Topic: FARS Considerations

[Sierra Guy]

Hi Everyone,

I've been considering the purchase of a Vantage Pro2 Wireless with Fan but am a little concerned about having a FARS.  Is there any indication of a fan motor failure other than by just listening?  I read somewhere on this forum that a FARS system with a non-running fan will give erroneous temperature readings and this doesn't sound real good.  I would just as soon not have to worry about continually monitoring the FARS if it can be avoided but this may not be possible. 

The people who have FARS seem to really like it but does it bother anyone to know that the motor has to be replaced every 1 or 2 years?  I'm a little concerned that I might be continuously thinking about the wear factor and unhappy about having to replace the motor that often.  Maybe it's no big deal but I'm really in a knowledge vacuum right now.

I know...all of these concerns are probably not important but I'm having a challenging time right now with my decisions which have ranged from the Vantage Vue to the VP2 with sun and uv sensors.

Thanks for being kind to a newbie and helping me choose the right Davis weather station!


Jim

[d_l]

I think a FARS motor can be considered good for at least two years.  Mine has run for 38 months without problem, but the current batteries have been installed for only 24.  I have a new one and am planning to replace it when the weather is right.

Listening to the motor or placing a tissue paper under the air intake on a calm day are the only tests that I know of to test for motor operation.

[SlowModem]

I read somewhere on this forum that a FARS system with a non-running fan will give erroneous temperature readings and this doesn't sound real good.

If that's the case, there's thousands of weather stations out there that are wrong.  I don't see how a non-operating fan would be any different than a non-aspirated station.  

[DanS]

Including many commercial Weather Service models.

[johnd]

I don't see how a non-operating fan would be any different than a non-aspirated station.  

Because the construction of the shield is different in the (Davis 24hr) FARS model. With passive shields, the shield elements are specifically designed to allow good natural airflow (ie wind) through the shield and past the temperature sensing element. So if you have a well-exposed site in a geographical location where it rarely falls dead calm (which is true of many locations, but not everywhere I know) then you effectively have a FARS shield anyway.

But with 24hr FARS shield, the primary design provision is for fan airflow and not natural airflow because of the more enclosed shield.

OTOH the Davis DFARS shield is a good compromise I'd suggest, because it retains much of the open design of the standard passive shield, which still allows reasonable natural airflow should the fan stop.

[Gulfcoast]

I went with the daytime FARS and am well pleased...  the motor should last longer and it's well ventilated also.

[SlowModem]

Because the construction of the shield is different in the (Davis 24hr) FARS model. With passive shields, the shield elements are specifically designed to allow good natural airflow (ie wind) through the shield and past the temperature sensing element. So if you have a well-exposed site in a geographical location where it rarely falls dead calm (which is true of many locations, but not everywhere I know) then you effectively have a FARS shield anyway.

But with 24hr FARS shield, the primary design provision is for fan airflow and not natural airflow because of the more enclosed shield.

OK, I'll buy that. 

[Sierra Guy]

Thanks, everyone for your comments!  They all help and yours, Dave, gives me a much better feel for longevity of the motor and how to test it.  I'm about ready to start digging a hole to plant a pole but just haven't quite decided what to put on it yet!


Jim

[PSJohn]

I'm in the 110°+ heat of the US Southwest! I had to get a FARS and i do replace the fan every 18 months. It failures like clock work, every 18 months give or take a month! Never had one last more than 20 months!

I can normally hear it running and verify with a tissue as mentioned.

[wmcatty]

Sierra Guy:  Go with the VP2...you will be glad you did after installing it and comparing it to the Vue...I sure did.  I have had my VP2 with solor sensor up and running for about 6 weeks now and could not be happier.  I spoke with another station owner a few miles away and he is sorry he installed the Vue set up and said he regretted not spending the extra bucks on the VP2.  I installed mine last month and am glad I invested the extra money...it works great.  As far as a FARS goes, I live in central Texas, where we just got out of a 93 day run of 100+ degree daily temps and my temp guage (non-FARS) was spot-on...with very little wind for the most part. Just food for thought.

[Sierra Guy]

Sierra Guy:  Go with the VP2...you will be glad you did after installing it and comparing it to the Vue...I sure did.  I have had my VP2 with solor sensor up and running for about 6 weeks now and could not be happier.  I spoke with another station owner a few miles away and he is sorry he installed the Vue set up and said he regretted not spending the extra bucks on the VP2.  I installed mine last month and am glad I invested the extra money...it works great.  As far as a FARS goes, I live in central Texas, where we just got out of a 93 day run of 100+ degree daily temps and my temp guage (non-FARS) was spot-on...with very little wind for the most part. Just food for thought.

Thanks very much for your thoughts on the VP2.  I've about decided to go all the way with it, the fan, and the sun & uv sensors.  Your other posts have also helped me think through how to get started and install and I really appreciate it.

[kered]

From the instructions the 24hour FARS can be made daytime only by leaving out the batteries, that way it only works with daylight, should make the faan last longer too.

