Updates from admin 
Buying a tankless water heater isn’t too difficult if you watch a few main concerns;
1. Size the unit properly – too small a unit will result in a large pressure drop & some times erratic temperature due to improper mixing. The unit will flow the correct temp. but the pressure drop will affect anti-scald valves and cause some cold water intrusion into the hot side occasionally.
2. Make sure the gas supply is adequate for the larger flow requirements of the tankless heater. Otherwise the heater will become lower in flow capacity to the btu’s available.
3. Make sure the heater is plumbed for your future service, primarly including flush kits & valving to isolate pumps or check valves.
4. Vent heater with proper approved venting, NOT B-VENT
5. Be careful to tie re-circ. if desired compatible w/ tankless( see previous article )
6. Select an installer who stocks parts & performs service ( we’ve encountered dozens of customers who’ve told us ” I’ve loved my tankless heater until it needed service & I couldn’t find anyone who services them ” ). Start with a full service installer, you’ll benefit through-out the installation & thru your heaters life.