How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

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Can I replace a single element water heater with a double element one?

Tuesday, December 25, 2018

     We rarely see single-element residential water heaters anymore, except in older mobile homes and Park Model RVs. Their only advantage is that they are usually less expensive to buy. Dual-element water heaters are rated as more energy efficient and have a faster recovery time.

    But, although dual-element water heaters have two elements, only one of them operates at a time. The top element comes on first and, when the water at the top of the tank has reached the temperature setting for the top thermostat, then the bottom element kicks in until its thermostat is satisfied. See our blog post What is the difference between a single element and dual element electric water heater? for more details. 

    Most single-element water heaters that are 30-gallon capacity or more can be replaced with a double-element one. Water heaters with a tank smaller than 20-gallons are always single element. Just check for these three sticking points first:

1) Most single-element water heaters are rated for 120-volts, whereas dual-element water heaters are 240-volts. If the circuit breaker for your current water heater takes up only one slot in the electric panel, it is 120-volt. There may be some 120-volt double-element water heaters out there, but we have never come across one. So you may have to stick with a single-element water heater for replacement if that’s the case, unless you want to rewire for 240-volts.
    While it is possible to connect at 240-volt water heater to 120-volt wiring, it’s not a good idea. Check out our blog post Can you wire a 240-volt water heater with 120 volts? for a full explanation.

2) The height and width of the available space is often an issue in water heater replacement. Make sure the new 240-volt unit fits the available space. 

3) Also, mobile home water heaters are plumbed on the side instead of the top. Our blog post How can I tell if a water heater is HUD-approved for mobile/manufactured homes? explains this difference further. Many local building departments do not enforce the requirement for a HUD-approved replacement water heater, but you don’t have to reconfigure the plumbing connections if you stick with a HUD-approved one.

   Visit our WATER HEATERS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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