Model # RETEX-18

Internet #300800620

Store SKU #1002624315

Rheem Performance 18 kW Self-Modulating 3.5 GPM Electric Tankless Water Heater
0020352682945

Rheem

Performance 18 kW Self-Modulating 3.5 GPM Electric Tankless Water Heater

  • Save money by heating water when you need it
  • Requires 2 x 40 Amp Double Pole Breakers
  • Call for an Installation Quote at 1-855-400-2552
$ 429 00
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Frequently Bought Together

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Product Overview

  • Save money by heating water when you need it
  • Requires 2 x 40 Amp Double Pole Breakers
  • Call for an Installation Quote at 1-855-400-2552
Rheem Performance Tankless Electric Point-of-Use Water Heaters help reduce energy usage, save on energy costs, and are small so they will be a perfect match for installations under a cabinet or sink in your home, office, boat or RV. Plus, it's a great value with a 5-year heat exchanger and 1-year parts limited warranty.
  • Energy and cost savings: heats water only when it is needed for savings of up to 50% on water heating costs when used in a point-of-use application or 34% when used as a whole-home solution
  • Instant, continuous hot water: instantly provides ample hot water for up to 2 showers and 2 faucets (review selection guide below to confirm this water heater will provide the hot water needed based on your geographic location)
  • Great investment and value: energy cost savings, and a 5-year heat exchanger and 1-year parts limited warranty
  • Great investment and value: energy cost savings and 5-year no-leak, 1-year parts limited warranty
  • Easy to adjust: electronic temperature control adjustable in 1° increments from 80°-140°F with easy-to-read display (Celsius and Fahrenheit compatible)
  • Easy installation: compatible with 3/4 in. water connectors for flex hose installation and no venting or T and P valve required for Easy installation (professional installation recommended)
  • Easy to maintain: durable, easy-to-replace heating elements
  • A reliable hot water solution from Rheem, the global leader in water heating
  • Selection guide
  • Other models available:



  • Click here to check out our buying guide on water heaters
  • Click here for more information on Electronic Recycling Programs
  • California residents see Prop 65 WARNINGS

Product Overview

  • Save money by heating water when you need it
  • Requires 2 x 40 Amp Double Pole Breakers
  • Call for an Installation Quote at 1-855-400-2552
Model #: RETEX-18
Sku #: 1002624315
Internet #: 300800620

Rheem Performance Tankless Electric Point-of-Use Water Heaters help reduce energy usage, save on energy costs, and are small so they will be a perfect match for installations under a cabinet or sink in your home, office, boat or RV. Plus, it's a great value with a 5-year heat exchanger and 1-year parts limited warranty.

  • Energy and cost savings: heats water only when it is needed for savings of up to 50% on water heating costs when used in a point-of-use application or 34% when used as a whole-home solution
  • Instant, continuous hot water: instantly provides ample hot water for up to 2 showers and 2 faucets (review selection guide below to confirm this water heater will provide the hot water needed based on your geographic location)
  • Great investment and value: energy cost savings, and a 5-year heat exchanger and 1-year parts limited warranty
  • Great investment and value: energy cost savings and 5-year no-leak, 1-year parts limited warranty
  • Easy to adjust: electronic temperature control adjustable in 1° increments from 80°-140°F with easy-to-read display (Celsius and Fahrenheit compatible)
  • Easy installation: compatible with 3/4 in. water connectors for flex hose installation and no venting or T and P valve required for Easy installation (professional installation recommended)
  • Easy to maintain: durable, easy-to-replace heating elements
  • A reliable hot water solution from Rheem, the global leader in water heating
  • Selection guide
  • Other models available:



  • Click here to check out our buying guide on water heaters
  • Click here for more information on Electronic Recycling Programs
  • California residents see Prop 65 WARNINGS

Info & Guides

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Price
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Ratings (253) (78) (66) (74)
Wattage (watts) 18000 18000 27000 36000
Water Heater Features Wall Mountable Wall Mountable Wall Mountable Wall Mountable
Flow Rate @ 45 F Rise (gallons/min) 2.73 2.73 4.10 5.46
View Product View Product View Product View Product

Specifications

Dimensions

Product Depth (in.)
3.5
Product Height (in.)
18
Product Width (in.)
14.5
Water Connection Size (in.)
3/4 In. NPT

Details

Amperage (amps)
75
Application Type
Residential
Electric Product Type
Residential
Finish Family
Gray
Flow Rate @ 35 F Rise (gallons/min)
3.51 gal (US)/min
Flow Rate @ 45 F Rise (gallons/min)
2.73
Flow Rate @ 55 F Rise (gallons/min)
2.24
Flow Rate @ 65 F Rise (gallons/min)
1.89
Fuel Type
Electric
Heat Exchanger Warranty
5 Year
Indoor/Outdoor
Indoor
Maximum Temperature (F)
140
Minimum Activation Rate (gpm)
.25
Minimum Temperature (F)
80
Product Weight (lb.)
11lb
Required Volt Connection
240 volt
Returnable
90-Day
Uniform Energy Factor
0
Water Heater Features
Wall Mountable
Wattage (watts)
18000
Wattage (watts)
18000

Warranty / Certifications

Certifications and Listings
1-UL Listed,CSA Listed,ETL Listed
Labor Warranty
No Warranty
Part Warranty
1 Year

Specifications

Dimensions

Product Depth (in.)
3.5
Product Height (in.)
18
Product Width (in.)
14.5
Water Connection Size (in.)
3/4 In. NPT

