If the hot water takes awhile the start flowing through the faucet, this really doesn’t have anything to do with the hot water heater. The cold water sitting in the pipes must first empty before the hot water can flow. The flow rate of the tankless water heater influences how hot the water will be, but cannot shorten the wait time for hot water.
The thermostats are less than the cost of a service fee to replace. Besides, they are made to last and only fail when damaged. Parts for some models are available online through our partnership with Encompass.
Because of their relatively simple design, troubleshooting is not too common on tankless water heaters. Nevertheless, we’re here for the repair, and the service fee should cover any troubleshooting, diagnosis, or exploratory labor.