Christmas trees, holiday lights, and your home fire sprinklers: what stays away from the heads

The repair calls we get in the first week of January follow a pattern. Someone on a stepladder taking down garland clipped a sprinkler head with an elbow. Someone hung a wreath from a pipe in the basement and the hanger wire sawed into CPVC over three weeks. Someone stored the decorations in the attic and stacked the boxes against the sprinkler line, and the pipe froze where the insulation got pushed aside. None of these are tree fires. They are how a holiday house in Ashburn, Burke, or Woodbridge puts a few hundred gallons on the carpet. Here is what the system does well in December and the habits that keep it from going off for the wrong reason.

A tree fire is exactly what the head over it is for

A dry Fraser fir with a string of old lights on it burns faster than almost anything else in a house. The flame reaches the ceiling in well under a minute, and that heat is what a sprinkler head reads. The ordinary head in a living room is rated to open at 155°F at the ceiling, as the temperature ratings article explains, and a tree fire gets the ceiling there in seconds. One head opens, puts a few hundred gallons across the room over the next several minutes, and the fire stays in that corner until the engine arrives. The myths article covers why the other heads in the house stay closed.

So the tree does not need to be moved away from a head. Put it where you want it. The only placement rule is the one that applies to every tall object in a sprinklered room: leave a clear gap between the top of the tree and the head so the spray pattern is not blocked, and keep the top of the tree below the deflector. A nine foot tree jammed into a vaulted corner with the tip touching the head is the one we ask people to trim.

Nothing hangs from a pipe or a head

This is the rule from the living with sprinklers article and December is when it gets broken most. Exposed sprinkler pipe in a basement rec room or an unfinished utility area looks like a convenient rail for garland, stockings, and light strings. A run of CPVC is rated for water pressure, not for hanging weight, and the fittings are the weak point. A kid pulling on a light string weighs enough. The same goes for the head itself. A hook over a sidewall head or an ornament wire wrapped around a pendent can crack the glass bulb, and a cracked bulb opens the head with no fire anywhere.

Hang from the joists, from drywall anchors, or from adhesive hooks on the wall. If the only thing at the right height is sprinkler pipe, that is the sign to put the garland somewhere else.

Keep the cover plates and heads clean of decor

Concealed heads in most Northern Virginia townhouses sit behind a flat cover plate that drops away at a lower temperature than the head itself. Spray snow, glitter paint, adhesive snowflakes, and the sticky residue from a removable hook all do the same thing to that plate: they glue it in place or insulate it, and a plate that does not fall means a head that does not spray. The what opens a head article lists paint as the most common thing we replace heads over, and holiday spray snow is paint. If it gets on a plate or a head, do not clean it off with a scraper. Call it in, the head gets swapped for a listed one, and the visit is priced per head.

Candles, space heaters, and the one honest heat source

People worry that a candle will set off a sprinkler. A candle on a table does not put 155°F on the ceiling. A candle on a high shelf a few inches under a pendent head can, and so can a cluster of them in a wall sconce directly below a sidewall head. Keep open flame a couple of feet off any head and the question goes away.

Space heaters are the real December heat source. A portable heater pointed at the ceiling in a small room, or one on a shelf under a head, puts hot air exactly where the bulb reads it. More often the heater is in a room because that room is cold, and cold is the other winter problem. A sunroom, bonus room over the garage, or finished basement corner that needs a space heater to be usable is a room where the sprinkler pipe in the wall or ceiling may be sitting near 40°F already. The freeze protection article covers what to do about that permanently. For the holidays, keep the heat on in those rooms, keep the heater off the shelf under the head, and leave the cabinet doors under any exterior wall sink open on the coldest nights.

Decorations in the attic and the garage

The attic is where the holiday boxes live the other eleven months, and in a sprinklered house the attic is where the pipe is most exposed. A standalone system in a 2000s Loudoun or Prince William house often runs its main line through the attic under a blanket of insulation. Every box pushed across the joists moves that insulation, and a bare run of CPVC at 20°F is how January leaks start. Stack boxes on a platform that stays clear of the pipe path, put the insulation back over anything you uncovered, and never set a box on top of a pipe. The attic work article shows where the pipe usually runs so you know what you are stepping around.

The garage has no heads in a 13D house, which the rooms without sprinklers article explains, so decorations stacked there are not a sprinkler question. They are a plain fire load question.

Away for the holidays

A house left empty from the 23rd to the 2nd is the single most common freeze call we get. The thermostat goes to 55°F, a cold snap takes the attic well below freezing, and nobody is home to hear the flow alarm. The empty house article has the full list. The short version is to leave the heat where you normally keep it, open the interior doors so warm air reaches the rooms on the end, and have someone with a key who knows where the valve is. A monitored flow switch, covered in the monitoring article, turns a ten day flood into a ten minute one.

The January checklist

• Take the garland and lights down from the floor or a stable ladder, and look up before you swing an arm near a ceiling head.
• Peel adhesive hooks off walls, never off cover plates. A plate that got spray snow on it gets replaced, not cleaned.
• Put the attic insulation back over any pipe the boxes uncovered.
• Walk past every head once with the tree gone and look for a bent deflector, a chipped bulb, or a stained ceiling ring. Any of the three is a call.
• Check the riser gauge against what it read in the fall. The riser article explains what a drop means.

If a head opens for any of the reasons above, the water is the cheap part, under a billing unit on the meter. The cleanup is not, and the after an activation article covers who to call first. County specifics live on the Fairfax County guide, Loudoun guide, Arlington and Alexandria guide, and Prince William guide.