"relaced the dhw/ch sensor.."
What about the temperature sensor, will be fitted in/on the HW outlet pipe.
Point 2 just be careful with the fine pipe, they are usually flare fitting, so just stick in the hole after making sure seat in the hole is clean.
You can always get an install manual download from Ravenheat web site, fault finding etc at back, plus how to fit/replace all parts.
SD
January 2012