In an upcoming issue of PM, you will be able to read an article I wrote recapping the first 25 years of residential fire sprinklers. It is a somewhat bleak report, considering that less than 1 percent of all new single-family dwellings constructed in the United States have a residential sprinkler system.

NFPA 13D systems can be piped as multipurpose systems using the water distribution system to double as the sprinkler system. The connection to a sprinkler is the same as a connection to any other fixture in the house. You conveniently run the piping and connect a tee and sprinkler. Since it is an integral part of the potable water system, the only contractor I would want installing such a system is a plumbing contractor. I am sure all of you feel the same.

While I have been harping on plumbing contractors for years to get into the residential sprinkler business, we still have only a handful of contractors actively involved in the work. When I stand on the soap box, I am often met with weak resistance. About five years ago, I received one strong statement of concern that prevented certain contractors from entering the business. “How can you install a residential sprinkler system on a well system?”

Being the smart engineer, I sat down to figure out this easy dilemma. NFPA 13D requires a 10-minute supply of water to be stored in the building when connected to a well system. This would mean the storage of anywhere from 90–260 gallons of water. Then I started to design the pump and tank system. The first thing that happened was that the pump got real big. Unfortunately, the pump only needed to be that big when there was a fire. For normal operation of the plumbing system, the pump was so oversized that it would only run for a few seconds and constantly cycle.

Friendly Help: That’s when I realized how stupid an engineer I really was. Then I started to talk to a good friend named Franz Hasse of Franz P. Hasse and Associates. Franz lives in New Hampshire and has his own design firm that specializes in residential sprinklers. Write Franz’s number down — 603/924-9229. Besides being involved in design, Franz tinkers as an inventor.

You can imagine, living in New Hampshire, there are many homes built with a well system. Franz loves to design single-family dwellings using a multipurpose piping system. So I thought he would have the perfect answer as to how to install a well system.

Franz’s first comment was, “Forget about a multipurpose piping system.” This surprised me since a multipurpose piping system is the least expensive way to install a residential sprinkler system.

Franz said, “It is the lowest cost if you have a public water supply. For a well system, it is cheaper to run a separate piping system for the residential sprinkler system.” My initial thought was, two piping systems, two pumps, how could this be cheaper?

As I told you, Franz loves to tinker. He doesn’t follow the norm; he invents. Franz developed a system whereby the water distribution system fills the sprinkler system and the standby tank of water. Don’t forget that NFPA 13D requires a minimum of a 10-minute supply of water. That is considered enough time to get out of the building. Many times, the 10-minute supply controls the fire with little fire damage to the home.

Once the system is filled, Franz isolates the sprinkler system from the potable water supply with a check valve. Then he connects a nitrogen supply to the sprinkler system. That’s right, he uses a nitrogen bottle you can buy from any welding supply house.

The nitrogen supply is controlled with regulators and special connections that Franz has designed. One of the beauties of this system is that it will work when the power goes out. Franz can assist you in obtaining the necessary controls for the system.

The nitrogen connection is the energy source that raises the pressure of the water on the sprinkler system. Very clever!

In plumbing, we always learn the way to raise the pressure on a water piping system is to either have a raised tank or a pump and accumulator system. Most people opt for the pumping system in a single-family dwelling. Franz realized there are other ways to raise the pressure, one being the connection of a compressed gas to the water supply.

Since the sprinkler system is only used when there is a fire, you never have to worry about the nitrogen supply. Of course, Franz has gauges installed just in case a leak in the system depletes the supply of nitrogen.

Still Another Way: While the nitrogen system is great, the newer low flow, low pressure residential sprinklers added a new twist to homes on a well system. Franz started to think of ways to get back to multipurpose piping systems on a well system. In order to lower the cost of the installation, he continued to tinker. He thought it would be cheaper to install a flexible 1/2–inch pipe throughout the home rather than a larger rigid piping system. He started with polybutylene. Then they stopped selling polybutylene. So he switched to PEX.

The system Franz developed was a looped and gridded piping arrangement with special fittings for connecting the sprinkler pipe. You guessed it, Franz patented the fittings, he’s a smart guy.

Everyone knows that 1/2–inch pipe cannot supply the water flow required for a residential sprinkler. However, two, three or four 1/2–inch pipes connected to a special fitting can handle the flow. You see, the system is designed so water can flow in two directions in the piping system. Thus, the piping loops around the house with two to three supplies connected to the main.

Using 1/2–inch PEX tubing, Franz’s system is easy to install. It is also one of the cheapest systems to install. The only problem is that NFPA and UL do not currently permit PEX tubing for residential sprinkler installations. But that should change in the very near future.

By the way, Franz’s 1/2–inch looped system with special fittings also can be used in a multipurpose piping system for houses that have a public water supply. It is not limited to well systems. Franz also rationalizes that in an existing home, it is easier to install a residential sprinkler system with flexible 1/2–inch tubing.

You need to get into the residential sprinkler business. If you deal with homes on well systems or want to use 1/2–inch flexible tubing, you need to contact Franz. Your pride as a plumbing contractor will soar the first time a sprinkler system you installed saves the lives of the people living in the home.