Victoria Johnson, PE, a Plumbing Engineer with Bass, Nixon & Kennedy Engineers in Raleigh, North Carolina, recently polled our experts on ASPE Connect to find out if they used hot or cold water to supply a coffee maker when designing a new break room. Victoria theorized that it would be a more efficient use of energy to use the hot water for the incoming water to the coffee maker but wanted to know if this was accurate.
As with many of our popular discussions in the ASPE Open Forum, our experts provided the requested information, as well as some other interesting insights.
The Consensus Is…
Cold water should always be used to supply coffee makers.
- Some codes may not recognize domestic hot water as suitable for consumption.
- Heating water changes the water, which can affect the taste.
- Most commercial coffee makers will receive filtered water, and it is not a good idea to filter hot water.
- Coffee maker heaters are typically designed for a cold water delta T.
- Plumbing fixtures and appurtenances are not tested and listed for their delivery of hot water for human consumption.
- Hot water will actually have higher levels of lead and other contaminants.
Why Is Lead Higher in Hot Water than Cold Water?
Hot water is a closed circulating loop with on-demand makeup added, and the circulation increases corrosion potential and scale potential. Scale increases the potential for deposition, and deposition increases the potential for galvanic corrosion cells around the deposits, according to Tim Keane, Consulting Engineer with Legionella Risk Management Inc. in Chalfont, Pennsylvania. Also, suspended solids will tend to stay in solution in cold water, but over time the suspended solids will tend to precipitate out of hot water, adding to scale potential.
What About Energy Concerns?
“Insulating the flexible tubing would be a challenge that needs to be taken into consideration, and I would imagine the cost savings would be negligible since you’re either directly heating the water with the coffee maker or having to heat the water supplied to the coffee maker with the central plant water heater,” says David Texter, CPD, Lead Plumbing Engineer with Browne Engineering and Construction in Cincinnati.
“I don’t think energy is a consideration in coffee brewing, yet, but I may be surprised before I leave the profession,” quips Dennis Connelly, CPD, with Newcomb & Boyd in Atlanta.
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