Cannot maintain pressure in the boiler. Heats the water up very well but turning on the hot tap it comes out cold or quickly becomes cold. It comes out much more fiercely than from the cold water tap! The pressure quickly drops. Running the water slowly can sometimes give enough water for a shower. I am always having to top up the system until the relief valve is about to blow off.
Could the water and pressure be leaking off through a fault in the heat exchanger?
