Mythbusting: Air Source Heat Pumps

5 myths about Air Source Heat Pumps busted!

Air source heat pumps are one of many emerging renewable solutions that are technically misunderstood or vetoed early on in a heating strategy discussion on the basis of mythical information. Our aim here is to hit these myths head on and dispel the commonly misunderstood features of the technology.

Myth 1: Air source heat pumps are too noisy

This myth heads up our list as it is one of the most common misconceptions in our experience. Most people visualise a modern day heat pump producing the same kind of racket that comes from one of those ageing air conditioning units you see hanging off the wall down the side of your local fish and chip shop!

Nothing could be further from the truth as the latest range of outdoor fan units are superbly acoustically engineered machines, aimed at making the units whisper quiet.

Whilst it is difficult to quantify the noise, most units become virtually inaudible at about 5m away from the unit and will not even be heard by the closest of neighbours.

Myth 2: Air source heat pumps are no good in cold weather

The fact that air source heat pumps during winter months have to turn freezing cold air into meaningful home warmth seems dreadfully inefficient for air source technology. Whilst air source heat pumps definitely have to work harder at colder temperatures the truth is a little more palatable.

Many pictures and stories of ice-encased outdoor units have been posted on the internet and are a result of poor design and installation, not baseline technology inefficiency.

Air source heat pumps are actually capable of working down to -20 degrees Celsius; for most this is more than ample. A properly sized outdoor unit and designed underfloor emitter system operating in the depths of winter will still cheaper than burning oil.

Myth 3: Air source heat pumps have to go next to the house

The aesthetic appearance of the outdoor fan unit for air source solutions can cause a bit of concern for some homeowners who are not keen on having a big box sat on their patio, manicured lawn, or worse, bolted to their home.

The good news is that air source heat pumps are extremely versatile and come in all sorts of configurations; one of which is a “split” system. This essentially means that the outdoor unit can be placed up to 60m away from the indoor unit in the house. For most this is enough to hide it away behind a shed, or even into the darkest and most forgotten corners of their garden: out of sight and mind.

Myth 4: Air source heat pumps can’t heat hot water

It is understood from extensive research that most people are comfortable having showers and baths at no more than 44C. Given that most standard heat pumps will achieve 50C without immersion backup this myth again is simply untrue. Whilst heat pumps indeed become more inefficient at higher temperatures they are suited to almost all hot water applications.

Myth 5: Air source heat pumps don’t work with radiators

Heat pumps in general work far more efficiently at lower temperatures in the range of 35-45oC compared to 60-70oC for traditional fossil fuel boilers. Any plumber will understand that if the flow temperature is lower the radiator area needs to be increased, for the same output of heat into the room.

If you don’t have any more wall space for bigger radiators there are low flow temperature radiators available that allow you to keep the same radiator “wall print” but with the same thermal output. Companies like Jaga are leading the way in energy efficient radiators.

So there are a few of the biggest whoppers dispelled for you. OF course there are others and we may well cover these in a later blog. If you have any comments, do leave one below.

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.