The importance of the vent
The importance of the vent In domestic plumbing systems the minimum diameter of the vent pipe is 19mm, as smaller pipes would be more prone to obstruction. The vent is a very important part of the system, its main functions being to maintain atmospheric conditions in the pipe work and permit the escape of air which has entered the system, and more rarely in the event of the water becoming overheated, allows it to discharge over the feed cistern. Another important factor to observe in relation to vent pipes is to make sure they are terminated well above the flood level, NOT THE OVERFLOW LEVEL, of the storage system. If this is not done, should the vent become submerged, cold water could be siphoned out of the cistern when a hot draw off is opened. It is also very important to ensure that the vent pipe is well insulated and securely fixed. If a draw off connection is taken from too high on the vent pipe this could result in a mixture of air and water coming from the taps. A cold feet of insufficient diameter can also be the cause of this problem.
