What is a combi boiler: Advantages and disadvantages

A combi boiler is a type of heating system that provides heat and hot water using just one appliance. It can be more expensive to install than other methods, but the savings are worth it in the long run. The energy efficiency of this system will save you money on your home’s heating bills. They generally work on electricity, propane or natural gas. 


Why invest in a combi boiler?

1. They’re more energyefficient

Combi boilers are more energy-efficient than other types of heating systems. This is because combi boilers don’t switch on and off every time you turn on a tap. This type of installation is also better for the environment.

2. They save you money

A combi boiler will save you money on your home’s heating bills, as they’re far more efficient than other systems. A combi boiler will save homeowners about $500 annually on their utility bills, compared with a traditional boiler. 

3. They provide hot water instantly

Another benefit of installing a combi boiler is that it can provide instant hot water, with no need to wait for the water to heat up first before use!

4. They are easy to install and maintain

Another advantage of a combi boiler is how easy they are to install and maintain as well as repair if necessary. Many companies offer warranties that cover installation, maintenance, and repairs under certain conditions for a set period of time after the purchase date – be sure to check if your chosen company offers these! Finally, many companies offer financing options so the initial costs aren’t so steep when purchasing one of these units.

5. They have low emissions levels

Last but not least: combi boilers have low emissions levels compared to other systems which make them perfect in homes.

6. Easy maintenance: This type of heating system requires less maintenance than a traditional boiler because all of the components are contained in one unit, making it easy for homeowners to clean and maintain their combi boiler on their own schedule.

7/ They take up less space. If you need a boiler for water and a separate one for heating, it can take up more space.

How does a combi boiler work?

A combi boiler is a heating system that provides both hot water and heat.  Cold water is pumped into them and this is circulated around a heating element. In natural as systems, the gas is burned by a flame and this warms up the heating element. For an electric heater, electricity is used to warm up this heating element. This requires more energy and for this reason, electric heaters are more expensive to run. The hot water is then pumped out. 

The heating system is a closed-loop. The same water is circulated over and over again. A vent is added to remove oxygen from this water so that the system works optimally. Sometimes a magnet filter is added to remove debris from the water as radiators can break down over time.

The water system always gets new city or well water. Rainwater is not that often used for hot water as it might contain impurities. A filter is often added for city and well water as well to make sure that dirt doesn’t get into the water heater.

Is my old combi boiler worth anything?

Yes, old combi boilers contain a lot of valuable metals. They can be worth anywhere from 10 USD to a few hundred USD. It depends on the weight of the boiler and the metal prices at that point in time. These can fluctuate quite a lot. You can bring them to a metal scrap company to get an accurate estimate.

It is possible that your local scrap company doesn’t accept individual boilers. You can give the boiler to your plumber to get a reduction on the installation price.

Some plumbers take the boiler without compensating the customer. They might adjust their invoice for this though. You can discuss this with your plumber.

Your old boiler might be worth a few bucks. You will have to remove it yourself and bring it to the scrap company. This can take quite a lot of time and this might not be worth it to you.

Can you use combi boiler just hot water?

Yes, during summer most people adjust the settings on ther combi boiler. This allows them to use less energy. Often this is just adjusting a switch.

Your combi boiler will only heat water at this point. If you want to turn on the heating function again, you simply adjust the setting on your combi boiler again. Some systems do this automatically.

Adjusting this setting can be really worth as your boiler will last longer and you are using less energy.

If you don’t know how to do this, you can consult the manual of your boiler or reach out to your boiler. Some plumbers do this for you while they are maintaining your system.

Can combi boiler go in loft or garage?

There are different types of boilers. Older types (that take air out of the room and vent the dirty air in the room) are not allowed anymore in most regions.

In most instances boilers that vent the dirty air outside can be installed in a loft or garage. Check your local code as there might be requirements with regards to the room size and the distance to other appliances.

Most modern boilers work very clean and don’t emit exhausts in the room itself.

Combi boilers can take up quite a lot of space so you have to plan where this can stand. You also need the gas or electric supply and a connection with the water pipes.

A plumber can check if these items are present in your room.

Is a combi boiler always running?

No, combi boilers should ony function when you need hot water or heating. They might work to heat up the water in the tank. Modern systems also heat the water up from time to time to keep it clean.