[d_l]

From the instructions the 24hour FARS can be made daytime only by leaving out the batteries, that way it only works with daylight, should make the faan last longer too.

If you leave out the batteries or simply do not pull out the battery starter plastic strips, the fan will spin at a faster rate during the daytime hours because the solar panel's output is not split between the batteries and fan. I'm not sure that this will extend fan life much due to the increased RPMs.

[LFWX]

I don't see how a non-operating fan would be any different than a non-aspirated station.  

Because the construction of the shield is different in the (Davis 24hr) FARS model. With passive shields, the shield elements are specifically designed to allow good natural airflow (ie wind) through the shield and past the temperature sensing element. So if you have a well-exposed site in a geographical location where it rarely falls dead calm (which is true of many locations, but not everywhere I know) then you effectively have a FARS shield anyway.

But with 24hr FARS shield, the primary design provision is for fan airflow and not natural airflow because of the more enclosed shield.

OTOH the Davis DFARS shield is a good compromise I'd suggest, because it retains much of the open design of the standard passive shield, which still allows reasonable natural airflow should the fan stop.

The Daytime FARS is almost identical to the passive shield, just a few extra segments to allow room for the fan. The fan is very open, so air should flow through easily if it stops functioning. BTW - I have a Daytime FARS running as a 24 hour FARS.

[WxLover16]

I don't see how a non-operating fan would be any different than a non-aspirated station.   

Because the construction of the shield is different in the (Davis 24hr) FARS model. With passive shields, the shield elements are specifically designed to allow good natural airflow (ie wind) through the shield and past the temperature sensing element. So if you have a well-exposed site in a geographical location where it rarely falls dead calm (which is true of many locations, but not everywhere I know) then you effectively have a FARS shield anyway.

But with 24hr FARS shield, the primary design provision is for fan airflow and not natural airflow because of the more enclosed shield.

OTOH the Davis DFARS shield is a good compromise I'd suggest, because it retains much of the open design of the standard passive shield, which still allows reasonable natural airflow should the fan stop.

I wish I had seen this post before I posted my "VP2 FARS airflow" post. This explains it perfectly!

[WXman]

I added the daytime FARS to mine about a year after purchase.  The only time I was getting bad readings was in the middle of the summer days, which makes sense.  And the daytime FARS doesn't require battery, etc.  And after a few years of use I still have never purchased a new fan.  Still working good.  It's been through some rough weather too.

[yacenty]

Is there any option to make battery in FARS bigger?
I'm from Poland and currently we have sun for only 10hours and it seems FARS stops in the night. What would be in the December when we would have about 6-7hours of sun daily?
My Vantage is 6153 so it's called 24hr FARS

[CW2274]

Is there any option to make battery in FARS bigger?
I'm from Poland and currently we have sun for only 10hours and it seems FARS stops in the night. What would be in the December when we would have about 6-7hours of sun daily?
My Vantage is 6153 so it's called 24hr FARS

You could buy a higher mAh but if it's not fully charging, might not matter. Or you're able, you can do like me and convert to an a/c fan and forget about all the other problems with batteries and stock fan motors.

[ValentineWeather]

I don't see how a non-operating fan would be any different than a non-aspirated station.   

Because the construction of the shield is different in the (Davis 24hr) FARS model. With passive shields, the shield elements are specifically designed to allow good natural airflow (ie wind) through the shield and past the temperature sensing element. So if you have a well-exposed site in a geographical location where it rarely falls dead calm (which is true of many locations, but not everywhere I know) then you effectively have a FARS shield anyway.

But with 24hr FARS shield, the primary design provision is for fan airflow and not natural airflow because of the more enclosed shield.

OTOH the Davis DFARS shield is a good compromise I'd suggest, because it retains much of the open design of the standard passive shield, which still allows reasonable natural airflow should the fan stop.

I wish I had seen this post before I posted my "VP2 FARS airflow" post. This explains it perfectly!

Yes if the fan is off you will see higher than normal temperatures daytime with the fan aspirated shield unless there's stiff wind.

Now the Dfars shield is the naturally aspirated shield with fan add on so no issue here if fan goes off.

[WheatonRon]

I added the daytime FARS to mine about a year after purchase.  The only time I was getting bad readings was in the middle of the summer days, which makes sense.  And the daytime FARS doesn't require battery, etc.  And after a few years of use I still have never purchased a new fan.  Still working good.  It's been through some rough weather too.

I have an eleven year old daytime fan in a VP2 ISS and it still works like a champ!

[Bunty]

I added the daytime FARS to mine about a year after purchase.  The only time I was getting bad readings was in the middle of the summer days, which makes sense.  And the daytime FARS doesn't require battery, etc.  And after a few years of use I still have never purchased a new fan.  Still working good.  It's been through some rough weather too.

If you haven't already, it's probably time to clean the fan and shaft of dirt.  I let mine go so long without cleaning it that a layer of dirt built up and blocked the fan from spinning.  It's a good time to clean everything else as well.