Vaillant EcoTec System Boiler heating water automatically

[Murdoch77]

We have a Vaillant EcoTec 630 System boiler which appears to be heating water automatically.
I've noticed that the water is always hot, even when we haven't switched it on but we were away last week so it wasn't switched on at all yet the water was hot when we got home and according to our smart meter, we were using quite a lot of gas on the days we weren't even here (no other gas appliances in the house).
Does the hot water switch on automatically if the water falls below a certain temperature or is there a fault somewhere? Any advice would be greatly appreciated.

 

[Harry Bloomfield]

We have a Vaillant EcoTec 630 System boiler which appears to be heating water automatically.

It should only heat the water, when it is programmed to heat the water. I would check what you have set up in the program. Even if the hot water is set to be on 24/7, then unless you are using lots of hot water, it shouldn't cost much gas, just to maintain the stored water temperature.

 

[Murdoch77]

I've checked the schedule/program and it is off completely. So if it should only heat water when programmed and the program is off, does that mean there's a fault somewhere?

 

[Harry Bloomfield]

I've checked the schedule/program and it is off completely. So if it should only heat water when programmed and the program is off, does that mean there's a fault somewhere?

The spec., claims that boiler is Smart, I'm not sure what the Smart might be, but might your smart phone be overriding the program?

It would be worth your while posting more information, detail, and photos of your system - the controls, the valves, the cylinder etc..

 

[Murdoch77]

Thank you. I've attached some photos.

 

[CountryFan]

Sounds like to could be a simple motorised valve failure, as in a stuck micro switch

 

[Harry Bloomfield]

I would investigate that 2-port valve, the upper one of the two in your fourth photo, perhaps being stuck on, and creating a constant demand, or the thermostat....

A potential issue, is the cylinder stat., in photo 7, is set rather low in temperature at 45C. Most are set at between 50to 60C, and it is usual to increase to 60C at least once per week, to kill off any Legionella, in the cylinder.

However, the thermostat might be the one creating the constant demand for heat. To eliminate that, try turning it up and down from it's present setting, whereupon you should hear a distinct click from it, which should be accompanied by that same valve opening and closing.

Those valves, you should hear them slowly wind open against a spring, then when power is removed, they should close quite rapidly via the spring - but they can stick in the open position, creating a constant demand for heat, which will cause your boiler to fire, to try to satisfy the demand.