boiler water softening/ treatment, etc

[pybyr]

for background, my domestic water, which comes from a great 180 year old spring, is both hard and acidic at the same time.

comes up as about pH 5.2 on test strips

has lots of some kind of hard minerals in it; laundry works OK, faucets and fixtures do not clog, but pots and pans scale up fast when boiled unless scrubbed.

local bedrock is a mix of granite and a limestone/ shale mix

My spring runs 24/7/365 down a gravity siphon line and out through the floor drain through my cellar, year in and out, rain, drought, whatever, so I'd be a fool to change it

but I want my new boiler install (which is progressing, slowly but surely) to outlive me.... and I want the flat plate HX between boiler and tank to not clog up

so

would I be best off to:

1) test and raise the pH of the fill of the system to 8.???something with baking soda?

2) use the "8-way boiler chemical?"

3) tote and fill my system with water-softener (Kinetico/ Sodium Chloride) - softened water from nearby relatives....

4) something else

thanks, says the guy who is heating a big ol' VT Farmhouse with a wood cookstove and some strategically placed fans to move the warm air, as he plumbs the boiler. For people like me who've gone bald, a warm cap is a good thing at night....

 

[chuck172]

pybyr brings up an important point. How important is it to test the water in a hydronic heating system?

 

[Boilerguy]

your best bet is to use the soft water and add a molybdate based closed loop water treatment, your system is not likley closed but try to keep it as closed as pracital, the molybdate product will work with oxygen present, most water treatment companies have it under there own label the one I know is GL5213 from Greal Lakes Treatment http://www.greatlakestreatment.com/ there smallest container is 5 gallons, that would last a small tight system about 10 years

 

[rickh1001]

pybyr,

I found this company that carries boiler chemical for commercial operations. They also sell to individuals.

http://www.BoilerandCoolingWater.com

The product is very economical. It comes as a solid, and one jar treats up to 800 gallons of water. They also supply test strips for measuring nitrite concentrations, and pH test strips. They state that you can't overtreat the water, so I added almost 2 jars to my 500 gal system. I checked the pH (I am a chemist, and we have our own analytical laboratory) and it came in around 7.5 after the system stabilized. Rather than buy one of the cheap, inaccurate hand-help meters on EBay, I would recommend you just get some pH test strips. I think you definitely want to be up over pH 7 for durability of the steel. If you have a good airscoop in the system, once you get rid of the initial oxygen, it should stay oxygen free, and the chemicals will buffer the pH to the correct level.

 

[pybyr]

Hmm- I keep looking into this and asked Econoburn and also a relative who knows chemistry better than I do'


Apparently, most boiler chemicals are based around compounds of sodium + something else (even the molybdate ones like Great Lakes, referenced in the post above)

Also, apparently, sodium causes corrosion issues of its own in a boiler over the long term. I assume sodium compounds are generally used mostly because they probably are easier and less expensive to formulate than other things.

Someone, like Adios Pantalones, who really knows chemistry and/ or boiler issues please help me understand what it is about sodium that causes boiler issues, and whether other alkaline compounds that I might use instead (pottassium or ammoniate based?) might help me raise the pH of my system with fewer drawbacks than the off-the-shelf sodium-based ones).

the pH of my water is down around 5, as best I can tell, so left to itself, that seems to bode eventual corrosion issues, but I don't want to merely trade one form of corrosion for another.

Thanks, all!

Trevor

 

[stee6043]

pybyr,

I found this company that carries boiler chemical for commercial operations. They also sell to individuals.

http://www.BoilerandCoolingWater.com

The product is very economical. It comes as a solid, and one jar treats up to 800 gallons of water. They also supply test strips for measuring nitrite concentrations, and pH test strips. They state that you can't overtreat the water, so I added almost 2 jars to my 500 gal system. I checked the pH (I am a chemist, and we have our own analytical laboratory) and it came in around 7.5 after the system stabilized. Rather than buy one of the cheap, inaccurate hand-help meters on EBay, I would recommend you just get some pH test strips. I think you definitely want to be up over pH 7 for durability of the steel. If you have a good airscoop in the system, once you get rid of the initial oxygen, it should stay oxygen free, and the chemicals will buffer the pH to the correct level.

I purchased this just last month based on your thread from a long time ago. They shipped fast at the dry chemical was very easy to work with. Two small jars treated my whole system and it was something like $70 delivered. Much cheaper than other treatments I've seen....

 

[rickh1001]

pybyr,

Sodium in itself is not harmful to steel that I know of. Chloride of course is, but sodium ions are fine as far as I know. It is just the salt form of the main compounds. The anti-oxidant in the chemical treatment I mentioned is a nitrite (they don't say if its in the sodium or ammonium form). The nitrite is being preferentially oxidized to nitrate, and thus serves a purpose similar to a sacrificial anode in a water heater. They also mentioned adding some sequestering agents to help tie up some of the Ca and Mg, as well as some lubricants.

