Steam/hydronic boiler heating systems vs split systems

Air Conditioning FAQs

Choosing an air conditioner to suit your specific needs is a significant financial investment. Making the right choice can significantly improve the comfort of your home, and could increase it’s value.

This article sets out the benefits and downsides of installing steam or hydronic heating on the one hand, and installing a split system on the other. As you might expect, our recommendation is that both systems have significant advantages, and the points you place as a priority and your personal preference will have an impact of which choice you make.

How the systems work

Firstly, it is worth setting out some basic facts about both types of systems.

A hydronic system works is as follows:

  • Water is heated and boiled to a certain temperature, then it travels though sealed pipes to the radiators within the home. It will then give the home continuous warmth and will keep the chill out by using a thermostat
  • It will then also recirculate hot water using panels or in slab, and will be heated by natural gas or LPG or solid fuel

A steam boiler system uses similar technology to a hydronic system, and in many ways it is a very similar heating system. The primary difference between the two systems is that a steam boiler (as the name suggests) uses a boiler to create steam, which travels through the pipes (rather than water), which then circulates to the radiators, giving off heat which then makes the room warm.

A split system air conditioner works as follows:

  • The system consists of two parts; the outdoor and the indoor unit.
  • The outdoor unit is installed usually on or close to the wall outside the room or area that you wish to cool or heat. The indoor unit contains the cooling coil, a blower and an air filter. Split systems are usually used to cool or heat multiple rooms or an open-plan area.

Pros of hydronic and steam boiler systems over a split system

  • There is less dust as hydronic and steam boiler systems are hypo-allergenic, meaning they are unlikely to cause an allergic reaction. Accordingly, this system is generally healthier, particularly for families with young children or adolescents with allergies. Split systems on the other hand do not have this benefit. Split systems operate by blowing hot or cold air around the house, so it is possible that dust will be stirred.
  • Hydronic and steam boiler systems are completely silent. While split systems are generally pretty quiet, they are not as quiet as boiler systems, which operate by radiating heat, rather than blowing hot or cold air.
  • Steam and hydronic boiler systems have excellent ongoing efficiency. This could lead to lower electricity bills, particularly during cold winters. Split systems are not as effiecient and often contributer to significant electricity bills during the winter months.
  • Only the areas you want heated will be zoned to that area. Generally a split system will only be installed in the living room, and maybe 1 or 2 bedrooms. Steam and hydronic boiler systems are generally installed in a greater number of rooms and areas in the house.
  • Water is a better heat conductor than air, and the water will be recycled so you won’t have to use a lot. Split systems operate differently. They don’t use recycled water, instead they blow hot/cold air
  • You can leave it running all winter long, as the whole house will be warmed by a gentle and comfortable heat, which means your energy bills will be far less expensive. Split systems do not generally warm a whole house, and attempting to do so using split systems can lead to very high electricity bills.
  • Those who install steam and hydronic boiler systems tend to see the benefits over a long period of time. They are more expensive to install at the beginning, but are easy to maintain and will lead to lower overall heating bills during winter. Split system are a lower initial financial investment, but you don’t get the same value over time.
  • With steam and hyrdronic boiler heating, your home is heated evenly, and you can turn off the heat to rooms not being used if you have a larger house, which means you can control the heat to certain zones of the home, whereas split systems only work in the area of the house in which the split system is installed, which will generally be the living room and 1 or 2 bedrooms.
  • Steam and hyrdronic boiler heating can be installed underneath floors. Split systems are generally installed high up on the wall, within the line of sight and are not as visually appealing.
  • Split systems do not require you to change filters, which means there is less maintenance involved. Split systems need filter changes, as they get clogged up with air and dust particles when the air circulates from hot to cold. In order to ensure split systems work at their optimal level, regular maintenance is required.

Pros of a split system over boiler or steam boiler heating 

  • Steam and hyrdronic boiler systems can be more expensive to install as you have to run pipes through the home especially for this system, whereas split systems you don’t have to run pipes through the home, and can be installed in almost any home and lower initial installation costs
  • Split systems are easy to install, quickly.
  • Reverse cycle split systems can provide both heating and cooling, whereas hydronic/steam boiler systems only provide heating and not cooling.
  • For hydronic and steam boiler response time can take up to half hour. It doesn’t give you instant heat once it’s turned on, and also, if you put furniture against the panels, it isn’t as efficient. Split systems will instantly blow hot or cold air (if you have a reverse cycle system) and will heat up the proximate areas relatively quickly.
  • Split systems use electrical wires and tubing to connect the indoor and outdoor units. There is no need for ductwork, making it cheaper.


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