Need help. Heating water question

[cody1smith]

Ok. So I have looked all over the world wide web and keep striking out.
I'm not even 100 percent sure how to Google this question so I'll try this

So I have a tank that has 350 gallon of water in it. I have a pump in the tank pumping water through an on demand water heater. I'm trying to figure out how long it will take to heat the water to certain temp.
350 gallon water
Heater puts out 1 gallon of Water per minute 25 degrees warmer than it comes in.
The tank is in a 50 degree room. So the water is 50 currently.
When I turn on the heater the water coming out is 75. But when the water is 75 it will be coming out 100.
Not that I really need to know for any good reason othetvthan when I was Building this today I had no clue how to figure it. I guess my question is how long will it take for the water to get 75

Thanks in advance

 

[Cackalacky]

Ok. So I have looked all over the world wide web and keep striking out.
I'm not even 100 percent sure how to Google this question so I'll try this

So I have a tank that has 350 gallon of water in it. I have a pump in the tank pumping water through an on demand water heater. I'm trying to figure out how long it will take to heat the water to certain temp.
350 gallon water
Heater puts out 1 gallon of Water per minute 25 degrees warmer than it comes in.
The tank is in a 50 degree room. So the water is 50 currently.
When I turn on the heater the water coming out is 75. But when the water is 75 it will be coming out 100.
Not that I really need to know for any good reason othetvthan when I was Building this today I had no clue how to figure it. I guess my question is how long will it take for the water to get 75

Thanks in advance

You need a differential equation to accurately solve that.

 

[cody1smith]

Yeah. Seems like the most complicated question of all time

 

[Cackalacky]

Yeah. Seems like the most complicated question of all time

Not unsolvable but it is multivariable. You are looking at the change in temperature, power input, changing volume and all with respect to time. Then mixing the warmer water in with the colder water that hasnt left the tank yet. Haha.

 

[Valpodoc85]

4.186 Joule= 1 calorie

1 calorie is the amount of energy it takes to increase one gram of water one degree C

350 gallons H2O = 2922 pounds

Convert and multiply

1 gallon increase by 25 degrees is max energy output/ time

Amount of energy needed/ (energy/time)= time needed to raise temp

 

[cody1smith]

Not unsolvable but it is multivariable. You are looking at the change in temperature, power input, changing volume and all with respect to time. Then mixing the warmer water in with the colder water that hasnt left the tank yet. Haha.

I sat down with paper and did not write down one thing that I felt lik was getting me closer to the answer. I can generally figure anything out. Or at least get close. Lol. This one had me stumped.
I will be back in the morning and I don't want the water to be 100 degrees lol. If I thought it would get to got I would go check it out tonight.

 

[irishff1014]

What in world kinda system do you have? I have never even heard of anything like that.

 

[cody1smith]

Lol. Long story short I own a mid sized fish farm. 99 percent of business/ work is in the spring- fall. Hatch and grow fish to marketable size then sell them. The vast majority of my fish go to people to put in their own ponds. So I can't really sell them now anyway. But if I could grow a couple hundred thousand through the winter I could sell them come spring (fish grow almost none through the winter) Trying to create profitable work for all my employees in the winter rather than cleaning trucks and pissin around like we have been doing for 30 plus years.

 

[Cackalacky]

I guess if you want ancrude answer:

350 gallons *1m/gallon=350 minutes to raise the tank 25 degrees. So a rough estimate is identify your target temp. Say 180 degrees.

Its takes 350 minutes / 25 degrees*180 degrees. Should give you a rough time. Not exact. 42 hours

Your best bet is to get it going and track the temperature then create your own model using the data in excel or such. It would be beneficial to you and your company because it woud be calibrated to the system you have.

 

[connor_in]

Need fire
Fire good

 

[BGIF]

Ok. So I have looked all over the world wide web and keep striking out.
I'm not even 100 percent sure how to Google this question so I'll try this

So I have a tank that has 350 gallon of water in it. I have a pump in the tank pumping water through an on demand water heater. I'm trying to figure out how long it will take to heat the water to certain temp.
350 gallon water
Heater puts out 1 gallon of Water per minute 25 degrees warmer than it comes in.
The tank is in a 50 degree room. So the water is 50 currently.
When I turn on the heater the water coming out is 75. But when the water is 75 it will be coming out 100.
Not that I really need to know for any good reason othetvthan when I was Building this today I had no clue how to figure it. I guess my question is how long will it take for the water to get 75

Thanks in advance

A. One minute.

The first bold sentence above, the stated capacity of your pump is 1 gpm with a delta T+ of 25 degrees. It's adds 25 degrees to one gallon in one minute.

The size of the ambient water tank isn't germane to the problem.

I don't known what your water source is, for example, city versus private well, versus rain barrel. If it's city or private well you're probably running warmer than 50 degree into the tank. BUT again it's NOT germane as the tank (350 times the size of the heat pump) temperature will adjust to your 50 degree room and is being withdrawn slowly, almost 6 hours to drain the tank through the pump.

