From Design to Delivery

Lincoln Square Apartment Hot Water Solution

Capitol District Supply Provides High Efficiency Water Heating Solution for 77 Unit 11 Story Apartment Building in Albany, NY

 

Capitol District Supply has been a long time provider to Albany Housing Authority.  Laura Moody, from their offices, reached out to us to asses the existing hot water system and provide a solution.  The result is an estimated annual savings of $10,000.

Thomas J. Hitter from Capitol District Supply designed the new system.  8 tankless water heaters replaced a 2000 gallon steam heated storage tank that was leaking steam and no longer repairable.

 

The Situation

The 60 year old original water heating system for this building was inefficient and failing rapidly. The 2,000 gallon storage tank was well beyond its expected service lifetime and had been often repaired. It’s internal steam to water heat exchanger was leaking steam condensate externally constantly at a high rate and was deemed irreparable.  Even as originally designed, this system was not energy efficient. It required a steam boiler located down the street in a different building to run non stop, year round, to send steam through exceedingly long pipe runs incurring large transmission losses. With a potential catastrophic failure looming something had to be done soon.

The design challenges:

  1. Any new equipment brought in would need to be brought through several doorways and several flights of stairs to the sub basement so any design incorporating any sizable tank or larger water heating boiler would not be practical.
  2. Since there is no chimney at this site, and the civil defense rated construction with 18” masonry walls and masonry floors, new fuel fired equipment would need excellent venting flexibility.
  3. None of the old existing main valves in this system could be assumed to be fully functional and the cold water main was 4” iron.
  4. Although the building did have a good size gas main, it too was old and the level and consistency of the gas supply pressure was questionable.
  5. The existing domestic hot water system also incorporated a fairly complex pumped re-circulation system to keep the water in the pipes hot at all time near all apartments. This would have to be retained with as little change as possible. Pressure drop through a new water heating system had to remain insignificant.
  6. How do we minimize disruption in water service to the large number of tenants during installation.
  7. Budget for a replacement as well as for future operation and maintenance costs were paramount concerns.

Fortunately water saving measures had been implemented in the building.  The water pressure at the site wasn’t a concern and the basement location had a floor drain existing, which could be used for condensate drainage.

The Capitol Solution:

After leaving that meeting, the Capitol District Supply team modeled water use for the building and determined that the hot water demand would be best met by combing a group of 8 on demand water heaters. The Navien NPE 240  was selected. Each Navien NPE 240 water heater is able to modulate its firing from 10% to 100% of its 199,900 maximum to deliver output hot water temperature that is nearly constant.   The built in cascading technology allows coordinated control of multiple units for that same precise temperature control in larger applications like this one. These 8 heaters would have a nearly infinite firing rate modulation range from 19,900 BTU/hr up to 1,599,200 to meet any demand. No tank would be necessary and there would be nearly no chance that high hot water use could ever cause a temperature drop as these systems only allow as much water to flow through them as they can heat to the selected temperature. In addition it would be possible to common vent all 8 with just 6” PVC pipe.
The Venting issue was solved by mounting the heaters near an unused opening in the side of the building to pipe the exhaust as well as combustion air intake.

“The tankless water heaters all fire together or they’re all off,” Hitter says. “They’re behaving as one larger system and they’re piped to get flowing water equally through the multiple storage tanks.”

The team made sure the system runs at optimal levels during key times of the day,  such as the early morning and after-work hours when hot water demand is at its highest.

The maintenance and reliability demands would be met better with this system than any other method. Having eight identical heaters would be the ultimate in redundancy and make service downtime highly improbable. Since these heaters enjoy huge popularity and are very widely distributed and installed any parts or service that may ever be needed are readily available. Furthermore, even in a commercial application like this, the parts have a 5-year manufacturer warranty and the heat exchangers come with an 8-year warranty.

By measuring the loss of steam condensate in the existing system and using ASHRAE and accepted industry data for estimating typical hot water usage we then estimated that the existing system was costing $16,000 per year for gas to operate and that if installed we estimated the 8 cascaded Navien water heaters which are 97% efficient would have an operational cost of under $6,000 annually.

 

Technological advances and lower costs are making tankless water heaters more attractive.

“What that means, is tankless becomes a more realistic option, not only because it can save space but also because of the price gap between traditional tank type and tankless is actually narrowed.”       -Tom Hitter,  Heating Specialist

To minimize interruption of cold water service we determined it would be best to replace an old blank companion flange on the large 4” cold water main with a new 2” main.  Propress copper fittings were used to expedite the entire installation.  Propress mechanical joints can be completed on pipes through which the water flow can’t be entirely stopped.

 

Observations just an hour after changeover showed return recirculation temperature being maintained and hot water demand being met with a much greater precision in temperature than a tank system ever could. There were already many intervals when only one of the NPE heaters was firing and that at very a low rate but when hot water use increased additional heaters fired and modulated flawlessly.

This sizable project was complete in just 5-1/2 days generally with just two men on the job and there were no tenant complaints.

We at Capitol District Supply are grateful for the trust placed in us by Albany Housing and the excellent team work and installation by Tri City Mechanical and Limitless Plumbing and Heating.

If you have a water heating challenge of any kind we hope you will call us for expert advice and solutions!

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Tom Hitter oversees the building of relationships with prospective and new clients as well as developing the firm’s brand. Mr. Hitter is known for taking the time to understand the unique needs of each client so that he is able to offer them tailored service.

He earned his LEED AP designation in 2008 and Refrigeration Engineer License in 1982. Tom received his AAS at SUNY, Farmingdale, and his BS degree at Manhattan College.