The guides on this site are general information, not professional advice for your specific heater. Follow the manufacturer's instructions on your unit. Rebates, rules and phone numbers can change, so confirm them with the source.
Elk River Water Heater Pros is a referral service. Work is performed by independent local professionals, who are responsible for their own work, pricing and permits.
If you smell gas, leave the building and call your gas utility or 911.