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Noisy Central Heating Pump – How To Fix it?

The last thing you want to hear on a cosy winter evening is strange noises coming from your central heating.

The good news is: noisy pipes are normal, and most of the time you don’t need to call a heating engineer to deal with them.

While there are lots of different things which cause banging pipes and a noisy central heating pump, they can be fixed simply and easily at home.

In this article, we’ll take you through exactly how to fix a noisy central heating pump, from what different noises signify, to how to ensure your central heating pump is safe.

How do you fix a noisy central heating pump?

Depending on the type of noise you hear, you can fix a central heating pump by fitting felt around pipes that are too close together under your floorboard, bleeding your radiators by carefully opening the bleed screw to let out the air until you hear a hissing sound, or using a chemical cleaner to clear out the build-up of limescale in your central heating system.

If the issue continues and you have not resolved it, then it may be best to contact a heating engineer to investigate the cause of the problem.

Let’s take a look at everything you need to know when it comes to a noisy central heating pump and how to resolve it.

What is a central heating pump?

Your central heating pump has a vital role in keeping your entire house warm. It is responsible for circulating hot water from your boiler to your radiators and taps. The pump will then direct the water back to your boiler to be reheated, to keep the warmth of your home consistent.

You can usually find your central heating pump near your boiler. The proximity of the pump to the boiler allows the pump to push water around your home as soon as it has heated up, rather than allowing it to cool along the way (causing you to turn up your heating and waste money trying to compensate). You may also find your central heating pump in the airing cupboard, or under the stairs.

Why does my central heating pump make noise?

As mentioned, it’s normal for a well-operating central heating pump to make a little noise, such as a low humming or vibration.

The reason for this is because your central heating system is mostly made from metal, which expands and contracts in tandem with heating up and cooling down.

As the pipework expands and contracts, it naturally creaks and groans. Usually, these sounds will not cause much disturbance in your home and are something you can get accustomed to.

However, if your central heating pump is making loud noises, it could indicate potential problems with your central heating system and in some cases, you may need to call in a plumber to investigate. The cause could be a number of issues, such as a build-up of limescale, loose pipes or components, overheating, leaks or your radiators may need bleeding.

The good news is, most of these issues can be carefully resolved yourself without having the call in a professional, saving you some money on expensive repairs.

Let’s take a look at what the different noises mean and how you can fix them.

What do particular noises from your central heating pump mean?

Look out for the following noises from your central heating:

Banging pipes

If you hear a banging noise whenever you open the taps in your bathroom, you are most likely experiencing a ‘water hammer.’ A water hammer is usually caused by pipework not being secured properly under the floorboard. Copper pipes in particular need to be secured, otherwise, they will rattle.

When you hear a thudding sound, the first thing you need to do is check the thermostat, which is usually on your wall or your boiler. You first need to allow the system to cool down by turning the boiler off. After a while, you can turn your heating back on again and increase the thermostat until you hear a click. If you do not hear a click, then you will need to turn to a professional to come and investigate the problem.

Another way to resolve banging pipes is to squash some felt around each pipe, focusing on every place where a pipe touches a joist or another pipe.

If you find you have exhausted all the options, including calling in a professional to take a look and still have not reached a resolution, then it may be worth investing in plastic pipework. Plastic pipes are more flexible and will be much quieter than copper.

Gurgling

The best way to describe a gurgling sound is similar to a kettle coming to a boil. If you hear this sound, it is likely to be an issue caused in the heating system, such as the radiators and the pipes.

Usually, the culprit for gurgling noises is air trapped in your system. You can check and confirm whether this is the case by feeling the radiator.

A radiator that feels cold at the top but hot at the bottom usually has trapped air inside. The air rises to the top of the radiator and prevents hot water from circulating properly, leaving you with a heating system that is inefficient.

Water that can’t travel freely around the radiator will end up overheating, resulting in gurgling noises.

To release trapped air, you need to bleed your radiators. Fortunately, this is a fairly simple procedure, which you can accomplish in just a few steps. It’s important to make sure you do this as fast as possible, as your boiler may eventually refuse to start at all, leaving you with an eye-watering repair bill.

