The Tank › G.E. gas water heater
- December 29, 2009 at 12:33 pm #12458
Help! I’m going in circles here! I have a high volume master bath with a Jacuzzi Tub, and a large walk-in shower. All fixtures have 3/4 supply lines. There are two new 50 gallon tanks directly above the bath, plumbed parrallel so both tanks feed into the 3/4 line at the same time. These are G.E. 50 gal. 40,000 BTU from Home Depot that were installed mid 2009. Both tanks together only supply about 20 gallons of hot water before running warm then cool. The thermostat is set to 120. VERY HOT. The water temp into the tub is 120 degrees for about 3 minutes then begins to cool down quickly. I have checked the supply lines. They are correct. The dip tubes are intact (new heaters) the pilot and flame are functioning correctly. The thermostat lights the flame shortly after the water flow begins and heats the water for about 45 minutes after the water is shut off. It is as though the cold water is mixing with the hot and cooling it down. When the heating cycle is complete and there is no water flow, even the cold water supply lines are hot from the water in the tank. No matter how high the temp is set, the hot water supply is very short. Both heaters are doing the same thing. I have isolated each of them with the same result. Aside from the dip tubes being bad (they are not), nobody seems to know the answer. What am I missing?
Are the tanks baffled, so that there is only hot water in part of the tank? Is there a false reading in the thermostat? The plastic dip tubes are 30″ long and go about 1/2 way down into the tank. They are intact with a spiral fitting at the end to “swirl” the water coming in G.E. tech was no help and referred me to Home Depot Service.
The old heaters were plumbed the same way and worked fine untill they rusted out.
Thanks,December 29, 2009 at 1:45 pm #12459Randy SchuylerKeymaster
Go to the homepage, click on Troubleshooting, then Tanklets, then read the one on Cross Connections, do the test described there and come back and tell us what you find. If it’s not that, we’ll troubleshoot till we do find it.
Randy SchuylerDecember 29, 2009 at 6:43 pm #12463
Ok. I turned off the cold water supply valves into both heaters. I opened the hot water valve in both lavatories and the large waterfall in the jacuzzi. Hot water emptied out of each of them for a few seconds and then stopped. I went up into the attic and loosened the 3/4 flex supply on the cold side and it sucked air in and hot water began to flow out of the faucets again untill I tightened the supply line. The water stopped.
SamDecember 29, 2009 at 7:51 pm #12466Larry WeingartenParticipant
Hello: Is there a hot water recirculation (instant hot water) line? Do you know the dip tubes are intact because you looked at them? Rarely, dip tubes are missing or in the wrong port.
If you have adequate pressure, I’d consider piping the heaters in series. That way, as rust builds up in the odd fitting, it will not throw off the delicate balance of flow between the two tank. It is possible to drain one tank and have the other mostly full of hot water with parallel systems. It’s common to find.
It sounds like you don’t have a cross connection, so the recirc line question could help us figure out what’s happening 😉
Yours, LarryDecember 29, 2009 at 10:18 pm #12472
There is no recirc system. These two units serve only the master bath. I have removed and examined the dip tubes. I wondered if there might be a dip tube on the hot side. How can the water in the top of a 50 gallon tank be 120 degrees and turn 80 degrees within 15 to 20 gallons?
I will reconnect them in series just to eliminate the possibility. If this mystery can’t be solved I am prepared to change to 2 on-demand, tankless gas heaters. It just irks me that I can’t find the solution.
SamDecember 30, 2009 at 4:18 am #12477Larry WeingartenParticipant
Hello: More detail; run water and try to do two things (might take two people). Measure in buckets about how many gallons you get before water starts to cool. Also, stand by the heaters feeling the hot outlets to both (let’s make sure hot and cold are really where they should be). You’ll certainly find one cools before the other. I’d check that one for a “hot” dip tube. This may only lead to more questions, but we’re dealing with hot water which does obey laws of physics. We just need to know what questions to ask 😎
Yours, LarryDecember 31, 2009 at 9:07 pm #12485
Thanks for all the input. Today, with the help of my son, I measured the output in the tub. It fills at 11 gallons per minute. Using the water from only 1 50 gallon tank, it fills with 30 gallons at 120 degrees then 10 gallons at 105 and finally 5 gallons at 100 degrees before dropping to 80 and below. With both tanks open the volumes double with the same temps. This is acceptable to the homeowner. Why it ran short earlier is still a mystery. Probably one of the heaters is not coming on and there is only warm water mixing in. But I can’t fix what aint broke! The homeowner agreed that if it continues to happen, even occasionally, he will change to tankless heaters.
Any suggestions as to best brands for high demand?
Thanks Again and A Happy and Prosperous New Year,
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