For several years, the option of using a wet fire sprinkler system in frigid climates was relatively rare, even though Wet Pipe has long been the most popular type of commercial – and even some residential – fire protection. It is the easiest to install and maintain, the least expensive option, and, since the water is already in the pipes, fire suppression is immediate.
In colder areas where you can’t maintain temperatures at or above 40 degrees, however, relying on a water-only Wet Pipe system to protect yourself and your investment isn’t feasible or safe. Not only is it a code violation (which could easily void any insurance claim), it’s also a high-stakes gamble. At a minimum, you’re looking at not having a working fire suppression system because the water is frozen inside the sprinkler pipes.
Thankfully, that has changed. But first, a look back:
Your only cold-weather fire sprinkler options used to be either a wet system where the water is mixed with an antifreeze solution, or a Dry Pipe system. Both have several disadvantages in comparison to a water-only wet sprinkler.
Antifreeze
For starters, traditional antifreeze’s inherent flammability has caused serious safety concerns in the past. Mixed with water at the proper concentration levels was supposed to render the main ingredient in antifreeze, glycol, safe for use in fire sprinklers. However, in 2010 when a high level of antifreeze in a residential sprinkler solution exploded a small grease flame into a fatal fire, the National Fire Protection Association (NFPA) reconsidered its position on antifreeze.
As a result, the NFPA has mandated that all wet sprinkler systems can no longer use traditional antifreeze after September 30, 2022. While technology has spawned some viable antifreeze alternatives, using this kind of freeze protection remains pricey to install and maintain.
Dry Pipe/Pre-Action Pipe
In these systems, the sprinkler pipes are filled with air instead of water. When the sprinkler activates, the air escapes, and pressurized water follows. Since the pipes are ‘dry’ when not in use, they are ideal for freezing climates. Pre-Action Pipe is roughly the same Dry Pipe, except that it has a second delay to ensure the sprinkler isn’t activated accidentally. This type is used chiefly for museums, art galleries, and labs where water can cause irreparable damage.
The drawbacks of these systems are significant, including delayed water release and more complex installation and maintenance. The substantially higher cost of dry systems also tends to put them out of reach as options for residential and small business consumers.
Fast-forward to the present.
Wet Pipe with Heat Trace
In 2019, the UL, NFPA, and the Institute of Electrical and Electronics Engineers (IEEE) recognized electric heat trace as a safe and reliable method of freeze protection for fire sprinkler systems and amended their regulations accordingly. The move put affordable, freeze-protected Wet Pipe back on the table for consumers and builders in colder climates, without the headache and complexity of mixing chemicals.
Heat trace cable has been around for a long time and is used in various applications, including roof and gutter de-icing, and plumbing protection. Still, it wasn’t officially certified for fire safety until the 2019 amendment. As there are some specific requirements for sprinkler use, it’s essential only to use heat trace certified for that purpose.
Some of those requirements include: Maintaining control of the system through an integrated ground fault protector; securing the heat cable to the piping with glass tape (if metal) or aluminum tape (if plastic); making sure temperature control alarm contacts are connected to the fire control panel; and encasing pipes and valves in closed-cell waterproof thermal insulation and a flame-retardant, waterproof covering. Insulation on the valve covers also needs to be removable for regular inspection.
If you plan to DIY it on your heat cable installation, you can find some essential tips in our previous blog post, 3 Easy Ways to Protect Your Pipes in an Unseasonable Cold Snap. Because of the detailed fire safety code specifications, though, also be sure to follow the manufacturer’s instructions carefully. Our experts at HeatCable.com prefer using Drexan Multi-Trace for its strength and versatility, and Drexan offers an in-depth tool for planning and installing heat cable on your wet sprinkler system from start to finish. Other heat cable manufacturers have similar detailed instructions and guides online.
It’s important to note that you cannot use heat cable everywhere in a sprinkler system. Heat trace is designed mainly for use on the supply lines for a sprinkler or standpipe system, the branch lines within a sprinkler system, and sometimes private fire service mains if listed explicitly for underground use. You are not allowed to use heat cable to provide freeze protection on valve enclosures for auxiliary dry or pre-action piping.
For additional questions on installing fire sprinkler freeze protection or information on any of the many other applications for heat wire for roofs, check back regularly with our heating professionals at HeatCable.com.