My wife and I are both analytical chemists with 30 years experience each, and I couldn't make heads or tails out of this whole boiler chemical business. I tried to buy some books on the subject, but it is most definitely its own specialty field, covering everything from nuclear reactors down to home boilers. Everything was highly confidential with only hints at the specific chemicals added. The one available from Cozy Heat seemed quit complex - although perhaps it is necessary to do the several step procedures the product they carries recommends.

In the end, the pH of the boiler water should not be acidic (below 7), which is the purpose of whatever buffers they add, in addition to everything else. While you could use washing soda or baking soda, or trisodium phosphate to bring the pH up, it is difficult to calculate the exact amounts needed, and then their is their potential effect on the lifetime of the circulators. In the end, I gave up trying to figure everything out, and it was a whole lot easier to just buy a jar or two of some (hopefully reliable) commercial stuff and dump it in the tank before you fill it. I referenced the one in my post, because everyone else I found only dealt with large commercial customers, or they were a service who wanted to come to my home and monitor the system periodically, like they do for large installations. The Cozy Heat one should certainly be suitable as well.

 

[sweetheat]

my daily experience with hard mountain water has been an ongoing build up of minerals if left untouched in your pipes, tea kettle and boiler. In my 806 gallon open storage system it took 3 boxes to acheive a PH of 8.2 natural baking soda is recommend! sweetheat

 

[jebatty]

I'll chime in on this again, fwiw. If an option, I think I would go with soft water. I don't think scale actually will be much of an issue unless you are adding water periodically, that is, adding minerals. I think a closed system should have minimal issues from hard water; an open system will have more issues, as you will be adding water from time to time.

Ditto on oxygen related corrosion. A closed system will quickly consume oxygen with minimal rust corrosion, and that will be the end of it. An open system will be of more concern, as adding water will also add new oxygen. Sodium sulfite is a common O2 scavenger.

Water pH is a concern. pH of about 8.2 is what Tarm recommends, I think. Anything between 8-9 should be OK IMO. Whether closed of open, you should treat the water to raise pH.

Following is from a prior post of mine on this issue.

+++

“Principal concerns are pH, total alkalinity, and O2 scavenger. Acidic water (pH less than 7) can cause lots of corrosion.

“O2 scavenger (sodium sulfite and other chemicals): follow directions provided by boiler chemical supplier.

“Total alkalinity: 200-700 ppm based on what I’ve read; buffers acid changes. Various chemicals used here.

“pH: this also relates to total alkalinity; pH of 8-9 probably OK. I used sodium hydroxide (lye, caustic soda). This is dangerous to work with, follow directions carefully.

“I used a swimming pool test kit to test total alkalinity and pH. Made a guess based on supplier recommendations for O2 scavenger. My system is closed, so if pH is OK, the rest should work out without problem.”

Google sodium sulfite or boiler chemical and you should find suppliers. Although I used it, I’m not convinced this (or other oxygen scavengers) is needed in a home, wood boiler, closed system. Any O2 in the initial water fill should be consumed quite rapidly (rust) and then be over. In an open system this will be more of a concern, and in any system where water is being added periodically, this will be a concern. Test kits are available; I’ve never used one, except a swimming pool total alkalinity test kit.

pH and sodium hydroxide. Note comment on “dangerous” above. I found this readily available at a local hardware store. You test for pH with litmus paper. Google that and you will find suppliers. Health food stores also may stock litmus paper which will test into the 8-9 range. Also swimming pool suppliers have test kits that test for pH.

In my experience pH is the most critical in home, wood boiler setup, open or closed, and even more so if open and water is being added periodically. My water supply had pH of 6.5, acid, and I got lots of rust in my initial open storage system before I took the time to discover why. My new system is closed, 1000 gallon storage, and I checked pH after filling and added sodium sulfite per directions from supplier and then sodium hydroxide to get pH at about 8. Other than a small, initial burst of rust, the water now is crystal clear, no further chemical treatment needed.

Your water supply may be closer to pH 7 or a little above 7 (base). This would pose much less a problem than pH less than 7.

 

[chuck172]

Thanks Jim, I've been meaning to test my ph.
Now I know what to look for.

 

[Adios Pantalones]

Ideal water would have no dissolved oxygen, neutral pH, little salt concentration, and be soft (for scaling issues).

Get the pH near neutral. Lots of good treatment options out there. Remember that many water softening sustems substitute salt for the hardness, so there is a tradeoff over the long term.

 

[penfrydd]

Why does it matter whether or not the system is closed or open? Are we not referring to the storage water? That water doesn't end up inside the boiler, correct? What's going to corrode? The outside of the coils? All the hydronic systems are "closed" with reference to the water in the pipes and radiators and boiler, aren't they?

Am I missing something major here.

Penfrydd
Tarm 40 sitting on pallet, waiting for time and someone to do the very final install

 

[sdrobertson]

Why does it matter whether or not the system is closed or open? Are we not referring to the storage water? That water doesn't end up inside the boiler, correct? What's going to corrode? The outside of the coils? All the hydronic systems are "closed" with reference to the water in the pipes and radiators and boiler, aren't they?