Standing water can get filled with dirt after a while. This is why combi boilers sometimes heat up the water to avoid problems.

If your boiler is working a lot, you can check the display to see if you get a warning or error code. If you see a code, you can check the manual to see if there is a problem with your system.

You can also adjust the temperature that the system has to produce. By lowering this, your boiler will have to work less often. This can save a lot of energy.

Most people just keep the factory settings while these might not be optimal for their situation.

Can combi boiler explode?

While it doesn’t happen often, boilers can go out with a bang. It can destroy a room or a house:

You can call your plumber or turn your system off if you really feel that the water heater is making too much noise. In most instances, it won’t be a problem and the system just needs some maintenance. You have to get it looked after but it probably won’t explode. It can get damaged though if the system makes noise for a while. There are other reasons why you have to maintain your system.

For example, if the sacrificial anode rod breaks, it can affect your tank and even your pipes! Sediment buildup such as chalk can also be an issue. Once again, your system should stop by itself. It often takes one hour or more to properly open and clean a system.

Some plumbers are lazy and don’t maintain the whole system. If they leave after 10 minutes, it can indicate that the plumber didn’t do a proper job. Every 2 years the system should be checked. Some systems just don’t get dirty as they used advanced systems. Still, the plumber can use additional sensors to see if it is burning clean and that there are no other issues. They can also check for cracks or other issues that can lead to big problems. 

Some people still have a system that is older than 10 years and these water heaters are less advanced and don’t have a lot of sensors. These are more prone to issues. If they are maintained well, there shouldn’t be too much of a problem though. It is hard to tell when a water heater will break. Some do so after a few months whereas others can last for decades. There are a lot of things affecting this, from usage, manufacturing errors to the cleanliness of the water. 

Can you use a combi boiler with water turned off

No, your combi boiler will stop quite soon after you have turned the water off. It might work for a while but the sensors in the system will detect that there is not water supply and shut down.

This makes sure that the system is not running without water as this can damage several components.

Heating is generally a closed loop of water but water needs to be added from time to time.

Modern water heaters have advanced chips that allow them to prioritize what they do. For example, if hot water is needed, they will stop warming the radiators for a moment and focus on offering warm water.

Once this is done, they go back to warming up the water for the radiators. Water heaters also have advanced sensors and if something is wrong, they can warn you so that you can fix the right part. They should get flushed from time to time to remove sediment and should get cleaned and checked every 2 years.

Some combi boilers have a tank with hot water. This allows them to work more efficiently as they can pre-heat water so that the system doesn’t have to work every time that you open up the tap to get hot water. If you don’t use a lot of water a system with a tank is not really needed. 

Newer systems reuse the heat and work more efficiently. This is called condensing boilers.

Drawbacks of a combi boiler

Although a combi boiler is cheaper to install than other systems, the upfront cost may be prohibitive for some. This type of system works best in homes that don’t need a lot of water or heating. If you have a big family, it might be needed to get a separate system as the heater can’t work when you need hot water. This can lower the temperature in a house if you take long showers. Separate systems can therefore offer more comfort to larger families.

The installation process is also likely to be more complicated and expensive than other heating methods, which may make it difficult for some costs to justify the purchase. A combi boiler needs more space than other types of heating systems, so it can’t be installed in smaller homes or apartments.

Is a combi boiler the best choice for you?

There are 4 main factors to consider for this: your budget, how much space you have and how much water you need, and the size of your home. 

Combi boilers can be more expensive than just installing a water heater. If you live in a hot climate, you might not need a lot of heating and decide to save money and just go for a water heater. Sometimes it is possible to wear a sweater instead of using a heating system. 

A Combi boiler takes up less space than installing a water heater and heating system. Especially in small apartments, this is a big advantage. 

If you need a lot of hot water, you might consider installing a water heater and a separate system for the heater. A combi system can’t heat and offer hot water at the same time. For this reason, some people opt to have separate systems as these offer more comfort.

To conclude, we can state that combi boilers have a lot of advantages. While they might be more expensive to install, they take up less space and can be cheaper to run. They don’t work in every situation so you will have to discuss with your plumber if it can work for your needs. They generally work on natural gas but we see that electric systems are becoming more popular as well as more people are getting solar panels. 

We have discussed the difference between a furnace and a boiler here.