Tankless Water Heater Comparisons
Compare gas tankless water heaters by brand and model. Please
view this page in its entirety as there are lots of water
heaters for comparison here, and a lot of information to absorb.
Gas Tankless Water Heater Review and Comparisons
(click here to
compare
ELECTRIC tankless water heaters)
| Model |
RTG-74
GT-199 commercial |
250SX
(2400) |
RTG-53 |
125FX
(1600F) |
125HX
(1600H) |
125B
(1600P) |
| Brand |
Rheem |
Bosch |
Rheem |
Bosch |
Bosch |
Bosch |
| Energy Factor (1) |
0.82 |
0.85 |
0.82 |
0.78 |
0.78 |
0.69 |
| BTU Input |
199,900 |
175,000 |
145,000 |
125,000 |
117,000 |
117,000 |
Water Flow - Gallons
per minute |
| @ 45 degree temp rise |
| 7.4 |
6.35 |
5.3 |
3.6 |
3.6 |
3.6 |
| @ 50 degree temp rise |
6.6 |
5.7 |
4.7 |
3.6 |
3.6 |
3.6 |
| @ 60 degree temp rise |
5.5 |
4.7 |
3.9 |
3.1 |
3.1 |
3.1 |
| @ 70 degree temp rise |
4.7 |
4.0 |
3.4 |
2.6 |
2.6 |
2.6 |
| @ 80 degree temp rise |
4.1 |
3.5 |
3.0 |
2.3 |
2.3 |
2.3 |
| @ 90 degree temp rise |
3.7 |
3.1 |
2.6 |
2.0 |
2.0 |
2.0 |
| Temperature Range |
100F -180F (GT199) |
100F - 140F |
100F - 140F |
100F - 140F |
100F - 140F |
100F - 140F |
| Min Water Flow (GPM) |
0.66 |
0.75 |
0.66 |
0.5 |
0.5 |
0.5 |
| Ignition |
Electronic |
Electronic |
Electronic |
Electronic |
Hydro |
Standing Pilot |
Venting |
| Exhaust Venting |
Vertical or Horizontal |
Vertical or Horizontal |
Vertical or Horizontal |
Horizontal |
Vertical |
Vertical |
| Flue Size (in) |
4” |
3" |
4" |
4" |
5" |
5" |
| Flue Type |
Stainless steel |
Stainless steel |
Stainless steel |
Stainless steel |
Type B Double Wall |
Type B Double Wall |
| Built-in Power Vent |
Yes |
Yes |
Yes |
Yes |
No |
No |
| Room Sealed |
DV models |
Yes |
No |
No |
No |
No |
| Air Intake Diameter |
4” (DV) |
3" |
N/A |
N/A |
N/A |
N/A |
Dimensions |
| Water Line (in) |
3/4" NPT |
3/4" NPT |
3/4" NPT |
1/2" NPT |
1/2" NPT |
1/2" NPT |
| Gas Line (in) |
3/4"+ NPT |
3/4"+ NPT |
3/4"+ NPT |
1/2" NPT |
1/2" NPT |
1/2" NPT |
| Height (in) |
25.75 |
24 |
20.5 |
29.75 |
29.75 |
29.75 |
| Width (in) |
14.8 |
16 |
13.75 |
18.25 |
18.25 |
18.25 |
| Depth (in) |
11 |
7 |
5.25 |
8.75 |
8.75 |
8.75 |
| Weight (lbs) |
55 |
47 |
36 |
52 |
44 |
44 |
| |
|
|
|
|
|
|
| Limited Warranty(2) |
10 yrs |
12 yrs |
10 yrs |
12 yrs |
12 yrs |
12 yrs |
1. Note: The energy factor represents the amount of
energy used that is realized in hot water.
2. Note: Term of limited warranty on heat exchanger)
listed is based on professional installation by a licensed
plumber or contractor. If installed individually the Bosch gas
tankless water heaters will have a 10 yr warranty with 2 years
on parts. Rheem units carry 10 years on the heat exchanger and
3 years on parts.
Gas Models (Natural Gas and LP Propane) General
Installation Requirements:
**See instruction manual for requirements in detail**
Venting:
125B, 125HX, 1600 Models: 5" type B (double wall) vent
- 6' minimum vertical height (no elbows), AQ1 Powervent option
will allow a vent run of 100 feet subtract 5 feet for every
elbow. AQ4 Powervent for use with the 1600P
125FX Model : 4" dedicated, sealed, single wall vent
(stainless steel or 26+ gauge galvanized). 15' maximum run with
two elbows - must terminate horizontally. FXHOOD required.
