Topic: Davis VP2 compared to 8in NWS rain guage

[dasman]

I have had a VP2 for over 10 years now. Every 2 to 3 years I get it refurbed. For 2018 I had the rain measurement track near my NWS 8 inch gauge. I am the COOP observer for Peotone, so I use the NWS gauge as official. I will change the monthly and yearly totals I save on the web site at the end of the year to match My NWS COOP gauge. This year January 1st thru today (Dec 8th) they are as close as I have ever seen them. My NWS 8inch gauge has 39.77 for the year to date and my VP2 has 40.16. That is about a 1% difference. The 2 gauges are located 20ft apart. In the past they have tracked 3% to as much as 10% apart. I guess I will not have to change the reed switch this year!

[CW2274]

This year January 1st thru today (Dec 8th) they are as close as I have ever seen them. My NWS 8inch gauge has 39.77 for the year to date and my VP2 has 40.16. That is about a 1% difference.

Wow. 

[Mattk]

Why would you have to change the reed switch each year?

[jzinckgra]

Mine missed 15" of rain this year. After 15 yrs and no refurbs, I'm just going to buy a new ISS.

[dasman]

I dont change the reed switch every year. Every 3 years i either send VP2 to Davis for a refurb, or if im not having problems i might change out the 24hr fan my self. My last reed switch changeout was 4 years ago.

[twcmaster]

Does Davis calibrate the rain gauge when getting an ISS refurb?

[dasman]

I would imagine at a minimum they test the reed switch to make sure it reads the bucket tips. But i dont know if they "calibrate " it!