Water Quality in Hydronic Systems April 16, 2015 with Guest Speaker Jim Poehling, P.E., LEED AP Q&A Documentation

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1 April 16, 2015 with Guest Speaker Jim Poehling, P.E., LEED AP Q&A Documentation I liked the Water Lab that Mr. Poehling had at his work bench. Can we obtain the items necessary to have a mini lab from Caleffi? Mini Water Lab I bought the glass portion of my mini-lab on Amazon.com (5) Erlenmeyer flasks ml, $16.00 (6) pyrex test tubes with stoppers and stand $8.00 (100) 3ml plastic transfer pipettes $5.00 (5) stoppers for Flasks (hardware store) $4.00 Test equipment I bought from Hanna directly prices were in the presentation. Whole thing, including the Hach water hardness kit is less than $ Any other chemicals of chemical tests are another story. The Hach website can let you test almost anything you can come up with. State Requirements for an active fill system on a boiler Our state requires an active water fill. So if using demineralized water, we must use a purging cart to fill a system. RO water is no danger because the mineral level that it will leach out of the system are very minor before it reaches a balance point? State Requirements for an active fill system on a boiler: I am not familiar with the state of Washington s requirements. I do know that in Wisconsin, the requirement is: a flow switch, a LWCO or an active fill system for a hydronic residential boiler. The object is to guarantee that the boiler combustion surfaces are covered with water when the boiler is operational. The inspectors fully accept no feed water valves when the flow switch or LWCO are in the system. Mineral Leaching from system in the RO Adding demineralized water is only half the requirement for a system. A chemical protectant needs to be installed and checked yearly. Are there potential issues with soft metals like copper or brass reacting with de-ionized water? Potential issues with soft metals like copper and brass There are two potential issues on open systems, such as humidifiers where di water is normally seen. The DI water will be below a 7 ph from the carbon dioxide that was not removed in the DI process (Only steam 1

2 distillation would remove the carbon dioxide). The lower ph will attack most metals used in a plumbing system. The water velocities are normally quick high in these systems and help accentuate the DI water attack. In a closed hydronic system, the water velocities are normally under 3 feet per second to minimize the pressure drop. Adding a chemical protectant is also recommended to either put a shield over the metal or to raise the water level above 7 by neutralizing the carbon dioxide. When aluminum is introduced into the system, the ph also has to be controlled on the alkaline side to protect from hydroxide attack. Does Caleffi have purge and fill valves? Caleffi has a purge fill valve Part No. NA Also, I use Webstone purge and fill valves. How do you fill a system? Personally, I use a five gallon bucket with a Liberty ½ HP transfer pump to fill systems. The only thing that needs to be added to this are two washer machine hoses. I ve used the same system for 20 years. The pump shows no sign of deterioration from pumping distilled water in that period of time. Any sump pump can work. For a large system, I have the contractor rent a demineralizer tank from Culligan and hook it up with garden hoses to handle the large volume of water. If you use an Axiom 5 gallon fill tank filled with deionized or demineralized water will the water stored in the tank eventually become mineralized or raw water again? De-ionized or demineralized water in a storage tank The water will pick up oxygen and carbon dioxide from the air, but it will not pick up any minerals but sitting in a plastic tank. What if all metal in system is stainless steel or brass. Can we have PEX without O2 Barrier? The boiler system probably has a 30 year life expectancy (which is much better than a furnace). The PEX system will be there for the life of the house, probably in excess of 100 years. Oxygen will continuously seep into the piping system in the coldest part of the system (the tubing) and then be released in the hottest part of the system (the boiler); those pesky solubility laws. Yes you can use non-barrier PEX, but you need a really good air separator and not an air scoop separator. The metal in the system still need to be protected by a chemical protectant. With a non-barrier system the only chemical treatment I would recommend would be the Fernox FI treatment that uses triethanolamine and sodium molybdate. The 2

3 triethanolamine reacts with the metal surfaces to protect them from the oxygen and carbon dioxide that is getting into the system. Please explain suggested location of LWCO with a little more detail. Low water cutoff location: The low water cutoff location must meet four conditions: 1. It must be above the boiler heat transfer surfaces to ensure those surfaces are always under water 2. There must not be any valves between the boiler and the low water cutoff. 3. The water must have enough conductivity for the low water cutoff to work 4. The low water cutoff must shut off the power to the gas valve but not to the blower system of the boiler. It can be mounted on inlet or outlet side of the boiler, either will work. Comment: Water quality is critical in hydronic heat pump systems not only for minerals but also for bacteria. Water quality for heat pump system is important. The temperatures are lower, so less calcium will come out of solution. Also more oxygen and carbon dioxide will stay in solution. Most hydronic heat pumps use a glycol as antifreeze. Glycol is an organic material and will provide energy for bacteria to grow. Since most hydronic heat pumps have piping buried in the earth and it is hard to keep the pipe pristine while installing, it is very easy to introduce both aerobic and anaerobic bacteria into the system. Once in the system, the bacteria form sticky colonies and will eventually plug the water flow. Through cleaning of the system should a requirement. First clean the system to remove the dirt, debris and oils. Then rinse the system, flush with over-chlorinated water, flush the system again and then fill with the glycol water mixture. What about testing for chlorides? And how do you test for the levels? The water to fill the system is coming from a potable source, chlorides should not be an issue. EPA limits them to 4 ppm. Swimming pools are a different story; there levels may exceed 200 ppm. There are many test kits on the market, ranging from $45 to $1,500. Hach Chemical Company has a test strip that can read from 30 to 600 ppm. 40 strips cost $46.00 or they have a titration kit for $52 that should give 200 tests. It s range is 5 to 400 ppm (mg/l). It uses silver nitrate, spill it and something turns black. What about using alkaline vs acid for flushing newly installed steel hydronic system? Does it matter if it s new pipe? 3

