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Combi Boilers - How They Work

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  • Combi Boiler, Boilers, Upgrading Boiler
  • Posted date:
  • 09-11-2022
Combi Boilers - How They Work

If you are planning a new boiler installation, you may ask what are combi boilers. This article looks at combi boilers and how they work.

What is a combi boiler?

There are three particular different boiler types that all function in various ways; these include:

 Combination Boilers

 System Boilers

 Regular Boilers

The combi boiler model is fantastic for delivering fast, hot water from the mains supply to numerous cold and hot water taps throughout your house all at once, whenever needed. System boilers and regular boilers, on the other hand, are of similar quality. 

Yet, their most significant disadvantage is that they require a separate hot water cylinder or sometimes a cold water tank, feed and expansion tank stored inside the loft to deliver hot water to your boiler so that it can be efficiently heated. When fitting a cylinder or tank inside your property, it's best to make yourself aware of the building regulations; you may find that your home is more suited to a boiler that doesn't require any installation groundwork. 

Is a combi boiler suitable for my home?

Combi boilers need reliable mains water pressure to function and deliver an efficient water flow rate with consistent flowing taps of both temperatures. A low mains water pressure can be identified by a poor trickle of water escaping your showers and taps. Such a system isn't suitable to live with, especially in winter when the demand for hot water is more significant as you need to heat your home.

Suppose your home has more than one bathroom and you're experiencing low water pressure; we recommend opting for a system boiler, as they would be far more efficient in this case. You must ensure your boiler's heat output is set at the right level for your household and its needs. Plenty of modern combi boilers have two specific heat outputs; one is geared towards domestic hot water, and the other is used to generate central heating.

Overall, they need more effort to produce hot water instead of heating the radiators, so professionals encourage customers and homeowners to look closely at the hot water output to determine which boiler they choose for their home.

If you need assistance selecting the boiler installed for your home, contact us today at Hampshire Emergency Plumbing and Heating Ltd, and our qualified staff will be happy to provide you with all the information and advice you need to make your decision. 

Combi boiler types

One of the most frequently installed combi boilers in the UK runs using natural gases. It is supplied and heated directly to your property, and the water heater appliance doesn't require storing on your site unless you desire it. 

One of the UK's most popular off-grid boiler properties is the oil boiler, which has been for multiple years. It is a boiler type that must be stored in a tank or cylinder underneath your property, and when it runs out, the system requires refilling by a trustworthy supplier.

LPG stands for Liquefied Petroleum Gas, another excellent alternative to various off-grid methods and properties produced during oil extraction and natural gas. The only downside is that you must store it in a tank in your garden or backyard, so its two heat output installation may be a little more complex. 

Electric boilers are gradually becoming a more prominent, high-demand part of home heating as they don't burn fuel to generate hot water and central heating.

Burning fuels like gas and oil aren't the most environmentally friendly methods of heating your homes as they release excessive carbon dioxide into our atmosphere. It's best to opt for a system such as this to offer an alternative sustainable solution to burning fossil fuels. 

How much do combi boilers cost?

Combi boilers are some of the UK's most cost-effective heating solutions, which is why they are a common choice for those looking to switch from conventional boilers. The combi boiler is typically priced at running costs of around £500-£1,500 before you even consider the complete installation.

Here is a list of some of the UK's best combi boiler models and the estimated cost of each before installation:

Baxi 800: £900-£1,200

Ideal Logic Plus: £700-£900

Viessmann Vitodens 200-W: £1,445-£1,565

Vaillant ecoTEC Plus: £1,000-£1,400

Worcester Bosch Greenstar: £800-£950

Combi Boilers - How They Work

Price of Combi boiler installation

Alongside the cost of its compact unit itself, you must consider the cost of the professional boiler installation, as such isn't a job for unqualified individuals as it deals with gas appliances and electricals. The typical combi boiler installation costs around £500-£700; however, the location of the instalment and complexity can bump the price to around £2,000.

To ensure you always receive competitive prices, you want to compare the price quotes from various plumbing and heating engineers in your local areas. Hampshire Emergency Plumbing and Heating Ltd has a team of fully qualified gas safe registered installers trained to provide excellent, high-quality services at affordable, cost-effective prices. 

