View Full Version : Venting an over the range microwave.
I am going to install an over the range microwave here. We've remodeled our kitchen, so this cutout was originally for a fridge and there is no vent.
https://lh6.googleusercontent.com/-Or_Jy4VjdhE/UtjGgvfYbhI/AAAAAAAAHmM/FVUeLF1L_Hg/w999-h562-no/20140116_225822_Richtone%2528HDR%2529.jpg
Here is the other side of the wall, taken with the cabinet open to give a height reference.
https://lh4.googleusercontent.com/-1yeKknBoOiU/UtjGrBIE0-I/AAAAAAAAHmk/1X3DBnLb2aw/w999-h562-no/20140116_225904_Richtone%2528HDR%2529.jpg
https://lh6.googleusercontent.com/-Bfv_n068I9A/UtjGtRvNg7I/AAAAAAAAHmw/4cIwYSFWZ9c/w999-h562-no/20140116_225913_Richtone%2528HDR%2529.jpg
I am going to be finishing the remodel on the laundry room as well, so at some point those holes will be patched and the water heater will be walled in from floor to ceiling. Eventually it won't be ugly, but for now, I can tear things up a bit to do them correctly if necessary. The range is gas. It has not been vented outside in the past at all. Does it matter that it is a gas range?
My questions are:
- I'd like to vent outside instead of recirculating. Is venting to the attic "good enough?" If not, should I try to tie in to the water heater vent?
- If there is a stud right where I need to cut into the wall for the vent, can I cut the stud and install a header, base, and side plates, assuming that this is a load bearing wall?
- How do I tell if the wall is load bearing?
- Any tips?
Standard size of over the range microwave is 30", if that cabinet used to be above the fridge - it's more than likely 36"...
Yeah it's 39" actually. I may have to build little end caps to make it all look even. Maybe little shelves or something. I'll mount the microwave, then figure out that part.
Venting to the attic is fine. Do NOT tie in to the exhaust for the hot water heater. You would be adding back pressure to that system, potentially causing the exhaust to flow the wrong direction.
If the roof is built with trusses, the wall may not be load bearing. You would need to check in the attic to see if it's stick framed or not.
Most new microwaves have an exhaust vent that can go out the back of the unit or the top. , this would allow you to stay in the cabinet and go straight up to the attic. You lose some storage room in the cabinet.
If you do vent to the attic I would recommend extending the pipe to a roof or gable vent, you can pump a lot of moist air up there and that could be an issue.
Is that a fan on the water heater exhaust pipe?
hghclsswhitetrsh
01-17-2014, 08:30
Is that a fan on the water heater exhaust pipe?
Vent damper.
hey Irving is that 3" pipe just kind of stuck up into that 4" pipe? Or is there a 3" pipe inside of the 4" pipe going all the way outside?
Dont vent to the attic. The moisture and grease will cause a lot of damage up there. You maybe able to retro fit a roof vent but it has to vent outside. Also it wouldn't pass a home inspection when you go to sell.
Baths are vented to attics all the time and they are much higher producers of moisture. There is nothing in the building code (last time I looked was 10 years ago) that specifies a vent must go outside. In fact, there is no requirement for a vent at all. I'll agree it's better to go all the way, but roof penetrations are not always simple. I've seen homeowners do it themselves and end up with a leaky roof.
Where are you planning to plug it in? I can't remember if a MW requires a dedicated circuit like a fridge, but I don't think so. They are big draws, however, and if you run one on a circuit that runs other high power devices you'll likely blow breakers.
It will be a bitch to clean the microwave over the oven.
I installed a kitchen vent and lived. I'd put one over your stove and vent to the outside. Don't forget a light over the stove.
trlcavscout
01-17-2014, 10:42
I thought gas ranges had to vent to the outside now? Maybe its a local thing. I would run it to the attic and have a roofer cut in a vent, better chance of it not leaking.
Highclass, I'm not sure on your question, I'll have to look. I don't think it is just crammed in there, but will check. It sure looks ugly though.
I think the only other thing on this circut would be range and dishwasher. The range shouldn't be much draw since it is gas right?
We had a roofer come out to correctly install the vent for the dryer that we relocated over there next to the hit water heater.
Can I run those two copper lines behind the drywall to clean stuff up? One is a ground for something and the other is a water line for the ice maker.
The wall runs parallel to the roof, so may not be load bearing. The house has a pretty small foot print so I wouldn't be surprised if just the curtain walls and the one perpendicular wall support everything. I will take pictures of the attic when I get home. Thanks for all the input so far.