Am I missing something major here.

Penfrydd
Tarm 40 sitting on pallet, waiting for time and someone to do the very final install

A totally closed system runs the water from the boiler directly to the storage and heat loads and back to the boiler. Its pressurized and you don't need any heat exchangers so the water is always mixed between the boiler and rest of the system.

 

[rickh1001]

penfrydd

The outdoor wood boilers are pretty much all open systems, while pressurized water boilers are closed. Open systems mean just that, that the circulating water is exposed to air, thus allowing oxygen to slowly dissolve into the water, causing corrosion. Pressurized systems, such as the Tarm, Eko or Econoburn ones common on this forum, are sealed. Once the dissolved oxygen is removed by the air scoop and/or reacts with the iron in the system, it is depleted. Unless fresh, oxygen bearing water is added, or the system is opened up, the dissolved oxygen will remain negligibly low. Chemical additives such as sulfite or nitrite are extra insurance that any oxygen finding its way into the system are consumed by these chemicals first, rather than with the steel. That is why outdoor boilers need to use a HX to pass heat to a normal closed loop conventional boiler, and why it is necessary to use oxygen barrier PEX in a closed loop boiler, since oxygen can diffuse through regular PEX and continuously get into the circulating water. Any open boiler system is going to suffer from potential oxidation (rust) and corrosion, to a much greater extent than closed systems, which can last practically forever if treated properly and kept leak free.

 

[jebatty]

Ideal water would have no dissolved oxygen, neutral pH, little salt concentration, and be soft (for scaling issues). Get the pH near neutral.

I haven't seen a boiler water reference that recommends neutral pH -- all recommend pH in the 8.0-8.5 range. I think the reason is that neutral pH can be thrown off substantially by introduction of very slight amount of impurities, and "throwing off" into the acid range spells big trouble. Therefore, pH in the lower 8 range is recommended. Perhaps this relates more to steam than hot water boilers, or more to open rather than closed systems, but I haven't seen any literature which draws that distinction definitively. And even in a closed system, it seems to me that introduction of new water, or loss of pressure and introduction of air (CO2), could result in acidification.

Help me understand why neutral pH is better.

"Since high purity water has no buffer capacity, addition
of even the slightest amount of foreign material
may change the pH significantly. Hence, some drifting
of the pH is to be expected unless extreme care is
taken."
(broken link removed to http://www.emersonprocess.com/RAIhome/documents/Liq_AppData_4900-85.pdf)

"Acidic Attack. If boiler water pH has dropped significantly below 8.5, a phenomenon called waterside thinning can occur. The normal manifestation of acidic attack is etching. In areas of higher flow, the surfaces are smooth. In addition, any stressed area would be a principal area for attack."
(broken link removed)

See also:

(broken link removed to http://www.energysolutionscenter.org/boilerburner/Eff_Improve/Operations/pH_Treatment.asp)

(broken link removed)

 

[Adios Pantalones]

Ideal is never reached or maintained- it's theoretical. Sorry, I do that a lot

Near neutral. 8 is pretty close (yes, I fully understand the hydronium/pH relationship). It shouldn't get thrown off too easily if buffered with additives suggested by boiler folks above.

as for oxygen, I would guess that most could be blown off when the system is heated as hot water does not hold much dissolved gas (CO2 would be an exception if forming carbonic acid- but that's a reaction more than a straight dissolution). make up water would carry more gas.

I didn't know about the 8.5 pH being some magic number, but I'm a chemist not a boiler dude. I can make metal corrode or replate, but pump it around your house etc. and it does funny stuff

 

[pybyr]

Thanks A.P. & everyone else. I have decided to fill and initially run with tap water, then at some point I will either drain and refill with softened water or leave the original fill water in and add some treatment to get the pH right.

 

[pybyr]

Ideal is never reached or maintained- it's theoretical. Sorry, I do that a lot

my idealism is crushed, just crushed !

 

[Garth B]

Found a couple links about water treatment in steam boilers
The first states the following;
Boiler water must contain a certain amount of causticity (i.e. Hydroxide alkalinity in order to accomplish three things:
1. To maintain a protective coating of iron oxide over the metal and thereby prevent certain types of corrosion.
2. To provide a proper environment for precipitation of desirable sludge materials.
3. To keep silica in solution so as to avoid deposition of silica scales.

(broken link removed)

The second pertains to dissolved O2, my wife works in a lab and is bringing home thier dissolved Oxygen meter tonight so we can test the water in my closed system, I am anxcious to see if the air scoop and automatic air valves are enough to take o2 levels down to an acceptable level. I was told an air separator should be installed to remove "microbubbles" but have read that air should have mostly come out of solution at 150deg. We will see soon enough

(broken link removed to http://www.scrantonassociates.com/techarticles/soc.pdf)