What's a restrictor valve?

[pwhalley]

Hi,

This is probably a real dumb question but as I'm not a plumber....

I have been advised to restrict the flow to the calorifier on my boat to allow the heating unit to operate efficiently, using a restrictor valve. This being cheaper than a motorised switch.Would that be a servicemans valve but only opened a little way?

Many Thanks for any help offerred

Paul

 

[kevplumb]

gate valve

 

[pwhalley]

Many Thanks Kev

Paul