Boxing Day Heat Pump Troubleshooting

I recently had a heat pump installed. Heat is extracted from outside and then pumped indoors. Pumping the heat tends to use a lot less electrical energy than the typical methods of turning electricity into heat. Plus, during the summer months, the cycle can be reversed, and the unit will act as an air conditioner instead. Sounds great, until you wake-up shivering. 

Spent an hour trouble shooting, then I found two critical valves. Actuating these for a minute or two, fixed the problem. Not something I particularly wanted to do on Boxing Day. But needs must I guess?!