Why is my Radiator Cold at the Bottom?

Central Heating Pump not working correctly

In conventional systems, a key part of the heating system is a central heating pump. It needs to be in good working order. If your radiators are taking longer to heat up, this could be a sign that the central heating pump is failing. 

You need to call a heating engineer to take a look at this and tests can be carried out to see how your pump is functioning. If your pump isn’t functioning properly or has failed, we can provide a quote for a replacement.

Trapped air in your heating system

In these circumstances, your radiators are likely to be warm at the bottom but cold at the top. Air can often be trapped inside your radiators, especially after your heating has been turned off over the summer. 

It makes sense to get your boiler serviced and heating system tested at the end of Summer or during the Autumn, before Winter kicks in. You can then ensure your system and boiler is in good working order ready for its busiest time of year.

What are the different types of radiators?

There are many different types of radiators, meaning you may have a tough choice when deciding what to replace your old ones with.

Don’t worry too much about this, as we can advise you on the most suitable radiators for your home. 

Central Heating Radiators

Central heating radiators use corrugated panels to radiate heat into a room, and tend to be the most popular choice due to their high efficiency and compact design. 

You can get either single-panel style radiators for small rooms, or double-panel ones for larger rooms which produce more heat. 

Column Radiators

Column radiators are great for anyone looking to add a classic period look to their home. 

They have a traditional aesthetic, yet the modern models offer great heat distribution and efficiency. 

Designer Radiators

Classic central heating radiators can ruin the look of your home, especially if you are aiming for a specific aesthetic. 

Stylish, contemporary radiators are space savers, whilst also providing functionality by doubling up as mirrors, memo boards and much more.

Designer radiators are one of our most requested new radiator installations. We can advise you on where to look to get an idea of the style that you like and what size and heat output you need for your designer radiators.

Vertical Radiators

When wall space is limited, vertical radiators are a saving grace. They can fit perfectly onto small wall spaces, meaning you can heat your home where you previously may not have been able to. 

They also come in a range of designs and colours, meaning you can find one to suit your home aesthetic. 

Towel Radiators

Towel radiators have become a must for many, due to the fact you can dry your towels whilst also heating your bathroom. 

They act as a stylish, space-saving solution, whereas in the past, they were always chrome; you can now get a variety of different styles and colours.

Cast Iron Radiators

Cast iron radiators are perfect for period homes with high ceilings. They remain warm for longer, whilst also providing a good contrast with modern decor.

Flat Panel Radiators

Flat panel radiators are light, compact and can fit into almost any room without taking up a vast amount of space. 

Stainless Steel Radiators

Stainless steel does not rust or corrode like other metals do, meaning a stainless steel radiator is guaranteed to last a long time. 

They are efficient, low maintenance and come in various different finishes. 

Space Saving Radiators

A space-saving radiator is a great option if you don’t have a lot of room and want to make the most of your space. 

They can fit into narrow spaces and even wrap around corners!

How to fix radiators that are cold at the bottom

Radiators that are cold at the bottom require urgent attention. There are a couple of options to take, but both must be carried out by a qualified heating engineer. 

Powerflush  

Power Flushing involves a chemical being circulated around the heating system at a high pressure. This process frees any blockages to allow the hot water to flow freely to your radiators, and can take around 6 to 10 hours in total.  

A heating engineer will connect a pump to the central heating system. The chemical is pumped through the pipework at a high speed to break down the sludge. 

Depending on how bad the blockage is, engineers may also need to use tools on the outside of the radiator to dislodge pieces.

It is also possible to manually remove each radiator from the heating system and clean them out without a machine. Ask your heating engineer for the best option for your system.

Chemical Flush

A chemical flush involves chemicals being circulated through the central heating system, but not at a high pressure like a powerflush. As the chemicals are flushed through the system, they remove any build-up of dirt, limescale and debris. 

The chemicals can be left in the system for about an hour or so, sometimes even upto a week, and once they have done their job, the system is fully drained and then refilled with clean water and a chemical inhibitor.

When you have your boiler changed, this type of chemical flush should be carried out as it’s a requirement from boiler manufacturers. 

Multiple radiators are cold at the bottom

If multiple of your radiators are cold at the bottom, this is likely to be caused by a buildup of sludge throughout the central heating system. 

If you think this is the case, you should also contact a heating engineer who can run a diagnostic on your heating system. Once they have established the issue, they can add a chemical cleaner to be flushed through your heating system. 

Alternatively, if you wish to fix it yourself, you can add a chemical cleaner yourself to the radiator system and let it run for about an hour or so, flush it out and then replace the water. 

We strongly recommend that you instruct a heating engineer to carry out work on your central heating system, especially when adding chemicals to the system as they are trained to carry out this work.

How to get rid of blockages in radiators

Although we do recommend having a professional to flush your radiators for you, avid DIYers may be able to manually flush sludge from a single radiator.

The process involves: 

1. Turn off the central heating and wait for it to completely cool down.

2. Place some towels and sheets underneath the radiator, concentrating on areas near the valves and pipes. The water from the central heating is very dirty and often black and thick. It will damage any carpets or materials that it touches.

3. Isolate your radiator from the central heating system by turning off the valves.

4. Turn the Thermostatic Radiator Valve fully to its off position, and then turn off the Lockshield valve – this is usually the one with the plastic cover. All you need to do is remove the cover and turn it fully clockwise using an adjustable wrench.

5. Place a bucket under the thermostatic valve and use a wrench to loosen it.

6. Next, loosen and bleed the valve using a radiator key. Ensure that the bucket is still under the thermostatic valve, as the water will begin to flow once the valve is loosened.

7. Use the radiator key to loosen the lockshield using the radiator key and tilt the radiator to get rid of excess water.

8. Use the radiator key to close the bleed valve.

9. Remove the radiator from the wall.

10. Take the radiator to an outside space to clean, using a hose to flush away any dirt and residue. 

If the manual flush doesn’t work, you may need a qualified heating engineer to carry out a power or chemical flush.

How to prevent your radiator getting cold at the bottom

Prevention is always better than a cure, which is why once your radiator has been cleared, it’s a good idea to take preventative steps to stop the issue arising again.

Add a central heating inhibitor 

A central heating inhibitor is a chemical which is added to your system to prevent the buildup of limescale and sludge. It works by coating the system to keep the water running smoothly. 

Add a scale reducer

Scale reducers are a good idea for homes in hard water areas, as limescale is much more likely to form a blockage in a heating system. 

Install a magnetic filter

A magnetic filter can be fitted within a central heating system to collect any rust or limescale from the circulating water. This also prevents a build up of sludge and reduces the chance of a blockage.  

Recent changes to Part L building regulations ensures that a magnetic filter must now be fitted whenever a new boiler is installed. This acts to protect the boiler from the debris in your heating system.

The best way to fix a radiator which is cold at the bottom is by hiring a professional heating engineer.

At Lacey Plumbing and Heating, our qualified and gas safe registered engineers are ready to help you no matter what heating or plumbing issue you’re facing. 

Feel free to contact us today to discuss your heating issue.