hot water?

i have a ravenheat ls80 silver star, hot water only just gets warm when it eventualy fires up, relaced the dhw/ch sensor(the clip on type, the dhw gets hotter than it did before but i think it should be hotter than it
is, is their something else that needs to be changed.

question 2.
i have a leak from the presure gauge where it screws into thevalve body, tried to give it a tweak but the coiled pipe broke and water started leaking, i released the presure and unscrewed the nut the pipe has broken off, endless calls to plumbers but no joy, searched for the part its coming next day is there a special way to fit this gauge? sorry about the long questions.

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