Redneck Pool heater

[NS Gearhead]

First post... so sorry if this is in the wrong section.
Thought you guys might like to see what I came up with to heat my pool.

Started with a plain old 45gal barrel. Cut out a door.




Draft (although I screwed up the spacing)


Chimney and damper


Shelf


100' of 1/2" copper, in/out guages, garden hose fittings


In use


About average with stoking the fire every 30min-1hr or so.


The pool and how far away it is


Good results the 1st weekend. Got it up to 27C/83F from 22C/70F in 24 hrs.

Didn't stay shiney long!


Built a damper to force the hot gases over the top of the coil before exiting. Made a significant difference.


Started playing with a waste oil burner


Cut out the center of the rotor and sat a 6" pipe on top.
Pre-heating with kerosene


introduced some waste oil


It did pick up more then this. Prob half way between this pic and the kerosene

Drip tube

 

[NS Gearhead]

The drip tube didn't work. It simply got too hot. The oil would smolder/ burn before getting to the end.

Temp alternate




At this point I had cut 8 slots along the 6" pipe with my grinder cutting disk. It's some kind of cast, so it doesn't drill. This wasn't enough air and smoked more then I'd like. I placed a box fan in from of the open door and this almost produced a smokeless fire. I do plan to open up the slots and try to make it work without the fan.


Got the insulation contractors at work to make me a blanket.


Salvaged another blanket destined for the dumpster... should have put it on cold. LOL Better job next time.








Got it passed my goal of 30C/86F this weekend to 32C/90F

Working on a new, bigger, flat door/damper.

Hope you like it!

 

[Highbeam]

The drip tube didn't work. It simply got too hot. The oil would smolder/ burn before getting to the end.

Temp alternate




At this point I had cut 8 slots along the 6" pipe with my grinder cutting disk. It's some kind of cast, so it doesn't drill. This wasn't enough air and smoked more then I'd like. I placed a box fan in from of the open door and this almost produced a smokeless fire. I do plan to open up the slots and try to make it work without the fan.


Got the insulation contractors at work to make me a blanket.


Salvaged another blanket destined for the dumpster... should have put it on cold. LOL Better job next time.








Got it passed my goal of 30C/86F this weekend to 32C/90F

Working on a new, bigger, flat door/damper.

Hope you like it!

Freaking cool thread.

 

[stee6043]

Ohhh I wish I had the space and time to do cool stuff like this. Neat thread and good work taking pictures of it all!

 

[tom in maine]

Just a word of caution as one who has worked with coiled hx. If there is ever a hiccup on the circulation system, you will flash to steam and/or melt that tubing in a couple minutes.
The steam part of this equation can be very dangerous. I would suggest a pressure relief valve on either end of the coil, although I suppose your garden hoses will burst off if that happens.
Also might suggest a shorter coil with a larger diameter or cutting the coil in two and paralleling it.

Just my 2 cents worth.
This is very similar to the woodstove coils we discuss here from time to time.
Years ago, Dick Hill melted a heat exchanger like this in moments without flow. He was very excited when it happened.

 

[NS Gearhead]

Thanks Highbeam!

stee6043; I'm blessed to have 4.2 acres and border on 100s of water commission property. Check me out on youtube; wannabejeeper

tom; thanks for the heads up. I'm a boiler operator, so I've got some idea of steam & pressure. Just curious; why would I want to change my coil? I'm getting the results I was looking for...

Forgot to mention I've got about $200 into this. Barrel, water temp gauges, fittings, 6" pipe, and insulation were free. Copper was at cost. Payed full price for chimney, chimney gauge, damper, and cast iron pan. Had scrap steel laying around for the door, latch, draft, etc.

I had the pool up to 32C sunday, lost 4deg overnight (evening are getting cool), and re-gained one deg yesterday with the sun and solar blanket... so I'm very happy with its ability to retain the heat! 29 is still nearly bath water... and we're supposed to have two really warm days today and tomorrow. I also discovered that a warm pool goes through a lot more chlorine!

 

[maple1]

NS eh?



We have a small pool out back, and are contemplating replacing it with a bit bigger one. I have been thinking once in a while about possibly heating it, and how I would plumb in my indoor unit to it. But I would almost be further ahead in jimmying something like this up, especially when also considering a firepit or outdoor fireplace has also been talked about around here. Have lots of steel barrels and scrap laying around too.

