Hot and cold water pressure problem

[watercolours]

Dear fellow sailors,
My cold water pump for sinks works great, but the hot water to the sinks and showers is very weak. I noticed that the sound from the pump below the galley is very quiet when a hot water handle is turned, but the pump is loud and strong when the cold water handle is turned.

Any thoughts about what the problem could be with the pumps(s)?

I'm a new owner of a Hunter 41DS, and don't know much about the systems yet.

Thanks!

 

[Jake N Eggs]

There is probably a temperature control mixing valve on the discharge from the water heater. There is a screen on the input to the valve (between the water heater output and the valve) that can get clogged with calcium deposits from the water heater. When the water in the water heater is cold remove the valve clean the screen.