Aluminum and glycol - (PAH)

Dave Yates (PAH)

Was called to see what can be done with a solar system whose aluminum tubing was run on the exterior of the home and cut off to accomodate a new addition. They want it re-connected.

First time I've ever encountered aluminum tubing and with glycol laden fluid no less! The installer must have been scratching his head a bit way back when this was installed as the panel connections appear to be short pieces of garden hose clamped over the connections between panel stubs and the al tube.

The HO dumped the solution too, so we're starting from scratch.



<A HREF="http://www.heatinghelp.com/getListed.cfm?id=98&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"</A>

hr

Is it glycol?

There were a lot of heat transfer fluids used over the years. I am removing an old (16 years) system on some apartments in Arkansas. It has a fluid called Slytherm. A Dow product that looks like glycol but is more like oil. A silicone based product with a very high temperature range, I believe.

I've also seen some transfer fluids that look like ATF. Make sure what you put back in is aluminum friendly. Check the ph of the fluid if you are reusing any. Happy solaring!

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

Dave Yates (PAH)

Reynolds Aluminum

model #100 crown top heat exchanger perched atop a Bradford White 80-gallon solar tank.

Solar Systems Command Module #CM-30

Panel is 4' x 12'- label is sun-burned beyond recognition.

Warnings on labeling regarding toxic glycol solution within system - HO drained & tossed.

I can't find a connection to Reynolds Aluminum for solar systems. Sure would be handy to have the installation & operating destructions! Longing for the early 70's here.

Can't see any reason why copper won't do & I'm not too keen on the aluminum stubbs on the panel. No wonder they used hose & clamps. The aluminum tubing sure does bend nicely and appears to be in good condition (if only they'd called before hacking it into short pieces).

T'was fun being on the roof in 65 mile per hour gusts of wind today. Felt like a PAH-kite(G).

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

hr

I'll bet

it had basic automotive anti freeze in it, it's aluminum friendly.

The CM-30 is a Goldline number, although it could have another solar company label on it. They are still available from Graingers and others, called a GL-30 now a days.

It's a nice control for wood boiler/ buffer tank controlling, as well as solar systems.

Copper could be a good choice, but I wonder about electroylsis if it got wet? Remember some of the aluminum panel baseboard

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

Mark Eatherton1

More troubles than you'd think...

Dr. George Lof (pronounced lerf) told me of a problem job he'd had once. Seems the installers on the roof were cutting the aluminum leg stock with Sawzalls on 5 gallon buckets.

Once the collectors were mounted, the saw horse buckets then became mixing buckets for the glycol. Eventually the glycol pyrolized due to stagnation. When circulation was eventually restored, the small pieces of aluminum got thrown into the mix, and bounced their way merrily around the piping circuit. It seems that where ever this happened, and aluminum came into contact with the copper pipe, just enough molecules of the aluminum were displaced into the copper to set up an electrolytic action that eventually turned the copper into swiss cheese. Bummer.

The pH had probably gone south and "helped" the process of failure.

Ya gotta keep a real sharp eye on the pH of aluminum, and it's not the same as it is for steel/copper systems.

Maybe the Rhomar guys will step in here and straighten us hot water jockies out:-)

RoyWhoo!

ME

Dave Yates (PAH)

salvation

If not, perhaps salvation can be had in Vermont(G)!

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

Drew_2

Alluminum Ph

The attachment is information I've picked up on Ph, Glycol and Metals. Hope it helps.

George_10

This situation that you have in hand

brings to focus many associated problems in both cleaning and treatment.

1) If you attach aluminum and copper tubing together somehow, without dielectric unions you are almost assuring galvanic corrosion at these system points. If you use brass couplers you have not solved the problem as you still have two different metals.

2)Since you are not sure what was in the system fluid originally, I would definitely clean it thoroughly with our Hydro-Solv 9100 and thoroughly flush it to make it as baseline clean as possible.

3)I would then add our Rhomar 922 to your glycol and water solution so as to protect the metals in the system including the aluminum and make sure that the pH is between 7.5 and 8.5. It would then or should be checked yearly.

4) I would also make sure that the water you use is not high in CL as this is deadly to aluminum. You could fill it with DI water and glycol and our 922 to be extra safe.

As you can see, you have an interesting job to solve and it is not as simple as it would look on the surface. The pH is the killer here as it cannot be too low or too high. The ranges in the aluminum doc are just about right.

Dave Yates (PAH)

tasty!

