Noises, drips and wet spots from a home fire sprinkler system in Maryland: what each one means.

A sprinkler system is quiet for years, so the first time it makes a sound people notice. Half the calls we take from Bowie, Waldorf, Crofton and Severn start with a noise or a stain. Sometimes it is the furnace duct. Sometimes it is a head starting to weep over a bedroom. This is the list we run through on the phone, with what is normal, what gets a visit this week, and the one that means go close the valve before you call.

A bang when a faucet or the washer shuts off

That is water hammer, and in a sprinklered house it almost always points to a multipurpose system, the kind in the townhome tracts where the heads run off the domestic PEX. The pipe is larger than a plain plumbing system would use, so there is more moving water to stop when a solenoid valve on a washer or dishwasher slams shut. The bang is in the plumbing, not the sprinklers, but the sprinkler pipe carries it through the house and a loose strap in the floor system knocks against a joist. The fix is a plumber’s job, hammer arrestors at the appliance valves and tightening the straps that can be reached. It does no harm to the heads. A stand alone system does not get this, because the riser is dead ended and nothing on it ever shuts suddenly. Which type you have is in our multipurpose versus stand alone guide.

A hiss at the riser

Stand next to the riser in the basement or utility closet and listen. A steady hiss is air or water moving where it should be still. The usual spots are the gauge fitting, the test and drain valve packing, and the backflow preventer’s relief port. A backflow preventer that spits a little water from the relief port once in a while is doing its job during a pressure swing. One that hisses or dribbles all the time has a worn check and needs a test and probably a rebuild, which is covered on our backflow testing page. A hiss with no visible water anywhere can be a pinhole in a steel pipe out of sight, more common in the older 13R townhouse systems near the water than in CPVC, and that is a visit this week. Why steel pipe near the Chesapeake pits from the inside is in our corrosion article.

Ticking or creaking in the ceiling

On the first cold night of the year and on the first hot afternoon, CPVC pipe in the attic floor and the upper floor joist bays grows and shrinks. Where a run passes through a drilled joist or lies against a strap, it ticks as it slides. The sound moves along the ceiling over a few minutes and then stops. It is normal, it is the same thing a hot water line does, and it does not need a visit. The exception is a run in an attic that has lost its insulation cover, where the ticking is a reminder that the pipe is exposed to the cold. Our winter article covers what to check before January.

The outside bell rang and stopped

The waterflow bell on the side of the house rings when water moves through the riser. A head opening rings it until the valve is shut. A ten second ring that stopped on its own is a pressure surge, most often when the utility works on the main, when a well pump kicks on, or on a windy day when a loose bell clapper swings. One short ring a year is nothing. A bell that rings for a few seconds every day has a flow switch or a retard chamber that needs adjusting, or a slow leak that lets the switch see movement. Every reason the bell sounds, and what to do in the first minute, is in our bell article.

A damp ring or a drip at a head

This is the one to take seriously. A head that is weeping, with a wet ring on the ceiling around the escutcheon or a drop forming on the deflector, has a seal that is starting to fail. It will not stop and it will not get better. It will either keep dripping into the drywall or let go entirely, usually overnight, and put a few gallons a minute into the room. Do not touch the head, do not tape a cup under it, and do not try to tighten it. Put a bucket under it, go to the riser and know where the control valve is, and call for a replacement. A weeping head is swapped the same day in most of our service area and the price for a head call is on our cost page. What the swap involves is in our head replacement article.

If the drip is coming from the ceiling a foot or two away from the head rather than the head itself, the leak is at a fitting or a drilled hole in the pipe above. Shut the control valve, open the riser drain, and call. The pipe section gets cut out and replaced. A hardware store clamp is not a repair the county will accept.

A brown stain with no drip

A dry brown ring on the ceiling under a sprinkler pipe run is an old event, a slow weep that dried up, a condensation drip in a humid summer, or a roof leak that tracked along the pipe. Press the drywall. Soft means wet behind it and a visit. Hard and dry means photograph it and watch it for a month. A stain that comes back after you paint it is a leak, not a memory.

Gurgling or air at the test drain

When the inspector opens the drain at the annual test, a system that has been undisturbed for a year spits air first and then water. That is trapped air at the high points and it is normal. Air that collects fast enough to show up on the gauge as a pressure that drifts up and down through the day points to a supply problem. How to read the gauge, and what a reading that moves tells you, is in our gauge article.

What the repair visit looks like

For a head or fitting leak, the technician shuts and drains the system, replaces the head or cuts out the bad section and cements a new one, waits for the joint to cure, refills, and tests at the drain before leaving. The system is out of service for the visit and, on a cold day with a long cure, sometimes overnight. If the leak was into finished space, the drying and the claim are covered in our discharge article. For the bell and the backflow preventer, the fix is an adjustment or a rebuild, done with the system live.

Common questions

• Can I close the control valve until someone comes? For an active leak, yes, and open the drain. For a noise or a dry stain, no. A closed valve is an unprotected house, and in a monitored home it may also trip a supervisory signal.
• Is a weeping head covered by the builder? In the first year, usually. After that it is a service call.
• The bell rang once at 3 AM and nothing is wet. Do I need a visit? Once, no. Note the date. If it happens again inside a few months, have the switch looked at during the annual inspection, which is on our inspections page.

Most sounds from a sprinkler system are the house settling around it. The two that matter are water where it should not be and a bell that keeps ringing. Know where the valve is, keep the drawings handy, and call before the drip becomes a ceiling.