I just moved into a house that has a Noritz tankless water heater (model: N-069M). It works fairly well for things like taking a shower, where there's a continuous need for hot water. But it's working less well for things like the dishwasher and washing machine, where the need is intermittent.

When I'm finished running a load of dishes, I often find that there is soap that is caked on to the dispenser, and I suspect the reason for this is there wasn't hot water, since it often takes 45 seconds or so to get hot water from the unit.

Has anyone else experienced this problem? If so, how were you able to resolve it?

Someone told me about something a "tankless metlund," but my understanding is that if I get one, I pretty much defeat the whole idea of having an energy-efficient, on-demand water heater.