The graying of residential buildings is a very real problem for building owners, especially in older US cities like New York and Boston. In fact, in a recent study published using data from NYC’s PLUTO database, one can determine that the median age of a surviving residential building in greater NYC is over 90 years old!

As initiatives like Local Law 97 and other go-green rebate programs drive upgrades and updates to heating system infrastructure,the other frontier in the upgrade of these buildings has to do with their solutions to domestic hot water and the ever increasing difficulty of delivering consistent, and safe hot water to residents. With the dramatic increase in reported cases of deadly legionella bacteria in the water supply across the country (including recent outbreaks in NYC) the pressure is on for building owners to provide updated solutions that satisfy city regulations for safety, provide safe, consistent temperatures to folks at their sinks and showers, and do it as efficiently as possible.

Common Problems with Domestic Hot Water Systems in Older Buildings.

At the end of the day, the net problem is getting reliable hot water to residents safely, at all hours of the day. Especially so called rush hours, when demand for showers and such is high. Yet age and other factors conspire to keep older DHW systems from maintaining their operational readiness.

1. Leaky Storage tanks. – Every tank has a shelf life of 15 – 30 years.
2. System Sizing – Changes to apartment layout, resident count and increases in peak demand over many decades, can tax an existing system not designed for it resulting in frequent rebuilds of the light-commercial gas water heater originally spec’d. These rebuilds are expensive and wholly unnecessary in a properly sized system.
3. Dissolved Mineral Content – Hard water supplies with high mineral content can tax piping and valves leading to expensive periodic rebuilds or replacements that take down hot water for the entire building.
4. Temperature Creep – Older thermostatic mixers can fail in such a way as to prevent mixing during dormant periods, such as overnight. In these cases, the first hot water users in the morning can find the hot water initially arriving at the sink or shower to be almost 160 degrees Fahrenheit, a temperature that can cause burns and scalding in a matter of seconds. These mixers then have to be rebuilt causing more expense and downtime not to mention potential lawsuits.
   
   

Heat-Timer® ETS is a Key Part of the Modern Solution to DHW Upgrades

Whatever heating technology your domestic hot water solution employs, a good heating design engineer will specify a DHW system designed for reliability, efficiency, serviceability and longevity. In 2022 with outbreaks of legionella on everyone’s mind, we must also add Safety to that list.

One key part of this upgrade is an electronic mixing valve like the Heat-Timer® Electronic Tempering Valve to finally deliver perfectly regulated hot water to residents. Heat-Timer® encapsulates this system into our Electronic Tempering Station (ETS) which is a pre-plumbed, small footprint assembly saving installers hours and hours of time doing installation, and limiting overall install downtime. The internal ETV control module uses remote sensors tied to proprietary algorithms to electronically control one of the industry’s most durable 3-way stainless steel mixing valves. The Heat-Timer® ETS can deliver an adjustable domestic hot water temperature to the end user, under any condition allowing hot water to be stored at a temperature that kills bacteria, while providing perfectly safe temperatures to users at the sink.

At Oklahoma University, the drive for excellence has a long and proud tradition both in the classroom and on the football field. Lesser known however, is the university’s constant drive toward excellence and efficiency in its building operations. That’s why during a recent retrofit of its domestic hot water equipment, UA selected the Heat-Timer® ETS (Electronic Tempering Station) as its choice for master mixing and control.

With over 30,000 students on campus, Oklahoma University has multiple on-campus dorms including the twin 12 story buildings of the Couch and Walker Centers.  These buildings are a focal point of student housing located in the center of the campus. As is common in high rise dormitories, the domestic hot water system includes steam to water exchangers and a master mixing valve.

UA Facilities Team Confronts A Hot Problem

Over the years the domestic hot water system in these (and other) buildings at OU, have required costly maintenance and repairs while still not providing the consistent hot water delivery required for safe use.

“The prior mixing valves were requiring a significant amount of maintenance,” notes Casey Yost of Federal Corporation out of Oklahoma city, who spearheaded the Heat-Timer® solution. “They were having to rebuild and replace the thermostatic mixers regularly, and the control head of the original package was failing.”

This was of course, causing all kinds of uncontrolled temperature variation in the water supply as well as a phenomenon known as temperature creep. This happens overnight under low or no demand conditions where the domestic water loop could reach as high as 160F and create a scalding hazard for the first, early morning student users. To combat this issue the University maintenance department had to continually rebuild and replace the thermostatic mixers, resulting in huge maintenance expenses.

Heat-Timer Rebuilds the Domestic Hot Water Solution Digitally.
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In this domestic hot water system rehabilitation, there were basically two main goals set by the University.  The first was to replace the existing thermostatic mixers with newer digital mixing valves that provide the accuracy needed.  The second goal was to limit the down time of the installation and have hot water service back to the students as quickly as possible. At the recommendation of Casey, OU decided to replace its unreliable tube bundles with the Heat-Timer® Electronic Tempering Station (ETS) 

The Heat-Timer® ETS product introduced in 2020, was a game changer for commercial plumbers in domestic hot water applications. Essentially the ETS encapsulates our industry standard Electronic Tempering Valve (ETV) system which has been a class leading DHW solution for many years with a strong track record in multi-family apartment buildings, hotels, elderly living facilities and college dorm applications. The ETV is a computer tied to our motorized 3-way mixing valve and sensors. Using proven software algorithms to control the mix, our solution delivers an exact, preset hot water temperature to the user, under any and all conditions. The ETV is able to perfectly detect and control the hot water supply temperature to a distribution line.
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The ETS assembly is a floor mounted unit that does not require valuable wall space that is difficult to find in most mechanical rooms.  The ETS assembly provides the installer the near valve piping configuration, and required fittings such as isolation valves, check valves and Victaulic couplings.  The ETS assembly also includes a high-temp limit valve that provides protection against delivery of extreme high temperature domestic hot water to the building in the event of a system failure. The ETV mixing valve actuator, control module and 3 temperatures sensors are included in the ETS assembly and are pre-wired for the installer.

Results of the Domestic Hot Water Retrofit at Oklahoma University

The initial project was for a 12 story dormitory building and the complete removal and installation of the ETS was done in less than a day. Here’s what water temperatures looked like before and after:

The result of having the ETS in place is shown on the computer screen above measuring the mixed water temperature going out to the system.  The graph on the left of the screen was the “before”, the huge dip was the system installation, and the flat line is the “after” with the ETS on-line.

“The big take away here is we were able to replace the tube bundles and add the ETS to create an almost completely new domestic hot water system for half the cost of replacing the original package,” notes Casey. This is the first of 2 ETS units sent to OU.  Based on the installation time and performance, there is an opportunity for many more to come.

But perhaps Oklahoma University’s Facility Maintenance Manager said it best: “I wouldn’t have believed how simple it was to install and how consistent our temperatures are if I hadn’t seen it for myself.”

You won’t believe it either.  Call Heat-Timer® Today for all your questions about our Domestic Hot Water Control solutions.
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Original blog posted on https://www.heat-timer.com/oklahoma-sooners-play-ball-with-heat-timer/