Boiler Troubleshooting
Hoffmann Brothers


Boilers either heat hot water or make steam to provide heating, and distribute that heat through the use of radiators. They are sometimes improperly identified as furnaces, which in turn produce hot air and distribute heat through ductwork and vents. When you have an issue that needs to be addressed with your boiler, first confirm that you are indeed dealing with a boiler and radiator, and not a furnace. That way you can accurately identify the precise problems and troubleshoot for the best results.

Hot Water Boiler Troubleshooting


Steam Boiler Troubleshooting


Hot Water Boiler Troubleshooting

Troubleshooting for boilers that produce hot water for heating systems is approached differently than steam boilers. Click here for steam boiler troubleshooting.
Radiator Boiler Troubleshooting - Hoffmann Brothers

Boiler Is Working Fine, But Not All Radiators Are Heating

Most likely the radiator is full of air. You will need a radiator key. Open the valve at the top of each radiator while holding a small cup under the valve. When the air stops and the water starts, the air has been removed. Close the valve and the radiator should start heating.

It is possible that the radiator water valve is closed but most of the time it is just air.

What If Boiler Is Not Heating Or Heating Poorly?

This could be multiple problems that require a trained technician using the appropriate diagnostic tools to correctly identify the issue.

Frozen Condensate Pipe – Causes And Reasons for a Failed Boiler?

High efficiency boilers create water that comes out of the boiler and piped to drain. They should never be piped outside because that line will freeze and stop the operation of the boiler.

Why Is Boiler Spewing Water?

A hot water boiler can spew water for two reasons: First because the heat exchanger is broken and secondly because the relief valve is discharging. Either situation is very dangerous and you should have a trained professional immediately inspect your system.

What Would Cause Higher Heating Bills?

Old boilers that were converted from coal or oil can be in the 50% efficient range. That means 50% of the energy consumed by the boiler is wasted up the chimney. The next models were in the 60% to 65% efficiency range. Back in the 1990’s the federal government set a minimum efficiency of 80%. Today you can buy hot water boilers up to 97% efficient.

Top reasons you might experience higher heating bills include:

  • Inefficient heating system in home
  • The boiler is not properly tuned up causing inefficient operation and increased utility cost
  • Cold weather

Why Do I Have To Keep Adding Water To The Boiler?

This nearly always indicates that the Boiler or piping has a leak.

Dripping Valves – Why Is Water Dripping From My Boiler Overflow Pipe?

This is typically the pressure relief valve. It could be a defective valve but it could also be a sign something potentially dangerous is about to happen. This system should be shut down, inspected and repaired right away.

Noisey Pump Motor – Why And What To Do?

On older pumps this is sometimes the coupling or the alignment of the coupling. The rubber grommets holding the motor wear out and the motor comes out of alignment with the pump.

Feeling Unsafe – The System Is Not Working Properly

Make sure your boiler receives annual maintenance by a qualified technician. Boilers use large quantities of explosive natural gas and create carbon monoxide. Older boilers do not have many of the safety features that new boilers come with.

Boiler Keeps Switching Itself Off — Common Reasons? What To Do?

The boiler is telling you something is seriously wrong and your need to do something about it. If ignition systems don’t properly light, they will try several times then lock out. Call your local professional right away.

Thermostat Issues – Not Always Accurate Or It’s Turning Itself On / Off When It’s Not Supposed To – Why? What To Do?

Most thermostats can be calibrated, but can’t be repaired. Our team notes that most thermostat issues are a result of improper installation.

Thermostat companies tell you to not worry if you don’t have a common wire. What they are not telling you is that without this wire your thermostat is running completely on a battery. When the battery wears out, you lose heating and cooling. It is much better to have the thermostat powered from the house and the battery only used as a backup. If the additional wire is difficult to run, then contractors have “ad a wire relays” where they can make five wires out of four.


Steam Boiler Troubleshooting

Troubleshooting for boilers that produce steam for heating systems is approached differently than hot water boilers. Click here for hot water boiler troubleshooting.

