Troubleshooting and Repairing your Boiler

Looking for tips on how to repair and maintain your boiler? Or are you wondering whether it’s time to replace it? This guide covers common repair and maintenance problems, provides troubleshooting tips and helps you decide when to call an HVAC professional.

Common boiler problems

Boiler switches off

If your boiler keeps switching off, the issue could be low boiler pressure or a blockage in the system that’s restricting water flow.

Should you try to fix it on your own or call an HVAC professional?

You can try to re-pressurize your boiler on your own. If your boiler pressure is accurate and doesn’t need re-pressurizing, you should call an HVAC professional.

Troubleshooting tips

You can re-pressurize your boiler in several different ways, including using a re-filling key or by adding water and raising the pressure through filling hoses. The first method involves the following steps:

  1. Turn off the power to your heating system.
  2. Pull out the tray underneath your boiler.
  3. Remove the filling key from the tray.
  4. Put the filling key into the key manifold keyhold.
  5. Turn the key to the unlocked position.
  6. Using a wrench, rotate the manifold nut counterclockwise.
  7. Check the boiler’s pressure gauge and turn the nut when the gauge hits 1.5 bars.
  8. If there’s too much pressure, turn the release knob on the closest radiator.
  9. Turn the key to the locked position.
  10. Remove the filling key and put it back in the tray.
  11. Turn the boiler back on.

You can also try adding water and raising the pressure through filling hoses by following these steps:

  1. Turn your boiler off.
  2. Check to make sure that the filling loop hoses are correctly attached.
  3. Using a screwdriver, open the filling valves.
  4. Close the filling valves once the pressure gauge hits one bar.
  5. Turn your boiler back on.

General cost for professional repairs: $40 to $60 for a new igniter switch (natural gas boiler); $25 to $50 (propane boiler); $35 to $60 (oil boiler); $60 to $100 (electric boiler). Labor could cost between $60 and $80 per hour.

Frozen condensate pipes

All boilers have a condensate pipe that carries acidic water away from the boiler. Usually, the pipe runs outside into a drain, but during the colder winter months, it runs the risk of freezing.

Should you try to fix it on your own or call an HVAC professional?

When your condensate pipes freeze, you can attempt to thaw them yourself or consult an HVAC professional.

Troubleshooting tips

To thaw them yourself, try pouring hot water over the pipe. You can also try a warm cloth or microwaveable heating pack on the pipe. After you thaw the pipe, you may need to reset the boiler. If you feel like you cannot safely perform this task, contact an HVAC professional.

General cost for professional repairs: $300 to $500

Radiators not heating up

When your radiator isn’t heating up, there could be a buildup of sludge or air in the system. You may have to bleed the radiator if only the bottom is heating up. If your radiators aren’t getting hot, they could need balancing.

Should you try to fix it on your own or call an HVAC professional?

This problem is fairly easy to fix and doesn’t require an HVAC professional.

Troubleshooting tips

Adjust the valves on all of the radiators on your property to make sure each one is getting enough hot water. To rebalance your radiators, you need these items:

  • Paper and pen
  • Radiator bleeding key
  • Lockshield valve adjuster (or adjustable spanner)
  • Digital thermometer or multimeter with thermometer function

Once you have everything you need, follow these steps:

  1. Turn off the heating system and let it cool off completely.
  2. Bleed your radiators to remove any air.
  3. Remove the lockshield valve covers and open all of the valves fully by turning them counterclockwise. Then, open the thermostatic radiator valves to full. Lockshield valves need a special adjustor or adjustable spanner to do the trick.
  4. Make a list of all the radiators in your house.
  5. Turn the heating back on and write down the order that the radiators start to heat up, which can give you an idea of the order in which hot water reaches each radiator. Numbering them just makes the process a bit simpler.
  6. Turn the heat back off and wait for it to cool down again.
  7. Turn it back on and go to the first radiator on your list.
  8. Turn the lockshield valve clockwise until its closed. Then open it again by one-quarter of a turn.
  9. Once the radiator is fully heated up, take the temperature of the pipe leading to one of the valves and write it down.
  10. Then, take the temperature of the pipe leading to the other valve on the radiator. Open the lockshield valve gradually until there’s a 12 degree Celsius (or # degree Fahrenheit) difference between this and the last temperature you took.
  11. Repeat the process for each one of your radiators and you should have a balanced system.

General Cost for Professional Repairs: $190 to $380. The average radiator replacement, including installation, is about $500.

