Discuss Frost protection on combi boiler in the Central Heating Systems area at ElectriciansForums.net
How old is the boiler??
A frost stat on the boiler is intended to protect the boiler from frost damage. A A stat internal to the property will independently fire up the boiler if it detects a risk of frost within the house for instance I.e. Opening up valves.
In answer to you question - just fire up the boiler.
Dave, the boiler will heat up until the frost stat upper limit is satisfied. If the heat can't go anywhere all the better.
Seem to recall some manufacturers have an internal frost protection, Worcester Bosch Greenstar for example;
'The boiler has inbuilt frost protection. When the primary temperature drops below 8°C the pump is switched on. When then temperature rises above 9°C the pump switches off after a 3 minute pump overrun. If the primary temperature drops below 5°C, a central heating demand is activated until the primary temperature rises above 12 °C. The demand switches off followed by the pump after a 3 minute overrun.
The boiler has the facility to connect an external frost protection device to protect in “at risk areas” (terminal block ST6, contacts FS and FR). This is used if the boiler is not located in the area needing protection i.e. boiler in kitchen but pipe work in the garage that needs frost protection.
If external frost thermostat is calling, i.e. temperature within frost thermostat below the set point, but the primary temperature of the boiler is above 5°C, the pump will run until the temperature within the frost thermostat rises above the set point. If external frost thermostat is calling and the primary temperature is below 5°C, a central heating demand is activated until primary temperature is above 12 °C. If the frost thermostat is still calling the pump will run until the temperature within the frost thermostat location rises above the set point'.
The internal pump operates an internal bypass valve, when frost protection is required (8-5'), or CH demand (using external valves etc) when below 5', or so I believe.
So hypothetically, if the boiler was in a garage, with short lagged pump runs, just the internal frost protection could be relied on.
Edit: If you are looking to do such an install, can I suggest you consult a competent plumber, gas safe registered to install your new boiler
Indeed they do, but it's not every model of Worcester boiler which has this so you have to read the instructions every time.
I can help the OP there, according to WB technical, only the CDI Regular hasn't internal frost protection.
But perhaps get a competent gas certified installer to read the instructions instead.
Well they could do with mentioning it in their installation instructions then, Somme of them mention it on the first couple of pages and others don't.
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