To bleed your radiators, you need to:

  1. Turn on your heating to check which radiators need bleeding, and make a note of them.
  2. Turn off your heating to make sure the radiator is not too hot to touch and to avoid hot water spraying out of the radiator and scalding you.
  3. Use your radiator key to turn the valve at the top of the radiator slowly in a clockwise direction until you hear a hissing sound. This is the trapped air being released. It may also be useful to keep a cloth nearby to catch any water that comes out.
  4. Once the hissing stops, retighten the value as quickly as you are able in order to avoid too much water escaping.
  5. Check your boiler’s pressure (you can use the gauge, which is usually on the front of your boiler). As bleeding your radiators can often cause water pressure to drop (some water will inevitably drip out in the bleeding process), you may need to re-pressurise your boiler. To do so, use the filling loop, which is the lever or tap on your boiler, to introduce water into the system.
  6. Turn on your heating and check your radiators. If they’re warming through all the way, you have successfully solved the problem!

Check out our article here to learn more about how to bleed radiators.

Gurgling noises can also be a result of a frozen condensate pipe. The condensate pipe is responsible for sending wastewater away from the boiler and outside down a drain. However, during colder months the condensate can freeze, which blocks and prevents the water from getting out. Until the pipe has been thawed, your boiler is likely to lockout, meaning that it will shut down due to faults in the system.

Alongside your pipe being frozen, other causes of a boiler lockout are high or low water pressures or a blockage in the system. A telltale sign of your boiler initiating the shut-down process is when you can see either red or green flashing lights, indicating that your boiler is not locking out. If you have a newer boiler, your display panel will show a fault code, giving an indication of what the issue is.

To thaw out a frozen condensate pipe, you will need:

  • Warm water
  • A container such as a jug or a watering can.

Simply pour a little bit of warm water onto the surface of the pipe to slowly thaw it out and remove the blockage. Usually, the most exposed external part of the condensate pipe will be frozen which is the end of the pipework and near the drain.

Be sure to use warm water and not boiling hot water, as this can damage the pipe. Once the pipe has been thawed and the blockage removed, the contents of the pipe will have fully drained and you are free to restart your boiler.


Tapping Noises

A build-up of limescale in your pipes and radiators is usually the cause of tapping sounds coming from your central heating pump. If this is the problem, all you need to do is turn off the heating and use a non-acidic cleaner to flush out the system.

Take your time to pick out the best chemical cleaner, and ask your local plumber’s merchant (shop selling plumbing and heating supplies), which chemical cleaner is the best for your system. For example, if you’ve got an older central heating system, you might need a stronger solution.

Humming

Humming sounds usually point towards the disfunction of heating elements in your immersion heater.

In this case, it is time to switch on your investigator skills and check your thermostat for any problems. If your thermostat is fine, then take a look at your central heating pump, as it may be set too fast and will need slowing down. You can also turn down the pressure, as a high-pressure setting also leads to clanging sounds from pipe damage.

Another reason why you may hear a humming sound is if you have recently refilled your heating system. If so, check whether you have left the filling loop open or forgotten to disconnect it.

It is also worth checking the valve of your immersion heater, as you may have accidentally knocked and loosened the valve, allowing a constant flow of water into the system.

Humming usually is caused by issues with the thermostat, pressure gauge or filling loop, which means the most common solution is adjusting the settings.

However, it’s worth checking with a heating engineer before reducing the setting and sometimes the pump may be set high for a reason.

Knocking Sound

Knocking sounds in your central heating system usually indicate an issue with insufficient room under the floorboard for your pipes.

As mentioned earlier, as the water in the system heats up it causes the pipes to expand as the hot water flows through, and then contract as the pipes cool down again.

If this is the case, it is important to adjust the pipes, for example, insulating them to make more room and dull their sound.

It’s also worth checking for trapped air as this also leads to knocking sounds. Again, this can be resolved by bleeding your radiators.

Whistling

If you hear a whistling noise that strongly resembles the sound of a traditional kettle, then the cause is often due to a built of limescale on the heat exchanger.

Unfortunately, this is not a DIY situation and you will need to contact a heating engineer to induce a power flush to fix this particular problem.

A power flush involves various chemicals being flushed through the system to clear the limescale.

What causes a noisy central heating pump

Now that we’ve identified the specific noises your central heating pump can make and what they mean, let’s explore what causes a noisy central heating pump in the first place.

Dirt Blockage

It is normal for your water to pick up some rust, sludge and any other debris as it circulates around your central heating system.

However, when left unattended this can build up over time, leading to blockages in the system and within the central heating pump. A tell-tale indicator of a blocked central heating pump is if your radiators heat up very slowly or not at all.

