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Roger Bisby ranted that heat pumps may NOT be the future - Steve Bolter replies that they WILL be part of our future

July 30, 2021 12:13 PM
By George Miles

Roger Bisby, on his Youtube video called "This is Why Heat Pumps May NOT Be The Future" says heat pumps are a waste of money.
GLD member and Physicist Steve Bolter replies below:

Steve Bolter writes:

Roger Bisby does not seem to understand that we need to stop using fossil fuels to avoid climate catastrophe, and action is urgent.

He focusses on current market cost, not the needs of the future.

Directly replying to counter his misleading generalisations, made from limited examples, would not work.
The fossil fuel industry could pump out support for Roger's view faster than we could counter it.
Green Lib Dems need to educate the more interested members of the public, so that they can see for themselves the role Heat-pumps can play, and may, if appropriate for them, become early adopters.

  • - -

Mains gas boilers burn natural gas, which is methane, a greenhouse gas.
It is the least "carbon-intensive" (or greenhouse gas producing) fossil fuel, but it is unsustainable, nevertheless.
The gas is subsidised by Government grants for exploration, and by there being no charge for the cost of the damage to the economy caused by the climate change driven by the greenhouse gases released by using natural gas.

We have nowhere near enough renewable-energy capture to replace all fossil fuel heating, so we should concentrate on getting rid of the more carbon-intensive (and generally more polluting) fuels first. It is thus appropriate that mains gas heating remains cheaper than using more carbon-intensive fuels, such as coal and oil, making it the first choice for those who have it available.

The majority of those off the gas grid heat by more polluting and more expensive fossil fuels. Most choose oil. Some still use more polluting coal and some use, less polluting but more expensive, propane LPG (Liquified Petroleum Gas, delivered under pressure by bulk tankers or in cylinders). These are the people who should be switching to lower carbon heating now.

Great Britain's Mains electricity is low carbon. A large fraction comes from near zero carbon sources such as wind turbines and nuclear power stations. A little comes from other renewables, and most of the rest comes from natural gas.

However, because of losses generating and supplying the electricity, direct heating with electricity (electric fires, kettles, radiators and immersion heaters) is expensive. The cost can be reduced a little with systems that store heat when demand is low and electricity cheap, for later release. It is much better to use electricity to pump heat into a building.

Heat-pumps use an electric pump to force a refrigerant fluid round a closed circuit with a restriction in it. This causes the fluid to change from very cold vapour to hot liquid and back as it goes round. The very cold part of the system is put outside. The vapour is warmed by contact with outside air or water or ground. The hot liquid gives off heat inside the building. Both the energy absorbed from outside and the electrical energy used for pumping are given off as heat energy inside. Typically for each kWh of electricity used, 2 or 3 kWh of heat is absorbed from outside and 3 or 4 kWh of heat is released inside. (That is the C o P is 3 or 4. see last section))


Currently using Heat-pumps is generally:-

  • more expensive than cut price mains gas;
  • competitive with oil heating;
  • and cheaper than heating by propane gas (LPG).

If a house is poorly insulated it will be expensive to heat whatever method is employed. There are grants for improving insulation. Homes should be well insulated BEFORE installing Heat-pumps, to avoid the cost of installing an unnecessarily high-power, high cost system,

It is true that Heat-pumps generally perform best in modern homes built to high standards of insulation and with underfloor warm water heating, but their performance can be good in older homes too.

Even if not to the latest standards, most houses and flats under100 years old have cavity walls and most of the houses have lofts. If not already done and in good condition;- adding draught-proofing strip; adding suitable insulation to the floor of the loft; and having cavities filled, are cheap and effective ways of increasing insulation. Most pitch roofs are suitable for having breathable foam sprayed on their insides. This is more expensive than traditional mineral wool laid in the loft, but more effective and longer lasting. In fossil fuel heated homes these measures can significantly reduce greenhouse-gas emissions and have a short payback time if starting from a low standard.

Adding double glazing is expensive, but it makes the home more comfortable as well as further reducing heating costs, greenhouse-gas emissions and pollution. If using cheap mains gas, the financial payback period if long, but if using an expensive fossil fuel the payback is quicker.

Taking these measures in my own rural house greatly reduced my energy need. Even in freezing weather the radiators do not have to be very hot. After the new roof insulation, I de-rated my 18 kW propane boiler to 14 kW, but it cuts in for only short times, indicating it is still bigger than needed,

Getting from this stage up to much higher insulation standards would be expensive and disruptive. Changing from fossil fuel (or from simple electric heating) to a Heat-pump would be an appropriate next move to reducing greenhouse-gas emissions. In the near future fossil fuel prices are likely to rise enough to make investment in a heat pump not only more sustainable, but also more cost effective than any fossil fuel, except perhaps for mains gas.


Electric heat pumps are not the only more sustainable alternatives to fossil fuel. There are biofuels, but the sustainability of some of them is questionable. Some areas may have local renewable energy available; others may be allocated a low carbon mix of hydrogen and other sustainable gases, delivered via the gas main, However in most rural areas Heat-pumps are likely to be the cheapest effective alternatives for many years to come.



For the common air to water Heat-pump systems, the colder the outside air is the more energy has to be pumped to the radiators, but also the higher the temperature difference between the place outside and the radiators to which it is being pumped, the more energy is needed to do the pumping. This means that performance of a heat pump is better if it can produce the required heat output by making a large area of radiators warm, than by making a small area of radiators hot. Underfloor heating has a very large area of pipework which only has to be slightly warmer than the desired room temperature. It is thus ideal for Heat-pumps.

My 1980 house had radiators sized for its initial poor insulation, Once insulated (as described above) the radiators no longer needed to be very hot in cold weather. I am planning to go over to a heat pump. The surveyor has recommended only a modest increase in total radiator area to achieve a satisfactory running cost and performance.

A more recent house, well insulated from the start and designed to have small hot radiators, would need to have more extra radiator area to achieve a similar performance.

The coefficient of performance of a Heat-pump system, CpP, is:
the heat energy output : electrical energy input
for a particular pair of outside and radiator (or hot water coil) temperatures.

The GLD website will give more detail in September.

Heat-Pumps Will be Part of Our Future.

Steve Bolter
23rd July 2021

Roger Bisby is an English television presenter, journalist and plumber, known for his superb YouTube channel Skill Builder and his expertise in the British building industry.
He was the building expert on the long-running British consumer affairs television series Watchdog and then later Rogue Traders, both for the BBC.

2nd August more from Roger: