If your boiler has just gone wrong, it is quite likely that the problem could stem from the central heating pump. In this guide, we will explain the eight most common problems with central heating pumps and explain clearly how you can fix them. If you are lucky, this article could save you big sums on calling out a gas engineer to fix it for you.
It is easy to panic when your boiler goes wrong. Most of us know little or nothing about how boilers work and the prospect of paying a substantial call-out fee to get a heating engineer to take a look isn’t a nice one. Especially when the possible cost for parts is added onto the bill.
But boilers are actually far simpler than you might think and while we wouldn’t advocate amateurs trying to fix their own boilers, that is not necessarily the case with the central heating pump. And it is this pump which quite often is the cause of all your boiler woes.
Central heating pumps can go wrong a lot and there are a number of common problems they are susceptible to. In this guide, we will reveal the 8 most common problems with your central heating pump and, crucially, we will also show you how to fix them.
If you are lucky, this guide will help you to fix your own boiler in just a few minutes and save a small fortune on calling out an engineer to do the job for you.
How does a heating pump work?
If you have never heard of a central heating pump before, it basically does exactly what it sounds like. The pump in your central heating system takes hot water from the boiler and pumps it around the pipework in your home.
It is the pump that forces the hot water into your radiators, towel rails, taps, and showers in your property. Buta central heating pump is not working, your whole central heating system can grind to a halt.
Where is the pump located?
In the majority of cases, your central heating pumps will be located behind the casing on your boiler. While technically part of the boiler itself, it operates independently and can sometimes be fixed quite easily by anyone.
In this guide, we will detail the most common heating pump problems. We will explain how to fix the issue and, if it is not possible to do the fix yourself, we will give you a ballpark indication of what you can expect a fix to cost.
So here are the most common heating pump problems we ran into.
#1. The pump is running, but not pumping water around the system
If your radiators are not heating up, the best way to check whether your central heating pump is running or not is by listening or looking.
If the central heating pump is working, it will be vibrating slightly. When you locate your central heating pump, look or listen closely to see if you can detect these vibrations.
If it is vibrating but still not pumping water around the system, the most likely cause of this issue is that the shaft or propeller on the pump has got stuck.
Sometimes the problem can also be caused by the motor. Central heating pumps will get warm but they shouldn’t get too hot. If your pump is hot to the touch, the engine could be the issue.
If the problem is being caused by a component on the pump getting stuck, try giving it a gentle tap. This can help to free the component and get it working again. We don’t recommend hitting it too hard! If this is the first time you have had this problem, this fix is fine. But if the issue is occurring regularly, you will probably need to get a new central heating pump fixed.
A replacement central heating pump will cost in the region of £200-250 including the labour costs of getting it installed. This quote is for a high-end pump from a brand such as Grundfos. If you opt for a more budget brand, they can be a little cheaper but are likely to be less reliable.
#2. Pump is blocked full of dirt
It is quite common for older central heating systems to begin to accumulate dirt and metal particles from radiators and pipework in the boiler and other components. This can include the central heating pump.
This dirt and grime build up is very bad for these components and sooner or later it will cause them to stop working properly. Don’t panic. Pump blockages like this are fairly simple to fix.
You can tell if your central heating pump begins to get clogged up with dirt because you will find that your central heating system takes a lot longer to heat up and sometimes will not reach full temperature.
The first and simplest way to solve this issue is to hot flush the heating system with chemicals. This is not to be confused with a power flush because it doesn’t increase the pressure in the system. In an older system, this can cause damage to joints and components and is not recommended.
Once the system has been hot-flushed and the pump has been cleaned, it is also a good idea to fit a magnetic system filter. This will catch a lot of the debris that is causing the problem and help to prevent any future blockages.
One good tip is to try and ask your heating engineer to check the heating pump when they do your annual boiler service as this is a problem you can catch early and easily prevent.
#3. Airlocks & noisy pumps
An air lock can occur in your central heating pump when air builds up in the pump component and stops it working properly.
A lot of heating pumps have what is known as a bleed screw, This allows you to bleed the air out of your pump much as you do a radiator. This can fix the problem without needing any expert help or replacement parts.
You can usually tell if you have an air lock because the central heating pump starts making strange noises or humming.
Find your central heating pump in your boiler and locate the small bleed screw. Open the screw slowly. Usually, less than a quarter of a turn will suffice.
