Simplified Tankless Boiler System Eliminates Pumps, Storage Tanks

Flooded basement inspired engineer to improve on existing designs
Simplified Tankless Boiler System Eliminates Pumps, Storage Tanks
Health center with boiler storage tank.

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Commercial water heating systems and their basic design methodology – tank style heaters or boilers with storage tanks – have been used for the past 75 years, says Sridhar Deivasigamani, president and CEO of Intellihot Green Technologies, and water has been heated in pretty much the same way for 150 years.

It took a personal experience for Deivasigamani, a mechanical engineer and former Caterpillar employee, to dig deeper into this history and future of water heating systems. When he returned home one day and found his own heater broken and his basement flooded, he began to wonder about the possibilities for improving upon existing design.

The core issue is how water is actually being used.

“We went around the country and put a flowmeter on and actively measured how water was being consumed in 100 bedroom hotels, 400 bedroom hotels, 800 bedroom hotels, whether in Canada or Florida or California or South Carolina,” he says. “The common thread is that the flow is transient, which means it goes up and down.”

What Deivasigamani found is that the way hot water is consumed is essentially mismatched with the way the equipment was designed for it to be used. He offers an analogy to help explain:

“Current devices are like bulldozers that travel at 5 mph and stop and start over and over again. Occasionally they might travel at a full capacity of 30 mph, but that’s only less than 1 percent of the time,” he says.

“If you walk into a 300 room hotel, you might find a couple of 3-million Btu boilers circulating through a 1,000-gallon storage tank. There are two because if one breaks down the other is needed to kick in and provide the hot water. It’s a setup with twice the amount actually needed, which means unnecessary equipment and operational costs.”

Overcoming inefficiencies

Deivasigamani set out to overcome some of the inefficiencies. If a building needs a 1-million Btu capacity, for example, the conventional approach is to put in 1.5 or 2 million Btu. Going tankless can eliminate overdesign and unneeded redundancy by using 1 or 1.1 million Btu while dividing that internally into chunks of 250,000 Btu. If one engine were to fail the others are able to communicate with one another like robots and automatically continue to supply hot water.

To accomplish this type of design, a tankless system needs to hit on a number of aspects: durability to handle thermal cycles, reliability to ensure hot water is always at the ready, precise temperature control, robustness to scale and low water side pressure drop.

“The installation itself is extremely simple,” Deivasigamani says. “It’s the same water, power, gas and venting that you do with a typical boiler but it is, in fact, greatly simplified. We don’t need any boiler pumps or storage tanks. We don’t need all of the associated controls and complexities that go along with that … installation is simpler and much quicker. The units weigh about a third of what traditional equipment weighs, so you don’t need reinforced floors, you don’t have to helicopter or tear off a roof, and you can maneuver very easily.”

The chief benefits of the design, he says, are reliability first and foremost but also added efficiencies in terms of storage, space and cost.

Leaks, flooding risks reduced

“Tankless eliminates leaks and flooding, risks associated with Legionella bacteria and the possibility of running out of hot water. In addition, outlay and installation costs can be reduced, overall footprint can be reduced by over 80 percent, and 30 to 62 percent can be saved in operating expenses.”

Although Deivasigamani notes that repairs are less needed and frequent with this device than traditional water heaters, there are some common issues and fixes. If hot water is not instantaneous, for example, check to make sure that the external recirculation pump is functional and installed correctly.

Also, make sure the pumps are sized correctly and verify that the gas lines are sized appropriately in terms of pressure and diameter. Intake and exhaust air should be installed according to applicable codes, and piping should be sized and installed according to the product manuals. Finally, ensure that the valves installed are in the correct position and orientation.

The following video from Intellihot Green Technologies shows how the tankless boiler has the ability to run on very low gas pressure.


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