I am typically the first one in my house to take a shower and I like hot showers. I have noticed that if I take a shower first, the hot water is not that hot and doesn’t last very long. But if others take showers before me and the hot water has to recharge then the hot water is HOT and lasts a long time.
I have a 50 gallon hot water tank.
The only two things I have (besides sinks and showers) that use hot water are a dumb dishwasher and a dumb washing machine.
What I was thinking was to set up an automation in HA to somehow trigger something to use hot water for like 10 minutes in order to get the hot water heater to recharge.
Any ideas?
Is it a gas or electric water heater?
If it’s electric you can add a tank temp sensor (to outside of tank) and a high current relay to bypass the lower thermostat and turn on the heater on command. When your sensor indicates the tank is at the desired temp you can turn off the bypass.
You might be able to do something similar on a gas water heater, but I don’t know enough about them to say.
It’s not that your water heater is recharging, it’s that when there is no water moving through your pipes, the hot water in the pipe eventually cools off. When you turn on the shower, all the water already in the pipes has to flow out of the shower head before the hot water in the tank heater reaches the showerhead.
You can waste a lot of water constantly running it for ten minutes, but if you’re willing to make the investment you can introduce a hot water recirculating pump into your home. A plumber adjusts your plumbing so that instead of pipes spidering out to all your taps from your hot water tank the hot water lines form a loop that returns back to the hot water heater, and the pump keeps water moving through the loop, so that any give tap always has immediate hot water (or at least warm water, the loop is never perfectly hot so you usually get a warm shower that gets hotter after a couple of minutes).
The downside is that unless your plumbing is easily accessible, the most likely approach to the loop is to use the cold water lines as the return loop, which means that instead of waiting for hot water from a cold shower, you’ll have a tap that is warm out the cold side until the loop clears and then you get cold water. They will usually leave the kitchen sink out of the loop so that people who fill their glass from the tap don’t have to wait.
Lots of other good ideas here. I’ll just add some thoughts.
Adding some pipe insulation from the hot water heater to your shower might help a bit.
I suppose you could add some instant hot water heater system or even a second small hot water heater close to your shower to eliminate the heat up time.
If you are this interested it might be worth having a plumber come out to consult about what the issue might be and what the possibilities are. A lot might depend on your specific setup and how accessible the pipes are without completely ripping apart your walls.
Honestly sounds like you need a new hot water heater. It should be keeping the temp through same, whether recently used or not. If shower is far away from hot water heater, a recirculation pump may help.
Cold pipes in the morning is not a water heater problem, that’s pretty typical.
A recirculation pump would definitely work and would have the added bonus of immediate warm water at any time, but it’s going to use extra energy 24/7 to do so–especially considering it sounds like OPs system already has a lot of passive heat loss along the pipes.
Might not be worth the extra cost if the primary problem is just the morning shower.
If you have “delay start” functions on your washing machines (dish & clothes), you can either do dishes overnight or clothes overnight as close to 3-4am as possible (assuming you’re waking up around 6 or 7).
There is not a great way to “automate” the heating of water in a traditional water heater and it would be a safety hazard to do so.
The only other good option is an inline electric water heater, but the cost of that will outweigh anything else.
If you’re eager to spend money on this, I’d look into newer appliances that you can set to run at a certain time of day if there is absolutely no functionality available.
This should be higher. No wasted water, low tech, and no cost. If the water heater has trouble retaining heat in the water then it definitely seems like an issue with the water heater itself, but this approach will reliably trigger a larger batch of fully reheated water at just the right time. Plus, if the water heater is electric then you’re even use electricity at non peak hours.