These are the boiler problems that cannot wait: no heat while the rooms cool down, water pouring from the relief valve or the boiler jacket, a burner that runs and will not stop, or a steam boiler with an empty gauge glass. Pipes in outside walls and unheated cellars can freeze once a boiler has been off for a while in a hard freeze.
Emergency boiler repair covers the failures that leave a building with no heat:
Gas burners that will not light: igniters, pilots, thermocouples, flame sensors and gas valves
Oil burners in lockout: nozzles, filters, fuel pumps, electrodes, transformers and cad cells
Low water cutoffs and water feeders holding a steam boiler off
Seized circulators: boiler hot, radiators cold
Zone valve motors stuck shut and relays that stopped switching
Aquastats, boards and 24 volt transformers with no output
Relief valves discharging and expansion tanks that filled with water
Burners that run nonstop on a shorted thermostat wire or a stuck control
Steam Boilers That Shut Down on Low Water
When the water in a steam boiler drops below the safe line, the low water cutoff shuts the burner off, and the building goes cold even though every other part works. The water went somewhere: out a leaking return, up the chimney as steam through a broken vent, or it never came back because a return line is clogged. A water feeder that stopped working is the other common cause.
Refilling the boiler brings the heat back for a while, but the low water happens again until the leak or the clogged return is found.
Leaks, Relief Valves and Pressure on Bronx Boilers
Boiler room floods come from a handful of places. A pressure relief valve that opens is protecting the boiler from pressure past its set point, and the pressure got there because the expansion tank filled with water or the fill valve kept feeding. A drip from a circulator flange, a zone valve or a drain valve is a gasket or packing failure. A leak from inside the boiler jacket usually means a cracked section or a leaking tankless coil gasket.
Each of those has a different repair, and only the cracked section means replacing the boiler.
Burners That Lock Out in Cold Weather
Gas boilers lock out when the control tries to light the burner and does not see a flame, which is usually a weak igniter or a dirty sensor; flame sensing works on a very small current and a coated rod loses it. Oil boilers lock out when the nozzle or filter clogs, the fuel pump loses its prime after an oil delivery runs low, or the cad cell gets dirty.
Start with power and fuel. A switch at the top of the cellar stairs, a tripped breaker, an empty oil tank or a closed gas valve will stop any boiler. After that, the usual causes are a burner in lockout, a low water cutoff holding the burner off, a failed igniter or a thermostat wire that broke.
What causes a boiler to lock out?
A boiler locks out when its safety control sees the burner try to light and fail. On a gas boiler that is usually a weak igniter, a dirty flame sensor or a gas valve that will not open. On an oil boiler it is usually a clogged nozzle or filter, a fuel pump problem or a dirty cad cell.
What causes a boiler to leak water?
Most leaks come from the parts around the boiler, not the boiler: a relief valve discharging, a circulator flange gasket, a zone valve body, a drain valve or a radiator valve packing. A steady leak from inside the jacket usually means a cracked section, and that is the one leak that means replacement.
Why does my boiler keep shutting off?
A boiler that runs and then shuts off is being stopped by a control. Common causes are a high limit tripping because a circulator stopped, a low water cutoff seeing the water drop, a flame sensor losing the flame, or a blocked flue or chimney tripping the spill switch.
What causes a boiler pressure relief valve to go off?
The relief valve opens when pressure in the boiler goes past the number stamped on it. On hot water systems the cause is almost always a waterlogged expansion tank or a fill valve that overfeeds. A relief valve that drips after it has opened a few times can also have a worn seat and need replacing.
Why won't my heating come on but I have hot water?
Many boilers in older houses make domestic hot water with a coil inside the boiler, so the boiler is running even when the heat is not. If you have hot water but cold radiators, the problem is on the heating side: the thermostat, its wiring, a zone valve, a circulator or a relay on the control.
Boiler Out in the Cold?
Emergency boiler repair for steam and hot water boilers in the Bronx.
