if its new why mess with it warranty springs to mind. my thoughts are check in-line gas taps usually three may be four serving fire,waterheater,hob/oven and fridge these may turned off so one will feed the waterheater and you get it to light once turned on but wait for air to disperse from pipe. It is set up like that so each appliance that needs servicing/ repair you are able to use the others.
bb, March 2011