APO FPV 15mm Solar Anti Frost Protection Valve

Overview

The APO Anti Frost Protection Valve FPV is designed to protect solar collector panels from frost damages. The APO FPV is compatible and a direct swap for other brands such as AVG and Caleffi frost protection valves.

The FPV anti frost valve employs a wax filled piston inside coupled with a spring to open or shut the valve. The wax will contract or expand according to the ambient air temperature in order to move the piston. To extend the APO FPV anti frost valve service life span, an optional 100mm "dead leg" extension fitting as shown in the last few photos is offered at an extra cost and is highly recommended.

When a frost condition is present, the wax contracts sufficiently enough to compress the string and open the FPV valve seat causing a water leakage from the solar hot water panels. The hot water from the storage tank will move into the solar panels to fill the void from the leakage. This warm water will in turn heat up the solar panels and protect the panels from freezing. At the same time the FPV anti frost valve heats up itself with the solar panels from the hot water, until the FPV piston shuts off the leakage by closing the valve sealing seat, as the wax in the piston expands. The cycle will then repeat when the solar panels slowly lose heat and the FPV anti frost valve opens again. 

Unfortunately, this piston/wax mechanism can often be damaged by the extreme heat generated by the solar panels during the summer. When the first frost comes in winter, the valve will usually fail to automatically shut off and cause non-stop water leakage from the roof. The "dead leg" extension fitting keeps the FPV anti frost valve further away from the panel and protect the valve from the heat. The FPV life span is significantly extended. In fact, some other manufacturers such as Caleffi will require such 100mm extension for their anti frost valves' warranty to be honored. 

Only one APO FPV anti frost valve is required for one solar hot water system with 2 or 3 solar panels. The FPV anti frost valve should only be installed at the bottom of the solar panels opposite to the cold water inlet, where the temperature is lowest. It is recommended to only use the supplied red fiber glass washer gasket and use the optional rubber seal included as a spare when used on the solar panels. Being installed at the right angle corner of the solar hot water panels, debris can accumulate inside the valve body and hence FPV frost valve should be flushed out periodically every 2 years as a maintenance schedule.

Technical Details

• Manufacturer: APO
• Model: FPV
• Thread Size: 1/2" BSP (15mm) female swivel loose nut
• Physical Thread Size Measurement: 20.995mm internal diameter (Please refer to the BSP sizing chart in the photo gallery)
• Material: Lead Free DR Brass and Stainless Steel
• Activation Temperature: 3-5 deg 
• Optional Dead Leg Extension Fitting: Watermark Approved DR Brass
• Intended Use: Solar water heaters in frost prone area
• SKU: APO-FPV & APO-FPV-E

Package Contents

• APO FPV anti frost valve with optional 100mm extension 
• Package weight 210g (380g with the extension fitting)