4" Z-Flex Stainless Steel Venting for Pool Heaters

Globaltowne carries a large supply of the 4" Z-Flex Stainless Steel (AL29-4C) venting and pool heater adapters.

The 4" stainless steel venting comes in all different lengths ranging from 6" - 5' long.  We carry all of the elbows, wall thimbles and terminators also.

Globaltowne carries all kinds of adapters for any type of pool heater and many different tankless water heaters.  The 4" Sta-Rite/Pentair Pool Heater Adaptor (4STPHA04) is the most common for the pool heaters and we always keep plenty on hand.

Replacing an Aquastar 125BL Low Pressure Unit with a Bosch 345ESR/450ESR

The older Bosch Aquastar model 125B LP L (Liquid Propane) or 125B NG L (Natural Gas) was 117,000 BTU and was a naturally drafting unit that was good for one major application at a time. The Aquastar 125BL unit was a low pressure unit design for non modulating applications for heating systems in conjunction with domestic hot water.  The Bosch 125BL had a standing pilot light and took it's combustion air from the room it was installed in.  The 125BL had to be vented with a 5" B-vent double wall venting going a minimum of 6' up through the roof vertical to a raincap.  The 125BL unit could have been vented out the sidewall also with the AQ1 powervent kit (now discontinued). The Bosch Aquastar 125BL unit is discontinued now and has not been made for over 8 years or so. The replacement model for the older Bosch Aquastar 125BL would be the Bosch 345ESR or 450ESR recirculating units.

Bosch 345ESR/450ESR

The gas tankless recirculating heaters, Bosch 345 ESR and the Bosch 450 ESR are temperature modulated and have electronic ignition. The ESR stands for Electronic ignition, Sealed combustion and Recirculating. These recirculating heaters are designed and approved for heating and recirculating potable water in conjunction with an indirect storage tank.  The Bosch 345ESR and the Bosch 450ESR would be able to replace the older Aquastar 125BL unit but there would have to be significant changes such as the venting is stainless steel, combustion air taken from outside using 3" PVC and that the gas line sizing would have to be appropriate.

The 345/450 ESR are not approved or designed for closed loop heating applications. The ESR units are not a tankless heater as they have no flow switch to respond to flow. Instead it’s a recirculating water heater designed for tank loading applications such as the older Aquastar 125BL units were designed for. When an AquaStat (not included) hooked up to a tank tells the ESR that water needs to be brought back up to temperature, the ESR will tell a circulator (not included) to turn on to create flow through the heater to reheat the water in the tank. Please refer to the installation and applications manual.  The basic setup for the indirect tank, aquastat, recirculation pump, check valves, etc. should be basically the same for the new ESR heaters.

The Bosch 345 ESR recirculating heater is a 95K BTU unit and can deliver 3.5 GPM at a 45 degree rise. Efficiency is 82%


The Bosch 450 ESR recirculating heater is a 120K BTU unit and can deliver 4.5 GPM at a 45 degree rise. Efficiency is 81%

The temperature control range for both heaters can be set anywhere from 115°F (45°C) - 190°F (90°C)

The 345/450 ESR comes with a standard ¾” pressure relief valve.

The 345/450 ESR has a special built-in freeze prevention cycle and is controlled by a sensor. Freeze protection is always assured by the operation of the appliance. If the primary NTC (temperature) sensor detects temperatures 9°F below the selected temperature, the appliance starts on minimum power until the sensor reads selected temperature. In the case of minimum set point temperature then it will start at 41°F. The use of non-potable additives like glycol is not approved.

The Bosch 345 ESR and the Bosch 450ESR must be installed indoors according to the provided installation manual. The 345/450 ESR is NOT approved for outdoor installations.

The Bosch 345/450 ESR recirculating heaters must be vented in accordance with the installation manual and require Category III 3” stainless steel sealed venting for the exhaust. These heaters are direct vent units and must be vented directly to the outside in accordance with the installation manual. These heaters cannot be combination vented with any other appliance. The intake should be taken from the outside and 3”PVC or other material can be used only for the intake air.

The Bosch 345/450 ESR recirculating heaters are gas specific so they cannot be converted from one gas type to another.

AQ3ES Vent Kit Versus AQ3 Vent Kit

The AQ3ES Vent Kit is the current horizontal vent kit sold by Bosch for the Bosch AquaStar 2700ES and Bosch AquaStar 2400ES Tankless Water Heaters. This horizontal vent kit is required for all 2700ES and 2400ES installations that will be vented out the side wall.

The AQ3ES Vent Kit has all of the parts required by the 2700ES and 2400ES warranty for a safe and complete installation assuming that you are mounting your tankless water heater on the same side wall that you are venting out of.

The AQ3ES Vent Kit has a total of 40" of straight vent pipe -- 36" of straight vent pipe are required for installations in freezing areas. If you use less than 36" of straight vent pipe in freezing areas and your heat exchanger freezes and bursts it will not be covered under the Bosch warranty!

Please note that for the intake air on the Bosch 2700ES and Bosch 2400ES heaters you must use 3" rigid vent pipe, such as PVC.

In contrast, the AQ3 Vent Kit was designed for the older Bosch 250SX and Bosch 2400E tankless water heater models. Bosch did NOT require a rigid vent pipe for the intake air on these older models. So, the AQ3 Vent Kit comes with a 10' length of 3" flexible aluminum hose for the intake air. (This flex hose CANNOT be used on the newer Bosch 2700ES/2400ES models.)

