When Do I Need a Manual Drain for a Solar Pool Heater?

The purpose of a manual drain is to allow a system owner to drain all water out of the system when the system is not plumbed to drain automatically by gravity. It is always ideal to install plumbing for a solar pool heater in a way that water can drain back to the pool without intervention every time the pool filter pump shuts off. Sometimes that is impossible or impractical due to roof geometry, panel placement, or obstructions.

The reasons for a manual drain are:

• Protect against freeze damage (even in Southwest Florida) — this is the primary reason.
• To allow drainage of the system during long periods where the solar pool heater is off (like summer) to avoid stagnation of water in panels.
• To allow for easier servicing if needed.

A manual drain is installed in this system because the solar plumbing feed and return lines go over the ridge and panels cannot drain by gravity.

Manufacturers require that your panels are installed in a way that they drain completely or a manual drain be installed and properly operated when needed. This protects your warranty, and avoids problems associated with trapped water. You should understand the importance and operation of your manual drain, and diligently protect your system by operating it when necessary.

An alternative to a manual drain is to use a freeze protection system supplied by a pool automation system or solar controller. However, this is not a fail-safe method, and it is not accepted by most manufacturers as a valid freeze protection method. If your panels have freeze damage, it will not be covered under warranty if there was water in the panels. We recommend installing a manual drain in all systems that do not drain fully.

A manual drain can be a simple PVC pipe directed to an accessible location where a ball valve or hose bib are placed for easy operation. It’s best to place the valve where it can be accessed with no ladder or a short ladder, and where it will drain to a location that will not damage plants or property. Once the valve is opened, to protect the system the valve should remain opened during the period of risk, and the system should be bypassed and isolated so no pool water will be sent to the panels. This requires proper isolation valves, which we install in every solar pool heating system.

If you are not capable or do not want to operate a manual drain, you should hire a solar energy dealer or competent person to help you, only install panels where they will positively drain (if possible), or use automation freeze protection as a last resort.