i have a problem with getting hot water. When i switch on the boiler, (ideal classic RS40), to heating and hot water, the heating is fine but the hot water is only warm. When i switch to hot water only then the same thing happens. I noticed that the motorised valve on my pump keeps turning back to heating everytime i turn on either heating or water and only turns back to hot water only when the boiler is not being used. The actuator is a Danfoss Randall HSA3 3 port valve. I have taken this off and can manually turn the valve to switch it to hot water only and this works. Does this mean that the actuator needs replacing? I would really appreciate any advice. Thanks.