It’s important to take preventative measures in order to avoid the worst-case scenario of particularly large build-ups. If this does happen, you’ll likely need to call in a heating engineer to perform a power flush.

To avoid this happening, you can install a magnetic filter to collect debris circulating around the heating system and avoid blockages from occurring. Additionally, fitting a boiler filter is also a great way to avoid the build-up of dirt and debris in your central heating system.

High-Speed Settings

If you have a newer installation that includes a smart control panel, you will usually find three speed settings to set and adjust the flow rate.

It’s important to check what speed setting suits your central heating system best, as most systems do not need the pump to be on the highest flow setting. Higher settings are usually the cause of noisy central heating pumps. However, before reducing the setting, it is always worth consulting your heating engineer to confirm whether the setting is high for a particular reason.

If not, it’s worth locating the flow setting switch and reducing the flow rate as by doing so you will not only minimise the noise but also reduce your electricity consumption, which adds longevity to the lifespan of your pump.

Once you find your flow setting switch, all you need to do is turn it down, if it is on the highest flow setting. Once you’ve done this, check the temperature of your radiators. If they are heating up as they ought to, this indicates that the setting is fine.

Fan Hitting Other Parts

Noisy central heating pumps can also be caused by a fault with the fan.

The purpose of a fan is to prevent the central heating pump from overheating. Often, faults such as a loose blade in the fan can result in metallic clanking noises.

Additionally, a poor installation can result in seized parts, and often all you need is a gentle tap to get the pump going again.

Pump overheating

It is normal for the central heating pump to warm up as it heats up. However, if it becomes too hot to touch, it’s likely that something is not functioning as it should be. Usually, with the pump overheating the issue is usually due to the motor.

Problems like this occur during long periods of time where the central heating has not been on, resulting in the central heating pump overheating when it is turned back on. For example, during the summer you may not need to use your central heating and then once it cools down and you use it, your pump could overheat.

The motor overheating occurs when a part gets stuck, and this can often be resolved with a light tap to free it. However, if this is a recurring issue then you may need to replace your central heating pump.

Incorrectly Installed Pump

Another common cause of a noisy pump is it being installed incorrectly, such as the pump not being horizontal as it should be.

When the pump is not installed properly, it will continue to get airlocked no matter how many times you bleed it. In fact, you will find that in a matter of a few days, you will experience a noisy pump again. If this issue is left unresolved, the pump will cause excess wear on the shaft’s bearing, leading to a whining noise coming from the pump.

Installing a pump is an intricate business, even a slight shift from being in a precise horizontal position will affect the circulation of water, leading to a boiler lockout and wearing out far before it is meant to!

As a point of reference, the bleed screw should be on the side and the pump needs to be horizontal, you will need to adjust it if so.

How do I prevent a noisy central heating pump?

Although is it well worth your time to know how to deal with any issues with your central heating pump, there are some measures you can take to prevent the frequency and likelihood of certain problems.

Invest in a water softener

Hard water refers to water with a high mineral count, and some areas have harder water than others. If you happen to live in an area with hard water, it is beneficial to install a water softener near your main water supply. Water softeners replace hard water particles with sodium particles, reducing and preventing the build-up of limescale.

Use an Electrolytic Scale Reducer

A cost-effective alternative to a water softener is by using an electrolytic scale reducer. Installing this improves the quality of your water and impacts the build-up of limescale significantly.

Check Safety Devices

A lot of the issues with boilers are automatically shut down to prevent your boiler from overheating or exploding, so you don’t have to worry about checking your boiler. However, corrosion, restricted water flow, dirt blockages and a build-up of limescale can affect your safety devices working properly. It’s important to make sure your boiler operator checks the safety devices are all in good working order whenever you get your boiler serviced.

Is my central heating pump safe?

It is easy to panic when your central heating system, boiler or radiators start making loud noises. Rest assured, your boiler is not about to explode and is still safe.

All water heaters and boilers come with built-in safety devices, including:

Safety Valves

Although it is good to check the pressure yourself when there is an issue, safety valves work to release pressure automatically as soon as the boiler pressure gets too high.

Low-Water Fuel Cut-Off

When the boiler water drops below a safe level, the fuel or heat source will be shut off automatically, which also shuts down the boiler completely. This stops your boiler from overheating, making sure that you stay safe.

So, there you have it. Everything you need to know about a noisy central heating pump, how to fix it, and how to keep it safe and functioning without burning a hole in your pocket.

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