Hot water element

powerplay

Senior Member
I was called for a hot water tank not working that had within 5% adequate voltage at the 4500 watt element, and 18 amp draw....still no hot water, just warm. The plumber changed the controls and elements, still same problem. I checked the resistance on the element at 13 ohms... seemed about right. With power at element, seemingly right resistance, why no hot water?
 

templdl

Senior Member
Location
Wisconsin
I was called for a hot water tank not working that had within 5% adequate voltage at the 4500 watt element, and 18 amp draw....still no hot water, just warm. The plumber changed the controls and elements, still same problem. I checked the resistance on the element at 13 ohms... seemed about right. With power at element, seemingly right resistance, why no hot water?
The 18A "draw" is that what you measured? If not, measure what the current actually is.
 

augie47

Moderator
Staff member
Location
Tennessee
You mention "elements"...have you check actual current draw on both ?
Is the water ever "hot" or only warm ?
The problem could also be with the piping. There is an internal pipe that takes the cold water to the bottom of the tank as hot water is drawn from the top. If that pipe breaks off the cold mixes immediatly with the hot at the outflow.
 

readydave8

re member
Location
Clarkesville, Georgia
Occupation
electrician
its rare but several times was leak , the one I'm remembering the best was a spraying leak under house, water was finding a place to go without showing, of course the lite bill was high that month.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Both top and bottom need to be tested but I would almost bet that either the thermostat is wired to the bottom element first and then the top, or the plumbing goes thru a mixing valve and the valve is not functioning properly
 

powerplay

Senior Member
You mention "elements"...have you check actual current draw on both ?
Is the water ever "hot" or only warm ?
The problem could also be with the piping. There is an internal pipe that takes the cold water to the bottom of the tank as hot water is drawn from the top. If that pipe breaks off the cold mixes immediatly with the hot at the outflow.
That may be the case... not sure how much water trickles out to warm water up for dairy cows to drink, but I would think with very little water being drawn, the cold water shouldn't cool down the top copper pipe exiting the tank to the point it is warm at best? I will suggest to shutting off the valves entering and exiting the tankto se if it gets hot. thanks for the feedback !
 

powerplay

Senior Member
Both top and bottom need to be tested but I would almost bet that either the thermostat is wired to the bottom element first and then the top, or the plumbing goes thru a mixing valve and the valve is not functioning properly
I checked all the control thermostats and the power does prioritize the top element first, but does not divert to bottom because the water is never hot enought o switch it into position.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I checked all the control thermostats and the power does prioritize the top element first, but does not divert to bottom because the water is never hot enought o switch it into position.
Well these are the only possibilities

1) there isn't 240V there
2) the element is not a 240V element-- can't imagine that scenario
3) the top thermostat is defective
4) Top element is defective
4) you're crazy....:lol:

Since all of this was changed then I have to go with #4 :D

Seriously, I can't imagine there is so much crud in the tank that this could happen. How old is the tank and are you sure the dpdt T-state was changed.
 

powerplay

Senior Member
Well these are the only possibilities

1) there isn't 240V there
2) the element is not a 240V element-- can't imagine that scenario
3) the top thermostat is defective
4) Top element is defective
4) you're crazy....:lol:

Since all of this was changed then I have to go with #4 :D

Seriously, I can't imagine there is so much crud in the tank that this could happen. How old is the tank and are you sure the dpdt T-state was changed.

The tank is a 3 month old James Woods and i have heard of issues with them formplumbers. Although I am a bit crazy, i do know the power is there at the element! This hot water tank is for an automatic robotic arm that attaches hoses to dairy cows udders individually. It uses the 140 degree water from the hot water tank with the heater in the robotic arm to steam clean and sanitize the arm after milking. The water line from the tank draws water to warm up water for the cows to drink so there is some water flow but I think not enough to cause the hot water line to be warm at best, from a broken pipe inside the tank not allowing the cold water to enter the tank closer to the bottom not mixing with the hot water as it exits.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
I believe Dennis is on to something, if you are drawing water from the cow's watering device, it may have a tempering valve built in as not to scald the animals.
 

broadgage

Senior Member
Location
London, England
It could be as simple as the water consumption is too great for the water heater to render it more than warm.
Not an electrical problem at all.

I once installed an electric water heater for a dairy that used the hot water to clean the equipment.
AFAIR it was 60 amps per phase from a UK 240/415 volt supply, or about TEN times the capacity of yours.

