I recently installed a new gas water heater myself, and it heats water fine for the most part—about 95% of the time it's hot enough. However, if the heater sits unused for half a day, the water coming out is only warm, even when the tap is set to 100% hot. It takes about 10-15 minutes after the kids start using the bath for the water to get hot again after it cools down. I'm not a pro, but I suspect the thermostat might be set too low, which causes the water to cool before the burners can heat it up again. I did adjust it from the manufacturer's recommended temp to a higher setting, but it's still not cutting it. My wife prefers really hot showers, and she's not happy with the lukewarm water. Any ideas on what could be causing this issue?
2 Answers
If your new heater is similar to the old one, then the piping is likely fine. However, I'm a bit concerned about the burner igniting properly or a potential thermostat malfunction. Pay attention to whether the burner turns on when you're only getting lukewarm water. You should also check the thermostat settings and ensure it matches the temperature at the faucet. And double-check that the inlet and outlet connections are correct, as miswiring could cause these issues too.
It sounds like your pipes might be cooling the water more than you'd like. If the run from your hot water tank is long and made of galvanized pipe, it can act as a heat sink. When you turn on the hot water, it cools down too quickly before the tank can refill it hot enough. One easy solution is to bump up the temp on your tank even more. If your previous heater was set higher and worked better, that could solve your problem. Another option? You could install a recirculation pump that keeps hot water flowing through the pipes, which can be done as a DIY project for under $100.
I have mostly PEX piping, and I can feel that the water is lukewarm in the bathroom, which is right next to the tank. But after giving it some time, we still get hot water eventually.
I'm pretty sure everything is set up right since it was a straightforward swap. I didn’t have to move any pipes, but I’ll check it again. The thermostat was set to the recommended temp and then turned up to 60C/140F, but my wife still had lukewarm water while the burner was on.