The older Bosch Aquastar model 125FX came in either Natural Gas (NG) or Liquid Propane (LP) and was 117,000 BTU and was a direct vent unit that was good for one major application at a time. The 125FX had electronic ignition and was fan-assisted and took its combustion air from the room it was installed in. The heater had a built-in fan so the heater could be vented right out the sidewall of the building. The Aquastar 125FX had to be vented with 4" sealed stainless steel venting going a maximum of 15' out the sidewall of the building into the FXHood. The FX Hood was a termination hood specifically designed for the 125FX and had a built-in flapper to keep cold air from penetrating the vent pipe and freezing the heater. The Bosch Aquastar 125FX is discontinued now and has not been made for over 8 years or so. One of the closest replacement models for the 125FX would be the new
Bosch Therm 830ES.
The new Bosch 830ES comes in either Natural Gas (NG) or Liquid Propane (LP) and is 175,000 BTU which is slightly more BTUs than the older 125FX. The Bosch 830ES needs a minimum of a 3/4" gas line and has 3/4" water connections also. The 830ES is a sealed unit and takes its intake air from the outside using 3" PVC. The unit is vented to the outside using 3" Stainless steel venting and this could be attached to the FX Hood that is already in place using a 3" to 4" increaser (Z-Flex Part #2SVSI0304). The 830ES is digitally controlled and can go from 100 - 140 degrees F. See below for more specifications and capacity.
| Therm 830 ES | Specifications |
|---|
|
| Condensing/Non-Condensing | Non-Condensing |
| Application | Residential or Commercial |
| Max Input (BTU) | 175,000 |
| Min Input (BTU) | 19,900 |
| Capacity at 35°F Rise (gpm) | 8.3 |
| Capacity at 55°F Rise (gpm) | 5.3 |
| Intelligent Cascading | Yes |
| Min Flow Rate | 0.5 gpm |
| Temp Range (°F) | 100 - 140 |
| Temp Stability (°F) | +/- 2 |
| Default Temp (°F) | 122 |
| Energy Factor | .82 |
| Thermal Efficiency | 82% |
| Installation Options | Indoor or Outdoor (for outdoor, kit required) |
| Dimensions (w x h x d) | 17 7/8" x 31½" x 11¼" |
| Weight (lbs.) | 67 |
| Inlet Connection | ¾" NPT |
| Outlet Connection | ¾" NPT |
| Gas Connection | ¾" NPT |
| Max Water Pressure | 150 psi |
| Min Water Pressure | 30 psi |
| Min NG Presure | 3.5" WC |
| Condensing Heat Exchanger | n/a |
| Venting Options | Stainless Steel |
| Vent Maximun Run | 61.25' |
| Energy Star Rated | Yes |