Details

Amperage (amps)
75
Application Type
Residential
Electric Product Type
Residential
Finish Family
Gray
Flow Rate @ 35 F Rise (gallons/min)
3.51 gal (US)/min
Flow Rate @ 45 F Rise (gallons/min)
2.73
Flow Rate @ 55 F Rise (gallons/min)
2.24
Flow Rate @ 65 F Rise (gallons/min)
1.89
Fuel Type
Electric
Heat Exchanger Warranty
5 Year
Indoor/Outdoor
Indoor
Maximum Temperature (F)
140
Minimum Activation Rate (gpm)
.25
Minimum Temperature (F)
80
Product Weight (lb.)
11lb
Required Volt Connection
240 volt
Returnable
90-Day
Uniform Energy Factor
0
Water Heater Features
Wall Mountable
Wattage (watts)
18000
Wattage (watts)
18000

Warranty / Certifications

Certifications and Listings
1-UL Listed,CSA Listed,ETL Listed
Labor Warranty
No Warranty
Part Warranty
1 Year

Questions & Answers

Will this work in a 1 bathroom tub an shower an on a kitchen sink? In southeast South Carolina th...

Will this work in a 1 bathroom tub an shower an on a kitchen sink? In southeast South Carolina thanks
Asked by: Mike
I’m in NJ and can run the shower and the sink at the same time up to 140 degrees all winter. It should supply hot water to at least two things at once. You may need to run water for a bath by itself without any hot water on anywhere else.
Answered by: Jim
Date published: 2019-03-22

Can unit be inset in the stud wall or is it required to be flush mount on the wall?

Can unit be inset in the stud wall or is it required to be flush mount on the wall?
Asked by: tdr
Yes. Get it professionally installed.
Answered by: Dan
Date published: 2019-01-18

When not in use, does this use electricity?

When not in use, does this use electricity?
Asked by: lakedude
No.
Answered by: Dan
Date published: 2018-09-24

So this unit will take up 4 breaker slots in my panel? How are these supposed to be replacements if your panel doesnt rm

Asked by: Steve93
Get it professionally installed.
Answered by: Dan
Date published: 2018-12-02
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Customer Reviews

Performance 18 kW Self-Modulating 3.5 GPM Electric Tankless Water Heater is rated 4.0 out of 5 by 78.
Rated 2 out of 5 by from During winter, in Washington DC, unit delivers only about 1.5 GPM (shower only) of hot water, whi... During winter, in Washington DC, unit delivers only about 1.5 GPM (shower only) of hot water, which is 1/3 what is listed on product headline - 3.5 GPM. I did read the selection guide for my geography and we are averaging outside air temp of 40 degrees F but the fact that the best this unit can do is heat one faucet OR a shower kinda hot (even when set to 140 degrees) is ridiculous. At inlet temp of 37-47 degrees it should power a shower and faucet. I get a shower kinda hot and if I turn on the hand faucet a trickle of COLD water it turns the shower 100% cold. So no use of other water in the house while someone is taking a shower. Not realistic. I’m sure it will be better in summer but hey winter does come for 25% of year. I talked with Rheem tech support, we troubleshooted all aspects but the unit just can not deliver 2.1 GPM of hot water (my shower is 1.6 GPM and faucet is .6 GPM). I believe the total output of hot water is really like 1.5 GPM since my shower is warm enough - ish. If the product can’t deliver the basics why bother manufacturing? The 27 kW should be as low as Rheem goes. I am swapping the 18 kw for a 27 kw from another brand and hope I can get my elusive shower and faucet hot at same time.
Date published: 2019-01-22
Rated 5 out of 5 by from I installed this in my single family home. This installation was fairly easy for the do-it-yourse... I installed this in my single family home. This installation was fairly easy for the do-it-yourselfer. I did have to replace one shower head with a low flow unit. The water it hot and endless.
Date published: 2019-02-26
Rated 1 out of 5 by from Would like to give this heater 5 stars, and I may yet, if I can ever get it to give me hot water!... Would like to give this heater 5 stars, and I may yet, if I can ever get it to give me hot water! I've purchased and installed 2 of these now in my home and neither one has heated the water. Tech support even sent me replacement flow meter and control board in hopes that that would help, but it hasn't yet. And with the company being on the East Coast and closing at their 5pm and me being on the West Coast and not getting the parts until after that, I will have to wait another night without hot water until I can get through Rheem's tech support queue to get more help. If I ever get this figured out, I will come back here and update this posting.
Date published: 2018-12-27
Rated 5 out of 5 by from I am very pleased with this tankless water heater. It was easy to install due to the excellent in... I am very pleased with this tankless water heater. It was easy to install due to the excellent instructions. It works great. Instant hot water only when you need it. The Black Friday price was an added bonus. Just be prepared to spend the additional money for the appropriate fittings, wiring and breakers. Still worth every penny. Couldn't be happier!
Date published: 2018-12-18
Rated 4 out of 5 by from Product performs as advertised. Was easy to install. Only problem encountered so far is trying to... Product performs as advertised. Was easy to install. Only problem encountered so far is trying to register the product for warranty purposes. Went on Rheem website and entered the serial number which is clearly marked on the unit. Keep getting a message that the number can not be found.
Date published: 2019-02-27
Rated 1 out of 5 by from Installed the unit in the basement In the boiler room.... Installed the unit in the basement In the boiler room. The unit does not supply hot water on the second floor bathroom.. I do not understand, this supposed to supply 2 Faucets and shower but not delivered what should do. Very disappointing.
Date published: 2019-01-18
Rated 1 out of 5 by from Rheem’s Support was at best average.... typical hold time was... Rheem’s Support was at best average.... typical hold time was 40+ minutes.... At the end of the day after installing to these units with at best hot water on random occasions I could not recommend this system to anyone.
Date published: 2019-01-15
Rated 1 out of 5 by from Does not operate or perform as advertised. Rated to have... Does not operate or perform as advertised. Rated to have a 40 degrees temp rise at 3 gal per minute but Im only getting 28
Date published: 2019-03-19
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