Recently had an energy efficient tank less hot water heater installed. I always thought these were "on demand" hot water systems meaning you turn on the hot water faucet and get hot water right away however we wait between 30 and 40 seconds, perhaps longer to get hot water from our kitchen faucet. I feel the savings in energy is offset by wasting water. I don't think I waited that long when I had a hot water tank. Is there something I should/could do to improve the time I wait for hot water?