Gurgling noise from pipes leading to boiler in hotpress - what is it??

I was just woken up (yes, at 5.45am) by a symphony of noise coming from my hotpress which lasted about 15 minutes. It sounded like very rhythmic gurgling and swooshing from the three pipes which go from our attic into the boiler in the hot press. Does anybody know why/what/is this going to cost me?

I know SFA about plumbing/stopcocks/rads but can tell you that
(a) we have natural gas
(b) a gas boiler
(c) the thermostat to the boiler in the hotpress was replaced about 2/3 years ago
(d) The pipes didn't freeze in recent weeks

The noise has now stopped completely - our heat & hot water is programmed to come on at at 6am.

All advice/theories welcome!!!

Used to get the same prob when the thermostat was set too high on the heating system...........i.e. in our heating system, there is a thermostat which dictates what temp the water must be before it is circulated to the rads....its an unpressurised vented system

When the thermostat is set high at say 90 degrees, it makes a lot of noise while the water is heating to 90 degrees, then it circulates and the noise goes away

Setting it to a lower temp i.e. 50 or 60 degrees solves the problem for us...

also check you have water in your small tank in the attic which feeds your boiler.

All seems to be fine now. We believe it was an airlock & may have been caused by the local council conserving water during the night.

Sounds like air all right, the only reason the water outage would have caused air, is that your heating system has a leak.

Best way to check, is to tie up ballcock on small tank in attic so it can't refill. Keep an eye on water level, if it drops much over a short period, you have a leak.