By Tom Secondino, Technical Sales Support Specialist for U.S. Boiler Company
Two young fish were swimming along one day and happened across a much older fish swimming towards them. As they passed, the older fish smiled and said, “Hey boys, how’s the water?” The two younger fish glanced at each other and swam past. A few minutes later, one turned to the other and said, “What the heck is water?”
I promise this will not be an article on existential angst! It is going to discuss the medium we all work with and how painfully unaware we can be of its unique properties and the importance of addressing potential issues before they become problems.
Our industry is changing more rapidly now than ever before. Due to price points, federal efficiency mandates, and changes in consumer demands, the manufacturers of today’s hydronic heating products face increasingly challenging criteria in designing competitive products that provide reliable service and safe, efficient performance. Due to these changes, today’s heating professionals are required to be more educated about all aspects of the trade, particularly moving heat from the boiler to the intended process site or heat emitter.
I would like to state at the outset that this will not be an exhaustive treatise on water composition, chemical make-up, erosion and deposition rates and processes, etc. There are extensive resources on the web which can provide all the information you can ever need (and then some!) and can answer your specific questions once you know what questions to ask. This month’s tech tip is designed to help you know when, why, and which questions to ask so you can find the answers you need.
When speaking with technicians who call our tech support line, we frequently discuss water quality. While reviewing potential system issues or worse yet, boiler failures, we will often review water quality. One technician was asked what his test procedures were before adding water, to which he gleefully replied, “Welp, it has to be pretty dang wet, son!”
Prior to installing a new boiler or diagnosing system problems you should assess the system and gather info to answer the following questions:
- What type of heat emitters or end processes will the new boiler serve?
- What is the material, approximate age, and condition of the existing piping and heat emitters?
- What type of boiler will perform best in this application?
- What do I need to provide to protect the boiler?
- What is the quality and composition of the fluid I will fill the system with?
Let’s look at a few examples and see why water quality can be so important.
What is it?
Deterioration of the internal surfaces of the system components or boiler due to excessive water feed or reaction between materials.
Internal corrosion can lead to costly system damage or early boiler failure.
What should I look for?
Older system with steel or iron components, especially when installing condensing products. With large expansions of gas mains occurring across the country, many contractors are tasked with installing condensing boilers, many of which are stainless or aluminum. In contrast to the cast iron heating systems we have installed for decades, these heat exchangers require contractors to consider factors that some in the industry are not aware of. Systems today contain a host of different materials which can cause adverse reactions if not addressed. Due to the system water creating a conductive path between dis-similar materials, erosion and/or unwanted deposition can occur.
How can we avoid this? Prior to installation, it is strongly recommended that, where possible, the existing boiler be left intact and a cleaning solution be circulated through the system prior to boiler replacement. After replacement, fill the system with water and then run the system. Drain boiler again and then fill with fresh water and a chemical treatment designed to prevent any reactions from causing deterioration of the system. Of particular concern are ferrous particles which will collect on the rotor/impeller of ECM pumps and contribute to early pump failure. Chemical treatment will help minimize this process. As always, any system leaks must be addressed prior to a new boiler install as any hydronic boiler will experience a shortened life when fed a constant diet of oxygenated water. Steam systems will be addressed in later paragraphs.
What is it?
Material which ends up in the circulated solution. This can be in the form of dissolved solids in the fill water, rust or scale from old system piping or radiators, or material introduced to the system during installation.
This material can be deposited in the boiler causing hot spots and early failure or can potentially clog water passages in water tube boilers.
What do I look for?
Older systems, particularly those with old steel piping, iron fittings and/or cast iron radiation. The debate rages on regarding filtration.
>> One of our tech team members, Rick Johnson, wrote a recent article on this topic for a more in depth look at system filters.
Some technicians historically have omitted installing any means of filtration for system water and there are those who feel a Y-strainer is sufficient. However, today we see an increasing number of installers using magnetic strainers which pick up not only larger particles carried by the system water but also ferrous particles which can be damaging to ECM pumps. This is always important to consider, but increasingly so when using cast iron sectional boilers or firetube condensing boilers. In a boiler with large open cavities on the water side, the water velocity through the boiler will drop and any material carried along by system water will usually drop out of suspension at the point of lowest velocity. This turns the boiler into a giant dirt trap. We recently received a cast iron boiler back which had developed a leak in the chamber area. When the boiler was cut apart, there was several inches of mud/system debris deposited on the interior surface of the exchanger. Failure due to system contaminants is not considered a manufacturer’s defect any more than filling the gas tank of a new car with pickle juice. However, this fact does not make the conversation less painful for any of the parties involved, including the manufacturer. Mag-strainers are great idea for cast iron boiler applications and can be critical for condensing boilers. An often overlooked application for strainers is on the wet return of a steam system, which can be loaded with mud/sludge/scale. A good full-size mag strainer and system treatment is cheap insurance against a potentially unpleasant and unnecessary failure.
