We stock a HUGE supply of both 3" and 4" Z-Flex Z-Vent 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 Bosch AQ3ES Vent Kit (used only with the Bosch 2700ES / 2400ES heaters) and the Bosch AQ3 Vent Kit (used only with the Bosch 2400E / 250SX 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.
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.
For our customers who purchase the Bosch 125FX, we automatically include the FXHOOD. However, you will need a 4" x 90 degree elbow and usually some straight run pipe. We strongly suggest that all Bosch 125FX customers purchase the Bosch 125FX / 425EF Adaptor to make a perfect seal between the heater and the venting system. All of these 4" venting parts can be found on our 4" stainless steel venting page.
The Bosch 2700ES / 2400ES and the Bosch 2400E tankless water heaters require two condensation drain points on the exhaust system.
The Bosch 2700ES / 2400ES Installation Manuals details these requirements.
Bosch has also recently released a Service Bulletin on the Bosch AquaStar 2400E Condensation and Rain Prevention Requirements.
This bulletin states that Bosch Water Heating now requires the installation of an external condensate drain (in addition to the one supplied with the heater) for ALL vertically terminating vent installations and Horizontal terminating vent installations where the total vent length is greater than 5 feet.
Bosch recommends to install the additional condensate drain as close to the heater as possible.
There are three 3" Z-Flex Z-Vent condensation drain parts that you can choose from:
Each of these will require a Bosch 2400E / 250SX Condensate Drain Kit (2SVEDTK24).
The 3" Vertical Condensation Drain Tee (2SVEVWCF03) acts as a 90 degree elbow and is the best choice for catching condensation and rain as it has a large reservoir.
Not all horizontal installations have an opportunity to use the 3" Vertical Condensation Drain Tee and they should therefore use the 3" Horizontal Condensation Drain Pipe (2SVEDWCF03) to replace a straight section of pipe.
The 3" Vertical Condensation Drainpipe (2SVEVDP03) has the least capacity for removing condensation and rain. It should be used as a last resort and only when 3" venting goes literally straight up from the heater. It is preferable to offset the Bosch 2400E from the vertical vent pipe and use the 3" Vertical Condensation Drain Tee (as a 90 degree elbow) along with an actual 90 degree elbow.
If you must go straight up from the Bosch 2400E, we recommend that you use the 3" to 4" Increaser (2SVSI0304) and then run 4" Z-Flex Z-Vent venting. This will allow you to use the larger 4" Vertical Condensation Drainpipe (2SVEVDP04). This 4" drainpipe has a much higher capacity for removing condensation and rain than does the 3" drainpipe.