Here is the attic. I don't think I have trusses.
https://lh6.googleusercontent.com/-zTdLJXZ4VuM/Utn2ECP_z_I/AAAAAAAAHng/smD14oJVQNI/w999-h562-no/20140117_203331_Richtone%2528HDR%2529.jpg
Red line is wall in question. Blue line is the wall I believe to be the load bearing wall as it spans the house and those supports attach to it. Green arrows are the original roof that terminates on the brick wall where my garage was added. 1 - Dryer vent, 2 - Hot water heater vent, 3 - gas line that goes down the wall in question. I don't think this wall is load bearing.
https://lh6.googleusercontent.com/-AKx33SM_BKo/Utn9UOh77kI/AAAAAAAAHoQ/Y4GoNK1zY9o/w900-h506-no/Roof.jpg
Is there anything I have that I could join into, or should I just get close to a regular roof vent?
Great-Kazoo
01-17-2014, 23:13
Your dryer vent goes up? How often you clean & check for lint build up ?
We just did it recently. It's actually been having problems, so that is next on my Ask-a-member list. I think I'll check it right now. It used to vent into the garage, then we moved it and up is the only option. I have no crawl space.
Code requires dedicated circuit, but not something most realestate inspectors will require you to change......now. Dumping vents in attic is against code and an inspector will catch that. Some will let you attach (to direct the exhaust out) at an existing roof or gable vent. All vents are also required to be a least 10' away from an opening, such as a window.
newracer
01-18-2014, 00:09
Like trlcavscout said, pretty sure a gas range must have a vent to the outside. That is what my builder told me.
I could see that. No one said anything when we bought the house with the original gas stove. We tore out the wall in the middle of the kitchen, so I know there wasn't one in there before. All the more reason to run this one to outside as well. Haven't had any issues so far. Again, a real vent will be nice though.
A couple of observations.
- ALL Dryer vents need maintenance and cleaning, the ones going up and out the roof need more. The total run by code is 14', elbows and flex pipe really slows down the flow.
- It looks like an addition was made and a roof was over framed on the original shingled roof. I would avoid cutting out any wall members below if you can.
- The micro exhaust vent pipe can be a 3x10 piece of ductwork to fit in a wall space and minimize structural remodel to the wall, turning to round pipe in the attic.
- New codes require venting for gas stoves, millions of homes don't meet code. Vent it if you can.
- Pull the insulation away from the Water Heater 'B' vent in the attic and as mentioned earlier, make sure that pipe is connected through the roof. Looks like weird retro above the water heater.
- Make sure you introduce outside combustion air to the water heater area if you frame it in.
- Have fun in the attic, looks cozy!
-Checked the dryer vent tonight and it is still clean as a whistle. It's new though and is only maybe four months old.
-Planned louvered panels on two sides for walling in the water heater.
-I never thought to ask what the minimum diameter pipe should be for this vent. What would be ideal?
-There is a roof vent within a few feet (10') of where this new vent will enter the attic. Can I just run the vent pipe up under the large roof vent, or would I need to seal it?
-As far as the gas stove vent, is it correct that this microwave vent will cover the stove as well, since one could just turn on the microwave vent anytime the stove is on?
I REALLY appreciate all the input you guys have been giving me. I hope I'm not wearing out this subforum because I have a lot more stuff on the list to improve this house before I move.
jerrymrc
01-18-2014, 06:38
When I did my kitchen the stove and vent was on an inside wall. I moved it to the outside wall and added a micro vented outside above it. In my case I have a real Jenn-air (circa 87) and it is vented outside as well.
Now in the winter we normally just use the microwave vent because as many know what goes out must come in and a Jenn-air vent can be overwhelming for normal stove top cooking. I do know that you can't hard wire the micro in, there has to be an outlet placed in the cabinet above.
hghclsswhitetrsh
01-18-2014, 07:23
When I get home later I will get my code books out and look up these questions. That will eliminate all guessing and speculation.
Also, anything over 400 cfm's require automatic dampened makeup air and don't forget to rotate your microwave blower for outside exhaust vs recirculating.
Ran into a problem with my plans. I went and bought the stuff to run the vent up through the wall. Glad I looked first because there are two 2x4's over the top of the wall in the attic. Looks like I can't run the vent in the wall up to the attic, and I'm also going to have a slightly more difficult time running the wire down the wall for the outlet I was going to put into the cabinet.
https://lh3.googleusercontent.com/-H0VU6r0Kl9c/UttIaI2cs2I/AAAAAAAAHpA/LcC5liNZgqw/w999-h562-no/20140118_203706_Richtone%2528HDR%2529.jpg
Now I'm having to rethink what I'm going to do here. The cabinet over the stove is custom built. It is a well built, but shitty cabinet, if that makes sense. Basically what that means is that I'd have to cut that shelf out of the cabinet, or cut through it, if I want to vent through the cabinet. It's not removable like store bought cabinets.