Advantages of combi boilers

The combi boilers are straightforward and faster to install since they require less pipework. The combi boilers provide unlimited and instant access to hot water. With combi boilers, you can guarantee there is no waiting around for the hot water cylinder to warm up.

Combi boilers can condense heat, meaning that the boilers use most of the energy they produce, and only some of the power is wasted. They generate heat from flue gasses that would otherwise be wasted away if the boilers were non-condensing. The combi boilers require minimal pipework, thus making installing the boilers easier, faster and cheaper. Here are a few select reasons as to why you should choose a Combi boiler:

When using a combi boiler, you can save plenty of space throughout your household compared to the regular or system boilers that take up more space.

Combi boilers don't carry bulky cylinders and tanks with combustion chambers that hoard space in your home, as they are single-combined units that only require straightforward boiler installation.

Another significant advantage is that with a combi boiler that counts as an all-in-one unit, you don't have to get any tanks or cylinders installed to store hot water. Hence, the installation process is relatively straightforward. 

Regular boilers, sometimes recognised as heat-only, traditional or conventional boilers, have tanks stored in the loft, relying heavily on gravity to deliver instantaneous hot water down to the boiler. Delivering water directly to your showers and taps allows the household to enjoy mains water pressure. 

Combi boilers are most known for the efficiency they provide to smaller homes. Some of the best combi boilers on the UK market are approximately 93% efficient, meaning 7p is spent on wasted energy and every £1.00 of your bill is spent heating your home. Thus, investing in combi boilers ensures you're always saving energy.

All mains gas and oil boilers are responsible for producing waste energy whilst operating; however, more modern models curate less. You could save considerably more money if you replace your old boiler that has an efficiency rating of 70% with a more highly efficient one. Plenty of systems and regular boiler's energy is spent heating your hot water storage cylinder.

One of the most significant advantages of a combi boiler is the lack of need for a hot water cylinder. 

Disadvantages to combi boilers

Ultimately, combi boilers aren't the most suitable central heating boilers for households, especially ones of a larger scale, as they are ideal for smaller homes with few bedrooms and one bathroom. If you're located in a much more extensive property, you better invest in a regular or system boiler.

Suppose the mains water pressure in your property is relatively weak, then water that exits out of your showers and taps. In that case, if you are set on purchasing a combi boiler, gas safe registered engineers can install a pump that will help increase your pressure; however, you must be wary that this will add to the final cost.

Whilst combi boilers are somewhat of a new model of boiler, they aren't the most compatible with older pipework, as they are skilfully designed to suit weaker water pressure. For those who wish to replace their old heating system, you will need to utilise radiators and pipework capable of withstanding higher pressure levels.

We recommend contacting a professional installer who can advise on the most suitable boiler system for your household. Contact us today for free quotes if you're located in our area. 

How Do Combi Boilers Work?

This type of boiler works by having the compact heating system heat both the radiators and the hot water. Such a system eliminates the need for an additional external hot water cylinder or cold water tank. The combi boiler can provide instant hot water. Immediately, you turn the heating and hot water tap on, which signals the boiler to start heating the water.

The water is heated faster as the independent heat exchangers transfer the heat produced from the burned flue gasses to the cold water. The cold water tank then delivers the water to the tap as required. The control valves found inside combi boilers function in different directions. The control valves allow the water to flow via the central heating system or help divert the water towards the appropriate hot water tap.

However, the control valves do not carry out these two functions at the same time.You can also set the temperature you desire your house to be heated by pre-setting the desired temperature with the heating controls.

The combi boiler works with the room thermostat to ensure the house is preheated at the desired temperature. Regarding combi boilers, the tap water and the water at the central heating system do not mix. The domestic hot water and central heating systems are in separate pipes; therefore, the water never mixes.

We recommend ensuring you consider the radiator's and pipework's cleanliness before a new boiler is installed in your home, as this can cause damage to the boiler.

If you require Combi Boilers Fitting in Southampton and the surrounding areas, contact our specialist heating engineer today. Follow the link to find Combi Boilers Fitting near you.