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#196495 10/09/10 12:42 AM
Joined: Dec 2003
Posts: 524
Hi gang,.. i installed a radon fan this week and the homeowner asked me a good question,..."How will I know if the radon fan motor quits on me?".. he went on to ask if there is a sensor or device to tell him of a motor malfunction as the location of the fan motor will be concealed after dry wall is installed.. short of installing a typical pilot switch which would only tell him that power was or was not GOING to the fan,.. he wanted something to alert him,..whether it was a light or an alarm buzzer,..something of the sort...any ideas guys? a friend of mine said to wire a pilot light in series with the fan lead and when the light went out would signal a malfunction with the motor,..but I wasn't too keen on that idea for obvious reasons.. HELP!!!!
thanx in advance..

.."if it ain't fixed,don't break a Licensed Electrician"
Attic Rat #196496 10/09/10 01:42 AM
Joined: Jul 2002
Posts: 8,443
Likes: 3
Attic Rat,
Welcome back, mate.
You could probably do that with something like a current-held relay to switch an alarm.

I remember reading Popular Mechanics magazine back in the mid-80's and pretty much every single issue had an ad for a radon alarm.
Now at the time, we didn't have the Google (or the Net either) where you could go and see what this was, it actually sounded pretty scary at the time.
Is this a US-wide thing or is it confined to certain areas?

Trumpy #196497 10/09/10 03:15 AM
Joined: Jul 2004
Posts: 9,872
Likes: 27
Trumpy, Radon is bad in some areas, virtually non-existent in other areas. In true American fashion we still have plenty of hucksters trying to scare us everywhere.

A.R., I am not sure if merely monitoring current will really help you much. If these are the small fractional HP fans that I am thinking of they are as likely to fail with a bad bearing as a winding going bad. Some can live with locked rotor. I guess after a while it will blow the thermal fuse but it can run with a seriously degraded output for a long time. If you can live with that, monitoring current should work for you. The other choices are to look at differential air pressure, probably the best solution or to look at shaft RPM like PC fans

Greg Fretwell
gfretwell #196499 10/09/10 04:28 AM
Joined: Dec 2003
Posts: 524
Thanx guys,.. I was thinking about perhaps an air flow switch drilled/tapped into the PVC pipe that would go to a relay, so if the fan decides to quit, the air flow leaf/reed switch opens and trips the relay, thus sending a signal to a strobe or alarm device.

Hey Trumpy, how's it going man? I hope all is well... I missed this place, glad to be back!!

Greg, thanx for the advice man, I've never encountered a dilemma such as this.. I love a good challenge...

.."if it ain't fixed,don't break a Licensed Electrician"
Attic Rat #196501 10/09/10 11:01 AM
Joined: Aug 2007
Posts: 853
I think the 'proof' switch is the best idea.Given the location of the fan.These can be installed before or after the fan.
I'm concerned with the 'no access' after drywall part.

leland #196502 10/09/10 12:04 PM
Joined: Dec 2003
Posts: 524
..^as I am,..but it seems that the fan was an afterthought installed at the last minute by the plumber and the only place to put it was inside the closet wall,..I suppose there will be an access hatch to be able to service the unit "proof switch" are you referring to the air flow switch I mentioned above?

.."if it ain't fixed,don't break a Licensed Electrician"
Attic Rat #196505 10/09/10 02:06 PM
Joined: Jul 2004
Posts: 9,872
Likes: 27
There are differential pressure switches you could install with the high and low side on opposite sides of the fan but at the low deltas I see on the radon fan specs they are expensive.

Greg Fretwell
gfretwell #196506 10/09/10 02:41 PM
Joined: Mar 2005
Posts: 1,803
As someone who lives in a granite 'high Radon' zone, it might be moot to point out that an 'added on as an afterthought' fan will very likely not work anyway. Radon is 8 times denser than air, tends to collect in basements and is often expelled from a sump or collected from under the slab before it can get in the dwelling. makes interesting reading.

The client may be better off [peace of mind-wise] by investing in a test kit rather than motor monitoring. ... is just one I found.

Last edited by Alan Belson; 10/09/10 02:42 PM.

Wood work but can't!
Alan Belson #196509 10/09/10 05:26 PM
Joined: Apr 2002
Posts: 7,372
Likes: 7

There are two commercial items that are made to monitor radon systems. One is a 'negative pressure' guage that is installed in-line in the 4" PVC pipe, somewhere where a HO can 'look' at it to see if the fan is operating. This install is prevelant at an apt complex for the 'grade' units; guage is installed outside, for mgmnt and tenant to see.

The other is an 'alarm' that sounds if the fan is not functioning. These devices are prevelent in town house complexes, and the sensor device is in-line. This is the method of choice in a newer townhouse complex. The condo units have the radon units tied into the central station FA system for monitoring.

You should have some 'exposed' radon 4"PVC that you can mount the sensor into; the 'alarm' type gets power from a wall wart. You should use a device that is UL listed/labeled, I suggest contacting the radon fan mfg.


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