What type of boiler do I need?
There are three main types of boiler: combi, heat only and system. Heat only boilers (aka conventional or regular) work with a cylinder in the airing cupboard. System boilers are often found in modern homes with an ‘unvented’ hot water cylinder. Combi boilers produce instant hot water. Verrall + Parks will help you identify which one you have and consider the advantages and disadvantages of each. You may be thinking about a new boiler which our Gas Safe registered engineers will install at very competitive prices and this guide can help you decide whether to stick with your existing boiler type or to install a different boiler type.
Identify your current boiler – what are the pros and cons?
Combi Boiler
A combi boiler is a single unit that generates all the heating and hot water for the home. There are no hot water tanks.
How does a combi boiler work?
A combination boiler heats water via an integral heat exchanger directly from the cold mains. It provides instantaneous hot water.
This is different from a traditional system which stores hot water in a tank in advance of use. A combination boiler does not need a hot water cylinder or tanks in the loft. Everything is done through a single, usually wall-hung, unit.
Advantages of a combi boiler
Creates space when removing old hot water tanks
Lower maintenance costs – the integral heating and hot water functions are covered by the boiler manufacturer’s warranty/guarantee
No long wait times for hot water
Disadvantages of a combi-boiler
They do not work well in properties with poor flow rates and/or poor incoming water pressure
Hot water flow rates are reduced when providing hot water to two or more outlets simultaneously, although this is really only a problem in houses with two or more showers.
High-performance combi-boilers that provide 12.5 litres per minute of hot water or more – may not be effective on 15mm pipework supplies and can be over-sized for the heating
System Boiler
A system boiler has all the same components as a combi boiler without the hot water production. It works with a steel hot water cylinder.
How does a system boiler work?
Like regular boilers, system boilers work with a hot water cylinder. Unlike regular boilers, the system is not open-vented, i.e. there are no tanks in the loft, and all of the components that would normally be outside a heat only boiler (pumps, valves etc) are integrated into the boiler. These are a modern version of the regular boiler and are often installed along side unvented hot water cylinders.
Advantages of a system boiler
Good for properties that have a high hot water demand, i.e. lots of showers, as the unvented tank can deliver good hot water flow rates to multiple outlets simultaneously
Good cover from manufacturer warranty/guarantee as there more of system’s components are integral to the boiler
Disadvantages of a system boiler
Good hot water flow rates depends upon good incoming mains water pressure, if the pressure is poor then internal flow rates will be poor
They are require more space than a combi boiler. If you are swapping a combi boiler for a system boiler you will need to find an appropriate location of the hot water cylinder, usually on the first floor
Heat Only
A heat only boiler only provides heating. It works with a hot water cylinder.
How does a heat only boiler work?
A heat only boiler (also referred to as a ‘regular’ or ‘conventional’ boiler) provides heating directly to the radiators and works with a cylinder to provide hot water. They often work on what is called an ‘open-vented’ heating system, i.e. there is a Feed and Expansion tank in the loft, but they can work on a ‘sealed’ system too.
What is a back boiler?
A back boiler is a type of heat only boiler that is situated in a chimney breast with a fire on the front. It is currently not possible to replace a back boiler in the same location. For those with an existing back boiler that would like to replace it with a new boiler then you will need to opt for a wall hung heat only boiler elsewhere in the house or consider a combi boiler.
Advantages of a heat only boiler
Work well with old radiators. Older radiator systems that are put under the high water pressure delivered by system or combi boilers may leak.
Low replacement cost as heat only boilers are the cheapest type of boiler to buy
Disadvantages of a heat only boiler
Only the boiler is covered by the manufacturer’s guarantee/warranty. This leaves lots of other components on the system (e.g. hot water tank, pumps and valves) that are subject to replacement and breakdown
Stick or change boiler type – Our Top Tips
- If you have old radiators or pipework buried in screed – stick with an open vented, heat only boiler
- If you and your family have lots of showers at the same time – consider changing to a system boiler with unvented hot water tank (if your water pressure is good)
- On a tight budget – replace your existing boiler with the same type of boiler in the same location
- Want low maintenance costs – install a combi boiler with a 10 year warranty/guarantee from Ideal which is our preferred manufacturer (providing your water pressure is good).
- Extending your property and adding bathrooms – consider a system boiler with un-vented hot water tank (if the water pressure is good).
We are Ideal Accredited Installers
As Ideal accredited installers we pride ourselves on our commitment to setting the highest standards, and maintaining Ideals reputation for quality, reliability and providing a great service. Every single Ideal boiler is put through rigorous testing and control measures during production to ensure that when we install we know we are fitting a quality product.
FAQ’s
Annual inspection plus copy of the Gas Safety Certificate cost: £90.00 inc VAT.
These must be fixed within 24 hours. Having no access to hot water or heating is a constitutional hazard.
The law states that minor repairs must be done in a “reasonable time”.
No matter your tenancy agreement, rental properties must have a working boiler that provides both heat and hot water. This can be an electric, gas or combi boiler.
The law requires landlords to carry out an annual inspection and provide tenants with a copy of the Gas Safety Certificate. Each certificate lasts 12 months.