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What To Do When One Hot Water Radiator Doesn’t Get Hot: Quick Fixes & Tips

One of the most common issues homeowners face with their hot water radiator systems is when one radiator refuses to heat up. This can be both frustrating and puzzling, as it often seems to happen without any clear reason. The good news is that a non-functioning hot water radiator is usually a simple issue to identify and fix.

Before diving into potential solutions, it’s essential to understand how hot water radiator systems work. Hot water radiators rely on a boiler to heat water, which is then circulated through a series of pipes and radiators, distributing warmth throughout the house. When one radiator doesn’t get hot, it’s often a sign of an issue with the flow of water or a problem specific to that radiator.

In this article, we’ll explain the most common causes of a single hot water radiator not getting hot and provide step-by-step guidance on how to troubleshoot and resolve the issue. By implementing these practical tips, you’ll be on your way to restoring warmth and comfort to the affected area of your home in no time.

Identifying the Issue

When a single hot water radiator isn’t getting hot, it’s important to identify the root cause of the problem. In this section, we’ll explore three common issues and their potential solutions.

Check for Obstructions

First, make sure that there are no obstructions, such as furniture or curtains, blocking airflow around the radiator. Adequate airflow is necessary for the radiator to function properly. Remove any items that could impede air circulation and provide sufficient space around the radiator.

Inspect the Thermostatic Radiator Valve

The thermostatic radiator valve (TRV) controls the flow of hot water into the radiator. It’s possible that the TRV may be faulty, stuck, or set too low.

To check the TRV:

  • Make sure the valve is set to an appropriate temperature setting.
  • If the valve is in the correct position but still not functioning, try removing the TRV head and gently wiggle the pin underneath to free any potential blockages.
  • If the issue persists, consider replacing the TRV.

Examine Air Vents

Air can become trapped in a radiator, preventing proper circulation and causing the radiator to remain cold. To check for trapped air, locate the radiator’s air vent (usually found at the top of the radiator).

Follow these steps to release trapped air:

  1. Turn off the heating system and let it cool down.
  2. Place a cloth or container below the air vent to catch any water.
  3. Using a radiator key or a flathead screwdriver, slowly open the vent until you hear a hissing sound (this is the air escaping).
  4. Once water begins to flow out, close the vent securely.
  5. Turn the heating system back on and monitor the radiator for improvements.

Troubleshooting Common Problems

If you find that one of your hot water radiators isn’t getting hot, there are a few common issues you can troubleshoot to identify the problem. In this section, we’ll cover three main areas: bleeding the radiator, fixing a stuck valve, and clearing a blocked pipe.

Bleeding the Radiator

Bleeding a radiator is a simple process that can solve many heating issues. Air trapped in the heating system may cause a lack of heat and can be released by bleeding the radiator. Follow the steps below:

  1. Switch off the heating system and allow the radiator to cool down.
  2. Locate the radiator’s bleed valve; it is usually a small square peg on one side of the radiator.
  3. Using a radiator key or a flathead screwdriver, insert it into the valve and turn counterclockwise.
  4. Hold a cloth or container beneath the valve to catch any water that may spill out.
  5. Once you hear air escaping, wait until only water comes out and then close the valve by turning clockwise.
  6. Check the pressure on the boiler and turn the heating system back on.

Fixing a Stuck Valve

A stuck valve can prevent hot water from flowing to your radiator. To fix this problem, try the following steps:

  1. Locate the thermostatic radiator valve (TRV) on the radiator.
  2. Remove the plastic cover from the TRV to expose the valve pin.
  3. Use a pair of pliers to gently wiggle or tap on the valve pin until it becomes loose.
  4. Replace the plastic cover and turn the heating system back on.

Clearing a Blocked Pipe

Blocked pipes can occur due to debris, rust or sludge buildup, causing your radiator not to heat up. To clear a blocked pipe:

  1. Switch off the heating system and let the radiator cool down.
  2. Drain the water from the radiator by disconnecting it at both ends.
  3. For small blockages, use a pipe cleaner or a handheld drain snake to remove debris from the pipe.
  4. For more significant blockages, consider hiring a professional to perform a power flush on the entire system.
  5. Once the blockage is cleared, reconnect the radiator and turn the heating system back on.

By troubleshooting these common problems, you’ll be better equipped to diagnose and fix the issue when one of your hot water radiators isn’t getting hot.

Seeking Professional Help

While a DIY approach may work in some situations, it’s important to know when consulting a professional technician is the best course of action. In this section, we’ll discuss when to consult a technician and how to find a reputable HVAC expert.

When to Consult a Technician

If you’ve tried the basic troubleshooting steps for your hot water radiator but it’s still not getting hot, it’s time to consult a professional HVAC technician. A technician can accurately diagnose the root cause of the issue and safely perform repairs. Some signs that you should seek professional help include:

  • The radiator doesn’t get hot even after bleeding it
  • There are other radiators in your home not getting hot
  • You hear unusual noises coming from the radiator or pipes
  • The issue persists even after performing basic troubleshooting

Finding a Reputable HVAC Expert

It’s important to find a reputable HVAC expert to work on your hot water radiator system. Here are some tips to help you find a reliable technician:

  1. Ask for recommendations: Reach out to family, friends, or neighbors who have had similar work done in their homes. They can provide you with referrals or share their experiences with local technicians.
  2. Research online reviews: Check online review sites and forums to see what other customers have to say about the technicians in your area. Look for professionals with high ratings and positive feedback.
  3. Verify licenses and certifications: Ensure the technician you hire is licensed and certified to work on hot water radiator systems. You can ask for proof of their credentials or search their licensing information online.
  4. Request multiple quotes: Ask for written estimates from at least three different technicians. This allows you to compare pricing, services, and warranties offered.

Section 5: Preventative Maintenance

Regular Inspections

Performing regular inspections on your hot water radiator system can help identify potential issues early on and prevent a single radiator from not heating up. Check for:

  • Leaks in the radiator, valves, or pipes
  • Proper water pressure in the system
  • Functioning thermostatic radiator valves (TRVs)
  • Adequate water flow


Keeping your radiator and the surrounding area clean can prevent dust and debris from interfering with heat transfer. Clean your radiator by:

  1. Vacuuming or dusting the exterior surfaces regularly
  2. Wiping down the radiator fins and panels
  3. Using a soft brush or cloth to clean tight spaces


Proper system servicing can prevent inefficiencies and extend the life of your radiator system. Have a professional perform the following tasks:

  • Flush and fill the radiator with a mix of water and corrosion inhibitor
  • Check and adjust the pressure in the system
  • Inspect and test all radiator valves, including TRVs
  • Examine and replace damaged or worn parts if necessary

Adhering to a preventative maintenance routine can minimize the risk of a single hot water radiator not getting hot and help maintain the overall functionality of your heating system.


A few minutes spent bleeding each radiator can ensure that your radiators heat up and your home is warm when the weather turns cold.

If you need any help or advice on bleeding your radiators or when it comes to any aspect of your heating system, Contact Us at (651) 294-7798.

We cover Blaine, Bloomington, Brooklyn Park, Eagan, Edina, Hastings, Maplewood, Minneapolis, Minnetonka, Roseville, North Saint Paul, Saint Paul, Saint Paul Park, South Saint Paul, Stillwater, West Lakeland, West Saint Paul, White Bear Lake, Woodbury, and many more locations.

Can’t find your town listed? Contact us at (651) 294-7798 to tell us where you live, so we can help you.


Schedule a HVAC repair anywhere in the Minneapolis or St. Paul area today by calling (651) 294-7798 or by requesting an estimate online.


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