Fill Water Quality
What is it?
We have to fill the boiler with some type of medium, whether that be straight water or a water/glycol mix to move heat from the boiler to the heat emitters or process equipment.
The quality of the fill water can have a significant impact on the level of corrosion that takes place in the boiler.
What do I look for?
As water tables become more contaminated from street run off, municipal water supplies are more heavily treated, and more homeowners are installing water treatment systems. The contractor is required to give additional consideration to the quality of water the boiler will be filled with. Most of our manuals list water quality specifications which should be reviewed and compared against the water onsite. Water with high chlorides, excessive total dissolved solids, and pH which is out of range when compared to the specifications found in the manual, should be cause for consideration.
Certain areas of the country experience extremely high chlorides in potable water. This is important to consider with any boiler but even more so with steam boilers. High chlorides will leave corrosive deposits on the water jackets of the heat exchanger leading to early failure. Considering that steam boilers will require make up water volumes that hydronic systems do not normally experience, it is critical with steam systems to minimize required make up water by ensuring that all system vents, traps, etc. are functioning correctly and that there are no leaks in the steam piping or returns. We strongly recommend that if a water feeder is used, the chosen unit includes a display which indicates total water volume used which will also maintain the water at the normal water level, rather than at the lowest permissible level. If an auto feed is not used, a water meter should be installed, and the water volume fed to the boiler documented monthly. Water use above the maximum listed in the manual should trigger an exhaustive review of the system to determine where the system is losing water.
Another item to stress in a steam application is water pH, as out of range pH can cause foaming issues. We’ve experienced some projects where the water is so problematic, that the contractor trucked in water in barrels to fill the system. Filling any systems with softened water should also be avoided where possible, but particularly with steam boilers.
What is it?
Applications where the piping or heat emitters/process station are subjected to potential freeze conditions require antifreeze to prevent system damage. Water is typically mixed with propylene glycol in these situations.
Glycol can change the system dynamics and requires that the boiler, system and pumps be engineered to facilitate the solution.
>> If you would like more information, last month’s US Boiler Report had a great article on glycol!
What do I look for?
Applications such as hydro-air systems with FCU’s located in areas subject to freezing (think attics/garages, snow melt systems, etc.) may require glycol mix. A common question is, “What should my mix ratio be?” The answer is no more than you need! Our products are designed and rated for a mixture of no more than 50% glycol, but the less glycol required the better. Many pump manufacturers rate their products at no more than a 50% mix. Many seals cannot tolerate a mixture greater than 50%, and you may end up with leaks where you would not have should you exceed the 50% ratio.
As mentioned in last month’s article, glycol systems should be checked regularly, not only for freeze protection but also pH. Glycol systems left unchecked can go horribly wrong, causing extensive damage to system components. System components must also be designed to accommodate your intended mixture as glycol mixes will have less heat transfer and create greater pumping losses than straight water. As mentioned in last month’s article, a water feeder connected to potable water is always a bad idea in a glycol system. A glycol make-up station should be installed to avoid system dilution and potential freeze damage. Finally, softened water added to glycol can be particularly difficult to correct for pH.
What is it?
The water that comes out of your faucets.
“Hard water” can leave deposits on domestic coils, whether that is a flat plate exchanger in a mod/con combi unit or a tankless coil on a cast iron boiler.
What do I look for?
If you are installing a unit that will serve the domestic hot water demands of the house, you may want to suggest the homeowner have the water tested or include it in your price. If the water quality is an issue, consider filtration if not already present. Also consider using a device that will reduce the potential for fouling the domestic heat exchanger surfaces. An inline unit, such as a Cuno AP430, can be used, or, any substantially similar product from alternate manufacturers. The media in this unit will coat the internal surfaces of the flat plate or tankless and prevent any water borne contaminants from sticking to and fouling the exchanger.
In conclusion, Samuel Clemens said it best. “Sometimes it ain’t the things you don’t know that get you, it is the things you are positively certain about that just ain’t so!” Burying our collective heads in the sand or relying on historical experience without considering technological changes can land us in hot water (see what I did there?). Our trade has become so diverse, it is difficult to always know the answer. But knowing the right questions to ask and having the resources available to help walk you through your learning curve is half the battle. And, as always, the U.S Boiler team is here to help!
It’s been a rough year for us all. The team at U.S. Boiler Company would like to thank our partners for your continued support and hope that you and your families are safe and healthy. We’re sure you join us in gladly leaving 2020 behind and looking forward to the coming year. Stay safe!