Solar Hot Water System: Reasons Why It Dumps A Lot of Water

Have you got a solar hot water system?

Does your solar hot water system dump a lot of water on a really hot day? Now, that might be normal, or it might not be. In the video below, we’ll explain when it’s normal and when it’s not.

The Two Valves

On your solar hot water systems there are two valves. There’s a valve at the bottom, which is the cold valve or the pressure relief valve. It usually dumps out water at a lower pressure than the second valve, which is the temperature pressure relief valve up on the hot water system tank.

Now the difference between the two valves is: the one on the tank has a long rod with two dissimilar metals that are welded at the end. When it reaches up to about 95 degrees, it forces the washer to open. So, when the water in the tank gets up to 95 degrees or hotter, before it turns into steam and starts to explode, the rod will heat up and force that washer open, so it runs full flow.

When It Is Normal

With the temperature’s building up, the rod pushes it open to drop that temperature. That’s why it’ll just be dumping water until that temperature goes down, back to about 80. Then it will start to shut off and go back to the pressure side of things. So it’s quite normal, especially on a 40 degree day because the water could get up to a 100 degrees really easily. And then the solar hot water system will start dumping a lot of water to reduce the temperature.

When It Is Not

As soon as that temperature drops with all the cold water getting introduced, it should turn off. So if it’s just dumping for an hour or so, all it is is dropping the temperature so the system doesn’t explode. But if it doesn’t and it just flows all night, then there’s a problem. You will need to call your local plumber, or call us. We’ll be happy to help.