New and old hot water tank same issue - quickly cooling water

Question

We had a Rheem 50 gal 12 yr gas hot water tank for 6 years with no issues. We started having an issue around Dec where the water was cooling during a shower. The same coolness was in other faucets and showers. We replaced it with the same new tank a month later and found the same issue. There is no leaking, no change to shower pressure, no new building, same amount of people. No change to anything to do with our gas. The only thing that’s out of the ordinary, was that we had our gas furnace serviced shortly before the issue started.

Why do we not have enough hot water?

Would love to hear from someone.

Thanks for your time

Answer 1

If you have an older home with cast iron pipes your gas line could have blockage in it or breakdown of the inside of your gas pipe line could be causing particle build up in your devices.

IF your water heater is not getting a good flow of gas and therefore is not producing a good flame, it will be limited on how hot it can get the water.

This might be especially true if the reason you had your furnace serviced is because it wasn't working efficiently and the service tech had to clean out particles in the furnace tubes.

You can have a company come out and inspect your gas lines. They can test the pressure and see if you have a leak somewhere, maybe it is outside and so you are not smelling the mercaptan (smells like rotten eggs) added to the gas to let you detect, through your sense of smell, that you have a leak.

You should check with your gas company to see if they did some repairs to their lines lately that could have knocked debris loose or be creating a low flow.

A higher than normal gas bill can indicate a leak.

If you have a gas stove and you cannot get the flame up as high as you use to, that could be an indication that a blockage could be located on your main line before the stove or low flow due to leakage.

Good luck! Hope this helps at least narrow down the mystery!

Answer 2

First idea: the service technician lowered the thermostat setting (just turn it to 60°C or hotter, otherweise hot water will just not less).

Another idea is that the hot "delivery" pipe, if your tank is wall-mounted "pipes from below" Or the cold "injection" pipe if your is floor type "pipes from above". (note: the longest pipe inside the tank)

Is corroded mid-heigt it causes cold water to be injected mid-height instead of at bottom (or, vice versa, hot water being sucked at the bottom) disrupting the stratification.

Both resulting in percived reduction of boiler capacity (but not causing leakage being those pipe inside the boiler. But this second scenario shouldn't happen with a new boiler.