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Of course, it makes perfect sense to add an inhibitor to your central heating system for longevity and efficiency. But what is a central heating inhibitor? Well, an inhibitor is similar to an anti-rust treatment for pipes and radiators. Over time, water moving through the system causes rust, sludge, and limescale buildup that makes your heating less effective and costs you more money.
With an inhibitor, you save your system, keep the radiators running accordingly, and avoid expensive repairs. But how to add an inhibitor to a central heating system? It’s actually quite easy, and one need not be a heating engineer. Let’s break it down step by step.
What is a Central Heating Inhibitor?
The central heating inhibitor is actually a specific type of chemical intended to keep your heating system running smoothly. Though it’s not a literal physical part of your system but a chemical solution that enters your system blended with the inner water in every pipe and any radiator. Its main job? To stop rust, sludge, and limescale from building up and clogging your plumbing system.
Given the fact that the heating system consists of metal pipes filled with water, rusting is a very natural problem to occur. Blockages, reduction in efficiency, and even complete breakdowns – all these can eventually result from the same.
Instead of waiting for problems to appear, add an inhibitor to prevent any issues before they can cause some damage. Actually, most of the manufacturers include inhibitors as necessary for maintaining a boiler’s warranty. So the process is somewhat important in house maintenance.
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Why Use a Central Heating Inhibitor?
Here is why you should make use of a central heating inhibitor:
- Prevents Rust and Corrosion: There are a number of metal pipes in your system, and water naturally causes rust. The inhibitor helps to ward this off and keeps your pipe in good condition for longer.
- Reduces the Limescale: Just as limescale often builds up within a kettle, so does a heating system get clogged. An inhibitor makes this whole process slower in order to keep such blockage avoided.
- Improves Efficiency: A clean system heats up very fast while using less energy, translating to reduced bills on your side.
- Prevents Costly Repairs: Sludge and debris can become major problems if not taken care of. The regular use of an inhibitor will help avoid costly breakdowns.
- Protects Your Boiler Warranty: Many of the manufacturers bind the use of inhibitors in most of their warranties.
When Should I Add a Central Heating Inhibitor?
You will need to add a central heating inhibitor at appropriate times so that your system can remain efficient:
1. During routine annual servicing
This practice is highly recommended each time your heating system is serviced to top up the inhibitor. This is because of the degradation with time, requiring refill if protection is to be continually accorded.
2. Where there has been a system flush
A process where a system is drained and cleaned, either to get rid of sludge or limescale buildup. For instance – the addition of a fresh dose afterward of inhibitor helps to prevent any further buildups.
3. When installing a new system
If you have just fitted a new boiler or radiator, an inhibitor should be added from the outset. It is to protect the system against corrosion and the build-up of debris.
How to Add Inhibitor to a Central Heating System?
Adding an inhibitor to your central heating system is one of those easy but necessary jobs that are often overlooked. The best way to add an inhibitor to central heating depends upon the type of system you have.
You may be able to add it to a radiator or add it more directly via an expansion tank or filling loop. How Put Inhibitor in Central Heating System: Follow these steps:
1. Turn Off the Heating
First of all, switch off the heating and let the system cool down. This prevents burns and allows safe handling.
2. Choose the Right Radiator and Release the Pressure
Choose a reachable radiator, ideally the highest in your house, as this reduces airlocks and makes it easier to re-fill. Loosen the air with the bleed key or, if possible, a flathead screwdriver until the pressure drops. Make sure the radiator is cold while doing this.
3. Drain Some Water
Put a bowl under the radiator valve with the nut turned a few turns to allow some water to trickle out. Then, reopen the air vent to help it drain. You want to drain about 600ml – just over a pint. Use a towel to catch any drips.
4. Close the Valve Nut
When enough water has drained, tighten the valve back up. You can also close the air vent to slow the water flow.
5. Pull Out the Radiator Plug
At the top of the radiator, you’ll see a small plug or vent. Use a spanner to carefully unscrew it. If it’s dirty, clean the threads with wire wool.
