The installation manual says:
Frost protection
The appliance has a built in frost protection device that protects the boiler from freezing. With the gas and electric supplies ON and irrespective of any room thermostat setting, the frost protection device will operate the pump when the temperature of the boiler water falls below 12 °C. A timer is used so that the temperature can be checked periodically. After 10 minutes the pump will be stopped if the temperature is higher than 10 °C or has already reached 35 °C. The burner will activate if the boiler temperature does not reach 10 °C after 30 minutes or at any time if the temperature drops to 5 °C. The burner will switch off when the temperature reaches 35 °C.
So I think what it's saying is:
Reason I ask is that I set my house temp to 9.5C when I'm away. This is actually a Nest's default Eco temp and is ok for me. Will this mean in cold weather the boiler will be periodically firing up frost protection just to get the water to 35C even though the house temp is between 9.5C and 12C? This doesn't seem very efficient. And worse if I set my Eco temp lower to save more energy when I'm away (perhaps for days).
Seems odd that the boiler's "frost" protection system involves such high temps (especially being initially triggered to run the pump at 12C). That's a 'normal' frost-free temp in the UK and if there's little demand for heat or water, wouldn't the boiler temp often drop to 12C?!
Frost protection
The appliance has a built in frost protection device that protects the boiler from freezing. With the gas and electric supplies ON and irrespective of any room thermostat setting, the frost protection device will operate the pump when the temperature of the boiler water falls below 12 °C. A timer is used so that the temperature can be checked periodically. After 10 minutes the pump will be stopped if the temperature is higher than 10 °C or has already reached 35 °C. The burner will activate if the boiler temperature does not reach 10 °C after 30 minutes or at any time if the temperature drops to 5 °C. The burner will switch off when the temperature reaches 35 °C.
So I think what it's saying is:
- Pumps runs if the water temp gets below 12C and periodically checks the water temp is between 10C and 35C
- If it's then not above 10C, it will heat it to 35C (which will also heat the rads to 35C I presume, or will it only heat the core of the boiler?)
Reason I ask is that I set my house temp to 9.5C when I'm away. This is actually a Nest's default Eco temp and is ok for me. Will this mean in cold weather the boiler will be periodically firing up frost protection just to get the water to 35C even though the house temp is between 9.5C and 12C? This doesn't seem very efficient. And worse if I set my Eco temp lower to save more energy when I'm away (perhaps for days).
Seems odd that the boiler's "frost" protection system involves such high temps (especially being initially triggered to run the pump at 12C). That's a 'normal' frost-free temp in the UK and if there's little demand for heat or water, wouldn't the boiler temp often drop to 12C?!
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