Underground Insulated PEX Pipe carries your valuable heat from your outdoor furnace to your home and other buildings. There is considerable technology in this pipe - One thing we make sure of is that the PEX tubing inside the insulated pipe is a CONTINUOUS RUN.

There should be no splices in the PEX in the underground pipe.

This is crucial because a splice would be the point of greatest risk of failure in the PEX, and in the waterproof outer casing.

The PEX cannot be spliced underground because PEX naturally expands and contracts. Since PEX will expand and contract 1-2.5" per 100ft of length with every 10°F change in water temperature, it cannot be spliced underground because that splice location (or coupling) will fail from constant expansion and contraction as heat temps fluctuate drastically with an outdoor boiler system.

Yes, there are several PEX elbows and connections at the indoor plumbing locations, but since those are much shorter lengths of PEX, they can absorb the expansion and contraction without stressing the connectors.

It is recommended to put an elbow just inside the home where the underground pipe emerges into the building that can absorb this considerable expansion and contraction.

Also, since the underground pipe outer casing must be waterproof, it is extremely difficult to splice the outer casing. We use only the highest quality outer casing, which is white on the outside.

We are able to splice that at our factory if needed, but we are experts at making perfect watertight seals and it is very difficult to achieve a watertight seal in the field.

Therefore, there is a 100 percent failure ratio (or a ZERO percent success ratio) when attempting to splice an underground pipe.

>>> If you are considering a new underground pipe for your outdoor wood furnace, do NOT buy black!

The black underground pipe is made of drain tile, and drain tile is not manufactured to be waterproof. 

Why is this a problem? If water leaks into your PEX insulation, then it will suck a lot of heat out of your underground pipe. Some customers report that their boiler water is 180 degrees leaving the boiler going into the underground pipe, but when it arrives in the house, they have already lost 40 degrees!  

This is an enormous waste of wood and money! (And time to cut, split, and stack all that extra wood!)

Again, never splice the underground pipe!

And do NOT buy an underground pipe that is black.

How To Get The Best Value On Insulated PEX?

Buy Heat Mizer Brand!

• "Forever Waterproof" design
• Lowest Heat Loss Ever – Less than one degree of heat loss over 200 feet!
• Industry Leading Warranty - Full Replacement Coverage, including LABOR!
• Perfect Performance Record - Over 1 Million Sold and ZERO Failures
• Experts Agree! Our proprietary design has been PERFECTED for over 30 years!
• Best QUALITY, Best PRICE, Best VALUE!
• All Insulated PEX customers get FREE Design Service ($695 value)

TOP 5 Ways To Avoid Wasting Money:

• How much heat loss does Heat Mizer brand Insulated PEX have?

"Independent lab studies have shown the heat loss of Heat Mizer insulated PEX to be the lowest in the industry - less than one degree over a 100-foot run! The actual results were about six-tenths of the degree - again, less than one degree. Our customers report that they usually cannot even measure ANY heat loss."

• NEVER use black drain tile

It is not waterproof and will leak. Underground pipe for an outdoor wood stove MUST be waterproof - it leaks and fills with water, and it SUCKS heat out of your system.

• Get discounted WHOLESALE prices - NEVER pay the retail price!

You can now purchase DIRECT from us and get wholesale prices! Get PROMO CODE for orders longer than 100' to get additional discounts!

(Click on the product photo below to select the promo code in the product description.) Call us at (888) Log-Burn or (231) 861-8200 with any questions.

• Never splice Insulated PEX underground

Spliced underground pipe fails 100% of the time. We make every roll custom-made to your ordered length. We will make you the exact length you need.

• NEVER overspend for underperformance

Many will try to sell you foam-filled underground pipe for $10, $15, or even $18 per foot. This is a waste of money on a poor product that fails. We call it a "Do-Over Pipe" because you will have to do it over once it fails underground.

For more outdoor wood boiler parts visit our online store! Call our office Monday-Friday 9 am - 8 pm EST at (231) 861-8200