Hot Water Heater, But Warm Tap Water

The TPR valve on my hot water heater was triggered and the entire contents drained out. From what I have read, the valve is triggered by either high temperature or a water pressure surge. I have been told that the hot water heater should be kept around 140 degrees. There are four settings on the hot water heater thermostat: A, B, C, and Very Hot. We keep it at Very Hot in order to have hot water in the shower. The temperature from the TRP valve is 160 degrees, but the temperature at the bathtub faucet is 108 degrees, bathroom sink is 107, and kitchen sink is 106. If I turn down the hot water heater to 140 degrees, we will not have hot water in the shower, so obviously there is a problem. What could be causing the heat loss? What should I do about it? Thanks for the help.

First off, turn down the heater. It's dangerously hot. If your T&P valve let loose because of high temp, then you need to change the gas control and the T&P) Your temperature issue is most likely a cross over issue. There are many many many possibillities of what could be causing that. Old Moen shower valves are commonly causing this, and a hundred other things. Has it been this way from the beginning? Do you have a recirc system? You can try to isolate moen valves and other mixing type faucets to see what affect that has. Need more info though to really help.

WHere your hot water pipes are routed (i.e., how close to the outside wall, through unheated spaces, etc.) can make a big difference in the amount of hot water getting to a fixture initially, but usually doesn't make too much difference after running for a while. Some shower valves have a high temp limit adjustment on them which may be incorrectly (or too conservatively) adjusted.

In most parts of the country, it is quite cold right now, and depending on the insulation and routing of your pipes, you might notice a significant change in dispensed water temps if the pipes are hanging out in the cold or uninsulated spaces.

A broken dip tube in the HW tank could cause this problem. The hot and cold water would be mixing as it leaves the tank, while the water at the bottom of the tank becomes superheated.

GoTanklessToday said:

First off, turn down the heater. It's dangerously hot. If your T&P valve let loose because of high temp, then you need to change the gas control and the T&P) Your temperature issue is most likely a cross over issue. There are many many many possibillities of what could be causing that. Old Moen shower valves are commonly causing this, and a hundred other things. Has it been this way from the beginning? Do you have a recirc system? You can try to isolate moen valves and other mixing type faucets to see what affect that has. Need more info though to really help.

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The condo I am living in is almost two years old. The water has never been very hot at any tap. It has been this way from the beginning. It is not just the bathtub faucet and shower, but the bathroom and kitchen sink too. I do no know if I have a recirc. system.

Try isolating what you can first. Go one by one and shut stops to any mixing type valve. (single handle shower, lav, ks faucet, etc) When you turn one off, check and see if that had any effect on the others. Leave it off, and continue. Close the shut offs to the washing machine. Your tub/shower valves may have stops, you have to pull the trim plate to see. Once you have done all you can do, go back and open the hot stops and check again. Once you have done all you can, then get your coveralls on and get in that crawl space.

Recirc? If the heater is a distance from the faucets, and you get hot water a your taps almost instantly you probably have recirc. If you do have recirc, you most likely have a bad check valve. Search and destroy! It could also just be a simple cross connection that a plumber made by mistake. Those can be a bummer to find.

Do you a mixing valve and outlet out in the garage for washing the dog/car with hot water? If so, make sure the valve is turned off. This one gets a lot of people. I doubt this is it though, since you are reporting the problem since you moved in.

Do some homework and report back.