Hmmm...

 

[tom in maine]

Running a long single run of copper in a boiler like this offers a bit more potential for localized boiling. Shorter loops would run at a lower Delta T and
afford you a bit more redundancy. I suspect you could use 1/4 the tubing length and get very similar results, since the hx is not in very uniform thermal contact with the exhaust stream.
Glad the pool is so warm. After all the pools we did with solar over the years, I would love to have one right about today!

 

[Highbeam]

Would be cool to set it up as a thermosiphon to avoid the localized boiling if the pump shuts off.

When I was a wee lad I worked at a high country outfitting service and we had a water "system" that was a piped intake high up a creek and this pipe fed a steel tank above a campfire that then fed the showers. We would burn a fire under that tank, out in the open, until you could hear the tank rumble from simmering and then have a much appreciated shower in the shower tent. Cold water was also piped to the standard shower mixing valve. Not much different than the setup on this thread.

Yes, chlorine burns off quickly in high water temps and high sunlight loads. It is easier to treat cold water.

 

[Ricky8443]

that is awesome. made my day.

 

[infinitymike]

Very, very cool, or should I say hot.

How long will copper last with chlorinated water running through it?
I bought my gasifier with a DHW coil, but never hooked it up.
Went with an indirect tank instead.
I thought about running the pool water through the coil,
but I'm afraid that over time it will eat away the copper and damage the boiler.

Does this only happen because the chlorine is in a gaseous form?

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[goosegunner]

If you have any blondes in the house they might not like it when there hair gets the nice green hue. I avoid copper in my pool water for that reason. The cheap algaecides have copper in them also.

gg

 

[infinitymike]

My friend told me he puts small copper tube slices in his skimmer box to help reduce the need for chlorine because it has algaecide properties to it.
Which is true. Look at any roof, and it will super clean under a skylight that has copper flashings or any area that has copper above it.
He hasn't seen any effects to people swimming in it and really doesn't see any visible damage to the tubing, but that doesn't mean the tubes aren't deteriorating on a micro level.

 

[DoubleB]

I, too, give kudos to your handiwork, and I'm glad it's working for you.

ust curious; why would I want to change my coil? I'm getting the results I was looking for...

Because you have an opportunity to get better results with less danger. I think Tom is right on. From the looks of it, most of your heat is going up the center where there isn't tube, and avoiding the tube because the tube appears densely packed around the perimeter to block combustion gases. Less tube, distributed evenly, with room for the hot gases to pass between the tubes, would probably get you even more heat with less fuel and better water flow.

Of course, more heat would tend to flash to steam quicker, unless you just burn smaller fires for the same amount of heat gain that you have today. And, less tube (shorter and/or parallel) would be much less pressure drop and get you closer to being able to siphon if arranged properly and if you otherwise lose power or flow for some reason.

Again, I can't argue with leaving it alone if it ain't broke. Just agreeing with Tom with some options for improvement since you seem to like to tinker.

 

[Highbeam]

Even if it were to flash to steam (boil) would it not just recondense down the line? Since this is open ended pressure can't build up or is the flashing so explosive that the pressure pulse blows the copper?

 

[tom in maine]

If water flashed to steam, it could stop water flow which can rapidly lead to melting the tube, if it is already a hot spot. A heat exchanger like this has to rely on high, constant flow. Momentary loss of flow with this kind of fire would flash the water to steam in well under a minute. Then the fun starts. It is exciting, really!

 

[NS Gearhead]

Hmmm, so it's either loved or I'm an idiot. LOL

First off, it's my understanding that the copper will not react with the chlorine as long as the PH of the water is kept in range. The vid above is under extremely... uh, extreme situation. LOL If it does break down over time I do treat my pool for metals weekly, so any copper that makes its way to the pool will be removed. As proof, my neighbor's extremely blond daughter's been in several times with no issues.

Make it more efficient by replacing the most expensive part? I think not. As I said, I made a baffle so that the hot gasses not only pass up through the center of the copper coil, they're then directed over top of them. The bottom of the coil is either in direct contact with the flames, or absorbing radiant heat.

Perhaps my explanation wasn't clear. Maybe this my explain better;


Ideally once I had coiled the copper to the side of the barrel I would have started to coil it down towards the fire, for better contact, but going up was much easier. The baffle helped direct hot gasses over this part of the coil and the proof is in the discharge temp going up a good 10deg C on avg after install.