6. Add the Inhibitor into the System
Pour the inhibitor slowly into the radiator using a funnel or applicator. For a standard system with up to nine radiators, 500ml should be sufficient. If you have 10 or more radiators, you’ll need 1 litre – two 500ml bottles.
7. Replace the Plug and Refill the System
Screw the plug in tight. If you have a combi boiler, allow water back through the filling loop. Ask someone to open a bleed valve of the respective radiator only until water flows out, then quickly close it. Keep filling the boiler until it reaches the correct pressure (usually 1–1.5 bar).
8. Restart System and Bleed Radiators
Turn the heat back on, then test for leaks. Once the system has been up and running for a while, shut it off and let it cool down a bit, then bleed the radiators again to let out any trapped air.
How to Add Inhibitor Through a Radiator?
If you need to add the inhibitor directly through a radiator, follow these steps:
1. Turn Off the Heating and Isolate the Radiator
Switch off your heating and water. Ensure the TRV is fully turned to its closed position. Remove the plastic cover from the lockshield valve and turn it with pliers in the clockwise direction to its closed position.
2. Open the Bleed Valve
Bleed the pressure off using a radiator bleed key. This allows water to drain out when you loosen the nut at the bottom.
3. Loosening the Valve Nut
Loosen the nut on the radiator to the TRV, careful not to spill water on the carpet. Let water drain out into a bowl or another container.
4. Attach the Filling Kit
With the bleed valve removed using a spanner, attach the filling kit. Open the stopper at the opposite end of the radiator so that air can be released as you add the inhibitor.
5. Add the Inhibitor
Gradually add the inhibitor into the filling kit, allowing it to slowly let it in. Do not pour too quickly as it may take some time to enter the system.
How to Put Inhibitor to a Feed and Expansion Tank
If your central heating system has a feed and expansion tank, which often is located inside the loft itself, adding the inhibitor is an easy process:
1. Drain Some Water from the System
Find the drain valve first – it’s usually next to a downstairs radiator. Connect to this via a jubilee clip with a hosepipe and run the other end outside so that some of the water in the system may be drained away. Don’t need to totally drain the thing, but drain enough so the inhibitor may flow freely around it.
2. Clean the Tank
Before adding the inhibitor, check the tank for dirt, rust, or sludge. If there’s debris, clean it out using a cloth and some water. Be careful not to let any dirt go down the supply pipe at the bottom of the tank.
3. Add the Inhibitor
Pour the inhibitor directly into the tank. Next, open the ball valve or release the mains water supply to allow the system to re-fill. When the tank is full, the inhibitor will circulate in the heating system itself.
How to Add Inhibitor to a Sealed Central Heating System?
If you only have one big tank in the loft, then you have a sealed system. You can then add the inhibitor via the boiler filling loop and not via a radiator or tank.
How to Put Inhibitor to an Open Vented System?
If you have an open vented system you will have two water tanks in your loft. The small one is for the expansion tank – this is where you add the inhibitor.
Steps to Follow:
- Turn Off the Water Supply: Either turn off the mains water or close the valve on the tank.
- Drain Some Water: Allow the tank to drain down enough to enable the inhibitor to go in.
- Check the Condition of the Tank: If there is rust or sludge inside, then it needs cleaning before you add the inhibitor.
- Add the Inhibitor: Start by pouring the inhibitor into the expansion tank.
- Turn the Water Back On: Open the mains supply or valve to refill the system.
How to Add Inhibitor to a Combi Boiler System?
As far as a combi boiler system goes, this would require that the inhibitor should be added via a radiator because there is no expansion tank.
Steps to Follow:
- Turn Off the Heating: The system should be cool before you start.
- Choose a Radiator: Choose any radiator that you can easily reach and has a bleed valve at the top or a top plug. More often than not, the towel radiators will be the easiest ones.
- Close Both Valves: Shut off both the thermostatic radiator valve (TRV) and the lockshield valve.
