What it delivers
The ThermoMate CZ750NG Natural Gas Tankless Water Heater is a non-condensing gas tankless with a 199,000 BTU/h burner and a stated maximum flow of 8.0 GPM. Its listing gives a UEF of 0.81.
Flow depends on how cold the incoming water is. Our estimate from its input: 6.8 GPM at a 45°F rise, falling to 4.4 GPM at 70°F, which is 2 showers at 2 GPM on a cold-climate winter day. Size it to your fixtures and climate.
Gas load at full fire: about 192 cubic feet of natural gas an hour. An older half-inch line that already feeds a furnace often can't spare that, so have a gas fitter check the pipe size and run.
Its exhaust runs hot, so the vent must be the material its manual lists, usually stainless; budget for the vent kit.
Also on the listing: connections: 3/4" npt; installation: Wall; model: CZ750NG.
Right unit for this house?
Install it when
- Houses running 2 showers at once in winter
- Replacing a gas tank heater
Look at another unit when
- More than 2 winter showers at once
- Homes without a gas line
Strengths and trade-offs
Strengths
- 199,000 BTU/h input
- Up to 8.0 GPM
- UEF 0.81
Trade-offs
- Needs a gas line sized for the load
- Stainless venting costs more
- Scale builds up without flushing
Install limits
- Figures are the maker's or seller's own. Flow at a rise is our estimate from the input; gas, venting and electrical work needs a licensed professional.
Rated performance
Every figure below comes from the source shown in brackets. Where the maker doesn't state something, we say so instead of estimating.
| Model number | CZ750NG | Retailer |
|---|---|---|
| Input (maker) | 199,000 BTU/h | Retailer |
| Mounting / installation | Wall | Retailer |
| Max flow (maker) | 8 | Retailer |
| Voltage | 120v | Retailer |
| UEF (maker) | 0.81 | Retailer |
| Fuel | natural gas | Retailer |
| Connections | 3/4" npt | Retailer |
Rival units at this flow
More gas tankless water heaters rated for similar demand
- MIZUDO HW180A0W-NG 180,000 BTU Natural Gas Tankless Water Heater
- Rheem RTG-70DVLN-3 160,000 BTU Natural Gas Tankless Water Heater
- Rheem RTG-84DVLN-3 180,000 BTU Natural Gas Tankless Water Heater
- Westinghouse HW180A0G-NG 180,000 BTU Tankless Water Heater
Full gas tankless water heaters spec grid · Every ThermoMate unit in the catalog
Final verdict
A practical non-condensing gas tankless for houses running 2 showers at once in winter.
Buy this unit
Our links open this exact model's product page. Prices and stock change; check what's included before you order.
Each button opens this exact model. We may earn a commission on tracked links; it never changes what we publish. Disclosure