Dimensional Data for Z-Flex Double Wall Stainless Steel Venting

Global Protankless Supply is an Authorized Distributor of all Z-Flex Z-Vent stainless steel venting.  We provide stainless steel venting in diameters of 3" all the way up to 24".  The Z-Flex Z-Vent stainless steel (AL29-4C) venting comes in either single wall or double wall venting.  Dimensions on the double wall venting is different than the single wall venting. All Z-Flex Z-Vent double wall venting has an inside diameter dimension and an outside diameter dimension.  As an example a piece of Z-Flex Z-Vent double wall stainless steel venting pipe 4" diameter by 4' long would have an inside diameter of 4" and an outside diameter of 6" due to the double wall.

Please call Global Protankless Supply at 866-289-4652 for any further questions or to place an order.

Z-Flex 3" - 4" Stainless Steel Increaser vs 3" - 4" Stanliess Steel Eccentric Increaser

The Z-Flex stainless steel venting comes in many different diameters and is available in single wall stainless steel or double wall stainless steel. 

The Z-Flex stainless steel 3" - 4" Increaser is single wall stainless steel and is designed for venting systems that go vertical and need to transition from 3" diameter to 4" diameter.

The Z-Flex stainless steel 3" - 4" Eccentric Increaser is single wall stainless steel and is designed for venting systems that go horizontal and need to transition from 3" diameter to 4" diameter.  This venting is best used in this application as the venting piece is offset.

For any questions or to place an order please call Global Protankless Supply at 866-289-4652.

Replacing an Aquastar 240FX with Bosch Therm 830ES

The Aquastar model 240FX was a unit that was distributed by Controlled Energy Corporation (CEC) many years ago.  The 240FX was manufactured by Takagi and was capable of 2 major applications at one time. The Aquastar 240FX was a 165K BTU unit, took 4" single wall sealed galvanized or 4" single wall stainless steel venting.  The 240FX took it's combustion air from the area where it was installed.  The 240FX could sit right on the ground as the water and gas connections came out the left side of the unit.  Wall mounting was also an option.  The 240FX was suppose to be vented out the sidewall of the home for a maximum of 15' using the FXHood as the termination.  The Aquastar 240FX has been obsolete for some time and now most of the parts are no longer made also.

The closest replacement for the Aquastar 240FX is now the Bosch Therm 830ES.  The Bosch 830ES is a 175K BTU unit and is good for 2 major applications at one time.  The 3/4" water and gas connection are on the bottom of the unit vs the left side of the Aquastar 240FX.  The venting on the 830ES must be either 3" or 4" stainless steel single wall venting (AL29-4C) venting up through the roof or out the sidewall.  There is a vertical vent kit, ES VVT vertical vent kit avalable and also a sidewall vent kit, AQ3ES sidewall vent kit for venting out the side of the home.  The intake air for the 830ES is taken from the outside also using 3" PVC and should be taken from the same wall or roof the exhaust is going out through.  Please refer to the link above for more information on the Bosch Therm 830ES or call us at 866-289-4652 with questions.

  BOSCH THERM 830ES

Bosch Therm 520HN NG & LP Tankless Water Heater

The new Bosch Therm 520HN comes set for either NG (Natural Gas) or LP (Liquid Propane).  The 520HN has a hydro ignition and is a naturally drafting heater and requires no power to operate.  This unit is basically for 1 major application at a time such as 1 shower at a time.  The Bosch 520 HN Needs to be vented vertically with a 5" B-vent up through the roof for a minimum of 6' to the raincap.  If the heater has to be vented out the sidewall then you must use the AQ4 Powervent kit and this kit would require 110V power.  The gas connection at the bottom of the heater is a standard 3/4" connection.

The new Bosch Therm 520HN is a direct replacement for many of the older model heaters.  Below is a list of the units that the 520HN would replace.  Please keep in mind to always be aware of gas line sizing and the length of the gas line run.

The Bosch Therm 520HN could replace:

Bosch 1600P or 1600H: (If either one of these units was vented horizontally out the sidewall with the AQ4 powervent kit then that same AQ4 powervent kit can be used for the new Bosch Therm 520HN)

Bosch Aquastar 125B, 125X, 125HX, 425PN or the 425HN: (If any of these units was vented horizontally out the sidewall with the AQ1 powervent kit then that AQ1 powervent kit WILL NOT work for the new Bosch Therm 520HN.  You would need to install the new AQ4 powervent kit for the new Bosch Therm 520HN)

ELM Le Blanc 170VP or 125VP:  (If either one of these units was vented horizontally out the sidewall with the AQ1 powervent kit then that AQ1 powervent kit WILL NOT work for the new Bosch Therm 520HN.  You would need to install the new AQ4 powervent kit for the new Bosch Therm 520HN)

The Bosch Therm 520HN is a direct replacement for the older tankless water heaters listed above but you still always want to make sure and refer to the installation manual and follow the gas line sizing chart and venting requirements.  Please also refer to local code for all other restrictions and approvals.

