Float switch vs. pressure switch

[serpentman]

Sorry, here is yet another top-off question.

I am puting together my direct connect (to RO/DI) top-off system and am wondering whether to use a float switches or pressure switches (see below). Which is more reliable?

The manufacturer below claims that because the pressure switch contains no moving parts, they are more reliable.

Furthermore, they claim that because the pressure switch lets the level dip 1" before refill, it allows the RO/DI system to flow longer and build sufficient pressure across the RO membrane.


Single Liquid Level Controller (http://www.premiumaquatics.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=SP-LLC-S&Category_Code=Dosers)

[thereefgeek]

I'm running a direct feed from my water purification system, but it's DI only and not RO (water quality is good where I'm located). I DIY'ed one just like the Spectrapure unit, and it works great! I've had problems with the "float switch" types in the past since they don't have the Amp capacity of the pressure switches (something like 0.5 amps for the floats vs. 5 amps for the pressure switch I'm using). One of the floats fried in the closed position and flooded my sump a few years back, and since I changed to a pressure switch, I haven't had a problem.

[svb57]

I set up the system that you are looking at over a year ago and it has worked great. One thing I like is having the manual float as a back up. If the pressure switch malfunctions that water level will only reach a certain point until the float closes off the water to the sump.

Jim Mc

[thereefgeek]

This month's Reefkeeping has a little info on pressure switches VS. float switches (about half way down the page).

http://reefkeeping.com/issues/2006-05/gh/index.php

[CW from the OC]

I've used the Kent Marine float switch for....8 years with no problems. The RO/DI is plumbed directly to it on my sump.

I know many people say it is riskier than a more sophisticated/expensive/complicated/redundant switch, but I've never had a problem.