Go to our Home Page About us Go to your Personal Shopping Cart Search our site for products or information Back to our AquaStar Main Page See our PowerStar Electric Water Heater Main Page See our PowerSream Electric Water Heater Main Page See our Atiston Electric Under Sink Water Heater Main Page Leave us a message - about products or whatever! See our Specials Page See our Radiant Heating Main Page See our Hydronic and Heating Supply Main Page See our Direct Vent Room and Space Heaters Main Page See our Filter Main Page See our Lighting Main Page See our Tool Main Page See our Misc Product Main Page We accept Visa, MC, American Express Cards


Tech Info for AquaStar 125 Series Water Heaters
General information for installing the AquaStar tankless gas water heater. See installation manuals for more detailed info about these quailty on demand water heaters.


Return to AquaStar Main Page

Installation info for the Aquastar gas water heater Model 125B, 125X, 125BS and 125BL

Follow information provided on this page.
Installation and service must be performed by a qualified installer, service agency or the gas supplier.

Other tips: when venting the 125 Series water heater - it is best to rise 12" off top of hot water heater before making any 45 or 90 degree elbows , then rise ¼" per foot when running any horizontal vent pipe. Size gas line properly. Install the provided gas regulator with its directional arrow facing the gas flow path (also be sure to properly regulate Liquid Propane (LP) Natural Gas at source when supplying Aquastar), this small regulator that is provided is NOT to be used on a high pressure line.


·Required clearances
MODEL 125 Series Amount
TOP 12"
FRONT 4"
BACK 0"
SIDES 4"
FLOOR 12"


·Gas & Venting Model 125 Series
Gas 1/2" 5/8" 3/4" 7/8" 1"
Liquid Propane (LP) Not Recommended 20 feet 60 feet 150 feet   
Natural Gas 10 feet    40 feet    150 feet
Venting Min. Diameter Min. Height
5 inches 6 feet


·Dimensions Model 125 Series
Height Width Depth Weight
29-3/4" 18-1/4" 8-3/4" 39 lbs.


·Combustion Air Required Model 125 Series

In order to ensure an adequate supply of combustion air, the National Fuel Gas Code requires that any conventional vented gas appliance be installed in a room with a minimum volume of 50 cubic feet per 1,000 Btu/hr rated input. The following is the minimum size of the open space in which the Aquastar tankless water heater Model 125 X may be installed in compliance with this requirement:


Model Volume Area with an 8' ceiling
125 Series 5,900 cubic feet 738 square feet


If the Aquastar water heater is installed in an area smaller than indicated above, then the installer must make special provisions for combustion air in the form of two openings, each one within 12" of the top and 12" of the bottom of the space, having a total free area of 1 square inch per 1,000 Btu/hr of rated input if the air is taken from inside the house. This requirement reduces to 1 square inch per 4,000 Btu/hr if the air is taken from the outside.

Note: This calculation assumes normal rates of "infiltration" of outside air. A super-insulated, super-tight space/building may require outside air for the Aquastar water heater even though the volume/area of the space meets this application.

Caution: In addition to the above, the Aquastar gas water heater must be properly vented to ensure safe and efficient operation.


Need more information - read, download or print a full AquaStar 125 Series Manual. For all of the heaters - 125B, 125X, 125BL and 125S - just click below and follow directions.
Install Manuals


Navigational note: Scroll through these pages and
point & click your mouse on any underlined text... for more information... or contact us directly.

HouseNeeds, Inc.
Post Office Box 525, Warren, Vermont 05674
802-583-2726