Water Fountain Heat Loss?

Cosmo_3

I have been unable to check my computer since I posted this question. From what I understand, the fountain will have no exposed structure, as in Mike's picture. The pump outlet nozzle is underwater.


Cosmo

Cosmo_3

Can anyone help?

I have to size a heat exchanger for the following;

12X12 X 2 foot deep outdoor fountain. I figure approx 2300gal, outside temp down to 5F, and we want enough heat to keep from freezing- 45-50F.

I have sized pools before, and a triangle tube #MF-80 would be fine however I am wondering how to account for heat loss when the fountain is running?

Anyone else involved in one?

Thanks for any help!


Cosmo

Mike T., Swampeast MO

Does the water pumped through the fountain travel over anything? Anything at all like this? If so, you're going to have some real problems. I've been selling and installing these for a few years--many of them very large (larger than this one) and some installed to decorate commercial structures.

I did not sell this one. It's located in New Mexico about 20 miles N of the Mexico border at the RV park owned by the club I work for. While they do not attempt to heat, they didn't expect this from a single cold snap! One of my commercial customers tried (against my recommendation) to keep it running through the winter. I believe they used 3-4 electric heaters made for large cattle watering troughs. With cold (especially cold and windy) weather, they had similar. Might look kind of pretty, but it's VERY bad for the fountain itself! Note however that water is still being pumped. Such will continue until nearly all of the water in the fountain has frozen onto the upper portion.

You may be able to keep the water fairly warm, but not the upper portions of the fountain. I truly have no idea how to prevent such unless you can actually heat the entire mass of the above-grade portions of the fountain independently of the water.

If the fountain sprays do nothing but travel through the air, I'd suggest adding in the amount of heat required to raise the temp of the FLOW from 32°F to 50°. In cold weather that water will likely hit the water in the fountain base at 32° but it won't freeze because it's moving.

When I think about this more, I'm not so sure. I can't remember if moving water can be below 32° but not frozen or if its movement keeps the water from dropping below 32°. I do know that in extremely cold weather with low humidity that even warm water when thrown through the air will become "frozen fog" almost instantly.

DanHolohan

Get Hot Rod to build the fountain.

He'll put tubes in the concrete.

Empire_2

Interesting question.

I would also think wind conditions would play an important roll in this calculation. Not only the water in the base, but the evaporation that happens as the water is dispensed through the fountain. You may want to post this in the HAVC section below to.:-) I think that smaller droplets out of the fountain head will tend to give up much more of it's heat content than the water in the base. With evaporation taking place here, there is a lot of heat being given up up through "latent heat of Fusion" For example to lower 1 lb of water 1*f at 33 to 32* only takes 1 BTU per lb of heat to be given up, while to drop from 32* water to 32* ice 144 BTU. The water being cascaded in my opinion will give up it's heat content very quickly due to its weight. I'm not too worried about what's in the base. The spacific weight of water is 1.0,...Ice is .5

I think Brad will love to tackle this one..

Mike T.

Mike T., Swampeast MO

Did you notice what I added to the original post?

I think I remember now what happens when moving water passes through cold air. The colder the air and the less the relative humidity the more it evaporates--the rest of the water stays at least 32° and liquid. I have no idea however how to calculate the evaporation rate from streams moving through the air.

Weezbo might be able to make some estimates...

hr

Think I would just add some glycol

pure food grade glycol is clear if color is an issue

hot rod

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Mike T., Swampeast MO

The largest ones I sell are about 8' in diameter and 18" or so deep. The 6' diameter one in between my house and the rental house next door seems to loose at least 10 gallons per day even in hot, muggy and still weather. Add a good wind and it's easily 4-5 times that amount.

I haven't actually measured--I just know my good hose bib in the front gives about 7 gpm.

BTW, we feel like Egyptians when installing the larger fountains. Lots of levers and rollers...

jp_2

temp of moving water

moving water contains more energy than still water. therefore more energy needs to be removed from it, colder outside air, for it to freeze.