George,

If possible, please fax the information regarding pricing and shipping to 717-843-4111

Thanks & Happy New Year

Dave

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

Dale Pickard

Reynolds Solar

Hey Dave,

I read your post on the wall. I installed a Reynolds solar system a LONG time ago. The absorbers and piping was aluminum and the connectors were high temp silicone hose. This was to prevent dielectric corrosion between the steel HX and the aluminum absorbers and piping. This was a drainback system. Rheem made a dhw tank with another tank surrounding it. There was a sump at the bottom of the outer tank. The collector return flow would come in the top and dribble over the outside of the inner tank holding the dhw. They gave us some nasty looking heat transfer fluid to use, I have no idea what it was. The collectors were aluminum framed, of course, and glazed with a polyester film material that 3M was producing for a while. Hopefully yours are glass.

I'd suggest using the same glycol additives that MZ recommends for their boilers with the aluminum HX. The alloy used in the tubing could easily make a difference as some of them are more corrosion resistant than others. Good luck.

The solar industry learned that aluminum was not the material from which absorber plates should be made.

Dale

Dave Yates (PAH)

Thanks

Dale,

So far we're only being asked to install new risers up and through the new addition's walls/roof (ahead of the drywall contractors) and the owner will decide if he wants to spend the money to restore the system.

Awaiting the fax from Rhomar!

I have no choice on such short notice but to run copper lines. If the panel is shot, that will be the material of choice anyway.

Thanks,

Dave

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

Dale Pickard

Piping

My next choice would be PAP. I think that the copper pipe would kill it in a hurry. You definitely don't want to directly connect it to the aluminum. If the absorber plates corrode, you're screwed. As I understand it, due to the position of the two metals on the galvanic scale, the aluminum will go into solution, and plate out on the copper or steel, so the the aluminum will be corroded. Reynolds also recommended the use of sacrificial "getters", which consisted of a cylinder of aluminum or magnesium shavings in the water way. Same use as how the magnesium anode rods protect a water heater from the steel tank.

I think that you might use PAP in a solar system as long as the first few feet of pipe on the supply and return were metal, in this case aluminum. I wouldn't connect the plastic directly to the absorbers. A drainback system won't give you the pressure problems that a closed loop system will give you. Good luck !

Dale

canuckDale

I'm with Drew

Al is an amphoteric metal. Meaning it's reactions to acids and bases is the same...corrosion.

Those metals require neutral pH for optimum service. That's why when the Jap-econo cars first arrived, Pep Boys and Canadian Tire sold specific glycol for those Al intakes, heads et al.

Those glycols went by the wayside because buffering agents can keep the pH...with normal maintenance...@ 7-9. Seven being the place, and 9 won't hurt that much. Additionally, azoles were added to 'film' those copper/Al alloys.

Don't change the antifreeze every 3-4 years? It's going to go acidic. Slight caustic is not the enemy of most metals.

Happy New Year!

Dave Yates (PAH)

PAP - Viagra PEX - Riles???

I was concerned that PEX might become exposed to sunlight as the years go by (a crack or bird pecking through the insulation cover) or that a pump failure could well lead to temperatures beyond rated levels.

CL is not an issue (it's well water). TDS and other contamination might be though due to a very large landfill being nearby.

I've got a fair amount of Wirsbo's PAP in stock. We used a ton of the 1/2 and 3/4 inch PAP when we converted a mansion's rads from steam to hot water and used Wirsbo manifolds with telestats to zone rooms on the first floor. The PEX had to run exposed through a basement hallway, so neatness was wanted and droopy expansion wouldn't be tolerated by the owners. PAP to the rescue!

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

Dale Pickard

PAP

The first few feet, as in anything exposed to the sun, should be done in aluminum with the silicone hose connections. Use the same hose connections to connect to the PAP....I know it's funky, but that's what they did. Maybe the HO has some of the tubing left over.

No way would the collector loop hold potable water. There has to be a HX involved. This really is a pretty funky system. It's possible to buy copper absorber plates that may fit the enclosures. If they are worth it. Are the collectors glass glazed? It truly may not be worth the labor to reinstall it. How much do you pay for fuel??

Dale

jw

UV resistant PEX -AL-PEX

Check out Ipex's black PAP as it is rated for indefinite exposure to uv. May be the answer you need.

jw

Drew_2

pH, AL and Fluid Temps

We produce a product for multi-metal systems. Noburst AL. It is both propylene glycol and multi-metal inhibitor. If anybody would like to see the ASTM test results, just drop me a line.

I would worry about using propylene glycol in some solar systems, they will have skin temps of over 300 degree F. This will cook propylene glycol, ruining the fluid as well as the system.

Drew