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Old 04-23-2005, 04:16 PM   #1
FredG
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M.O.C. #1309
Bathroom and Range Vent fan replacements

Well, I finally got the bathroom and range vent fans replaced with computer fans.

The bathroom vent was relatively easy. I drilled 2 holes in the old fan mount to accomodate the new fan. Using a Sound Pressure Meter on scale A, the original bathroom vent fan measured 74 DB at approx 1 meter. The new fan measured 53 DB at approx 1 meter.

I also replaced the original range vent fan (which so happens to be the same motor and blades used in the bathroom vent). This one was a bit trickier. I took down the range hood, there were 4 square head screws going into the bottom of the cabinet. Once I got the vent down, I removed the original fan and used the original fan bracket for one of the screw mounts for the computer fan.

The fit was not perfect for the 120 mm fan, but I could not figure out a way to mount two 80 mm computer fans to the exit vent in the rear of the range hood. The 80 mm fans were about 3-4 mm too large to fit. I improvised by using a wire tie on the opposite corner mount to secure the fan.

The result was a reduction of 22 DB. Original fan measured 74 DB and the replacement measured 52 DB. Now, we can watch TV in the Living room even when cookign with the range vent on.

The fan I used for both was an Antec Pro Series Double Ball-Bearing 120 mm Case Fan with these specs:
12 VDC .24 A
79 CFM
2000 RPM
29.8 DBA

I think the difference in measured noise versus rated noise is caused by echos in this application.
Also, a note on the range vent fan...the original did not have special marking for flammability safety, etc. I assume the metal grill in front of the fan reduces the chance of grease, etc getting to the fan. However, I am not sure if there are any safety issues in using a different fan.

I posted photos at:
http://fifthwheelliving.com/gallery/...umName=RV-Mods

Fred
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Old 04-23-2005, 04:24 PM   #2
DrivesBGM
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Fred,

I hate the noise level of the exhaust fan in the range hood!

Can you offer an opinion about how much air is moved with the computer fan that you used verses the OEM fan?

Thanks,
Craig
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Old 04-23-2005, 05:18 PM   #3
FredG
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Craig,

i just installed it today and we won't be camping for at least another week or so (I need to get the hitch installed in my new truck first).

I'd estimate it to be about 3/4 of the air movement. It keeps the outside vent cover open about 3/4 of the way. Doing a search for the range hood using the fan motor manufacturer shows that it is made by Elixir (also known ad Jensen). The rated air flow is 85 CFM (http://www.dyersonline.com/p-1221-el...ange-hood.aspx). Since the computer fan is rated at 79 CFM, I figured it's close enough to work. There are other computer fans of about the same size that spin faster and move more air, but they are also louder by 5-10 DB and my focus was on quiet.

Also, if you don't want to replace the fan, I have seen other mods online to control the speed of the motor in the range hood. It involves adding a resistor in line.

one other side effect is that these fans draw a lot less amperage...0.24 Amp vs the original fan's 1.6 Amp. This is a good point for anybody that boondocks.

Fred
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Old 04-25-2005, 06:31 AM   #4
tweir
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Yeah, I was wondering if you can install a rheostat control in the kitchen "F-18" fan---that bugger is really loud. Anyone out there do that yet?
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Old 04-25-2005, 12:54 PM   #5
FredG
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I haven't seen any mods with rheostats, but here's a link to the resistor mod I mentioned earlier:
http://www.rverscorner.com/info/rangehood.html

Fred
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Old 04-25-2005, 06:42 PM   #6
sreigle
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I did the bathroom fan a couple of years ago but haven't yet done the range fan. Our range fan runs backwards so the factory is going to check that out when we are there in May.

I don't have any numbers but can attest that the computer fan in the bathroom draws a lot more air. I make sure to turn it off when flushing because opening the flush valve that fan will suck bad odors out of the black tank right into my face. Once was enough to learn. The fan is much, much quieter, also, as FredG attested. We've had it run for hours without realizing it was still on because the bathroom door was closed. We got a ball bearing fan since they tend to be quieter and last longer.

FredG, our range hood fan is different than the bathroom fan was. It has larger blades and they are white on ours. I may someday replace it with a quieter fan but first want the factory to figure out why it's running backwards. It sucks that outside door closed and blows air onto the stove rather than the reverse.
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Old 04-25-2005, 09:07 PM   #7
FredG
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Steve,

If your range fan is like ours, you should be able to pull the fan blades off and put them in upside down (or would that be right-side up?). Basically, reversing the fan blades to blow out. Our fan just slips onto a D shaped shaft.

It's interesting that your two fans were different. Ours were exactly the same. Color, diameter, and motor all matched. I do think you hit the nail on the head with the comment about ball-bearing fans. The original motors in our rig look to be brush-type motors and when I manually turn the fan shaft you can feel quite a bit of resistance. It's probably the reason that they are so noisy, not to mention have such a higher amperage draw.

I'm also going to keep your warning in mind...we don't need any extra odors being sucked into the rig

Fred
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Old 04-26-2005, 01:22 PM   #8
sreigle
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Fred, I already tried that. The blades do pull off but when you turn it over they're pointing the same direction as before and pull air in. Sure boggled my mind for awhile. The blades on ours are white while the bathroom fan's were black.

The fan I put in the bathroom is a little larger than the oem fan. I'd have to go measure it but I think it's 4 inches. Like you, I re-used one mounting hole from the original fan location and drilled two more to give it support on 3 corners. I then just spliced the wires to the original switch. Works great!