That will let the air out and, like bleeding a radiator, this will be followed by a small amount of water. Be ready for this. The water is your cue to close the bleed screw again.
If this doesn’t solve the problem, you might be able to buy anti-vibration brackets which are easy to install and should solve the problem.
If there isn’t a small bleed screw on your central heating pump, you will need to consult an engineer.
#4. Incorrect installation
Sometimes the heating pump problem is not actually caused by the pump itself. In a few cases, it is the installation of the pump that is causing the problem.
If a central heating pump has been installed incorrectly, it can cause noise or wider problems with your central heating systems.
It is not that common for a central heating pump to have been fitted incorrectly. But it is now unknown either. Sometimes, it can even have been fitted the wrong way round.
If this is what is causing your problem, you will need to get a heating engineer to come and reinstall the central heating pump.
This can be a time-consuming job as it requires your entire central heating system to be drained, As a result, it is often not the cheapest of fixes either.
After refitting the central heating pump, your central heating system will then need to be filled. All your radiators and towel rails will need to be bled too. However, once this is complete your problem should be resolved.
#5. Pump speed settings are incorrect
Some newer pumps like the Grundfos 15/60 are equipped with speed and flow settings. These can sometimes be set up incorrectly, but don’t worry. They are extremely easy to adjust.
Usually, these settings options are between 1 and 3 with 1 being the slowest flow rate and 3 being the fastest. If the pump flow rate is not set up correctly, this can lead to radiators not heating up or systems taking much longer to heat up than they should.
Work out where your boiler central heating pump is. If it is a newer type of pump, it will have a switch on the top which can be used to adjust the flow rate. If this switch is set to 1 or 2, it is quite likely that the flow rate is too low. Flick the switch to 3 which is the most powerful setting and the problem should be resolved.
While this is a fix you can do yourself, it is still worth consulting a Gas Safe engineer first. It is possible that your pump may have been set at 1 or 2 for a reason. For example, if your system has microbore pipes, it might not allow any further flow. If you increase the pump speed on a system that can’t take it, it can cause major problems.
#6. Leaking pump
There are all sorts of different reasons why your boiler can leak but an issue with the pump is one of the most common ones.
It can be caused by incorrect installation or even the pump working itself loose if it has been there for a while. Sometimes, the pump seal can blow as a result of incorrect pressure settings.
Check that the pump is secure in its setting in your boiler. If it’s not, this could be the cause of your leak and tightening it up can sometimes be enough to solve the problem.
Next, check all the fittings on the pump too. If there is evidence of corrosion, this could be the cause of the leak and you will need to get a new central heating pump fitted.
Lastly, check the joint on your pump. If this is where the leak is coming from, there is a good chance that the seal on the pump has blown.
If you need to replace the seal, there are two options. You can either replace just the seal, which is normal if the pump or the boiler is fairly new. But if it is an older pump, replacing the whole unit is usually the best choice.
#7. No power
If you find that your pump and your boiler both have no power supply but there is no issue with the power supply to your property, it is likely that there is an issue with your boiler’s PCB unit.
If your boiler has power, but the pump doesn’t, the most likely issue is a wiring problem. Sometimes, small leaks can ruin the wiring on the pump and cause this problem, although these issues are quite rare.
The first and most obvious step is to check that the fuse on your boiler hasn’t blown.
You should also check whether or not there are any leaks. If there is, you will need to get a gas engineer to come and check the wiring to your pump.
If the pump itself is old and beginning to look corroded, it is likely to be coming to the end of its life. Your best bet in those circumstances is to replace the entire pump.
#8. Pump won’t turn off
Sometimes, far from not working, a central heating pump can run constantly and not switch off. This is an issue that has been reported a number of times with the Baxi Solo boiler range in particular, but it has been known on other makes and models too.
If this is the problem with your boiler, you will need to get a proper pump diagnostic from a trained engineer. There are a number of different things that could be causing the problem including:
- Faulty PCBs.
- A faulty pump overrun stat.
- A sticking mid-position valve – this one can be fixed quite easily with a bit of WD40.
Central heating pumps are the cause of far more boiler problems than most people realise. Sometimes, these problems are serious and require an experienced gas engineer to fix them. Other times, it is a simple issue you can fix yourself.
In this guide, we have highlighted the top 8 most common problems with central heating pumps and explained how to fix the problem. Where possible, we have also given some indications of what these fixes will cost.