Water Too Hot / Overheating

How to Fix It

1. Install or check the tempering valve.

   A tempering valve (thermostatic mixing valve, TMV) mixes cold water into the hot water outlet to deliver water at a safe temperature — typically 50°C. This is a mandatory safety installation for solar hot water in most regions. If your Chromagen system does not have one, contact a licensed plumber to install a Chromagen-compatible TMV.

2. Turn off the electric boost in summer.

   Chromagen solar systems have an electric boost element to heat water on cloudy days. In summer, the solar collector usually provides all the heat needed — leaving the boost element on adds unnecessary heat to an already-hot tank. Switch the boost timer to OFF or set it to only operate in the early morning (before solar gain begins).

3. Use hot water more during peak solar hours.

   The most effective way to prevent overheating is to use hot water during the day — run the dishwasher, washing machine, or take showers during midday or early afternoon. This draws down the hot tank temperature and gives the solar collector room to add more heat without reaching the safety limit.

4. Check the thermostat setting on the tank.

   Some Chromagen models have an adjustable thermostat on the tank — typically accessible via a cover on the electric element. Set the thermostat to 60°C maximum — this is sufficient for legionella prevention while reducing the risk of extreme overheating. The solar collector can still heat above this, but the boost element will not add extra heat unnecessarily.

5. Consider a solar diverter or dump load for excess heat.

   On very sunny holidays or long periods away from home, excess solar heat builds up with no way to dissipate it. Some Chromagen installations use a heat dump device that diverts excess collector heat away from the tank when it reaches maximum temperature. Consult a solar plumber about adding heat management if overheating is a recurring problem in your location.