4 Alkaline water can certainly be used to clean a new system although it will not remove any rust within the system. If a proper chemical protectant is used after the flush, the rust should be of little consequence. The important key is to remove all the grease, oil, pipe dope from the system so it will not plug up the air vents or coat the heat transfer surfaces that will impede the system heating. New steel pipe normally has some type of oil on its interior, especially when shipped from overseas. My suggestion, take some of the oil and pipe dope put it into a glass bottle with a top. Add the cleaner of your choice. Shake the mixture up, let it sit, check what s happening to oil and pipe dope. Every time you get a chance, shake it up again and check to see if the oil and pipe dope have broken down or whether they are still globs of material. If, at the end of the day, they are still globs of material, try heating the mixture (put the jar into a pan with water covering half the jar; heat until the water bath boils, then turn off). Chemical reactions double in speed for every 70 degree temperature rise. The water bath should have raised the temperature of liquid within the jar to degrees. If, after it sits for an hour, the oil and pipe dope are still globs, the chemicals used will not clean your system. What are your thoughts on electronic water treatment units? What is the effectiveness of a 5 micron side stream filter to remove precipitated solids over time instead of using DI water? Electronic Water Treatment units: Let me expand this discussion to include magnetic water treatment units. I have seen these units come into the marketplace about once a decade. With the magnetic units, just strapping two dollars worth of magnetic on the outside of the pipe will rearrange the spin of the outer electrons and prevent the molecules from adhering to one another. With the electronic units, they are operating (on most of them) as electro-margets; and for just pennies a day, they will rearrange the spin. When I was with Kewanee Boiler in the 1970 s, Westinghouse approached us and asked us to try their electronic water treatment units for steam boilers. Westinghouse had been using these devices in the plastic injection molding industry to keep the water passageway open on the injection machines. And they did work in that application. The unit would put a slight electric charge on the solids that were in the water and this would keep them from adhering to the metal passageways. However, the water had to be continuously treated to have this effect and the effect lasted for less than 30 minutes. The units that we were using at Kewanee Boiler were 480 v 3 phase 60 hertz, 20 amp devices for water flow rates of 10 gpm. For steam boilers, it did not work. For the plastic injecting industry, it does work, but at very high electrical energy consumption. The literature for these units typically have pictures of boilers that were tremendously fouled and then six months later, they are clean. The pictures are not retouched. A good friend of mine who was the head trainer for Nalco Chemical Company explained it to me this way. Those boilers that were fouled where poorly chemically treated boilers, usually lacking proper blow down. When the device is mounted on the water inlet, the chemical treatment is stopped. The boiler water starts to change as a new equilibrium of chemicals begin. The old fouling gradually removed through boiler blow down. In 4

5 about six months, if you open the boiler up, it will be spotless. Come back in another six months, it will now have hard water scale that will take years to disappear with acid cleaning. Side Stream filters In a retrofit application, filtering the return water is almost a necessity. The problem that filtering does not address is the formation of scale at the hottest part of the system and that is the combustion chamber of the boiler. Here is another failed boiler picture. 7,000 grains is equal to one pound. Given the amount of scale in the picture, which I estimate at 5 pounds just in this part of the system, this boiler saw more than 1,500 gallons of makeup water. The sealed hydronic system didn t exit. Filtration, where mainline or side stream would not affect the boiler scale in this picture. The other problem with filtration, someone must clean the filter on a regular basis and add back the water that is blown down when the filter is cleaned. Additionally, a 5 micron filter may very well have a 1 psid pressure drop at 1 gpm and 3 to 4 psid as it gets plugged up. To be effective, the side stream filter should have a pump in its circuit. When the instructor has a chance, can he address the addition of sodium to the boiler water from a softener? Sodium in boiler water: Ions, within the water solution, will have an equal number of positively and negatively charges. Sodium cations (positively charged ions), introduced from a water softening process will not normally have any effect on the attack of the metals. The negatively charged anions that came in with the sodium ions can have a very large effect. Basically, this is the study of corrosion, which is a very important subject, especially for external corrosion along seacoasts. Where I have found high concentrations of sodium in boilers, they have been steam boilers with high levels of make-up and inadequate of no blow down to control dissolved solids. It is the total amount of dissolved solids that have caused the problems, typically foaming and priming of the steam boiler water out into the system. If the initial water fill is from a potable water source, the total dissolved solids will be below 500 ppm. Even with La Crosse water at 427 ppm of TDS, I have seen no problems in any of the commercial boilers that use softened city water. # # # 5