Leaving a sprinklered house empty: vacations, vacant listings, and the winter away

Every winter we get the same two calls. One is from a homeowner in Ashburn or Springfield about to leave for three weeks, asking whether to shut the sprinklers off while nobody is home. The other comes in February from a listing agent standing in a vacant townhouse in Woodbridge with water coming through the ceiling, because the seller moved out in November and turned the heat off to save money. The answer to the first call prevents the second one. Here is how to leave a sprinklered house in Northern Virginia empty for a week, a season, or the months a listing sits on the market, without coming back to a problem.

Leave the valve open

Closing the sprinkler control valve before a trip does not make the house safer. It removes the one thing in the building that can act on a fire while nobody is there to smell smoke or call 911. A 13D system is designed to hold a fire in the room where it started long enough for the fire department to arrive, and an empty house is exactly the case where that matters most, because the call to Fairfax County or Loudoun County dispatch comes from a neighbor who sees smoke, not from someone inside. The valve stays open. What you manage while you are away is temperature and water supply, not the valve.

Heat is the whole job

Almost every empty house sprinkler failure we have seen in this region is a freeze, and the freeze protection article covers how cold it gets here and where pipe runs get cold first. The short version for an empty house: wet CPVC has to stay above 40 degrees everywhere it runs, and it runs in places the thermostat does not measure. Closets on exterior walls, the room over the garage, the bump out bay window, the finished basement corner behind the furnace, and any attic branch that was never insulated the way the plans showed.

Set the thermostat no lower than 55 and leave interior doors open so warm air reaches every room. If the house has zoned heat, every zone stays on. Open the cabinet doors under sinks on exterior walls, the same habit plumbers recommend for domestic pipe, because on a multipurpose system that pipe is also the sprinkler supply. If you have a smart thermostat, turn on its low temperature alert and give the alert to someone who can get to the house. A thermostat that texts you from Florida is only useful if a person in Virginia can act on the text within a few hours.

The water supply has to stay on

Two things quietly cut off a sprinkler system in an empty house. The first is the smart shutoff valve. Whole house leak detectors that close the main on continuous flow are common now, and if one sits upstream of the sprinkler tee, it will read a sprinkler discharge as a leak and close the water on a working fire. The softeners, filters, and PRVs article explains where the device has to go. Before you leave, know which side of the tee yours is on, and if it is on the wrong side, set it to alert only rather than auto close until it is moved.

The second is the utility. A vacant listing where the seller has closed the Fairfax Water or Loudoun Water account, or an estate where nobody is paying the bill, can end up with the meter locked. When the meter is locked the sprinkler system is a network of pipe full of still water and nothing behind it. Keep the account open through closing. If the house is on a well, the power outage article covers what the pump needs, and the electric account has to stay on for the same reason.

A short trip: a week or two

• Thermostat at 55 or above, doors open, under sink cabinets open on exterior walls.
• Sprinkler control valve open and, if it has one, the chain or tamper tag still in place.
• Glance at the riser gauge on your way out. It should read close to what it always reads.
• Smart shutoff, if you have one, set to alert only if it sits upstream of the sprinkler tee.
• A neighbor or friend with a key, the riser location, and our number.

That is the whole list. You do not drain anything, you do not touch the inspector's test valve, and you do not need a service visit before an ordinary vacation.

A season away

Houses that empty out for the winter need one more layer. The heat stays on as above, and a person walks the house every week or two and after every hard freeze. The walk is simple: check the thermostat is doing what it was told, look at the riser gauge, look at ceilings for stains, and listen. A slow weep at a fitting that froze and thawed makes no sound, but a head that let go sounds like a shower running behind the drywall.

If the system has a dry sidewall head serving a porch or a dry pendent in an unheated garage, it was built for cold and needs nothing. If a previous owner ran an antifreeze loop to an attic or garage branch, that is the one part of a system worth having looked at before a long absence, because the rules on antifreeze changed and an old mix may not be what is in the pipe. The older systems article explains what to look for at the riser.

A vacant listing

Vacant listings are where the expensive failures happen, because the house belongs to someone who has already moved on and the agent does not think of it as their pipe. Three things go on the house card next to the lockbox instructions: the heat stays at 55 or above until closing, the sprinkler valve in the utility room stays open, and the number to call if the bell rings or the ceiling is wet. The selling article covers what buyers and their inspectors ask about the system.

If the listing runs through a winter, put the bill for keeping the heat on against the bill for a ceiling repair and a system repair after a freeze, then a disclosure of a water event on the listing. The heat is cheaper. Sellers who insist on winterizing a sprinklered house should know that draining a wet 13D system is not a plumber's job, has to be reversed and tested before the buyer takes possession, and leaves the house with no protection while it is drained. We rarely recommend it.

Insurance while the house is empty

Most homeowner policies change how they treat a house after it sits vacant for a period, often 30 or 60 days, and some exclude water damage from frozen pipe unless heat was maintained or the water was shut off. Read that clause before a long absence, because a sprinklered house is the case where you cannot satisfy the shut off option without giving up the protection. Maintaining heat is the answer the policy usually accepts. The insurance article covers how carriers treat the system the rest of the year.

When you come back

Walk the ceilings, look at the riser gauge, and run a faucet on a multipurpose system to confirm supply. If the gauge reads lower than it did when you left, or reads zero, call before touching the valve. If you find a stain or a wet spot, the leaking head article has the first ten minutes. Nothing else is needed after an ordinary absence. The system was doing its job the whole time, which is the point of leaving it on.