No Hot Water - Not Sure If Water Heater or Pipes

[Tony_Hua]

I just recently purchased a new water heater to replace a 14 year old unit after hearing complaints about the hot water becoming warm/tepid, except we haven't been able to get any hot water from the new water heater.

After hooking everything together, turning on the boiler, and leaving it for an hour or two, we got only chilled (as opposed to cold) water from the hot taps. Water taken directly from the tank through the relief valve was also lukewarm at best. If I switch off the incoming cold water flow into the tank, the water inside of the tank will heat up appropriately in about an hour, which I verified with a sample from the relief valve. Turning the cold water intake back on, the the hot water will flow to faucets for about 10 minutes before returning to the chilled temperature before.

It seems no matter the temperature setting I select on the water heater, all I'm able to get is chilled water from faucets and barely lukewarm water from the relief valve. We had the water heater running all night, and it didn't seem to make any difference.

When I was installing the water heater, I noticed that there was a very weak cold water flow coming the hot water pipe (the one that's supposed to receive hot water from the water heater). It seems there is a crossover somewhere in the system, although I haven't been able to identify it. Nonetheless, I expected the water to be at least lukewarm, even with a small crossover.

At this point, I'm thinking of returning the water heater to see if it isn't a defective item, but I'm hoping if anyone else has some ideas. At the very least, it should rule out a defective unit. Here's a link to the water heater for reference:

https://www.homedepot.com/p/Rheem-P...ural-Gas-Water-Heater-XG50T12HN38U1/300437337

 

[breplum]

In my 42 years in the trade, I have never heard of a water heater not heating when you can look in and see that the burner came on. And goes off after the tank has heated up.
Did the flue get hot?
Indeed you likely do have a cross connection.
Nothing we can see from here....

 

[Tony_Hua]

It's certainly a conundrum. The burners are clearly working, and there is definitely steam flowing from the flue. My best guess right now is that the cold water input is somehow forcing the water in the tank to flow out through the hot water pipes, essentially running the water out before it gets a chance to warm up.

I don't know what the mechanisms are that would normally keep the hot water in the tank until a faucet opens. I wonder if there's a leak or something that's leading to all the hot water to flow out. I do know that without the cold water input, the water heater doesn't have enough pressure to push the water out through an opened faucet.

 

[breplum]

Cold water cannot push anything unless there is an open hot tap (or it is mixing at a fixture). Or you have some broken pipe leaking.
This assumes you are in the U.S. and not somewhere where they use unconventional stuff.
I couldn't believe some of the things I saw in Indonesia.

 

[Tony_Hua]

The residence is in California.

We have a combination of double dial mixtures (one for hot and one for cold) and those single lever devices (where you adjust temperature based on the position of the handle).

Everyone else in my household is convinced it's the water heater, but it's definitely able to heat from cold/chilled to 140 degrees F within an hour (when I close off the cold water intake).

The fact that we had the hot water being less warm a few days prior suggests to me that there is some piping crossover issue that has only gotten exacerbated.

 

[jeffmattero76]

With all faucets closed, there is only one way that any "cold water can be pushing the hot water out". That would be a leak somewhere.

I would suggest closing all faucets, and then looking at your water meter to see if it is measuring any water flow. If it is, you need to find a leak. From what you describe, that leak would have to be in a hot water pipe.

Good luck.

 

[Tony_Hua]

I’ve also noticed a “whooshing” sound coming from the crawl space, close by the water heater. This sound was definitely not there a few days ago. The sound stopped once I turned the main water valve off.

As an experiment, I also tried just turning off the water intake for the water heater specifically but the whoosh sounds persisted. Will have to check once morning hits.

 

[jeffmattero76]

I’ve also noticed a “whooshing” sound coming from the crawl space, close by the water heater. This sound was definitely not there a few days ago. The sound stopped once I turned the main water valve off.

As an experiment, I also tried just turning off the water intake for the water heater specifically but the whoosh sounds persisted. Will have to check once morning hits.

I would strongly suggest investigating that whoosh noise. My guess is that you have a broken hot water pipe, and that is pouring hundreds of gallons of water into your crawlspace. If you can't check into it right now, I would suggest closing your incoming main water valve, or, at least, the valve on the cold line feeding the water heater. If you shut off the water heater valve, be sure to also turn off the gas to the water heater, until the issue is fixed.

In fact, regardless of which valve you close, you should probably turn off the gas to the water heater. You don't want the flame to be heating an empty water tank.

 

[CT-18]

Is the dip tube missing from the new heater. You may be pulling the water off the top when you open a hot water valve. That would pull the cold that is mixing into the tank. Have you opened the drain at the bottom of the tank and is that water hot.

 

[Tony_Hua]

Checked the crawl space and couldn't find any signs of leakage.

Opened the cold water nipple and the dip tube is present.

We have a couple of hot water lines that lead to areas outside of the house proper. I wonder if it's possible that there's an underground leakage.

The water flow from the hot water line (regardless if it's hot or not) is noticeably weaker than the flow from the cold water line, but I'm not sure if this is a related issue.

We will be returning the water heater for another unit, just to rule that aspect out.

 

[jeffmattero76]

With all faucets off, did you look at your water meter to see if it was measuring any water flowing? That would tell you whether or not you have a leak somewhere.

 

[Tony_Hua]

I took a look at the meter. It's a digital meter that switches between a very large number and a smaller number, alternating every few second. Assuming the smaller number is the flow rate and with all the faucets closed, I got these metrics:

Water Heater intake opened: 6.22
Water Heater intake closed: 1.72
Main water valve shut: 0

The bigger number rose according, depending on the flow rate, so I won't bother listing those.

So I think there's a leak in one of the hot water lines and due to a crossover issue, cold water is entering the hot water line which explains the smaller 1.72 value.

Does anyone know if these values seem to indicate a leak? Is there an acceptable flow rate for when nothing is being used? I'm not sure what the value's unit measurement is.

 

[jeffmattero76]

I would suggest leaving all valves open, and all faucets, dishwasher, toilets, etc in the off position. Take a meter reading. Wait 15 minutes and take another meter reading. If the second reading is higher than the first, you have a leak.

 

[Geofd]

do you have :
single handle faucets
a shut off valve on your shower head
is the diverter on you shower seperate from the shower
valve body and do you use that to shut off the water

 

[Tony_Hua]

Alright. we've found and isolated the issue. One of the pipes leading out of the house seem to have broken underground. We've shut off the valve to that pipe for the time being until we can get proper repairs. Thanks everybody for commenting!

 

[jeffmattero76]

Alright. we've found and isolated the issue. One of the pipes leading out of the house seem to have broken underground. We've shut off the valve to that pipe for the time being until we can get proper repairs. Thanks everybody for commenting!

Glad to hear you found it. Just curious... why do you have a hot water pipe running out of the house?

 

[Tony_Hua]

We have a patio area with a working faucet, which gets its hot water supply from that hot water pipe.