If your boiler is not heating, start with the simple things: make sure the thermostat is set to heat and above room temperature, the boiler's power switch is on, the breaker has not tripped, and you have fuel. Then look at the pressure gauge. Many hot water boilers typically run around 12 to 15 psi cold. If none of that fixes it, or you smell gas, stop and call a pro.
Safety first
- If you smell gas, leave the house right away. Do not flip switches, light anything or use your phone inside. Call your gas utility or 911 from outside.
- If your carbon monoxide alarm sounds, get everyone outside to fresh air and call 911. The EPA describes carbon monoxide as a colorless, odorless gas, so you cannot rely on your senses.
- Do not open the burner cover, touch wiring or adjust gas valves. The checks below are the only ones we suggest for homeowners.
Safe checks you can do yourself
- Check the thermostat. Make sure it is set to Heat, not Cool or Off, and set a few degrees above the room temperature. If it runs on batteries, replace them. A blank screen is a common cause of no heat.
- Check the emergency switch. Most boilers have a red switch plate on the wall at the top of the basement stairs or near the boiler. It looks like a light switch. People flip it off by mistake all the time. Make sure it is on.
- Check the breaker. Look in your electrical panel for a tripped breaker labeled boiler or burner. Reset it once. If it trips again, leave it off and call us.
- Check the fuel. On oil, look at the tank gauge. Running out of oil can pull sludge into the line and may need a service call even after a delivery. On gas, see if your stove or other gas appliances work.
- Look at the pressure gauge. Most boilers have a gauge that shows pressure and temperature. For many residential hot water boilers, a typical cold reading is around 12 to 15 psi, and it rises some as the system heats. The relief valve on most residential boilers is set to open at 30 psi. If the gauge reads near zero, the system may be low on water. If it reads near 30, or water is coming out of the relief valve pipe, call us and do not try to add water.
- Press reset only once. Many burners have a reset button. Pressing it once is fine. If it locks out again, do not keep pressing. On an oil burner, repeated resets can flood the chamber with oil, which is a real hazard.
- Look for an error code. Newer high efficiency and combi boilers have a display. Write down any code and look it up in your owner's manual. It helps us bring the right parts.
Some rooms are cold but others are warm
If the boiler runs but some radiators or baseboards stay cold, the cause is usually air in the lines, a stuck zone valve, a failed circulator pump or a zone thermostat problem.
- Bleeding radiators: Cast iron radiators often have a small bleed valve at the top. With the heat running, hold a cup and a rag under it and open it slowly with a radiator key. Air will hiss out. Close it when water comes out in a steady stream. Water may be hot, so be careful.
- Baseboard systems: Most do not have easy bleeders in every room. Purging air from them usually means working at the boiler, which is best left to us.
- Check each zone thermostat. If one zone is cold, make sure its thermostat has power and is set to call for heat.
Our no heat and cold radiators page has more on this.
When to call a licensed plumber
- The burner locks out after one reset, or the breaker trips again.
- Pressure is near zero, near 30, or the relief valve is dripping or spraying.
- You hear loud banging, gurgling or kettling sounds from the boiler.
- You see water leaking from the boiler or near the circulator pump.
- You see soot, smell fumes, or the burner flame looks yellow or lazy.
- The boiler is old and keeps needing repairs. Our boiler repair and replacement page explains how we look at repair versus replace.
A note on radiant floor heat
Radiant floor systems run on lower water temperatures and heat up slowly. If a radiant zone seems cold, give it time after you raise the thermostat. Radiant systems also use mixing valves and their own pumps, so a cold floor is often a controls or pump issue. See our radiant and hydronic heating page.
A yearly tune-up prevents most no-heat calls
Most of the no-heat calls we get in the first cold week of the season could have been caught with a fall service. A tune-up lets us clean the burner, check combustion and venting, test safety controls and catch a weak pump or a low expansion tank before the weather turns. If your boiler has not been looked at in a year or more, fall is the time.
Why this happens around Budd Lake and Morris County
Hot water baseboard and cast iron radiators are very common in homes across Mount Olive, Roxbury, Randolph and Hackettstown. Many of the boilers in 1970s to 1990s houses are still the originals, or on their second round. They sit quiet all summer, then get asked to run hard on the first cold night, which is when weak parts give out. Lake homes around Budd Lake and Lake Hopatcong add another risk: if a boiler quits while the house is empty, pipes can freeze.
Frequently Asked Questions
What should my boiler pressure be?
For many residential hot water boilers, around 12 to 15 psi cold is typical, and it rises as the water heats. Check your owner's manual, because the right number depends on your home and system. If it is near 30 psi, call a plumber.
Why does my boiler keep losing pressure?
Usually there is a leak somewhere in the system, a failing relief valve, or a problem with the expansion tank. Adding water over and over without finding the cause can damage the boiler.
Why are my radiators cold at the top?
That usually means air is trapped in the radiator. Bleeding it often fixes the problem. If it keeps coming back, air is getting into the system and a plumber should look at it.
Is it safe to press the reset button on my boiler?
Once is fine. If the burner locks out again, stop and call for service. Repeated resets on an oil burner can be dangerous.
If you want a second set of eyes on it, call or text us at 862-362-0634 or request service online. We are a family owned shop in Budd Lake, and we will tell you straight what we find and what it needs.
Sources
- EPA: Carbon Monoxide's Impact on Indoor Air Quality
- ENERGY STAR: Boilers
- NFPA: Carbon Monoxide Safety
Micky Cipolla is a New Jersey licensed master plumber (License #13478) with more than 15 years in plumbing and heating. He owns Tucker's Plumbing in Budd Lake and works on homes across Morris County every day. Verify the license.