- Attach the Inhibitor Bottle: Depending on the radiator type, you can add the inhibitor via a bleed valve, or the plug at the top is removed and it’s poured in.
- Reopen the Valves: After adding the inhibitor, you must open both the valves of the radiator.
- Turn the Heating Back On: Check for leaks, and allow the inhibitor to circulate through the system.
How Much Inhibitor Do You Need?
The amount of inhibitor required depends on the sizing of your central heating system. Generally, 1 litre is sufficient to treat 8 or 10 radiators. If you are using more than 8 radiators, you will probably need 2 bottles of 500ml each.
Too much additive above what is required will not enhance protection, but rather too much inhibitor may lead to problems such as filter damage, especially magnetic ones. So, it is better to use the amount recommended for better results.
Install a Magnetic Filter for Better Protection
The magnetic filter is really something to consider to include in your heating system. It would aid in trapping rust and debris and hence avoid sludge from building up inside the pipes and radiators.
While standard filters catch some dirt, a magnetic filter would capture the smaller bits easily, thereby keeping your system much cleaner for a longer time.
You might require professional assistance in installing magnetic filters. Hence, if you cannot do them yourself, then you shall require the help of a qualified heating engineer.
Consider Adding a Scale Reducer
Limescale can be a big problem if you happen to live in a hard water area. This builds up inside your heating system, especially on the boiler’s heat exchanger, thermostat, pipes, and radiators. Thus reducing efficiency and potentially causing damage.
A scale reducer will do this by breaking it down and ceasing the limescale in the first place, which may be good for the life span of your heating system and efficiency.
When Should You Top Up Your Central Heating Inhibitor?
You will need to top up the central heating inhibitor every year, as over time it dilutes, cutting its potential ability to stop limescale and rust.
The best time to inhibitor is when the system is drained, which could be at an annual service of the boiler. Inhibitor levels can also be checked using a test kit. This involves taking a small water sample from a radiator.
How Often Should You Add Inhibitors to Your Heating System?
An inhibitor should be added with every change of water, normally within 1-2 years, in order to maintain an ideal condition for your heating system. Regular maintenance avoids corrosion and reduces sludge buildup to a minimum, helping you avoid expensive repairs.
You should also replenish with a new inhibitor each time you drain the system because draining takes away the previous treatment.
The reward for staying on top of inhibitor levels is an extended life with your boiler and radiators, plus a trouble-free heating system.
The Bottom Line
One pretty easy yet necessary approach to taking care of a heating system properly would be to add a central heating inhibitor. It helps prevent rust, sludge, and limescale buildup, resulting in fewer breakdowns and keeping your radiators heating properly.
Regular servicing, like topping up the inhibitor every 1 to 2 years, will also add some considerable life to your boiler. As it increases its efficiency and can even eventually lower energy bills. Plus, if you live in a hard water area, combining it with a scale reducer and a magnetic filter can provide even better protection.
Frequently Asked Questions
This depends on your type of heating system. Among the popular and well-acknowledged brands are Fernox, Sentinel, and Adey. Look for one offering good corrosion protection in accordance with your system type.
The inhibitor should be added with the system turned off and cold. Take off a little water from the system, then add the inhibitor through a radiator, filling loop, or expansion tank. Once you have added it, repressurise the system and fire up the boiler to make sure it is properly distributed.
No, you don’t need to drain the whole system just to add an inhibitor. You can simply add it through a radiator or the filling loop. But if the system hasn’t been flushed in the last 2-3 years, a full drain and flush might be a good idea to remove sludge and ensure optimal performance.
No, too much inhibitor cannot be added. Although having more does not automatically translate to superior protection, too much of the same does no harm either to the system. Just use exactly what the product manufacturer calls for so that there is no wasting of the product.
Without an inhibitor, it is highly probable that your system will start building up rust and sludge over time. These can block further down the radiators, leading to reduced performance. Even worse, one day, the entire system can go out and is in need of costly repairs.
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