Electrolysis

David Ashton

I have a older radiant floor heating system. The slab mats are Solaroll, with (6) 3/16" tubes per mat, in a closed loop system with a 40% mix of propylene glycol. Its powered by a PowerVent Model HI-B by Hydrotherm, 85000btu.

My cold water supply line and return from slab line are 3/4" copper with various brass valves. On the discharge side (returning hot to house slab) the riser is galvanized pipe, 1-1/2". Its approx 3' tall and turns to support the expansion tank and exp tank relief valve, then connects to brass then back to copper. Photos attached.

We have sprung a leak in the galvanized where it connects to the exp tank pressure relief valve. I am now told that galvanized pipe has an electrolytic reaction with both cast iron, black pipe and the glycol mixture. I know you cannot connect gal. to copper but am not aware of electrolysis between gal and black, or gal and glycol, and gal and cast iron.

1. Is there a reaction between gal and cast/black?
2. Does gal react with glycol?
3. Since I have a leak in the gal pipe where it connect to the expansion tank relief valve, should I replace the riser in copper?
4. If its replaced in copper, how do I isolate the copper from the cast iron boiler tank?
5. How do I isolate the copper from the expansion tank pressure relieve valve?
6. Why would gal ever have been used?
7. How can I test the boiler tank to ensure that electrolysis hasn't degraded the tank?

Thanks for any advice.
Dave

ALH_4

Oxygen

I think you have an oxgygen diffusion issue through the Solaroll causing a rust problem inside the pipes. I don't think this is electrolysis. Galvanized pipe will react with antifreeze, so it should never be used in a heating system. The Solaroll should be isolated from the iron parts of the heating system with a heat exchanger.

hr

Ugly

it's the zinc in the galv coating that will react with inhibited glycols.

Regardless though that tube does not have any O2 barrier. As such it will deplete the O2 inhibitor in your glycol. Assuming you are using an inhibited hydronic glycol?

I'd test the ph of the fluid, that's a good indicator of the quality.

I agree that you would be best to separate the heating loop from the boiler. Use non ferrous components in the heating loop side. I prefer the stainless pumps to the bronze bodied.

Pressure test the entire SolarRoll system to assure you don't have any small leaks.

Do you really need glycol? It does bring some seep baggage and maintenance requirements. Especially in a non barrier system. A necessary evil ? !

hot rod

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David Ashton

help

> it's the zinc in the galv coating that will react

> with inhibited glycols.

>

> Regardless though that

> tube does not have any O2 barrier. As such it

> will deplete the O2 inhibitor in your glycol.

> Assuming you are using an inhibited hydronic

> glycol?

>

> I'd test the ph of the fluid, that's a

> good indicator of the quality.

>

> I agree that

> you would be best to separate the heating loop

> from the boiler. Use non ferrous components in

> the heating loop side. I prefer the stainless

> pumps to the bronze bodied.

>

> Pressure test the

> entire SolarRoll system to assure you don't have

> any small leaks.

>

> Do you really need glycol?

> It does bring some seep baggage and maintenance

> requirements. Especially in a non barrier system.

> A necessary evil ? !

>

> hot rod

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 144&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_



We do need the glycol because the house is located in the Sierra Nevada mountains and during the winter is often below freezing. The house is used only on weekends, and can often sit vacant for a couple of weeks at a time without any heat whatsoever. We have it installed with a telephonic device that allows us to call the house, dial in a code and activate the system on thursday for a Friday night arrival.

So based upon our photos, any recomendations on how to install a heat exchanger and how we would replumb the system. We hired an outfit that said they specialized in boiler installations to put this in back in '93. I guess they really didnt know what they were doing.

Question on the water makeup valve. The system is close looped, but we have to add water to the system periodically, especially since the galv pipe sprung a leak. We have been leaving the cold water makeup valve open during operation. The valve they installed is a standard ball valve. Shouldnt this be a check valve so when we turn off the water supply to the house when we leave, that the fluid doesnt get sucked out of the radiant floor system?

What the heck do we do about this system?

hr

The skis and chain saw blades tipped me off to your locale

Fond memories of those Fishers with the Markers!

Really you don't want a water fill system connected to your glycol system. Solaroll holds a very small amount of fluid and even a gallon of water will dilute your glycol freeze protection.

A heat exchanger fix is fairly easy. I've used flat plate, tube and shell, or even a small indirect tank. Any device that has two separate fluid paths will work.

In your case you would still want to glycol the boiler side and the tube side I suppose? Although the fill system with water doesn't have any freeze protection currently?

If in fact the system loses more than a few cups of fluid over the summer SOMEWHERE there is a leak. In your case it could be all those seeping threaded joints. I'd prefer to see it repiped with all soldered connections, personally.

A glycol fill system could be added to assure it maintains pressure on both A & B sides.

You have a bit of work, and expense ahead of you to accomplish all this. Be 100% sure that SolarRoll is worth the expense. Some held up well over the years. Others in the Rockies of Utah, my former stoomping ground crashed big time. Operator error as much as anything, but the non O2 barrier was a ferrous metal consuming machine. Usually a pile of dead expansion tanks around the boiler

hot rod



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David Ashton

> Fond memories of those Fishers with the

> Markers!

>

> Really you don't want a water fill

> system connected to your glycol system. Solaroll

> holds a very small amount of fluid and even a

> gallon of water will dilute your glycol freeze

> protection.

>

> A heat exchanger fix is fairly

> easy. I've used flat plate, tube and shell, or

> even a small indirect tank. Any device that has

> two separate fluid paths will work.

>

> In your

> case you would still want to glycol the boiler

> side and the tube side I suppose? Although the

> fill system with water doesn't have any freeze

> protection currently?

>

> If in fact the system

> loses more than a few cups of fluid over the

> summer SOMEWHERE there is a leak. In your case it

> could be all those seeping threaded joints. I'd

> prefer to see it repiped with all soldered

> connections, personally.

>

> A glycol fill system

> could be added to assure it maintains pressure on

> both A & B sides.

>

> You have a bit of work, and

> expense ahead of you to accomplish all this. Be

> 100% sure that SolarRoll is worth the expense.

> Some held up well over the years. Others in the

> Rockies of Utah, my former stoomping ground

> crashed big time. Operator error as much as

> anything, but the non O2 barrier was a ferrous

> metal consuming machine. Usually a pile of dead

> expansion tanks around the boiler

>

> hot

> rod

>

>

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 144&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_



Well, I sure appreciate the help. This is a bit frustrating, because I basically have to start over.