|
Post by bobblehat on Nov 21, 2014 8:38:42 GMT -5
I have discovered another great design 'feature' on early model 185s.
With a fully cold heating system, when the heating demand comes on, the heating pump fires up and the radiators get hot from the water in the thermal store. The burner does not light initially as the store temperature does not decrease enough for the main thermostat to kick in.
The cold water from the radiators is returned to the bottom of the store where the cold start thermostat is located. Under certain conditions, the temperature at the bottom of the store gets cold enough to turn off the cold start thermostat and so stop the pump. If the top of the tank is still hot, the burner will still not kick in as the main thermostat is at the top of the store.
The system remains like this for some time as the hot and cold water in the store tend not to mix (hot water is less dense and stays near the top).
Eventually (or when you turn on the hot water tap) the top of the store cools enough to turn on the burner and the water at the bottom of the tank gets hot, the cold start thermostat closes, the pump starts and you have heating again!
All this means is that on a cold morning, you get an initial few minutes of heating and then it all goes quiet!
The designers were obviously aware of this flaw and modified the cold start thermostat after serial number 71100. The new design turns off the pump, but also fires up the burner.
Thanks again IMI Range!
|
|