Essential Fittings for Underground PEX Pipe


What Fittings Should I Include on My Purchase of Underground PEX Pipe

When installing an underground plumbing system using PEX (cross-linked polyethylene) pipe for your outdoor wood furnace system, choosing the proper fittings is crucial for a reliable and leak-free installation. Crimp fittings are commonly used with insulated PEX pipes and offer a secure and durable connection. This is, for us, the BEST PEX fittings to use.

In this article, we will guide you through the necessary crimp fittings you should consider including in your purchase of underground PEX pipes.

Crimp Fittings to Use in Different Applications

Suppose you are going to connect our Heat Mizer InsPEX 1” Crimp x 1” Female Sweatulated PEX Pipe or any PEX B tubing to a copper pipe. You should use PEX crimp x female sweat fittings, of course, the size depends on the sizes of your PEX pipe and your copper pipe. Click HERE to purchase PEX 1” Crimp x 1” Female Sweat and HERE for PEX 1 1/4” Crimp x 1 1/4” Female Sweat.


PEX Crimp x NPT Brass Female


To connect our Heat Mizer Insulated PEX to any male threaded ports such as plate heat exchangers, you should use PEX Crimp x NPT Brass Female, depending on the size.


PEX 1” Crimp x 1” NPT Brass Male


To connect 1” PEX Pipe to 1” Female threaded ports such as street elbow - use PEX 1” Crimp x 1” NPT Brass Male. Call our office for other sizes available.


PEX Crimp Brass Coupling


PEX to PEX connection - use a coupling PEX Crimp Brass Coupling. They are ideal for extending or repairing sections of the underground PEX plumbing system. Other sizes are available at our online store.



PEX Crimp Elbows. Crimp elbows are typically used to navigate corners and obstacles, ensuring a smooth and efficient flow of water. You can easily manage curves and bends in your PEX pipe installation by purchasing a suitable quantity of crimp elbows. They are available in a variety of angles, including 90 degrees and 45 degrees, to meet different installation requirements.

PEX Crimp Tees. These fittings feature a T-shaped design, allowing you to connect three PEX pipes at a single point. Crimp tees enable the distribution of water to different areas or fixtures, making them crucial for complex plumbing layouts. Be sure to consider the number and sizes of PEX crimp tees required to meet your project's specific needs.

PEX Crimp Valves. In any plumbing system, it is essential to have shut-off points for maintenance, repairs, or isolating specific sections. PEX crimp valves serve this purpose, allowing you to control water flow through underground PEX pipes. Purchase Ball Valve 1” Full Port Threaded. We also have other sizes available.

PEX Crimp Rings. PEX crimp rings are a fundamental component of the crimp fitting system. These rings, typically made of copper, stainless steel, or brass, are placed over the PEX pipe and compressed using a crimping tool. We have a PEX 1” Crimp Copper Ring - (bag of 10) and a PEX 1.25” Crimp Copper Ring - Bag of 10.



Finding the appropriate parts is one of the most difficult aspects of installing an outdoor boiler. You will pay more than TWICE as much for your parts if you buy them from any retailer. Additionally, it can take you months to determine how to connect one thing to another and which fittings will function properly and reliably interface with one another.

That is why we, at, have created our proprietary system of Outdoor Boiler Installation Kits. We have spent millions on perfecting the design for outdoor boiler systems and now you can benefit from this.

1. Outdoor Boiler Back of Boiler Fittings Kit. This expertly designed kit contains all the fittings needed to connect one Insulated PEX line to the back of the outdoor wood stove. This kit has been optimized to minimize flow restrictions with minimal space requirements. (Pump sold separately.)
2. Outdoor Boiler Fill Kit. All outdoor boilers are open to the atmosphere and will require that you add water monthly. The best solution BY FAR is to be able to just open a ball valve in your basement for a few seconds to add water. Otherwise, you have to use hoses or carry buckets of water during the dead of winter. The most important component of this kit is the backflow preventer required by the code to protect your domestic water supply.
3. Outdoor Boiler Filter Kit. The Outdoor Boiler Filter Kit (PEX) is a pre-assembled kit of all the components needed to protect an outdoor wood boiler system from failure due to sediment buildup using a high temperature-tolerant filtration system. This kit is the PEX version, and it contains all the fittings needed, along with the complete filter assembly, fittings, and bypass, but does not include short pieces of PEX which are typically supplied from leftover pieces from the installation process.
4. Outdoor Boiler Bypass Kit for Downdraft Furnace. A downdraft furnace is commonly used in certain manufactured homes that have ducts on the floor. This Bypass Kit will, once the indoor furnace blower fan shuts off, stop water from flowing from the outdoor boiler through the water-to-air heat exchanger, and re-route the flow of this hot water back to the outdoor boiler.
5. Outdoor Boiler Domestic Hot Water Kit. The Outdoor Boiler Domestic Hot Water Kit (PEX) is a pre-assembled kit of all the components needed to connect an outdoor wood boiler to a domestic hot water system to provide endless hot water to the home.


Including the above-mentioned PEX fittings will definitely save you time and could possibly save you money when you order an underground insulated PEX Pipe. Always make sure that the fittings you select match the PEX pipe's diameter. You can build your underground PEX pipe system with confidence and reap the rewards of a dependable and effective plumbing solution by considering these essential fittings.

Visit our online store for more outdoor wood furnace parts or contact We guarantee that we will do our best to provide you with the right answer to your question or solution to your problem.