Heat Exchanger

Peter Marino

Question;
Who makes the smallest, least exspensive, indirect hot water heater? I'm looking for a heat exchanger for my solar panels. Which will heat the water for a 20 x 40 inground gunite pool.

Also, is there a wallie willing to give me an estimate on resurecting my solar hot water system?

Thanks,
Peter

flange

why indirect? you could get a very small shell and tube or plate and frame. if you have deired flow rates, etc i got someone who makes custom units.

Peter Marino

Heat Exchanger/ flow rates

I thought an indirect unit would quick and simple to install. I'd be very interested in getting a quote for a custom H.E. No flow rates as of yet. There are (10) 4' X 10'
flat panels.

Peter

flange

i would guess you need more exchanger than you think. there is quite a bit of water in the pool, on a normal size pool you would expect to see about two inch lines running to your heater/boiler with about 185000 btu capacity. if you had line sizes, we could most likely size this for you, would also need to know what your expected water temp is from your panels. the closer you would like to see your pool water temp to your solar temp the bigger the exchanger would need to be. initial cost i think would be more than you expect, but after that you only pay fpr pump horsepower.

Peter Marino

pool heat from solar panels / flow rates

Right now, I run the pool water directly through the panels. I have a ball valve, that I use to throttle the water flow back from the panels to the pool return. I basically go out there at the peak of sun (maximum insolation) and fine tune the return valve to produce the most heat (and no steam). With a solar pool cover, I can eaisly get the pool to 90+F through out july and august.

I want to stop running the pool water through the panels, for various reasons. If I run the panels as a closed loop, through a 20 gallon superstor, as the heat exchanger, using a taco 007 and ball valve to throttle the flow (if neccessary) through the superstor coil. I could then plumb the pool water in and out of the storage part of the tank, and use another ball valve to throttle the flow back to the pool return to maximize heat transfer.

I'm not sure how important flow rates would be? Other than to keep the panels from making steam ;~) Or if I wanted to resurect the domestic hot water part of the system. But I have every thing in place from the old system, including the heat exchanger.

Peter

Peter Marino

Flow rates

Sorry John just got the question......
Yes I have done flow rates for my 1 1/2" pool plastic and 350lb sand filter. I'm running a 1hp pump that gives a complete turn over in 8 or 10 hrs( I'd have to find my old figures).

Peter

Joe_10

HX

A couple of questions. What will be the fluid in the panels? What will you do with the heat in the off-season? Once you go to a closed loop there are a whole lot of concerns that need to be addressed. I have seen temps 325* in stagnant systems. Be careful and build in safeguards. Open loop for pools works well but copper plates do corrode after a while. Fafco makes plastic that are inexpensive and durable and designed for pool water flow.There are also controls with sensors to divert water to collectors when needed.Check the web there are sites that can help. One is aaasolar.com pretty basic site but the guys have been doing solar for over twenty years. A bit scattered but not much info to go on.
Joe

Peter Marino

I plan on running water, which will be drained out for winter (unless I get them hooked back up for DHW). I've got the array sitting right next to the pool and pump house. My main concern is that I will corrode the panels out and ruin them, if I keep running the poool water through them. I want to get them hooked back to house, eventually. Thanks for the site Joe, I've surfed the web throughly, but have not found simple heat exchanger plans. A tube, in a tube is pretty basic to do, I was wondering if there any other simple efficent designs..

Peter Marino

I'm not surprised by that temp Joe. Even in my open loop system, I have managed to melt sch 40, at the screw in copper fittings. I have since swithched to 4' of 1 1/2" copper to accept the 3/4" return from the panel.

[Deleted User]

About flow rates...

With a solar panel, especially one heating a swim pool, you want maximum flow and minimum differential. This will go counter to your thinking about generating heat. Trust me on this, with pool collectors you want to chill that baby out.

In your minds eye, which moves more energy, 1 GPM @100 degree rise, or 100 GPM at a one degree F rise. You do the math.

If you decide to turn the solar collectors into a high temp operation, the staandard flow rate for a closed loop system is .02 GPM per square foot of active solar panel. Therfore, 400 sq. ft time .02 equals 8 GPM.

Technically, you'd need 1" pipe to handle this flow rates velocity, and you should use that on the supply, but on the return, I'd recommend 3/4" on the down comer. It makes purging a delight.

If you want to continue using the collectors for heating the pool AND doing DHW once the pools topped of, I'd suggest you send the whole solar array to closed loop and set a nice fat shell and tube HX on the pool loop too. THis way you will RARELY run out of polaces to put the solar heat. Maximize your utilization. Wash all vehicles and clothes from the solar water heater and save $$.

By the way, don't go cheap. If its worth doing, its worth doing right, the first time (or 2nd...)

ME

[Deleted User]

Where...

are you located?

ME

Peter Marino

I'm on L.I. or as Dan calls it; The Isle of Long

Peter Marino

Thanks Mark for the particulars. It has 1", I just reduced to 3/4" because when I started plying with it, I had a bunch of 3/4" left over from doing the hydronic in the house. What size should the HX be? What do you think of the Quad Rod?

Peter Marino

I forgot to mention, I've got 360 gal of storage in the house. I've also got a real nice HX inside also. Just gotta pressure test it all.

[Deleted User]

The quad rod

is OKay for a double walled heat exchanger. I guess the question the remains, is do you NEED double walled protection. Double wall really impedes heat transfer. If no, I'd recommend you look more towards a flat plate/ brazed plate heat exchanger. More bang for the buck.

They'll both require a pump on both sides to make them more efficienct.

ME

Peter Marino

HX

I really don't need double wall for the pool. Which flat plate do you reccomend? I'm also thinking about building a tube in a tube system with stock parts. Is there a formula for figuring out how much surface area is needed for my panels?

flange

there are various optionas for heat exchangers, however there are coaxial exchangers out there that are used alot in refrigeration work. they are basically a coil within a coil, they can be made out of coppernickel, which makes them very strong, as well as very resistent to fouling. use them alot on water cooled systems where they are open to condenser water which is very dirty. just a thought.

Peter Marino

Thanks John,
Do have a name (manufacturer), I can check out?

hot_rod

Tony Conner HX king

hangs out around here. He can fix you up with a "mac daddy" stainless hx.

tdpindustrial@on.aibn.com or 519 6457 1393

Here is a picture of a piece of 1" pex I used to connect my solar panels. The pump was switched off one sunny day! I run copper the entire way now

hot rod

[Deleted User]

Any good manufacturer

worth their salt should be able to help you size a FPHX for your application.

Do a google search for flat plate heat exchangers.

G'Luck!

ME

[Deleted User]

That looks...

just like the piece that I applied flame to that had 100 PSI air pressure on it. OOOooopppss... BOOM!!!

Thats what happens when you're in a hurry on a Friday afternoon.

ME

hot_rod

The crimp ring held!

pretty amazing. Sounded like a gun shot when it split!

hot rod

flange

check out this link:http://www.eere.energy.gov/consumerinfo/refbriefs/bb2.html its a brief description of types of exchangers and some ideas.

flange

http://www.turbotecproducts.com/coax.htm go to this site and check out the coaxial exchangers, if you have an interest in this or any other types and need help purchasing, email me and i'll give you to a custom supplier in my area.