Sprinkler head types in a DC rowhouse or condo: pendent, sidewall, concealed, and what the bulb color means
Most owners have looked up at a sprinkler head a thousand times and could not say what kind it is. That matters the day one drips, the day a painter asks if he can tape it, or the day the condo association sends a notice about replacements. Here is what the heads in a District house or condo actually are, why only one of them opens in a fire, what the little colored bulb is telling you, and how to read the stamp on the frame before anyone orders a part.
One head opens, not the whole house
The movies have done real damage here. A sprinkler head is a plug held in place by a glass bulb full of liquid. When the air at the ceiling reaches the rated temperature, the liquid expands, the bulb shatters, the plug drops, and water hits the deflector and sprays the room. Nothing else happens anywhere else. The head in the next bedroom has its own bulb and its own temperature, and it stays shut unless the fire reaches it. Smoke does not open a head. Burnt toast does not open a head. A cigarette lighter held under one would, which is why we tell tenants in Columbia Heights and Navy Yard buildings not to test that theory.
That is why a home system can run on a one inch water service instead of a fire main. NFPA 13D sizes the supply for the two most demanding heads flowing at once, not twenty, and most house fires are held by the one head over the fire until the engine company arrives. The power outage article covers why none of this needs electricity.
The glass bulb and its color
The bulb color is a code for the temperature at which it breaks. It is standardized across every maker, so the color in a 1990s Cleveland Park condo means the same thing as the color in a Navy Yard tower finished last year.
| Bulb color | Rating | Class | Where it goes in a house |
|---|---|---|---|
| Orange | 135 F | Ordinary | Bedrooms, halls, living rooms, basements |
| Red | 155 F | Ordinary | Same rooms, the most common residential head |
| Yellow | 175 F | Intermediate | Kitchens near the range, boiler rooms, under skylights |
| Green | 200 F | Intermediate | Attics, near heaters and flues |
| Blue | 286 F | High | Rare in a house, commercial kitchens and industrial spaces |
Ordinary temperature heads go almost everywhere in a rowhouse. Intermediate heads go where the ceiling runs warm on a normal day, so the head does not open while someone sears a steak or the July attic hits 150 degrees. The standards publish distance rules from ranges, flues, and recessed lights that decide when the hotter head is required, and the kitchen heads article walks through the rowhouse version of those rules.
The four shapes, and where each one lives
| Type | What it looks like | Where we use it |
|---|---|---|
| Pendent | Hangs down from the ceiling, deflector below the bulb, usually with a white or chrome trim ring | Finished ceilings on every floor, the default head |
| Upright | Sits on top of the pipe, deflector above | Exposed joist bays in an unfinished basement or cellar |
| Horizontal sidewall | Mounts high on a wall and throws water across the room | Rooms where the ceiling cannot be opened, plaster medallions, the dry head in an unheated rear addition |
| Concealed | A flat cover plate flush with the ceiling, head hidden above it | Living rooms and bedrooms in a renovation where the owner does not want to see hardware |
A pendent costs the least and is what most of a system uses. A concealed head adds a cover plate and a deeper rough in, which is why a quote that calls for concealed heads throughout lands higher inside the $2 to $7 per square foot retrofit range on the cost page. Sidewalls are the problem solvers: a Capitol Hill parlor with an ornamental plaster ceiling gets one sidewall head high on the back wall instead of two pendents cut through the cornice.
Residential heads are their own listing
The heads in a house are not the same product as the heads in a parking garage. A residential sprinkler is listed separately, opens fast, and throws its water high on the walls as well as down, because the point in a home is to keep the room survivable long enough to get out, not to protect pallets. NFPA 13D calls for listed residential sprinklers in the living space, and the DOB inspector reads the model number on the final to confirm it. A 13R condo building uses the same residential heads inside the units and standard heads in the garage and mechanical rooms.
Concealed heads and the cover plate
The concealed head is the one that gets damaged by people who mean well. The flat plate is held on by a solder link that lets go at a temperature below the bulb inside, so the plate drops first and the head drops into position. Three rules follow from that. The plate cannot be painted on site, because paint changes when the solder releases; makers sell plates in custom colors and we order them with the heads. The plate cannot be caulked, wallpapered over, or trimmed with a decorative ring that is not listed for it. And the plate has to be the one listed for that head, so a plate from a different maker that happens to fit is a failed inspection item, not a repair.
Reading the stamp before anyone orders a part
Every head carries, on the frame or the deflector, the manufacturer name, a model or sprinkler identification number, the K factor that sets how much water it flows, the temperature rating, and the year of manufacture. When a head needs replacing, all five have to match or the hydraulic calculation on file with DOB no longer describes the system. A plumber swapping in whatever the supply house had on the shelf is one of the things we find on the inspection page list, and the recall article explains why the year matters in older buildings. Photograph the stamp, send it, and the replacement arrives right the first time.
One practical note. A condo building keeps a cabinet of spare heads and a wrench at the riser because its standard requires it. A house usually does not, so at the end of a rowhouse install we leave two spares of each type in a labeled bag taped to the riser. Ask for them if you did not get them.
Quick answers
Do all the sprinkler heads go off at once?
No. Each head is its own heat sensor. The glass bulb in the head over the fire breaks at its rated temperature and only that head flows. The rest of the house stays dry unless the fire spreads and heats the next head. In most house fires one head does the whole job.
What does the color of the glass bulb mean?
The color is the temperature rating. Orange and red bulbs are ordinary temperature heads, the kind in bedrooms, halls, and living rooms. Yellow and green are intermediate temperature heads for kitchens, attics, and near heat sources. Blue is a high temperature head and is rare in a house.
Can I paint the cover plate on a concealed sprinkler head?
No. The cover plate is held on by solder that melts at a set temperature, and paint changes that. Factory painted plates in custom colors exist and are ordered by the sprinkler contractor. Any plate painted on site has to be replaced.
Not sure what head is in your ceiling?
Send a close photo of the head and the stamp on the frame. We will tell you the type, the temperature, the maker, and whether it is on a recall list.
Call (202) 410-0120