Kieran McCarthy: Is electric heating the solution for your home?

Builder Advice: There is a wide range of electric powered options when replacing an old oil-fired central heating system

The most up to date modern electrical radiators are quite efficient and thermostatically controlled. They are relatively cost effective to buy and can be installed by an electrician or indeed some of the smaller radiators can be plugged into a domestic socket. They will impact your electricity bills, however.

Hi Kieran,

I would be grateful for your advice please. Our oil-fired central heating system has a leak (possibly more than one), which despite numerous attempts cannot be found. The house is a 45-year-old (approx) bungalow, around 2,500sq ft. We are looking at options and wondering if electric radiators may be an option. Also we are looking at electric underfloor heating. What would be your thoughts/recommendations?

Thanks, Maria, Dundalk

Hi Maria,

This is a good question and one I was pondering myself recently too in conversation with a BER assessor I know. In the golden age of photovoltaic solar panel installation, it is very tempting to look at electrical heating as the cure to all your ills but is it the best solution? Let’s see.

Firstly, we now know that the days of fossil fuels are nearing an end. Any new home or a deeply retrofitted home will benefit from the installation of a non fossil fuel heating system. In most cases this fuel tends to be electricity, particularly when you look at the most popular heating systems such as air to water or geothermal heat pumps but are there other electrically fuel systems that could work too? Let’s examine the options and the characteristics of the electrical systems available.

Given your house is heated by an ageing oil fired system, and it is 45 years old, I am assuming your house isn’t very efficient and generally the external envelope (the ground floor/walls and windows/roof) has only a little amount of insulation if any. An oil system is a high temperature system so when you fire up that burner and the radiators get up to temperature, the house gets warm — and fast. (It may also be that when you turn the heating off again it loses heat quickly due to the lack of insulation and the draughts present.) So, now as you have lost confidence in your old oil fired system, let’s look at the alternatives as you transition to an electrically powered system.

Electrical radiators may in fact be a solution for you. The most up to date modern electrical radiators are quite efficient and thermostatically controlled.

They replace the storage heater you may be familiar with from the 1990s, particularly if you lived in an apartment from that era. They are relatively cost effective to buy and can be installed by an electrician or indeed some of the smaller radiators can be plugged into a domestic socket. (My father, who is very energy conscious and indeed thrifty, swears by this system because it allows him to heat whatever room he is using in his house without having to resort to turning on his whole oil-fired heating system and heating his entire house).

Electrical underfloor heating system

Next, as you suggest, is the option of installing an electrical underfloor heating system. I am not sure exactly what you are suggesting here as the only electrical heating element I am aware of is the element that you can install under a tiled floor. If this is the case then I certainly do not recommend this approach. I have generally found this system is only effective on a first floor when it is placed on ply-wood before the tiles are laid.

Assuming you have a concrete ground floor slab, when you lay these elements on top they tend to heat the concrete slab downwards rather than the tiled surface on top and whereas this may sound like it will allow for a store of heat in the concrete slab (just like most underfloor heating systems) the electrical heating element is just not powerful enough to move the needle and raise the level of the concrete slab temperature enough to heat your room. (It needs to heat the slab 150mm downwards until it reaches your thin insulation under before some of it rises to the top again to heat your room, this is a tall ask).

If your ground floor is composed of plywood sitting on joists it may help in that there is less depth to heat but you also have to deal with the draught from underneath and the thin, if any insulation between your joists. All in all this system is really designed to supplement a central heating system rather than stand on its own two feet, so it is not advised.

Heat pumps

The market leaders nowadays are the air to water and geothermal heat pumps. Though they employ electricity to run the system, the electricity is not actually creating the heat itself, it is only moving heat that the system extracts from the air or the ground. Therefore the efficiency is four to five times greater than electrical radiators. So, what’s the catch? Well, these heat pumps run at a much lower temperature (which you would notice if you place your hand on these radiators). This means that they require a much more efficient external envelope (insulation and airtightness for your floor, walls, windows, and roof) to ensure that as they emit a modest flow of heat into your home, a very high amount of this heat is retained and your house remains warm. This of course means that you would require a deep retrofit for these systems to run efficiently and this certainly would require a significant investment in your 45-year-old home.

So, to sum up, electrical rads would certainly be an option if your budget is tight. They will likely work but your electricity bills will be considerably higher. You could of course consider fitting photovoltaic solar panels to help with these elevated bills.

If you were considering a more long term, holistic investment, then the deep retrofit and heat pump is certainly a great option and, don’t forget, there are generous grants available from SEAI for these works.

Now, if only there was a new TV show coming out later this year that could shine a light on how these systems work!

Kieran McCarthy is a building engineer and director of KMC Homes bespoke A-rated new home builder, serving Cork and Limerick. 

He is also a co-presenter of the RTÉ property show Cheap Irish Homes. Check out KMC Homes’ brand new website kmchomes.ie Follow Kieran on Instagram @kierankmc for more home building information, tips and Q&A advice.

You can also follow Kieran on the Built Around You Youtube channel and @kierankmc on TikTok