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Old 04-26-2005, 01:29 PM   #9
FredG
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Hmmm...that boggles my mind a bit too, I've seem posts elsewhere where inverting the fan blades fix that. Oh well. if the range hood is similar to ours, you should see a metal cover over the wires behind the switch. One screw holds that in place. Our fan had one wire (postive) going to a switch with a slide on connector and the other wire went into a wirenut for the negative side (with two white wires). Both wires on our fan were black, so I wonder if the fan is actually reversible. There were no markings on the fan to show + or -, either.

Fred
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Old 04-26-2005, 03:50 PM   #10
Mels Musty Music
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Fred - Have to show my ignorance again (or as usual as my wife would say) butwhen you refer to a computer fan are you talking about a cooling fan in a PC power supply? If not what is a source for the fan you installed?

Steve - Had a Cougar 5er before our Montana and the bathroom fan brought air in instead of exhausting it like your range hood fan is doing. Took it in for that and other warranty issues and was told that it was running correctly. When I got it home I pulled the fan housing so I could get at the electrical connections. Reversed the wires to the fan and it exhausted fine after that. Don't know if the range fan is similiar as I've never had that apart. Incidently. the dealer that did my warranty work is no longer in business.

Hank
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Old 04-26-2005, 04:27 PM   #11
sreigle
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That probably would work, Hank. Fred, ours is likely like yours. There is a metal cover back there. I thought I tried reversing those but it's been so long I'm not sure anymore. I'll look again.

Hank, mine is a computer case fan, the kind that mounts on the case to exhaust hot air. Also known as a "muffin fan".Here's just one example from a quick google search... Ours is chrome. I've seen blue and other colors, too. Best Buy and other stores with computer parts will have them. You should be able to get a good one for somewhere between $5 and $10. Be sure it's 12 volt.

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Old 04-26-2005, 07:57 PM   #12
Montana_2957
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Here is another variation on the bathroom fans if one likes color at night - 80mm - 2500rpm, 32.5cfm, 1.6 watts, .13 amps, 12 volts. The ceiling switch adds the 3rd original fan if one wants to move lots of air - all controlled by wall switch too.
http://geocities.com/dgullick1/1coolpc.jpg
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Old 04-26-2005, 10:04 PM   #13
FredG
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Hank,

Yes, it's basically a fan like in a computer power supply, but larger. It's normally called a "case fan" since some of the hotter running computers have multiple fans within the case, in addition to the Power supply fan.

Here's a link to the exact fan I purchased from NewEgg:
http://www2.newegg.com/Product/Produ...82E16835129030

I saved on shipping by ordering 3 - 1 for the bathroom, 1 for the range hood vent, and 1 for my father-in-law who wants to do the same bathroom mod on his RV.

There are other fans out there, but I'm not a fan of the light up fans (it seems that most clear fans light up) and Antec is a well known brand in "techie" circles. Also, computer fans come in 4 common sizes, 60, 70, 80, and 120 mm. The 120 mm is the one I used, larger blades to move more air at slower speeds.

Fred

Quote:
quote:Originally posted by Mels Musty Music

Fred - Have to show my ignorance again (or as usual as my wife would say) butwhen you refer to a computer fan are you talking about a cooling fan in a PC power supply? If not what is a source for the fan you installed?
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Old 04-27-2005, 10:06 AM   #14
Mels Musty Music
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Fred & Steve

Thanks to you both for the information. Will be installing a computer fan before our next trip.
Thanks again.

Hank
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Old 04-27-2005, 02:29 PM   #15
mazeeff
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Quote:
quote:Originally posted by dgullick

Here is another variation on the bathroom fans if one likes color at night - 80mm - 2500rpm, 32.5cfm, 1.6 watts, .13 amps, 12 volts. The ceiling switch adds the 3rd original fan if one wants to move lots of air - all controlled by wall switch too.
http://geocities.com/dgullick1/1coolpc.jpg
Can you get these in a UV light, so that the pee shows up, when you miss the toilet!
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Old 04-27-2005, 05:44 PM   #16
sreigle
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Mike, don't need one of those lights. There's a resident in this Montana who is very capable of noticing that!
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Old 05-20-2005, 07:52 AM   #17
mobilrvn
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Changed the bathroom fan and it is now so quiet that we leave it on most of the time---the air is fresher! We have a 5cf upright freezer installed in the D/W closet which wasn't vented very well. Added one of the fans which now runs full time except when we're are going down the road or not plugged into AC. Has made a world of difference with the heat build up in the bedroom area and the freezer runs less often.
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Old 07-29-2005, 05:05 AM   #18
Bob & Lee
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FredG, after searching and reading the posts Iam going to change the fans. Now my question is there a reason you chose this fan ? on the NewEgg site I find a fan 120mm with 114.7 CFM and 45 dbA noise for $17.99..is there a reason you chose a lower CFM..thanks you have been a great help it trying to get that noisy thing out the kitchen.
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Old 07-29-2005, 12:43 PM   #19
FredG
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I went with the lower CFM fan because it produces less noise. I decided the tradeoff in air flow vs noise was worth it. The other reason is aesthetics. It's a clear fan with no lights on it. For the location in the ceiling vent, I was looking for either clear or white fans.
The one fan moves enough air, in my opinion, but there is always the option to add a second fan to the bathroom. For the kitchen where a 2nd fan is not an option, you may want to look for a fan that moves a bit more air. When I looked at the specs of the original fan, I believe it moved 86 CFM. So, the replacement I put in is just a bit less at 79.

Oh, one other thing I just thought of, don't get a variable speed fan...many use a thermistor in the fan itself to determine the fan speed, which is ok in a confined computer case, but not for this application.

Fred
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