Empire_2

JP...

I think I get what you are saying, but I think it depends on the actual weight of the water whether it be light spray, or heaver clumps of water or even heaver clumps. the patterns are always changing out of the fountain head. At say 5*f,..outside temp and dropping 1 lb of water off of a hi building, letting it fall or 1/2 lb of water. Which would freeze quicker?

I think I getting brain tied here, but I still think it has to do with weight, not how it moves.......

My .02

Mike T.

jp_2

weight=internal energy.

yep, shape has a lot to do with it, the more spheretical, the lower the freeze point. In outside tests I got small water dropets to stay liquid at -20F. surface tension kept the molecules aligned differently than in a 'freezing' pattern.

dropets were highly unstable and would freeze in an instant.

remember, weight= btu content, so more weight, more btu's you have to extract before a weight of water will freeze.

Empire_2

Got it JP....

Great point.......;-) I knew I was close, but like I said by brain was starting to wonder.......:-) BTW the fountain looks like the one in Elvis's mansion......

Mike T.

jp_2

moving with respect to what?

remember, moving water, as in a river, the molecules are in constant colliding motion, as in a pipe too, but a droplet of water moving can have a lot less internal motion.

motion within the droplet which counts the most.

LarryC

Salt if the mechanicals can handle it

What is the liquid de-icer the highway departments now use? Relatively non toxic I think. Will people, animals, or kids be in close proximity to the fountain? Will there be plants or fish in the water?

Larry C

Weezbo

I like that idea *~/:)

here is a bit of trivia ...a friend of mine owned a plumbing company that ran a residential goulds shallow well pump outside continuously, pumping only water all year round for over ten years out of the pump to a 3/4 hose bib onto the heavy icicle:)and back into the pump.

as long as the pump keeps rolling the water keeps moving as long as the water keeps rolling it cannot freeze...when the water slows down then it freezes

another toughie runs the water out of a gravel pit( man made over grown swimming pond ) through the floor of his "Garage" no Door:) just a really gert space in the one side of the building where a wall would be :)and back into the gravel pit all year round with a gould pump...its "warm" in there. i know you guys are laughing secretly...:)) one thing is the out door temps are drastic cold and the idea that 34* water could produce Comfort is a significant spiritual leap you must take to digest that frame of mind. however it is,... relatively... warm, to someone working out doors in super chilly weather

i can honestly say that it would look a lot worse than your fountain in 66 below F however you didnt notice it as much, as you would be lucky if you could see your hand were it outstreched from your body...

the difference as far as ican determine is the ability of the pump to move water and the rate at which it is replenished to the source.

an ice maker was draining "indirect to the ground beneath a building "built on steel pilings driven into the ice (about 4' to ice)there was quite the icicle beneath the floor yet because it was continuously draining, there was an interior passage way that remained open in some ,far Icking ...cold weather:))

as long as the right kinda fish live in the water like the pinner fish with glycol in their bodies they can make it through the winter Hey ! maybe they might like a drop of glycol Too:)

Cosmo_3

Update

Here is a pic of the dreaded fountain.

Yes Mike, as I feared it is just like the one in your frozen pic.

So, any new suggestions? Hot Rod mentioned clear glycol, can you point me to a manufacturer?

Design temps around here in the beautiful Lehigh Valley, PA are 10 deg F, although we have been known to dip down to zero for a few hours now and then.

You can find water capacity in my first post. I also have about 400,000BTU to work with.

Thanks for all your help guys, this one must be done soon!!

Gotta love cold Octobers!!



Cosmo

jp_2

hot rods

hot rod has the best solution, food grade gycol.

Mike T., Swampeast MO

Seriously

Is drainage for the winter not an option? Judging by the wet pavers, there'd be an awful lot of wasted, expensive glycol...

How many GPM truly delivered? Something really tells me that you have to assume that the total flow can return to the pool at 32F.