If warmed drinking water is supplied to the cows, this should be diluted with cold automaticly, but cows drink vast amounts of water and it is still a significant hot water demand.
If 100 cows each drink five gallons, each gallon consisting of 25% hot and 75% cold ?
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
The tank is a 3 month old James Woods and i have heard of issues with them formplumbers. Although I am a bit crazy, i do know the power is there at the element! This hot water tank is for an automatic robotic arm that attaches hoses to dairy cows udders individually. It uses the 140 degree water from the hot water tank with the heater in the robotic arm to steam clean and sanitize the arm after milking. The water line from the tank draws water to warm up water for the cows to drink so there is some water flow but I think not enough to cause the hot water line to be warm at best, from a broken pipe inside the tank not allowing the cold water to enter the tank closer to the bottom not mixing with the hot water as it exits.
:? Two questions....what do you mean by "the water line from the tank draws water"?
And, why do cows need warm water to drink?
 

broadgage

Senior Member
Location
London, England
Cows do not HAVE to be provided with warmed water to drink, many domestic cattle and similar wild animals drink water at close to freezing point and survive just fine.

It is however a fact that if dairy cows are provided with slightly warmed water that they drink more of it, and are therefore able able to produce more milk, which is of course the whole idea of keeping the animals.
There is also a very slight saving on feed since the cow is not expending as much metabolic energy on warming the considerable volumes of liquid that it consumes.

Opinions differ as to the best temperature, well above freezing point but below blood heat is generally accepted.
I normally fit trace heating tape to the water pipe that feeds a cattle trough, mainly to avoid frost damage, but it also slightly warms the water.
In the bottom of the drinking trough I would fit a standard 240 volt 3KW heating element controlled by a thermostat set to about 20 degrees centigrade.

In the absence of an electricity supply, it used to be common practice to place a small oil burning lamp under water troughs.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Cows do not HAVE to be provided with warmed water to drink, many domestic cattle and similar wild animals drink water at close to freezing point and survive just fine.

It is however a fact that if dairy cows are provided with slightly warmed water that they drink more of it, and are therefore able able to produce more milk, which is of course the whole idea of keeping the animals.
There is also a very slight saving on feed since the cow is not expending as much metabolic energy on warming the considerable volumes of liquid that it consumes.

Opinions differ as to the best temperature, well above freezing point but below blood heat is generally accepted.
I normally fit trace heating tape to the water pipe that feeds a cattle trough, mainly to avoid frost damage, but it also slightly warms the water.
In the bottom of the drinking trough I would fit a standard 240 volt 3KW heating element controlled by a thermostat set to about 20 degrees centigrade.

In the absence of an electricity supply, it used to be common practice to place a small oil burning lamp under water troughs.
Agh...educated from abroad(gage), thanks! :D
There are lots of dairy farms around me and I never knew that.
 

powerplay

Senior Member
At what point are you testing the hot water? Are you sure there is no mixing valve involved?
We have been grabbing the copper tube at the top of the tank where the hot water exits the tank. have touched the metal tank abover where the element is screwed into and no heat there either... I would't think enough water being drawn to cool the tank near the heat source... even with broken cold water tube in tank i would have thought the tank itself would be hot
 

kwired

Electron manager
Location
NE Nebraska
We have been grabbing the copper tube at the top of the tank where the hot water exits the tank. have touched the metal tank abover where the element is screwed into and no heat there either... I would't think enough water being drawn to cool the tank near the heat source... even with broken cold water tube in tank i would have thought the tank itself would be hot
With broken cold water tube in the tank the incoming cold water gets to the hot water outlet pretty quickly if water is being drawn from the tank. If no water is being drawn the tank, it should eventually reach set point temperature. But when water begins to be drawn again the water will lose temperature pretty rapidly. In typical residential setting one may start taking a shower and water will seem fine initially but will only take minutes and temperature will drop pretty pretty rapidly, yet all electric components of the heater seem to test out fine.

If you measure current to elements they are heating - where else is that energy going to go? The conductors are low enough resistance that losses through them is rather insignificant as compared to the element.
 

broadgage

Senior Member
Location
London, England
If the water heater is being supplied with about the right voltage, and the current draw is roughly correct, by actual measurement, then the energy used MUST be heating the water. It cant go anywhere else !
Therefore if the water does not get properly hot, it MUST be being used, or wasted via a leak, at a greater rate than about 4.5kw can heat it.
Therefore a larger loading water heater, or a smaller hot water use is called for.
 
J

janagyjr

Guest
Or replace the broken pipe in the tank.

I've been following this discussion for several days now (at least two days) without saying anything but goodness. Every possibility has now been explored except for popping open the tank to look for broken pipes. Unless you installed the tank and are absolutely sure no one has replaced it in the intervening time, you have no clue what is inside the tank. Scroedinger'd Paradox: There are and are not pipes and a mixing valve in there.
 
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