My Halstead Ace High combi boiler has been intermittent with the hot water. There's no hot water tank so I have to turn the hot tap on high to get the flow going before the boiler kicks in. Then after a few minutes the boiler shuts off and eventually comes back on, then off again, etc all while the tap is still running. Recently this issue has gone away but I believe this is because the weather is colder so the water going in to the boiler is colder. Still, I'll need to fix it before spring--any thoughts as to the fault?