The Garnet 709-HP3W SeeLevel II packs more features into a standard-size panel than any other 3-tank model. In addition to accurate tank monitoring for fresh, grey, and black water plus LPG, it includes both a 3-way water pump switch and a single-pole water heater switch. This makes it the ideal choice for RVers who want to consolidate their control panel while upgrading from unreliable factory tank monitors.3 TanksLPGPump SwitchHeater Switch
On / Off / Auto control
Single-pole electric control
Track propane levels
0-100% accurate readouts
The 709-HP3W includes a single-pole water heater switch that controls the electric heating element in your RV water heater. This allows you to turn the electric water heater on or off directly from the SeeLevel panel. Important Notes: • This switch controls the electric heating element only – not gas operation • It's a single-pole switch, meaning it controls one circuit (typically 120V AC) • Your water heater must have an electric element to use this feature • If your water heater is gas-only, this switch won't be functional • Rated for typical RV water heater element loads (check your heater's amp draw) Perfect for: RVers who frequently switch between electric and gas water heating based on shore power availability.
The built-in pump switch provides three positions: • ON: Pump runs continuously • OFF: Pump disabled • AUTO: Pump cycles on demand when faucets open Most RVers leave it in AUTO mode for normal use. The ON position is useful for priming the system or testing. The pump switch is rated for 10 amps max – use a relay if your pump draws more current.
The 709-HP3W is the right choice if you want both pump AND heater switches plus LPG monitoring in one panel. If you don't need the heater switch, the 709-P3W offers the same features without it. Use our SeeLevel II Comparison Guide to compare all models.
Traditional RV tank monitors use probes that extend inside the tank. These probes quickly become coated with waste residue, toilet paper, and struvite buildup – causing the dreaded "always shows full" problem.
The SeeLevel II difference: Sensors mount externally on the tank wall using 3M adhesive. They measure tank levels through the plastic tank wall using capacitive sensing technology:
• Battery Voltage: Know when batteries need charging • Fresh Water Tank: Know exactly how much water remains • Grey Water Tank: Plan showers accordingly • Black Water Tank: Know exactly when to dump – no guessing • LPG/Propane: Monitor propane level via existing sender • Pump Switch: 3-way pump control (On/Off/Auto) • Heater Switch: Single-pole electric water heater control
The 709-HP3W connects to your RV's existing propane tank sender (the sensor built into your LP tank gauge). It does NOT include a propane sensor – it uses the one already installed in your RV.
Garnet offers three sensor sizes to match your tank heights. Sensors can be cut shorter or stacked for taller tanks:
Tip: The 710-ES3 (12") is the most popular choice. Do NOT mix sensor types when stacking.
SeeLevel II sensors work on plastic/polyethylene and fiberglass tanks only. They will NOT work on metal tanks. Tank walls must be 3/8" (10mm) thick or less.
Most RV owners can install the SeeLevel II system themselves:
Complete installation instructions included. For detailed guidance, download the SeeLevel 709 Manual (PDF). Professional installation recommended if you're uncomfortable with electrical work, especially for the water heater switch connection.
The SeeLevel II includes diagnostic capability that allows you to check the operating characteristics of each sensor. If a sensor develops a problem, the display can show you the signal level and help identify the issue.
Want a display in multiple locations? The common bus wiring allows you to add a second display to the same sensor network. Simply purchase a 709-HP3W Monitor Only and wire it to your existing sensors. When using dual displays, one must be set to "secondary mode" to avoid reading conflicts.
Want a display in the wet bay? Add a 709-HP3W Monitor Only to your system. Wire it to the same sensor network – no additional sensors needed!
→ View Complete SeeLevel II Comparison Guide
Manual: SeeLevel 709 Manual (PDF) Support: garnetinstruments.com/support Warranty: 1 Year Limited