We have moved into new property and have very low hot water pressure. The central heating is working and the cold water pressure is good. We have two tanks (a hot water and a cold water storage tank). We have tried connecting a hose to the washing machine outlet pipes and flushing system with water to get rid of airlocks as recommended. This does work initially, however the pressure slowly drops until in about 2 weeks we have no hot water pressure again. We have removed air 3 times now. Can anyone tell us what the problem could be and how to fix it.