Solar Pool Heater Valves

Solar pool heaters can have many different types of valves and it can get confusing, here is a run down of the different types and their functions.


manual pool heating system plumbing diagram

Figure 1. Example manual pool heating system plumbing diagram


independent pool heating system plumbing diagram

Figure 2. Example independent pool heating system plumbing diagram

Pump Non-return (17)

For an independent type system (or booster type, see different system set ups page) - there should either be a separate non-return valve (17) (with 6mm hole drilled in the flap) after the pump or the pump itself has an integrated non-return flap installed on the outlet. The function of this non-return is important. It prevents water from gushing down as the pump stops and potentially undoing the rotor by spinning it backwards. This valve should be non-perfectly sealing and should allow drain back to the pool. All solar pool heating systems are called drain back type systems (although not all water will drain from them).

Vacuum Release Valve (7)

Solar pool heater must have a vacuum release valve (7) installed on or just off the roof. As the pump stops and the system wants to drain back, the function of this valve is to open on negative pressure and allow air to enter the collectors so that the weight of the water pulling internally on system components does not internally crush collectors and PVC piping up on the roof. A system will not last long if this critical valve was not installed.

3-Way Ball Valve (9)

For manual systems there is a 3-way ball valve (9) installed on the main filter line, the purpose of this valve is to divert water up to the solar collectors. This valve can be manual or it can be motorized and controlled by a specialized controller. It is good practice to have a stop installed on the valve, to make sure it cannot open past a certain point so as not to over-pressurize collectors.

Ball Break Valve (16)

Some systems, especially two story installations have what's termed a break valve (16) on the return line. This is a standard PVC ball shut off valve. The function of this valve is to slow the return flow in the return line as the water flows so that the vacuum release on the roof can positive pressurize on start up. If the vacuum release is at negative pressure as the system is running it will draw in air and you will see constant bubbling in your pool solar return outlet. Note: some bubbling coming out of the outlet return during start up is normal.

Pressure Limiting Valve

Some systems have a PVC ball shut off valve installed after the pump outlet (not shown on plumbing diagrams), this is to pair back excessive flow to the collectors if the pump was oversized. We now recommend these be replaced with a ball by-pass valve (18) as this is gentler on the pump. This is installed after the pump outlet short circuiting the solar supply and return lines slightly. Flow is increased in this valve until the flow and pressure to the collectors up on the roof is reduced sufficiently.

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Product Listings

  • Vacuum Release Valve for Solar Pool Heating Systems
  • 3-Way 40mm PVC Ball Valve

    3-Way 40mm PVC Ball Valve

    $44.00
  • Non-return 40mm PVC Ball Valve

    Non-return 40mm PVC Ball Valve

    $44.00
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