RTG-53 Model: 4" dedicated, sealed, single wall vent
(stainless steel). 34.6' maximum run - subtract 1.5' for each
elbow.
250SX Model : 3" dedicated, sealed, single wall vent
(stainless steel). 26' maximum run with one elbow - subtract
2.5’ for each elbow.
RTG-74, GT-199 Model: 4" dedicated, sealed, single wall
vent (stainless steel). 47.6' maximum run - subtract 5' for each
elbow.
Combustion Air:
- 125B, 125HX, 125FX, 1600P: Minimum 5,900 cu. ft OR
permanent inlet air supply for the heater.
- RTG-53PV: Minimum 7,250 cu. ft OR
permanent inlet air supply for the heater.
- 250SX: 0 cu. Ft if utilizing the inlet pipe system
otherwise 8,250 cu. ft.
- RTG-74, GT-199:
0 cu. Ft if utilizing the inlet pipe system on DV model
otherwise 10,000 cu. ft.
Note: None of the Bosch or Rheem gas tankless models
cannot be installed in a mobile home, bedroom, bathroom, or any
other confined living space normally kept closed.
Gas Line: Gas line must be properly sized to
meet required BTU input.
| Natural Gas: Maximum
Length of Pipe Run |
| Nominal Iron Pipe Size |
½" |
¾" |
1" |
|
125B,
125HX,
125FX, 1600 |
10 ft |
40 ft |
150 ft |
|
RTG-53 |
Not Recommended |
30 ft |
100 ft |
|
250SX |
Not Recommended |
20 ft |
75 ft |
|
RTG-74,
GT-199 |
Not Recommended |
15 ft |
55 ft |
Electric Tankless Water Heater Comparisons
| Model |
AE125 |
AE115 |
AE12 |
GL6+ |
GL4 |
GL2.5 |
| Energy Factor (1) |
0.95 |
0.95 |
0.99 |
|
|
|
| Type |
Tankless |
Tankless |
Tankless |
Mini-Tank |
Mini-Tank |
Mini-Tank |
Water Flow - gallons
per minute |
| @ 45 degree temp rise |
4 |
2.6 |
1.5 |
|
|
|
| @ 50 degree temp rise |
3.6 |
2.3 |
1.5 |
|
|
|
| @ 60 degree temp rise |
3 |
1.9 |
1.25 |
|
|
|
| @ 70 degree temp rise |
2.6 |
1.7 |
0.75 |
|
|
|
| @ 80 degree temp rise |
2.3 |
1.5 |
|
|
|
|
| Temperature Range |
95F - 131F |
95F - 131F |
100F - 130F |
65F - 145F |
65F - 145F |
65F - 145F |
| |
|
|
|
|
|
|
|
| Min Water Flow (GPM) |
0.8 |
0.6 |
0.75 |
|
|
|
| Water Line (in) |
3/4" NPT |
3/4" NPT |
3/8" NPT |
3/4" NPT |
1/2" NPT |
1/2" NPT |
Electric |
| Wire Size |
8 GA |
8 GA |
6 GA |
Hard wire |
Plug-in |
Plug-in |
| Voltage |
240 |
240 |
240 |
110 |
110 |
110 |
| Kilowatts |
26.85 |
17.25 |
12 |
1.5 |
1.5 |
1.5 |
| Amps |
120 |
80 |
50 |
12.5 |
12.5 |
12.5 |
Dimensions |
| Height (in) |
15.25 |
15.25 |
12.25 |
17.5 |
14 |
14 |
| Width (in) |
15.5 |
15.5 |
6.5 |
17.5 |
14 |
14 |
| Depth (in) |
4.5 |
4.5 |
3 |
14.5 |
12.25 |
10.25 |
| Weight (lbs) |
22 |
20 |
6 |
35 |
25 |
22 |
| |
|
|
|
|
|
|
|
| Limited Warranty(3) |
10 yrs |
10 yrs |
5 yrs |
6 yrs |
6 yrs |
6 yrs |
Buying Guide For Tankless Water Heaters
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