Pentair MasterTemp 400
A strong pick for in-ground pools already on Pentair automation, though online buyers get only a short warranty.
Amazon $4,079$4,079
3.7/5
A Pentair built heater for owners on Pentair automation who want low NOx and high efficiency; compare prices with the MasterTemp first.
- 400,000 BTU/hHeating input
- 84%Efficiency
- Natural gas or propaneGas type
- 1 yearWarranty
Check price at Amazon$4,499
Price checked October 31, 2026. As an Amazon Associate we earn from qualifying purchases.
Pros
- Low NOx and approved for indoor or outdoor installs
- 84% efficient copper heat exchanger burns less gas per degree than 82% models
- Connects to Pentair automation
- High input heats a large pool or a spa quickly
Cons
- Only a 1 year parts warranty when bought online
- Copper heat exchanger is less tolerant of salt and low pH than cupro-nickel
- Costs more than the near identical Pentair MasterTemp of the same size
The Sta-Rite Max-E-Therm family
Every Sta-Rite Max-E-Therm model we rank, smallest first. Ratings compare each against its own size.
| Model | Heating input | Rating | Price |
|---|---|---|---|
| Sta-Rite Max-E-Therm 200 | 200,000 BTU/h | 3.3/5 | $3,650 |
| Sta-Rite Max-E-Therm 400 (this one) | 400,000 BTU/h | 3.7/5 | $4,499 |
How it scores
The rating comes from 4 measured or published factors, each scored 0-100 against fixed reference points for its size. How we rank explains each one.
Specifications
| Model number | SR400NA / SR400LP |
|---|---|
| Heating | |
| Gas input | 400,000 BTU/h |
| Gas type | Natural gas or propane |
| Thermal efficiency | 84% |
| Condensing | No |
| Low NOx | Yes |
| Heat exchanger | Copper |
| Installation and controls | |
| Venting | Both |
| Digital controls | Yes |
| Automation or app | Yes |
| Warranty | 1 year |
Alternatives in this size
Raypak Digital 406A
Good value for in-ground pools outside low NOx areas, provided it comes from an authorized dealer so the warranty holds.
Amazon $4,421.17$4,421.17
Hayward H-Series H400FD
A low NOx, salt tolerant in-ground pool heater for owners who buy online and can live with a short warranty.
Amazon $5,099$5,099
Compare
Compare the Sta-Rite Max-E-Therm 400 with any other gas pool heater →
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