Bosch Therm 520PN NG & LP Tankless Water Heater

The new Bosch Therm 520PN comes set for either NG (Natural Gas) or LP (Liquid Propane).  The 520PN has a standing pilot and is a naturally drafting heater and requires no power to operate.  This unit is basically for 1 major application at a time such as 1 shower at a time.  The Bosch 520 PN Needs to be vented vertically with a 5" B-vent up through the roof for a minimum of 6' to the raincap.  If the heater has to be vented out the sidewall then you must use the AQ4 Powervent kit and this kit would require 110V power.  The gas connection at the bottom of the heater is a standard 3/4" connection.

The new Bosch Therm 520PN is a direct replacement for many of the older model heaters.  Below is a list of the units that the 520PN would replace.  Please keep in mind to always be aware of gas line sizing and the length of the gas line run.

The Bosch Therm 520PN could replace:

Bosch 1600P or 1600H: (If either one of these units was vented horizontally out the sidewall with the AQ4 powervent kit then that same AQ4 powervent kit can be used for the new Bosch Therm 520PN)

Bosch Aquastar 125B, 125X, 125HX, 425PN or the 425HN: (If any of these units was vented horizontally out the sidewall with the AQ1 powervent kit then that AQ1 powervent kit WILL NOT work for the new Bosch Therm 520PN.  You would need to install the new AQ4 powervent kit for the new Bosch Therm 520PN)

ELM Le Blanc 170VP or 125VP:  (If either one of these units was vented horizontally out the sidewall with the AQ1 powervent kit then that AQ1 powervent kit WILL NOT work for the new Bosch Therm 520PN.  You would need to install the new AQ4 powervent kit for the new Bosch Therm 520PN)

The Bosch Therm 520PN is a direct replacement for the older tankless water heaters listed above but you still always want to make sure and refer to the installation manual and follow the gas line sizing chart and venting requirements.  Please also refer to local code for all other restrictions and approvals.

PP Common Venting Systems for Cascaded Units

New for the Greentherm C 950 ES and C 1050 ES, and the Therm C 1210 ES and C 1210 ESC, is a common venting system of polypropylene pipe for up to four appliances. Offered in either a side by side or back to back configuration, the kits allow for a single vent pipe for all units. Combustion air must be taken from the room for multiple units common vented.  A 3" PVC 90 degree elbow would want to be placed on either the left or right air intake hole for the combustion air to keep anything from falling into the heater.  This is mandatory for commercial applications, with multiple units installed and that the multiple units are common vented with either the side by side or back to back venting option.  All other applications such as residential, single units, etc. must take the combustion air from the outside using 3" PVC or 3" dia PP pipe.  Please refer to the installation manual for the Bosch tankless water heater for the combustion air requirements for the heater. 

Side by side with horizontal termination (left),

back to back with vertical termination (right)



The new polypropylene pipe (PP) common venting system features different kits for cascaded units of 2, 3 or 4 units.  Kits would have to be ordered as needed:

Kit A - side by side, units #1 & #2 (2 heaters) (7736501100)

Kit B - side by side, units #3 & #4 (1 heater) (7736501254)

Kit C - back to back, units #1 & #2 (2 heaters) (7736501253)

Kit D - Extension back to back, units #3 & #4 (2 heaters) (7736501252)

There are also additional 6" diameter PP venting pieces available.  There are additional:

Horizontal Termination Dia 6"  (7736501117)

Vertical Termination Dia 6"  (7736501119)

Extension rigid straight pipe 20" Dia 6"  (7736501137)

Extension rigid straight pipe 40" Dia 6"  (7736501135)

Extension rigid straight pipe 80" Dia 6"  (7736501133)

Rigid 90 degree elbow Dia 6"  (7736501132)

For example:

Say you were common venting and cascading 4 units side by side and venting up through the roof then you would want 1 - Kit A for units #1 & #2, 1 - Kit B for unit #3 and then 1 - Kit B for unit #4.  You would also then need 1 - 90 degree elbow, how many extra feet of extension straight pipe and then the vertical termination.

Venting requirement for Bosch AQ4 Powervent kit

The Bosch AQ4 Powervent Kit with built-in freeze protection is designed for the Bosch Therm 520HN (Hydro Ignition) and 520PN (Pilot) tankless water heaters. This accessory allows the Bosch 520HN and 520PN tankless heaters to vent horizontally out the sidewall of the home.  The AQ4 does require power to operate and operates on 120V and comes with a 3' cord to plug into the outlet.  

