Oil fired central heating.

[Sandy-Wroe]

Is there a separate tank which supplies the water in the radiators? If the pipe which supplies the taps is frozen, is it safe to use the heating if you don't use the hot water taps?

[S_C]

your central heating will be fed from your cold water supply.
If the cold water supply is cut off then you find you central heating run dry which will not be good for the central heating . most dodern units hold the water under presure however when the presure increases thgere is a release valve and thats when fresh water is needed to top up the unit.

most modern units dont hold a tank for supply and a lot of older models would draw from the original cold water tank " if there is one "

Simply put if your water supply is off for what ever reason its not a good idea to use the central heating.

[Sandy-Wroe]

I must have been lucky. I did run the central heating but didn't use either the hot or cold taps. I guess if the water in the radiators needed topping up there was enough in the cold water tank.

[S_C]

lucky , however i would not recomend doing to often or for to long. " for obvious reasons.
the tap that is frozen . " something i should have checked b4 " is it the main inlet water supply tap or just a utility tap " like the sink ?

if its just a utility tap i would turn the tap on so as it defrosts the presure is realeased " any may prevent any further damage " if its not already damaged.

when your water is back on the sysytem will need bleeding to release any air that maybe in the pipes / radiators .

[AlBags]

That's only half of the answer .. and not a good one anyway.
1. Central Heating (Gravity system) Fed and topped up from a small header tank in loft or adjacent to main storage tank. Freezing of it's supply pipe will do nothing for probably months and months.
2. Central Heating (Sealed pressurised System) Like a Combi radiator system, where primary heating system is pressurised. Does not use Header tank, but does use a pressure vessel (accumulator) Freezing supply pipes have no effect whatsoever. Pressure will only deplete with leakages and/or bleeding of radiators.