Both vent kits come with a 3" x 90 degree elbow, a wall thimble, an exhaust termination box with a bird screen and an intake termination box with a bird screen.

GlobalTowne.com carries both the current AQ3ES Vent Kit and the legacy AQ3 Vent Kit in stock.

Steve

Z-Flex Z-Vent Stainless Steel Venting

GlobalTowne is an Authorized Distributor of Z-Flex Z-Vent Stainless Steel Venting.

The Bosch AquaStar 2700ES / Bosch AquaStar 2400ES / Bosch AquaStar 2400E / Bosch 250SX requires 3" or 4" stainless steel venting for Category III Gas Appliances. Our Z-Flex Z-Vent venting meets these requirements and is rated AL29-4C.

Z-Flex Z-Vent 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-Flex Z-Vent comes in 3" diameter vent pipe all the way up to 24" diameter vent pipe.

We stock the following:

• 3" Z-Flex Stainless Steel Venting
• 4" Z-Flex Stainless Steel Venting

We can special order the 5" diameter through 24" diameter vent pipe and have it shipped directly from the factory in New Hampshire -- Same Day Shipping!

Z-Vent is manufactured using AL29-4C advanced ferritic stainless steel** with unmatched corrosion resistance for use with condensing furnaces and boilers. Z-Vent was developed in the early 1980s and has thousands of field installations to date. Z-Vent is now manufactured utilizing a fail-safe gasket connection. No sealant required.

The lengths of pipe may be cut on non-expanded end using aviation snips or a hacksaw (24tpi). The cut end must be filed or sanded smooth before joining.

Call us at 888.726.9752 to help you select the stainless steel venting parts or just to verify your venting run.

Steve

Z-Flex Z-Vent Stainless Steel Venting Tips

We stock a HUGE supply of both 3" and 4" Z-Flex Z-Vent Stainless Steel Venting. And, we now carry 5" Stainless Steel Venting! Why Z-Flex products? Simply because they are the best!

Our 3" Z-Flex Z-Vent stainless steel vent pipe mates up directly with the following Bosch Vent Kits:

• Bosch AQ3ES Horizontal Vent Kit (used only with the Bosch 2700ES / 2400ES heaters)
• Bosch ES VVT Vertical Vent Kit (used only with the Bosch 2700ES / 2400ES heaters)
• Bosch AQ3 Horizontal Vent Kit (used only with the Bosch 2400E / 250SX / GWH 635ES heaters)

Bosch requires that either 3" or 4" stainless steel vent pipe (AL29-4C) be used when installing the Bosch AquaStar 2700ES / 2400ES / 2400E / 250SX / GWH 635 ES / GWH 715 ES model heaters. The GWH 345 ESR and GWH 450 ESR heaters require 3" stainless steel vent pipe (AL29-4C).

Using other types of venting with the Bosch 2700ES / 2400ES / 2400E tankless water heaters will void your warranty and put your family's health in serious danger. Many of our Bosch 2700ES / 2400ES / 2400E tankless water heater customers ask us if they can use their existing venting. The answer is always NO. And, the Bosch 2700ES / 2400ES / 2400E tankless water heaters must have their own dedicated venting system.

Most customers use the 3" venting with the Bosch 2700ES / 2400ES / 2400E tankless water heaters. If you choose to use the 4" venting, you will need the 3" to 4" Increaser Z Flex Z Vent SS Venting (2SVSI0304).

The two main reasons to use 4" venting with the Bosch 2700ES / 2400ES / 2400E tankless water heaters is if you already have the 4" venting in place or if you intend to go literally straight up with no elbows (see comments below).

Customers installing non-Bosch tankless water heaters often require 4" stainless steel venting. Many of these customers require our 4" Universal Adaptor: Takagi, Paloma, Rheem, Noritz (2SVSNA04.5) to connect their water heater to the 4" piping system. We also carry the 3" Rheem/Paloma Adaptor (2SVPA03) for connections to certain Rheem and Paloma tankless water heaters.

Some of our customers take great care to measure exactly the distances of their pipe runs. Sometimes they have to come back to us to purchase an additional length of pipe.

Here's a tip: Buy a length of straight run pipe that is a little longer than you need. Each piece of straight run pipe can be cut with a hacksaw. You must leave at least 1.5 inches at the male end of the pipe so that it will snug up with the female gasketed end of the next piece of Z-Flex vent pipe. Any part of the male end of the pipe you cut off must be discarded as it no longer has the gasketed female end.

You do NOT need to purchase gear clamps to connect the stainless steel pipes to each other. Each female end includes a clamp and a sealed gasket to ensure a tight and snug fit. Gear clamps are only needed to secure the intake air hose to the Bosch 2400E collar and again to the intake air termination box.

We do sell the Z-Vent Sealant 3oz Tube (2SILRRTV1O6X), but sealant is NOT needed to connect one piece of Z-Vent pipe to another. The sealant is only needed to help ensure that there is a tight connection between the Top Support / Support Collar and the 3" vent pipe so that rain water does not run down the outside of the 3" vent pipe and into the flashing. Sealant is also needed in certain applications in which the normal connections cannot be made, such as when certain Z-Flex adaptors without gasketed seals are used.

Steve