I am really tempted to just yank the shelves on the other side of the wall, pull all the drywall out of the laundry room (I have holes to patch and pipes to replace, and other stuff I need to do in there). With all the dry wall gone, I can more easily go through the kitchen wall, up, then out through the laundry room wall and up into the ceiling. Then, since I'm re-drywalling everything anyway, I can build the new shelves easier, and box in and clean up all the crap running through that wall.
By the way, I checked on that water heater vent, it IS 3" pipe all the way out the roof, it just passes through a 4" pipe every time it goes through a wall.
EDIT: Of course each wall will have a top plate. I was talking to a friend who lives up the street in the same model home, and he was saying how he can look down all his walls from his attic. I don't know why he can do that. Just realized how silly this last post sounded.
Remember, a kitchen remodel should only take about 20 minutes to complete according to those DIY shows on TV (riiiight!)
At this point you might be better off venting out the back of the wall like you mentioned, you might be able to put an offset elbow in to miss the shelving in the laundry room. That way you can keep the kitchen cabinet space which is always at a premium. You had said there was a stud in the wall where you need to cut the vent through, looking at your last pictures with the gas line showing, I would advise just cutting the stud out with a sawzall, it doesn't look load bearing. Just cut out the 4" section of stud thats in the way and run the vent through.
You had also asked about covering up the copper ice maker line and ground wire by the water heater. It shouldn't be a problem BUT, if that ice line is the same copper line shown in the last picture (behind the gas line) it is running in unconditioned space with no heat through the attic to the refrigerator, it could freeze and break. Thats not good.
Good news on the WH vent though!
You better get busy, you have about 15 minutes left!
I checked with the stud finder and fortunately no studs where I need to cut for the vent. Copper water line goes from one interior wall, into the attic, and down into a second interior wall. Haven't had any issues with it so far.
Go for it Irv! Post some pic's when you get it done.
rockhound
01-22-2014, 08:27
first every gas stove now needs a vent, second every wall in your home will have a double plate at the top, the wall that runs parallel with the roof is not load bearing,
your easiest and best option would be to go through the wall and build a chase to the exterior wall if it is available , you could go back into the attic behind the wall, but it looks like your chase for the water heater exhaust may be in the way. do not use flex line for this vent
you need a reducing collar at the water heater vent, no way the thing is drafting properly
as for your dryer if it is an older unit, take it apart, you may find a giant ball of lint in the filter system, have seen several dryers that were not drafting properly that were internally clogged.
Found the problem with the dryer. There was a screen in the roof vent that was packed with lint. While trying to scrape it clean with my fingers, it popped out onto the roof. It can stay there. Damn clogged vent ran up my utility bill from running the dryer so much.
So I have the hole cut for the microwave vent and the new power source. I'm going to run new outlets (each on a dedicated circuit) for the stove, microwave, and washer/dryer since they are all on the same wall. I have a roll of 14/2 wire from remodeling the kitchen, but I'm under the impression that I should be using 12/2 instead with 20 amp circuit breaker and 20 amp outlet.
Here are some photos of the 10 minutes worth of progress.
Hold a box under your hole to keep drywall off the stove. Don't forget to tape up the stove. *Pro Tip: If you unplug the stove and turn off the gas, this reduces the chances of you nearly setting your house on fire every 10 minutes when you find yourself leaning up against the burner knobs. Or you can NOT do that and melt that plastic bag all over the stove, revealing the just as combustible cardboard laying on top of the plastic.
https://lh4.googleusercontent.com/-8N4Tf0EH30c/Uu3C67F0qmI/AAAAAAAAH-8/HllNaFqmPWg/w999-h562-no/20140201_205952_Richtone%2528HDR%2529.jpg
Use the template to drill holes in the right places under your cabinet.
https://lh6.googleusercontent.com/-5LgdZ_oupPU/Uu3Nm8Cq1eI/AAAAAAAAH_c/lbz-g_q-V44/w999-h562-no/20140201_214614_Richtone%2528HDR%2529.jpg
Hole and old construction gang box. First attempt was just for fun (for some reason there is a piece of wood directly behind that).
https://lh3.googleusercontent.com/-pl8E8mRsZ3E/Uu3ULQ2jAtI/AAAAAAAAH_w/8wftWgp0wxQ/w999-h562-no/20140201_221317_Richtone%2528HDR%2529.jpg
What is the difference between these three circuit breakers?
http://www.homedepot.com/p/Square-D-by-Schneider-Electric-Homeline-20-Amp-Single-Pole-Circuit-Breaker-HOM120/100045009?N=5yc1vZbm16
http://www.homedepot.com/p/Square-D-by-Schneider-Electric-QO-20-Amp-Single-Pole-Circuit-Breaker-QO120CP/100028706?N=5yc1vZbm16
http://www.homedepot.com/p/Square-D-by-Schneider-Electric-Homeline-20-Amp-Single-Pole-CAFCI-Circuit-Breaker-HOM120CAFIC/202353306?N=5yc1vZbm16
The middle one has the light, but why the big price jump to the third one?