 

[Cackalacky]

I guess I was thinking it was recirculated back into the tank he wanted to know how much time to heat the whole tank.

 

[loomis41973]

bumfuzzled

 

[cody1smith]

I guess I was thinking it was recirculated back into the tank he wanted to know how much time to heat the whole tank.

It is. No water in no water out

 

[cody1smith]

It seemed so hard to figure cuz the Water in the tank is constantly going down as it rises due to the temp in the building being 50. Plus as the water in the tank heats the water coming from the pump gets hotter to. It's tricky for this conman peasant

 

[BGIF]

I guess I was thinking it was recirculated back into the tank he wanted to know how much time to heat the whole tank.

That could be what he's after. We engineers tend to think about a problme as we see it not as others do. I agreed with your intial differential equation approach until I read his question a second time. It may be a question of wording, he may have actually wanted to know what you looked for.



A millennium ago, I took a Hydrology course taught by the Chairman of the Civil Engineering Department. In one class he went off on a tangent about relevant data in problem solving. He mentioned that he was one of the preparers of engineering questions for our state's Professional Engineers Licensing Exam. This was long before the National Exam.

He gave us two example problems. The first one was a celestial surveying problem. "Your in the Libyan desert on a camel drawn cart, along with your transit, you carry a day's supply of water in goat skins and the sun is shinning over your left shoulder". He then proceeds to give all sorts of constellation and star data, some azimuths, declinations and so forth, almost a page's worth of data. You are to locate your position by shooting the stars.

The problem actually took several hours to compute by slide rule (pre-calculator days) and anyone who did the computations got a zero grade on the problem ... unless they noted that the problem was unsolvable at that time. The question asked had noted "the sun was shining over your left shoulder" thus you could not see the stars to "shoot" your position. Stating that the problem was unsolvable due to it being daytime got you full credit.

The point being that not all data given is relevant. What was the question? What data do you need to solve?


The other example problem was how many feet does a barge of given dimensions in Newark harbor draft when the water temperature is 72 degrees and the barge is loaded with 200 tons of alfalfa.

A simple problem. Archimedes figured this one out in a bathtub 2000 years ago. Water is 62.4 lbs/c.f., now plug in the rest of the numbers, calculate and ... get the wrong answer. A harbor, an estuary, has a salt component with a lesser density than pure water. Failure to adjust for the salinity got a failing grade on the problem.


Years later when I took my P.E. exam, the barge harbor question was on the test. Yes, I aced it.

 

[GATTACA!]

Wouldn't you need to know the return temperature of the water to figure this out? It doesn't really matter temperature the water is when it leaves the heater, you would need to know what how hot it is when it comes back into the tank to figure out what effect it has.

 

[Cackalacky]

That could be what he's after. We engineers tend to think about a problme as we see it not as others do. I agreed with your intial differential equation approach until I read his question a second time. It may be a question of wording, he may have actually wanted to know what you looked for.



A millennium ago, I took a Hydrology course taught by the Chairman of the Civil Engineering Department. In one class he went off on a tangent about relevant data in problem solving. He mentioned that he was one of the preparers of engineering questions for our state's Professional Engineers Licensing Exam. This was long before the National Exam.

He gave us two example problems. The first one was a celestial surveying problem. "Your in the Libyan desert on a camel drawn cart, along with your transit, you carry a day's supply of water in goat skins and the sun is shinning over your left shoulder". He then proceeds to give all sorts of constellation and star data, some azimuths, declinations and so forth, almost a page's worth of data. You are to locate your position by shooting the stars.

The problem actually took several hours to compute by slide rule (pre-calculator days) and anyone who did the computations got a zero grade on the problem ... unless they noted that the problem was unsolvable at that time. The question asked had noted "the sun was shining over your left shoulder" thus you could not see the stars to "shoot" your position. Stating that the problem was unsolvable due to it being daytime got you full credit.

The point being that not all data given is relevant. What was the question? What data do you need to solve?


The other example problem was how many feet does a barge of given dimensions in Newark harbor draft when the water temperature is 72 degrees and the barge is loaded with 200 tons of alfalfa.

A simple problem. Archimedes figured this one out in a bathtub 2000 years ago. Water is 62.4 lbs/c.f., now plug in the rest of the numbers, calculate and ... get the wrong answer. A harbor, an estuary, has a salt component with a lesser density than pure water. Failure to adjust for the salinity got a failing grade on the problem.


Years later when I took my P.E. exam, the barge harbor question was on the test. Yes, I aced it.

I love stories like these. Not nearly enough of those happen anymore.

I hear ya about how to view the problem. I am currently preparing for the S.E. I was thinking about just taking the PE but South Carolina just declassified the term PE but kept protections for the term engineer. So in SC now any one can put PE on their cards or call themselves a PE even though they are not. I have seen numerous Project Engineers out and about lately but they are not licensed engineers. Anyway i figured i should go ahead and get my SE while I am at it. Whats a two day eight hour exam compared to a one day eight hour exam.

