HOT WATER MYSTERY

[fried1765]

This is a mystery all about hot water (or lack thereof).
I have a 50 gallon water heater that I assumed had an element, or thermostat problem.
I have drained the heater, replaced the elements, and replaced the upper thermostat.

My problem is, that when I select the hot side on ANY of my three point faucets, I get hot water for only about a minute, and then the water temperature drops to just warm.
The real mystery is that when I shut both the supply and outlet lines, at the heater itself, (90 degree ball valves) I get cold water from both the left and right hand selections at each of the three point faucets.

No plumbing work has been done in this system for 5+ years.
Why do I get cold water when the hot is selected on these faucets, when both the inlet and outlet to the water heater is completely shut off?
There should be no flow when the hot outlet from the tank is completely shut off!

When I turn the hot supply back on, why do I get hot water for a minute or so, and then only warm water?

This is driving me crazy!

 

[MoKelly]

This is a mystery all about hot water (or lack thereof).
I have a 50 gallon water heater that I assumed had an element, or thermostat problem.
I have drained the heater, replaced the elements, and replaced the upper thermostat.

My problem is, that when I select the hot side on ANY of my three point faucets, I get hot water for only about a minute, and then the water temperature drops to just warm.
The real mystery is that when I shut both the supply and outlet lines, at the heater itself, (90 degree ball valves) I get cold water from both the left and right hand selections at each of the three point faucets.

No plumbing work has been done in this system for 5+ years.
Why do I get cold water when the hot is selected on these faucets, when both the inlet and outlet to the water heater is completely shut off?
There should be no flow when the hot outlet from the tank is completely shut off!

When I turn the hot supply back on, why do I get hot water for a minute or so, and then only warm water?

This is driving me crazy!

Seems to me, somehow, you are getting water flow from BOTH the heater and cold feed line on your hot faucet side.

This would explain why you get cold water from the hot faucet when the valve is off.

It also explains why you get hot then warm water from the hot side when the valve is open (it is mixing hot with cold to get warm). I think you get hot initially as only hot is in the pipe initially before the cold gets mixed in).

How that is happening, I don’t know.

MoKelly

 

[Wakey]

This kind of thing never seems to happen in the summer!

 

[GolfAddict]

I had a similar experience once, and finally discovered that an outside pair of hose bibs had their faucet valves left open. The sprayer end on the hose was off so water wasn’t actually running, but the faucet valves themselves hadn’t been spun to close.

The pair of bibs, one hot and one cold, are Y’d together with a washing machine Y. To control water temperature out the hose, you adjust the two faucets to what you want coming out the hose end. With the two faucets left on, water was flowing from the cold side backwards around the Y hose, and come out the hot side of another opened hot faucet in the house.

Drove me crazy for a while trying to figure it out. Is it possible you have something like that going on?

 

[LS Tractor Owner]

Do you have a recirculating pump? There may also be a mixing valve some where.

 

[fried1765]

Seems to me, somehow, you are getting water flow from BOTH the heater and cold feed line on your hot faucet side.

This would explain why you get cold water from the hot faucet when the valve is off.

It also explains why you get hot then warm water from the hot side when the valve is open (it is mixing hot with cold to get warm). I think you get hot initially as only hot is in the pipe initially before the cold gets mixed in).

How that is happening, I don’t know.

MoKelly

Is it possible that a 3 point cartridge could fail internally to allow this to happen?
Which cartridge.....I have 3 of them.
If one cartridge failed internally, would it affect the supply to the hot side of the other two?
Could a failed toilet mix valve be the problem?
This is all not good!

 

[Hay Dude]

Seems to me, somehow, you are getting water flow from BOTH the heater and cold feed line on your hot faucet side.

This would explain why you get cold water from the hot faucet when the valve is off.

It also explains why you get hot then warm water from the hot side when the valve is open (it is mixing hot with cold to get warm). I think you get hot initially as only hot is in the pipe initially before the cold gets mixed in).

How that is happening, I don’t know.

MoKelly

Agree. The cold from your water source is bypassing HWH and coming out of cold valve. Almost like some kind of air lock above HWH when cold turned on, but that shouldn’t happen....

 

[MoKelly]

Is it possible that a 3 point cartridge could fail internally to allow this to happen?
Which cartridge.....I have 3 of them.
If one cartridge failed internally, would it affect the supply to the hot side of the other two?
Could a failed toilet mix valve be the problem?
This is all not good!

I believe that is possible. Perhaps the information below will be helpful.



MoKelly

 

[skipmarcy]

Just guessing on my part but don't water heaters have an internal tube on the inlet (cold) side down to the bottom of the tank and the hot water is drawn off the top of the tank ? I think I've heard of these tubes either rotting away or falling off inside the tank and causing a similar situation but I'm getting older and my mind isn't quite as sharp as it used to be. Anyone else know what I'm talking about ?

 

[PILOON]

My problem is, that when I select the hot side on ANY of my three point faucets, I get hot water for only about a minute, and then the water temperature drops to just warm.
----Could it be that the lines are running along a cold outside wall? Some insulation problem along the way?

The real mystery is that when I shut both the supply and outlet lines, at the heater itself, (90 degree ball valves) I get cold water from both the left and right hand selections at each of the three point faucets.
-----Residual pressure in the lines? combined with one defective mixing faucet? also could be a defective (leaking) ball valve .
Is that flow 'full flow or trickle'?

Shutting the 2 tank valves only kills the HOT SIDE, not cold, which would explain how water still flows and one defective mixing faucet would allow flow from all hot and cold side.
Less than full flow would suggest this might be your problem.

If you laundry has separate hot/cold taps (most are) you should be able to confirm proper water flows and confirm that one of the mixer valves as the problem source.