As far as receptacles go, I understand that you DON'T want a GFCI for the refrigerator because if it trips in error, the food goes bad. For the washer/dryer, I think that one would want a GFCI since it is next to the washer and there is a higher chance of the outlet getting wet (already happened to me once). Should the washer/dryer and stove be on a 20-amp circuit as well?
Third one is an arch fault breaker which are now being required in all bedrooms, VERY sensitive to tripping.
Also I believe ALL kitchen, baths and laundry circuits are required to be 20 amp (with exception to lighting circuits). Hopefully one of our resident electricians will correct me if I'm wrong.
Thank you jslo. Let's just bump this right up so I can shop deserted aisles during the game today.
I bought 3" ducting for this. Will that be a problem? I don't think the microvent fan will be able to move more air than this 3" pipe can support. Someone please respond if you know one way or another.
newracer
02-03-2014, 21:49
Microwave needs a 20 amp circuit, which will require 12/2 wire.
Picked up 250' of 12-2, three 20 amp receptacles (one GFCI for washer/dryer), and three 20 amp circuits tonight. :) Tearing out some drywall in about 10 minutes. All I need now is a short length of conduit to run from my soffit into my breaker box. I'll get that when I pick up the other crap I bought that I don't need.
Didn't get much done tonight because it was bedtime for the kiddo so I couldn't be pounding around. I had to take the end off of a custom built shelf. I didn't want to tear the whole thing off the wall, and the part I was removing was secured to another portion. I knew there were screws holding it all together, but they were hidden be 50 year-old paint that was super thick. I used a magnet to make sure I found all the screws so I didn't put any unnecessary force on the part I wanted to preserve. Magnets, how do they work?!
https://lh6.googleusercontent.com/-qbGUbQHm1AU/UvBseD2WlyI/AAAAAAAAIAw/ZQkzfxqIPH8/w999-h562-no/20140203_212835_Richtone%2528HDR%2529.jpg
Never updated this thread. I got the two 20 amp circuits wired up without killing myself. Microwave is mounted and in service. Now I just need to finish sealing up all the cracks and spaces, then finish routing the vent and seal everything up.
https://lh5.googleusercontent.com/-eH4j-vlCf6c/Uvb9nF4NwcI/AAAAAAAAIFs/eMogeD0TAUc/w999-h562-no/20140208_210129_Richtone%2528HDR%2529.jpg
This will be "boxed in" when I'm done. It will look like when you box in any other duct work, only it will only stick about 1" out from the wall. Should end up looking relatively clean, then I'm going to box in the whole water heater area anyway.
https://lh6.googleusercontent.com/-cFgTFVIJRHc/Uvb9yJ8e6CI/AAAAAAAAIGE/9stJn9s0VT8/w999-h562-no/20140208_210213_Richtone%2528HDR%2529.jpg
This looks a bit better. Tried to make it so this whole thing can be removed easy enough if I need to get back in there. This whole area will be boxed in eventually, so I'm not too worried about it. Thanks for all the help and advise for this project guys. Oh yeah, I picked up some window AC unit weather striping from Home Depot. This goes around the vent outlet to keep the air in the vent, and not blowing out the sides of the microwave.
https://lh6.googleusercontent.com/-iYm3MVvqH_g/UxviD4MtT1I/AAAAAAAAIfY/Wz-U3K_vygg/w316-h562-no/20140308_203746_Richtone%2528HDR%2529.jpg
https://lh3.googleusercontent.com/-6CXbrPLo7UE/UxviWucm7xI/AAAAAAAAIfM/Itih8SOqLUM/w999-h562-no/20140308_203836_Richtone%2528HDR%2529.jpg
rockhound
03-11-2014, 08:27
the wiring is not installed properly, unless you secured the wiring outside the juction box etc before closing up that wall. the sslack in your wiring is wrong and it is not secured within 8 inches of the outside of the box.
The wiring is secured to the wall within 12" on the wire that goes to the junction box in the picture; but I do have quite a bit of extra wire. Is it a huge deal to have too much extra? The other wire goes to the outlet in the floor and I didn't have access behind the wall to secure within 8" of the box. However, looking at the picture again, it sure would have looked cleaner to have secured that wire to the wall in a few places. Is it something I should pull the panel off for to fix, or just do better next time?
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