Just had a tankless water heater installed today in the garage. After closing the garage up and doing a load of wash, I went into the garage and noticed a strong smell--like a burnt plastic odor. The smell seemed to dissipate after I unplugged the unit. Any thought regarding the source of the chemical-like odor?

We install tankless water heaters since 2002 - but I have never heard of such a problem. There is really no "plastic" to burn - unless there is some electrical problem associated with the heater. Are you sure it is coming from the heater ? Not from the dryer or other appliance ?