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Pilot light keeps going out

If your pilot light keeps going out, a faulty thermocouple could be inhibiting the gas supply from reaching the boiler. Check to make sure there are no issues with your gas supply before trying to reignite the pilot light.

Should you try to fix it on your own or call an HVAC professional?

If you feel comfortable enough to attempt to relight the pilot light yourself, make sure to follow the instructions provided below carefully. However, it’s highly recommended that you contact an HVAC professional to help you safely correct the issue.

Troubleshooting tips

If you want to try to fix this issue yourself, follow these steps to ensure your safety:

  1. Check to make sure there aren’t any issues with the gas supply (if not, contact your gas supplier).
  2. Follow the instructions found in your boiler’s manual for igniting the pilot light.
  3. If you can’t do it yourself, contact an HVAC professional to help you get it done.

General Cost for Professional Repairs: $80 to $100

Dripping and leaking

The most common cause of dripping and leaking is a broken internal component like a pressure valve or a pump seal. To find out what’s causing your boiler to leak or drip, you need to contact an HVAC professional.

Should you try to fix it on your own or call an HVAC professional?

Do not attempt to fix this issue on your own. Contact an HVAC professional.

General Cost for Professional Repairs: $35 to $55 per linear foot for labor and materials

Low boiler pressure

A leak in the water system, recently bled radiators or the need for a new pressure relief valve can cause low boiler pressure.

Should you try to fix it on your own or call an HVAC professional?

You can check for a visible leak in the system, but once you find it, it’s best to call an HVAC professional unless you feel comfortable trying to re-pressurize the system on your own.

Troubleshooting tips

Follow the instructions in your heating system’s manual to ensure your safety.

General Cost for Professional Repairs: $200 to $600 for faulty pipes, valves, or circulator

Strange banging, whistling or gurgling noises

If you hear strange banging, whistling or gurgling noises, you might have air in your system. Low water pressure, a faulty pump, a faulty expansion tank or kettling can also lead to unusual noises.

Should you try to fix it on your own or call an HVAC professional?

You should consult an HVAC professional. Act quickly to avoid more costly repairs or the need for a new boiler.

General Cost for Professional Repairs: $100 to $250 for a faulty expansion tank

Unreliable thermostat

If your thermostat is losing its accuracy or turning the heating off or on when it’s not supposed to, you need a new one. Check to make sure your thermostat’s settings are correct and that it’s in the “on” position.

Should you try to fix it on your own or call an HVAC professional?

You can replace your thermostat yourself. However, there’s nothing wrong with consulting an HVAC professional.

Troubleshooting tips

Make sure to turn off the breaker to the HVAC equipment before you do anything. Read all of the instructions that come with your new thermostat before attempting to replace the old one. If the job requires more than just a replacement, you need to consult a certified HVAC professional to ensure proper installation and operation.

General cost for professional repairs: $103 to $277

Intermittent heat and hot water

Intermittent heat and hot water — or no heat and hot water altogether — could mean broken diaphragms and airlocks, issues with the thermostat or failed motorized valves. You may need to replace your diaphragm.

Should you try to fix it on your own or call an HVAC professional?

Call an HVAC professional to help you diagnose the problem and replace any broken parts.

General cost for professional repairs: $140 to $250

Kettling

Kettling occurs due to a buildup of limescale in the system, which can restrict the flow of water within the heat exchanger, thereby overheating the water and causing it to steam and boil.

Should you try to fix it on your own or call an HVAC professional?

Contact an HVAC professional.

General cost for professional repairs: Up to $258

General maintenance tips for your boiler

Daily

  • Check for any leaks underneath your boiler equipment.
  • Check temperature readings/pressure readings to ensure all of them are within the right range.
  • Watch for any error codes (jot down any you see).
  • Listen for unusual noises.

Monthly

  • Examine boiler hydronic piping for possible leaks.
  • Check any recommended connections or gauges.
  • Inspect the burner flame (if you can) and make sure the flame doesn’t look different than usual.
  • Test your low water cutoff to ensure it’s working correctly.

Yearly

  • Make sure water pH levels are within the correct range.
  • Clean and inspect the heat exchanger.
  • Survey the vent terminations and air inlet to ensure they’re clear and unobstructed.
  • Make sure all boiler wiring and connections are intact.
  • Turn on the unit once every season even when it’s not in use.
  • Change the filter every few months.
  • Schedule yearly maintenance with an HVAC professional.
  • Check the condensate system and make sure to clean and flush it if necessary.
  • Clean the burner assembly, igniter and flame sensors.

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