Yes, potentially the pump could fail causing the water to flash to steam. Maybe the next version will have some type of safety valve... but in the mean time this is at least 50' from anything valuable, or where people spend time. The discharge hose is zip tied to the ladder and would become very obvious, very quick if something went wrong. Steam explosions become worse with pressure and volume of water. As it sits it's an open ended system, and the copper coil holds a very small amount of water at any given time. So, it would either flash to steam bursting the soft copper... which the steam would then shoot out the chimney, or the copper wouldn't burst and the steam would be forced to the open end of the system through 80' of garden hose... loosing heat as it goes... not being replaced by more water/ steam because the pump failed.

Anyway!... I've been looking a smudge pots thinking this may be version 4.0 for a pool heater. I could build one in a day no prob, and have several sources of free waste oil. I'm thinking the copper coil could be placed inside the upper non-perforated section of chimney. What do you think of this idea?

 

[hobbyheater]

Really like your thread its a breath of fresh air , interesting because its definitely not the norm!

allan

 

[infinitymike]

I really like this thread as well.

I posted the youtube video just as a point of reference.
I don't think that would happen in this type of system because the chlorine in the video is in a gaseous state, here it is mixed with water, although I think heat causes it to off gas, I still don't think it is any where as extreme as the video.

In all honesty though, if the chlorine does have a deteriorating effect on copper and your copper tubing fails its will suck but really won't be as bad as if the coil in my gasification boiler crapped out.

Thats my concern.

So does any one have any info on what effect chlorine in water has on copper.
I may just try and hook my DHW coil in my boiler up to the pool system.

Or maybe I should just wait and see how long your copper tubing last

 

[DoubleB]

Even if it were to flash to steam (boil) would it not just recondense down the line? Since this is open ended pressure can't build up

If I had to guess, this is hopefully what would happen, instead of...

or is the flashing so explosive that the pressure pulse blows the copper?

If water flashed to steam, it could stop water flow which can rapidly lead to melting the tube,

Which is (among many other problems) part of the catastrophe at Chernobyl. Obviously, an entirely different situation, but the idea is the same on a much smaller scale. I'm not urging you to change anything if you don't want to, just pointing out some possibilities in case you find it applicable.

Make it more efficient by replacing the most expensive part? I think not.

You don't have to replace it, just cut it shorter, re-do one of your fittings, and bend it more efficiently. Even make a buck if you want to scrap the remainder. Obviously, entirely your option.

proof is in the discharge temp going up a good 10deg C on avg after install.

That's good proof. 20C with a more efficient coil would be even better proof. The drawing helps me understand the baffle, which seems like it would help. You would still get better heat transfer if the gases could penetrate through and around each loop of coil, instead of breezing over the top of all of them.

I'm not criticizing at all, just always in search of ways to improve things.

 

[NS Gearhead]

I see what you're saying about the coil. If the tubing was square and tight together your method would make a significant difference. Being round, there's very very little contact between the coils... so let's say 45% of the loop is in contact with radiant heat or direct flame from the fire, the upper 45% is having hot combustion gases directed over it by the baffle under the lid. Sure, if I separated the coils (which they're not that tight anyway), there may be 10% more coil exposed... but what I gained there I'd loose in length of coil removed. I think anyway. LOL Think of this as an oven, and the coil is being "baked" constantly.

So nothing on the smudge pot idea? I wanna get the criticism BEFORE I make it. ; ) LOL

Here's a primitive example;


More what I'd aiming to make;


Lighting off;

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[NS Gearhead]

That's good proof. 20C with a more efficient coil would be even better proof.

My max discharge temp has been around 65deg C. 20 more would put me dangerously close to boiling.

 

[Bob Rohr]

A more portable version

 

[infinitymike]

What type of pump are you using?
Is it a submersible in the pool?

 

[NS Gearhead]

What type of pump are you using?
Is it a submersible in the pool?

Yes, it's a sump pump. 2,000 gal/ hr I believe, 1/3 hp. Seems to be a good flow. It's reduced down to 3/4" from 1.25", and going through about 300' of garden hose and copper tubing. It's coming out the discharge hose about the same as water from my well does out a garden hose.