oh yes it dose but you cant see it if you have read the artical in silicon chip you will see how you set up the differential via a pot inside the box .
but any how you are correct if you were thinking how inconvenient i do agree there sould be a dail on the front easy to do though .
better still it would have been even more nice if you could set your temps via a digital pannel .
i guess it comes down to price . it cheap and easy to build so buy a few and preset them .
thats my thought on the subject