Case Study! Chemical Treatment

James R. Stringer

Background: like many buildings and properties around the world, austerity measures had to be taken during the Covid-19 pandemic to cut costs. By doing so at this particular facility, chemical treatment took a backseat to any maintenance for 2 years. Eventually, the hot water heating (HWH) system turned from a normal well taken care of system to a bit of a problem child.

For any outdoor air temperature above 20° C, the heating pumps would turn off and not come on; over the course of several years, this did not help keep the water from becoming stagnant. Heating valves around the facility would close and remain closed if heating was not needed, further allowing the HWH water to become stagnant. We found the air vents were clogged and were not properly allowing oxygen, carbon dioxide, and any non-condensable gases to escape. Though a corrosion inhibitor was added through the years, samples of the HWH were not lab tested that could have portrayed a story of deterioration.

HWH water drained from a point in the boiler room.

HWH water drained from the lowest point in the system.

Micron filter after heating valves began to open during colder weather. Notice the filter to the right behind this one, 1 month apart.

Chemical Contractor lab tested the HWH water and found it to be just below 6 pH. Checked with a pH strip to confirm.

Micron filter housing Epic purchased and installed. Holds eight 10″ filters or four 20″ filters.

HWH system water drained over the course of 10 weeks. You may notice that the water seems to get worse before it gets better. We attribute this to a few reasons: heating valves began to open due to cold weather, system pressure was increased from ~20 PSI to ~35 PSI, and water was drained from the system during the duration of the chemical treatment – all helping to clean the pipes. Pump strainers were actually quite clean when we checked!

Inside micron filter housing during filter change. This component holds down the micron filters. Covered in sludge!

Drained HWH system water as per recommendations from Chemical Contractor and made up system water until pH was closer to city water or 7-7.5 pH.

Introduced a molybdate based corrosion inhibitor. This coats the inside of the pipes and provides a protective barrier while increasing the pH of the HWH system water.

Micron filters from the filter housing. These filters were changed twice a week, 3-4 days apart.

Final micron filters before we uninstalled the filter housing; these filters were cleaning the HWH system for 2 weeks.

Final micron count after approximately 6 weeks. A Graveyard!

The difference in the colour of the HWH system water after 6 weeks of our treatment.

pH strip after 6 weeks. Close to what we want (8.5 – 10 pH) and we will have a sample laboratory tested after boiler work is completed (we will be draining additional water).

Conclusion: though the HWH system and boilers may not be overly needed during the hot summer months, we need to run the pumps at a minimum or intermittently to ensure flow. The air vents should be cleaned once a year as we want to make sure oxygen, CO₂, and other gases are allowed to escape and not lower the overall pH of the system. Taking samples of the HWH system, as well as the glycol system, and have them lab tested will give us greater insights and allow us to make proper, timely decisions moving forward.

Recording the water meter on the make up system periodically would be a wise exercise to see if the system is making up water – lowering the pH over time and introducing gases into the system (that get heated out of the water), and allowing us to potentially discover that there is a leak somewhere in the system.

After conversing with ABSA for another facility that is also a closed system – it may be prudent to do a blowdown of the heating water every year to help protect the system’s water. For this, we will be choosing the lowest point in the heating system as well as the heat exchanger that services the HWH and glycol systems.

Our mandate with the filter housing is to rotate it between the facilities we look after and complete a system cleaning as part of our preventative maintenance strategy, even if the system does not necessarily need it (you should go to the dentist once a year!). When we take on a new property, we will hook up the filter housing to do a great introductory cleaning, we will see quickly what condition a system is in, and if any changes will be needed.

Looking at the data of our daily checks: we found that over the course of the chemical treatment program starting from the beginning of February, the heat exchange between the HWH and glycol systems remained relatively constant while the boilers were able to fire less. This means there was greater thermal efficient heat exchange between the two systems. This provides both energy and cost savings, becoming more economical to operate as well as friendlier to the environment.

As facility managers, technicians, and operators – we must always try new and innovative ways to add value. By completing this exercise for this facility, Epic has increased our knowledge base and taught us many lessons that we are now able to share with all of our clients and customers. From my point of view, and truly most important, it was both engaging and fun – a complete level of satisfaction in solving a problem in-house with advice from our trusted partners. The proof is in the pudding! Or hot water, I suppose.

BONUS PICTURE!