Thinking About Installing A Heat Pump? Don’t Forget This Critical Service!

Whether you are planning to install, or have made your mind up to install, either a ground or air source heat pump there are still a fair number of integration points to consider, and of course there are often numerous other build related concerns too.

But have you ever stopped to fully consider what is powering this fancy low carbon technology. Well some will roll their eyes and be muttering under their breath “electricity you idiot” and indeed they would be right, but it leads me onto my next more thought provoking one…how much do they use and have you got capacity?

At this point people start scratching their heads and “googling” relevant search queries, or scrabbling around for product datasheets.

Heat Pumps: Have You Got Capacity?

The key point is here that it varies and as the systems get bigger they require more electrical power than you may think; this must considered in full during the project planning phase.

Here we have to explain that ground source and air source heat pumps work differently and as such have different electrical load requirements.

Ground source heat pumps always run at full capacity and tend to start with an electrical spike and then settle down into a steady running current. Air source heat pump compressors start at about 1/3 of their total capacity and then steadily increase in load as more work is required of them.

The point is that most homes have single phase electricity and between 80-100A of load capacity for the entire home. So for existing houses with around 200sqm in floor area a heat pump would require about 20% of the available power to the home during winter.

For larger, particularly rural homes they have exactly the same power available but need much larger heating systems. Combine with that the other electrical demands on the home such as electric AGAs, electric showers, immersion heaters, electric hobs and ovens you can quickly find yourself in a sticky situation.

The solution is to work out with your electrician what you will be using for the remainder of the home and discover what the remaining capacity of the power supply to the home is. From this point you can discover whether a heat pump will work on this reminder.

Indeed for many houses over 400sqm it makes sense to investigate 3-phase electricity for two reasons

  1. A 3-phase supply will provide approximately three times the power of a similar single phase supply giving you much more available capacity.
  2. Heat pumps above a certain size are no longer manufactured to run on single phase electricity due to efficiency. As a result instead of installing multiple smaller units it becomes more cost effective to install one 3-phase unit.

Costs for upgrading to 3-phase can be significant, so it is better to have budgeted accordingly. So don’t get caught out and make sure that your building and budget are suitable for a heat pump and the services it requires before going any further.

If you would like to discuss integrating renewable technologies into your home or project, contact me on 08445 003383 or email

Doug Johnson

Doug is a chartered mechanical engineer and has had the pleasure of being involved in the UK renewable sector since 2008. With wide-ranging operational and design experience in both the domestic and commercial sectors across a wide range of recognised technologies he hopes to be able to share his experience to help enlighten and save you hassle along the way.