents that never would be used on high-temperatures exhausts.
Clothes dryers certainly cause houses to burn down at times, and I suspect they can cause CO deaths (although I don't recall any recently).
But before going to the (not required by code) MetalBestos route, I would, in order of importance:
1) Keep the run as short and straight as possible
2) Use aluminium tape designed for that purpose (not, "duct tape" or, quack, "duck tape").
3) Use rigid (not flex) metal ductwork only.
4) Use pop rivets instead of screws to snag less lint.
5) Aluminium tape the length of the seam of each piece of ductwork. OF COURSE you tape the junction of one section to another!David Thomas Overlooking Cook Inlet in Kenai, Alaska
Thanks for the info on gas dryers. They are a rarity in my area, and I have never had to deal with one.
I thought it would be good to bring up, because when I see DIY, gas, and venting, all in the same post, red flags go up.
BTW, I've been to Kenai, and Soldatna. Beautiful country. I've also made it on down to Homer a couple of times, once for a halibut charter. What an experience that was! The sight seeing was the best, the fishing was just a bonus! (Shipped home 80 lbs. of halibut-never thought I could get tired of it, but it took a long time to consume, even after giving some of it away)
John Svenson, Builder, Remodeler, NE Ohio (Formerly posted as JRS)
"80 lbs. of halibut-never thought I could get tired of it, but it took a long time to consume"
At least it keeps well frozen for a long time - a year or better if vac-packed. Salmon you gotta use in a few months. Salmon is great smoked (I do 2/3s of mine that way), but you can also smoke halibut and serve it on crackers or in omelets. In addition to backed and grilled, frozen frozen halibut goes very nicely in some casseroles. Got a friend up here who does great halibut enchiladas.
But I shake my head when I see tourists in Kenai or Anchorage checking (and paying for excess baggage) on six 70-pound boxes of frozen fish. Do they have any idea how long 420 pounds of fillets will take to eat?! Even for their whole extended family? 2 halibut and 20-30 sockeyes are all we need each year and that's in a no-red-meat house.David Thomas Overlooking Cook Inlet in Kenai, Alaska
Dave,
420 lbs.-unbelievable. I really did get a little tired of the halibut, but I guess I didn't realize it preservrd that long frozen. The casserole sounds delicious, I wish I would have thought of that. Had most of it baked, broiled or grilled.
I've got family in Palmer and Anchorage, next time I come up I'd like to look you up. It probably wouldn't be for a couple of years. I've got kids in college. Maybe when I'm down to one.
Maybe an Alaska-fest someday? Bet you could get some of those Oregon & Washington Breaktimers up there!
JohnJohn Svenson, Builder, Remodeler, NE Ohio (Formerly posted as JRS)
Thanks for all the advice. Here's what I was recommended to do by a sheet metal/ducting contractor:
1. Gas dryer exhaust vent to 90deg. shallow clearance duct attachment = 2 90deg's
2. 4" 90 deg elbow to straight run of about 11' of 4" galvanized rigid duct. = 3 90's
3. Capped clean out T installed low in straight run to permit vacuum house cleaning as needed. Joints sealed with "Duct Butter" sealant and taped with silver duct tape. Pipe wrapped in fiberglass batt insulation
4. Straight duct terminates at underside of roof where it attaches to rectangular flat aluminum flange with attachment for 4" duct.
5. 4" hole in roof and hooded aluminum roof jack/vent made by Lambro which has damper activated by air flow and at very end a critter screen (not fine mesh). Vent properly flashed and sealed. Hooded vent/jack is another 90 degrees = 4 90 deg's
Anything seem out of place here or suggestions for improvement?
thanks again to all.
Adam
Everything sounded fine up to step 4? I wish I could see this Lambro roof jack your
talking about. Any kind of screen or damper in this WILL be a constant source of lint
accumulation. Hopefully you'll be able to access from attic to clean.
Each 90 elbows count as 5 ft of straight pipe.
Looks like you are right at the maximum recommended run 25 ft. Plus transistion or two.
You might want to make allowance to add a booster fan if the drying is slow.
Or up as much as you can, specially the elbows to 5" pipe.
"Pipe wrapped in fiberglass batt insulation"
A nice and helpful step, not common. Helpful to keep the temperature up in the duct work so you don't get condensation in the duct work. Wet lint gets stuck to the inside of the dutwork. Dry lint keeps moving.David Thomas Overlooking Cook Inlet in Kenai, Alaska
We never use double wall vent(use galv. rigid pipe) because that in itself creates a
fire-hazard. The reason being that lint accumualtes between the two pipes creating
a potential fire hazard. I always leave 1" clearance around any penetrations.
Interesting discussion. I did a full renovation on a couple of 19th. century stone buildings over the last couple of years and, with rubble walling up to 22" thick, installing vents just wasn't very practical. In both cases, the owners went with my suggestion to install electric dryers imported from Europe as the condensation is 'caught' in a removable drawer. Yes, the cost was higher but they are much more efficient (and the Inspectors agreed!) Maybe, as we now have gas-fired boilers (as they have had in Europe for over 30 years) with balanced-flue vents, there are gas dryers out there with the same system?
Rockbeare
"my suggestion to install electric dryers imported from Europe as the condensation is 'caught' in a removable drawer"
And, if there's a long heating season, you might as well kept those BTUs (and some leaked moisture?) inside the house. But in the cooling season (what's that? - hah!), I'd want a big operable window in the laundry room to dump the heat.David Thomas Overlooking Cook Inlet in Kenai, Alaska
My personal experience with dryer vents is that elbows dramaticly decreases airflow. In the instrucion book for my Maytag gas dryer, it states that runs of up to 25 feet with four inch rigid pipe are allowed. Our run was 16 feet with two 90 degree bends. After a few months, my wife noted one day to me that it was taking up to two hours to dry a load of bath towels. I called Maytag help line and they said that according to their specs, all was right and that I should have the unit checked to see that the fan was running the correct speed.
Anyhow, after a lot of checking that produced nothing, I decided to route the vent through the side of a cabinet and out the adjoining wall. The total run with flex tubing was just under five feet. The same load of laundry now drys in under 30 minutes.
So....keep the runs as short as possible and use sweeps in the turns when you have to make the turns at all. Take the most direct route. I would advise against using an outlet in a horrizontal or sloped position that was designed for a verticle installation. It is very possible that he amount of airflow will be to small to keep the flapper open, and may result that the dryer will vent into your living space.
"After a few months. . .it was taking up to two hours. . .(after installing) flex tubing of five feet the same load of laundry now drys in under 30 minutes."
But that the problem worsened over time, makes me think of something instead of, or rather in addition to, the long duct run. The air flow/velocity may have been too low in the 16 feet plus 2 elbows. Allowing lint to fall out, moisture to condense, then more lint to fall out. It kind of snowballs because as the flow decreases, more lint is deposited.
You might have been able to restore performance by snaking the 16 feet run with a duct cleaning brush. But your installation of a shorter run is a vastly better solution that will involve little future maintenance. Higher air flow, drier air in the duct because it doesn't cool as much. Little lint deposition. Better drier perfromance and less energy consumption.
Shorter is always better. Contrary to all those spams I get about adding inches.David Thomas Overlooking Cook Inlet in Kenai, Alaska