Frequently Asked Questions

What does a Thermostat do?

Thermostats for Water Heating (PDF, 0.2MB)

Please download the PDF Factsheet above.

What is a Tempering Valve?

What on earth does it do?

The Tempering Valve (TPV) is a safety device designed to control the delivery temperature to you taps. It does not change the temperature of the water in your storage tank. The TPV restricts the delivery temperature to around 40-55°C by blending cold water with the hot water to this safer temperature. Tempering valves blend hot and cold water to deliver mixed water at a constant temperature. They incorporate a temperature sensitive element which expands and contracts depending on the temperature of the water flowing across it. This action of the element in turn moves a piston which shuttles between the hot and cold ports. In doing so the valve maintains an essentially constant outlet temperature, and thus reduces the risk of scalding accidents.

A TPV is required by law; hence we include this installation whenever we complete a full installation of a new solar hot water system. Solar hot water systems can reach water temperatures of up to 99°C; therefore the need for a safety device is more vital when installing a solar hot water system. The tempering valve works mechanically.

The water is colder than my old hot water system, why?

Your old hot water system most likely did not have a tempering valve installed, therefore you may have been getting around 65-70°C water delivery to your taps. With a tempering valve installed the delivery temperature is now anywhere from 40-55°C.

Can the valve be made hotter?

If you feel that the water is too cold, the TPV may require adjustment. We have found that some TPV’s self adjust down over time and require resetting. If this is the case, please contact our office to arrange a service call to inspect the valve. But please keep in mind that the temperature is still limited to that range of approximately 40-55°C.


How do I operate the Booster?

Please be aware that this is only a general guide, your installation may be different.

2 Ways you can Use It

  1. The booster can be left on all the time. The thermostat in the Solahart will only use that power if required. The switch only allows the power to be made available to the thermostat operation.
  2. Play the guessing game. You can stretch out you savings a little more by playing around with the switch, such as turning it off when you go away, or if you have evening showers you may shut it off at night to stop it boosting overnight to let the sun do its job the next morning. But this can leave you at risk of running out of hot water.

What does the light mean and when should it be on?

booster The light, if on, merely indicates that power is available which is particularly handy if you are on off-peak as these times vary. It does NOT mean that the solar is using that power. The thermostat in the unit will regulate if it actually uses any of that power.

Why do I need to use it more in winter?

During the winter period the water coming into the solar is a lot colder, the days are a lot shorter and people tend to have longer showers, therefore the sun may not keep up with your needs. This is the time of year you tend to use the booster a bit. Please keep in mind that it is still heating up from the sun, the booster just tops it up that bit extra that is required.

Why is the water colder the next morning, isn’t the tank insulated enough?

The Solahart tanks are insulated quite well, however overnight the hot layer and cold layer in your tank will begin to blend so if you use a lot of hot water in the evening and you do not have the booster on overnight you will notice a change in the temperature.

The light never comes on and I run out of hot water.

Check that the fuse has not been tripped and that the circuit breaker in the meter box is in the on position and that the booster switch is in the on position, if they are all fine then there may be a problem with your supply, please call your local energy supplier to check your meter.

I am on Off-Peak, how does this work.

Off peak power is a cheaper tariff rate that most electric hot water heaters are connected to. When off peak switches on varies quite a bit. Off Peak tariff 31 (Night Rate Super Economy) usually is on overnight weekdays and most of the weekend. Off Peak tariff 33 (Controlled Supply Economy) gives you the addition of a couple of hours extra around lunch time. The light on the booster will only go on when off peak is in effect.