This question is a follow-up to How can I speed up my slow hot water?.
I have a tankless water heater, and it takes over 90 seconds to get hot water to my kitchen. (This is not acceptable as I'm not renting out this property.)
I'd like to install a "unit" close to the kitchen faucet. Ideally, this unit would not store water, but would heat the water as it passes through. This way, when the hot water finally reaches the sink from the main water heater, the local unit could stop working and let the main water heater do the work.
But, as I type this, I'm thinking that this may not be the ideal solution. The problem is that, to get hot water, the sink has to be turned on full blast (to trigger the water heating mechanism in the tankless water heater). So maybe I should have a 5gallon water heater near the kitchen sink to handle all hot water that the kitchen sink will need. If I went this route, would the kitchen sink ever be able to use hot water from the main hot water heater? Put another way, would turning the hot water on the kitchen sink on full blast trigger hot water to come from the main water heater?