Say 20 gpm @ 32F heated to 52F = something around 200 mbh and that's not counting losses from the pool itself!!!!

Cosmo_3

believe me

I told the guy that it would be completely impractical. However he is trying to sell the place for 4+ Million and he says that the fountain must be on all year.

Crazy eh?

edit- the day I took the pic it was very windy, but not abnormal as the home is located on a hill in the middle of open farmland.


Cosmo

jp_2

return temp

are you assuming you want the return water at 32F or that it would be at that temp regardless?

I would think you only have to heat the water to something like 35F.

Mike T., Swampeast MO

Am mainly guessing. Just saying that the water pumped out the top [could] return at 32°F. As to actual temp required, I'm genuinely at a loss. Do except it would need to be warmer than 35°F or so because I doubt that temp would keep the concrete above the pools above 32°F.

Unlike an in-ground pool, you have walls and even a base that wants to be at or near ambient so you don't have the benefit of low-level heat from the earth. Snow is another wild card.

jp_2

bird bath heater

if you could get bird bath heaters in the upper pools that might work.

since it looks like the upper structure is bathed in water, the concrete should stay at water temperature, thats why I think about water temp under 40F, but that just guessing too.

Mike T., Swampeast MO

Another (bad) thought...

...unless the area surrounding the fountain is heated anytime the temp is below freezing, this could be a setup for a nighmare of an icing problem on the drive!

Cosmo_3

update

I had a meeting with the homeowner. He asked me how much energy it would take to keep the thing heated, and I smiled. So he backed off and asked for options!! Nice, didn't even have to give a number.....

I found that there are two supply lines going to the fountain; one for the fountain itself, and one just for the pool. I told him that one option may be to simply shut-off the fountain supply line, and drain the line. Then we would simply have to keep the water from freezing in the fountain basin which is fed with a separate supply line. He said if it can be done then that would be an okay compromise.

Whew!!!


Cosmo

Mike T., Swampeast MO

Here's an idea:

Sense air temp. Once such drops a few degrees below freezing, stop the fountain pump and heat the water--maybe to 40° or so.

Then once the air temp rises a few degrees above freezing, start the fountain pump and lock out the heating.

You can then size the HX as if the fountain were a simple above-ground pool.

Mike T., Swampeast MO

Oops. You don't even have connections available to heat anyway, right?

A "cattle trough" heater or three [might] be able to keep the thing liquid as long as the pump isn't running, but you'll need adequate power.

Cosmo_3

Okay man

Your confusing me.... not that hard to do

The pump, piping, and valves are all accessible-located in the mech room next to the boiler system.

I like your idea, I would have to use a 1 1/2" PVC valve actuator, and close the valve when temp gets below say 35 to account for calibration error, but then how would I drain the line that runs through the fountain mast automatically?

I guess I could use another valve actuator as a dump valve, and drain to the 3" standpipe that is available.

hmmmmmmm


Cosmo

Mike T., Swampeast MO

It was me who was confused. The fountain pump's in the mechanical room, not the fountain. Duh!

Do you see any way to heat the water WITHOUT the fountain running?

SVDW

Drain the mast line..

How about a small (1/4") hole drilled in the mast line underwater so it can drain back to the pool when the pump is off? Common practice on sump pumps to make sure they don't air lock but I think it might be a low-tech answer to the drainback issue. I don't think you would notice the volume loss on this fountain when it is running.... Another thought: If you put in a 3 way diverter valve to switch between the mast sprayer or pool actuated by an air sensor would it circulate the water in the pool to keep from freezing?

hr

Treat it like a drain back solar

and install a large tank to allow drain back at 35F.

Clear glycol is available from suppliers that cater to the food industry and supply food grade PG.

Too bad you couldn't find some clear RV antifreeze. It's much cheaper than inhibited hydronic glycols, and doesn't smell as bad

We have a glycol recycler here in Springfield. He collects used glycols from car dealers, filters, RO's it then re-formulates it. After the RO it is a clear fluid again.

hot rod

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