Boiler Is Working Fine, But Not All Radiators Are Heating

Two things block steam from entering the radiator: air and water. Air and water escape the radiator through the trap. If the trap is clogged, the air can’t escape — blocking steam from entering the radiator. Also the main lines are sometimes full of air. In the basement you will see air vents on the main headers. Sometimes these vents get blocked and need to be replaced.

What If Boiler Is Not Heating Or Heating Poorly?

This is an indication of something more serious. Steam boilers are more likely to have a major catastrophic event, so a professional should be called if this happens.

Frozen Condensate Pipe – Causes And Reasons for a Failed Boiler?

This could happen on a steam boiler especially if the combustion air comes from outside and discharges on the condensate return pipe.

Boiler Making Hammering Sound or Banging Sounds – Why? What To Do?

Be aware that many troubleshooting guides may not provide consistent input for this common issue. Steam radiators or pipes sometimes make loud hammering noise. This noise is caused by hot steam hitting water in the lines and the surface of the water flashes off into steam causing the loud banging noise. Anything that would cause water to be held up in the pipe or radiator could cause this.

All piping and radiators need to be sloped back to the boiler. As a house settles sometimes you lose the slope, causing water to stay in the pipe. A defective trap could hold water in the pipes or radiator. These can be difficult issues because sometimes the issue is in pipes that are buried in walls or ceilings.

Hissing Sound from Boiler Radiator – What To Do?

Some steam radiators use Hoffman #40 steam vents. (No relation to Hoffmann Brothers) These vents are typically located on a one pipe steam system. A one pipe system has one pipe to each radiator. The pipes are large and the steam flows to the radiator at the top of the pipe while the condensate flows back to the boiler on the lower section of the pipe. The Hoffmann Steam vent looks like a silver bullet on the side of the radiator and opens when air flows. When the radiator fills with steam, the valve closes.

Why Is Boiler Spewing Water?

If your boiler is spewing water turn it off immediately and call a professional. This is a sign of a serious issue.

What Causes Higher Heating Bill?

The efficiency of the steam boiler is peaked at 80%, much lower than hot water.

These issues may raise your heating bills:

  • Inefficiency of home heating system
  • The boiler is not properly tuned up causing inefficient operation and increased utility costs
  • Cold weather

Why Do I Have To Keep Adding Water To The Boiler?

This can happen for two reasons:

  1. You have a leak. The leak can be at the bottom of a pipe or boiler. The water should be obvious. The leak could be at the top of the pipe and only leak steam. These leaks may not be so obvious.
  2. The boiler is surging. Surging is common with newer boilers. The oils from when the boiler was cast float to the surface of the water. As the water boils, plumes of water shooting up to the top of the boiler sometimes take that water into the discharge pipe. The boiler would need to be skimmed to remove the oil.

Why Is Water Dripping From My Boiler Overflow Pipe?

This is commonly the pressure relief valve. It could be a defective valve but it could also be a sign something potentially dangerous is about to happen. This system should be inspected and repaired right away.

Noisey Pump Motor – Why And What To Do?

Most residential steam boilers don’t have pumps. Larger boilers and commercial boilers have condensate return pumps. Call your local professional for service.

Feeling Unsafe – The System Is Not Working Properly

Make sure your boiler receives annual maintenance by a qualified technician. Boilers use large quantities of explosive natural gas and create carbon monoxide. Older boilers do not have the same safety features common to newer boilers.

Steam boilers fortunately do have more safety issues than hot water boilers. In a steam system you have iron pipes, air, and water. Iron, air and water combine to make rust, and lots of it. The rust tends to clog things up, including pressure switches. Rust also reduces the life of the boiler and piping. Hot water boilers have iron and water but don’t have air, causing them to last much longer because you don’t get the rusting.

Boiler Keeps Switching Itself Off — Common Reasons? What To Do?

The boiler is telling you something is seriously wrong and your need to do something about it. If ignition systems don’t properly light they will try several times then lock out. Call your local professional right away.

If you’re having issues with your boiler and can’t solve it on your own, give the team at Hoffmann Brothers a call today and we’ll point you in the right direction.

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