Hj az the stationary water the the panel is overheating and opening the pressure valve if the feed and return valves are closed.
Solar hot water panel valve.
In this way any heat available from your solar gets used.
Typically in solar applications the valve port opens on descending temperatures allowing the near freezing water in the solar panel to be discharged and replaced with warmer supply water.
The photovoltaic solar panels or pv solar panels convert the sun s energy into electricity which then can be used to heat water.
Caleffi freeze protection valve for solar hot systems frost protection valve 10 x 15mm 603 the caleffi frost protection valve was used by various solar hot water manufacturers to meet the requirements of solar collector panels installed in a frost.
530c calibrated pressure relief valves are spring operated bronze valves designed for use only as protection from the build up of excessive pressure in systems containing water oil or air.
There is an issue with your system s thermostat.
The thermostat on your solar hot water system is designed to shut off once it has reached 60 c 65 c.
When you restart it however either do it very slowly or at night when the panel is cool.
Solar panels can also directly heat water by heating water filled pipes within the solar panels or by heating a transfer fluid such as antifreeze usually propylene glycol.
Series 530c valves incorporate a calibrated adjustment feature for setting the valve to the relief pressure required.
When the warmer water reaches the valve the port closes and water discharge stops.
There are various styles of vacuum relief valves but all automatically allow air into the system when there is a vacuum created by a void of water pressure.
You can shut it off and drain the water out of it.
In systems that use other types of heat transfer fluids such as glycol an anti freeze scaling can occur on the surface of the heat exchanger that transfers heat from the solar collector to the domestic water.
This relieves the vacuum that would be created by falling water inside the solar panels and plumbing on the roof.
If the thermostat element keeps heating the water and the temperature exceeds 99 c the ptr valve will activate expelling steaming hot water to regulate the temperature.
A valve must be installed in every solar pool heating system to allow air into the system when pool water drains out of the panels.
Scaling may also cause valve and pump failures on the potable water loop.