 

[cody1smith]

? The water going into the heater is 50. It comes out of the heater at 75. From the heater it goes back into the samectank. It's tricky. I've spent tons of time on it. And I'm not even trying to take into itvtgat it's 50 in the room where the tank is. Tgecway the heater works also kinda messes with it due to it not having a temp setting. Just heats the water 25 degrees no matter how hot it comes in

 

[Cackalacky]

Wouldn't you need to know the return temperature of the water to figure this out? It doesn't really matter temperature the water is when it leaves the heater, you would need to know what how hot it is when it comes back into the tank to figure out what effect it has.

Yes this is a heat and mass flow problem. The water entering the tank will be 75 degrees but then mixes with the 50 degree water. The internal tank temp will continue to increase but also adjust to the outside air temp the whole time as well.

Its essentially a mas balance problem.... input plus accumulation = output plus waste all withe respect to time and temp. A differential set of equations is probably the most accurate way to solve this.

 

[BGIF]

It seemed so hard to figure cuz the Water in the tank is constantly going down as it rises due to the temp in the building being 50. Plus as the water in the tank heats the water coming from the pump gets hotter to. It's tricky for this conman peasant

cody, I'm apparently missing something. I took the first post as you were using the 350 gallon tank as a holding tank to supply your heat pump to raise the temperature of the water for hot water use like domestic use, 1 gpm. Sounds like cackalacky's recirculation approach appears to be what you have.

As I read this post you raise fish in a 350 gallon tank but are you telling us either the water level drops (needs make up water due to evaporation/spillage) OR the temperature in the tank keeps dropping due to temperature loss from the tank to the 50 degree ambient room?

I'm assuming the fish tank is open topped.

I don't know what you googled earlier but get the name of the pump manufacturer and model and contact them. Ask them how to put a thermostat feedback loop in your pump control to maintain whatever optimum temperaturerange you want to maintain. If not do they have a variable pump that fits your situation.

 

[Cackalacky]

? The water going into the heater is 50. It comes out of the heater at 75. From the heater it goes back into the samectank. It's tricky. I've spent tons of time on it. And I'm not even trying to take into itvtgat it's 50 in the room where the tank is. Tgecway the heater works also kinda messes with it due to it not having a temp setting. Just heats the water 25 degrees no matter how hot it comes in

Sounds like your solution is a thermostat

 

[GATTACA!]

? The water going into the heater is 50. It comes out of the heater at 75. From the heater it goes back into the samectank. It's tricky. I've spent tons of time on it. And I'm not even trying to take into itvtgat it's 50 in the room where the tank is. Tgecway the heater works also kinda messes with it due to it not having a temp setting. Just heats the water 25 degrees no matter how hot it comes in

Oh maybe i'm misunderstanding. I thought the water went through the heater then was pumped out for whatever you use the water for and then returned to the tank. So the heater is separate from the system that pumps the water around? Even still you have to account for the temperature of the return water regardless of the heater. The water coming back has to have lost some of it's heat and that's going to offset what the heater is doing.

 

[Sherm Sticky]

When I saw the title of the thread I thought Koon created it. Haha


Sent from my iPhone using Tapatalk

 

[cody1smith]

Well just checked it and the water is 65. So 15 degrees in 4 hours. Water coming out is 90. Will I continue to get a 15 degree raise every four hours. I'm thinking yes. But this whole deal is making me stupid

 

[Cackalacky]

Well just checked it and the water is 65. So 15 degrees in 4 hours. Water coming out is 90. Will I continue to get a 15 degree raise every four hours. I'm thinking yes. But this whole deal is making me stupid

Where did you take the temperature? At what depth?

 

[cody1smith]

It's a digital temp gauge with 4 leads in the tank. It's suppose to average the temp. They are on the bottom one in each corner

 

[Irish#1]

Lol. Long story short I own a mid sized fish farm. 99 percent of business/ work is in the spring- fall. Hatch and grow fish to marketable size then sell them. The vast majority of my fish go to people to put in their own ponds. So I can't really sell them now anyway. But if I could grow a couple hundred thousand through the winter I could sell them come spring (fish grow almost none through the winter) Trying to create profitable work for all my employees in the winter rather than cleaning trucks and pissin around like we have been doing for 30 plus years.

Math isn't my strong suit, so I have no frickin' clue how to calculate that. However, I like your forward thinking on trying to expand the business. Good luck with your project. BTW......fish hatchery is such a non-traditional vocation. Mind telling us how you got into this business?

 

[ulukinatme]

 

[woolybug25]

Lol. Long story short I own a mid sized fish farm. 99 percent of business/ work is in the spring- fall. Hatch and grow fish to marketable size then sell them. The vast majority of my fish go to people to put in their own ponds. So I can't really sell them now anyway. But if I could grow a couple hundred thousand through the winter I could sell them come spring (fish grow almost none through the winter) Trying to create profitable work for all my employees in the winter rather than cleaning trucks and pissin around like we have been doing for 30 plus years.

Interesting. What kinds of fish do you breed?