Firstly, the water heater is functional. There is a crawlspace but no access. There is hot water at the sink and tub of the upstairs bathroom. Where there is water flow, the pressure is good.
The problem is on the main floor over the crawlspace. There is no hot water at the kitchen sink or dishwasher. There is no hot water at the sink in the powder room. The cold and hot water shut-off valves are all open below the sinks. Yet there is normal water flow from the cold side at the sinks and toilet tank. My guess is possible frozen pipes in the crawlspace, but it doesn’t seem right if there is cold water flow as they would be frozen too. Do you folks have any ideas? I, of course, am leaving it up to a licensed plumber to figure it out and correct it for my client.
If you let the hot water run for a long time and still nothing my money is on either a Harry Homeowner or bad Plumber FU where those fixtures have two cold runs and no hot run.
So… are you saying that there is water flow but no HOT temp water out of the Hot side, or, that there is no water flow on the HOT side at all, regardless of temperature?
Without knowing more info… my WAG is there is likely a BAD Tempering Valve inline somewhere!
Are there single handle faucets?
If so a rare condition I’ve encountered only once could be plumbing crossover.
While plumbing crossover is a common cause of a “no hot water complaint”, there can be a number of issues that also lead to a domestic hot water system not operating correctly.
Since you mentioned that the valves under the sinks are open, I’m going to assume you have no water flow on the hot side of the faucets, meaning it is likely not a water heater malfunction, you just don’t have any flow at all. Since it involves multiple sinks, I’m going to rule out a sink malfunction. At this point, my guess would be that a valve in the crawl is closed. This valve controls the hot water flow to the main floor. All just guesses based on limited info.
It could be and it is rare. I opened an outside spigot on a 11 month warranty house yesterday and the spigot was about 8 feet away from the tankless water heater. The water heater turned on every time I opened the spigot. I tested another spigot further down the house and the same thing. I perform the same test on the kitchen sink cold side and the water heater did not turn on.
Somewhere in the house there is a crossover. It’s a multimillion dollar house on the intercoastal waterway, and the plumber is going to have a ball locating the crossover.