  The AQ4 is a power vent kit and will allow a horizontal vent run of up to 25 feet with one elbow (subtract 5 feet for every elbow). This kit includes the power vent motor.  There is also a vent hood with damper that gets mounted on the outside of the home and this built in flapper prevents the cold air from coming in when the heater is not in use.  Please make sure to refer to the installation manual and that the hood is properly installed so that the flapper stays closed all the way when not in use.  

The AQ4 powervent kit comes with a 5" to 4" reducer. This reducer fits right on top of the heater and then you would use 4" type B, C or stainless steel AL29-4C venting (not included) to go to the powervent motor.  There is a minimum of 2 feet of straight pipe required between the reducer and the blower motor.  Any venting (if needed) "after" the powervent motor must be 4" sealed stainless steel AL29-4C.  The Blower motor should be placed right at the opening where the termination hood with damper is to be installed on the sidewall of the home.

The AQ4 powervent kit is activated by a flow switch and gets attached to the cold water pipe on the right side of the unit just before it goes into the heat exchanger. 

The blower motor for the AQ4 has a new design and includes a delay setting that goes from #1 - #5 and this lets the installer set the blower motor so that when it senses flow it can be delayed for 1 - 5 seconds before the blower comes on.  This will help to ensure the pilot and burners light without getting sucked out by the blower motor. 

There is also a built in safety spill switch that gets attached to the tankless water heater and this will detect high temperatures from any flue gases in the case the blower motor does not activate and will shut the unit completely down.

Bosch Therm 520PN & 520HN vs Bosch Therm 660EF

This blog entry compares the Bosch Therm series 520PN & 520HN models to the Bosch Therm 660EF heater.  The Bosch Therm 520PN & 520HN gas tankless water heaters are 117,000 BTUs as the Bosch Therm 660EF is 140,000 BTUs.  These tankless water heaters are designed for 1 major application at a time such as 1 shower at a time or maybe 2 small sinks at once. They all are available in natural gas or propane models.

The Bosch Therm 520 PN, 520HN and the 660EF all take thier combustion air from the space where they are installed in.  You will want to make sure you refer to the installation manual for these units and make sure you have enough combustion air for the area where these are to be installed.  You can always consult a HVAC technician to calculate and make sure you have enough air supply.  These units should NEVER be installed in a bathroom or bedroom where the door is normally kept closed as the heaters while running would deplete the oxygen from the room causing illness and death.  This statement is on the front of the heaters and also noted in the installation manual.  The National Fuel Gas Code states this also but the installer would also want to go by local code.

The Bosch Therm 520PN has a standing pilot light and is a naturally drafting unit as the P stands for standing pilot and the N stands for naturally drafting.  The Bosch Therm 520HN has a hydro generator ignition and is a naturally drafting unit as the H stands for Hydro generated and the N stands for naturally drafting.  The Bosch Therm 660EF requires power and plugs into 120V outlet.  The 660EF has electronic ignition and is fan assisted which makes it a direct vent unit and the E stands for electronic ignition and the F stands for fan assisted.

The Bosch Therm 520PN and the Bosch Therm 520HN both use an exhaust vent of 5" diameter double wall type B-vent and should be vented vertically up through the roof for a minimum of 6' to the raincap.  There is a vertical vent kit called the H/P VVT Vertical Vent kit and has all the material for penatrating the roof.  If venting the 520PN or 520HN up through the roof is not an option then the heaters could be vented horizontally out the sidewall but MUST use the AQ4 Powervent kit.  The 660EF is a direct vent unit and requires to be vented verically or horizontally with 3" stainless steel sealed vent pipe.  The 660EF requires a 660EF adapter first on top of the heater to accomadate the venting.

There is also the Bosch Therm 660EFO Outdoor unit and it is just the same as the 660EF but is designed specifically for outdoor installations.  The 660EFO has a special top that it exhausts out of and also has the electronic ignition and is fan assisted.  The Bosch Therm 660EF/EFO heaters plug into a 120V outlet.

Z-Flex Z-Vent Stainless Steel Vent Pipe

The Bosch Therm 940ES and Bosch Therm 830ES tankless water heaters require either 3" or 4" single wall stainless steel venting.

The Bosch Therm 940ES is a 199,000 BTU heater and the Bosch Therm 830ES is a 175,000 BTU heater. Read the manual carefully as these two heaters have been approved for longer runs using 4" Z-Flex stainless steel venting.

At Pro Water Heater Supply we carry the full line up of Z-Flex Z-Vent 3" and 4" stainless steel vent pipe. This special single wall venting is rated AL29-4C and is approved for Category I (vertical only), II, III & IV applications and is designed for use with boilers, high efficiency gas and oil heaters and water heaters where cool flue gases are vented under pressure.

Z-Vent contains a built-in, fail-safe gasket and locking band connection. No sealant is required.

Z-Vent is available in up to 24" diameter and is also used to vent boilers.

Global ProTankless Supply