The drive to turn us into a nation of heat-pump owners is back in fifth gear.

Led by the fervent Ed Miliband, Secretary of State for Energy Security and Net Zero, homeowners are once again being encouraged to rip out their gas boilers and replace them with expensive heat pumps to help save the planet (believe me, heat pumps will make NO difference to the planet’s survival).

Although the Tory government of Boris Johnson was the initial flag-waver when it came to heat pumps, Mr Miliband – a heat pump zealot – has taken the flag-waving to a new level. A sea of green flags is now being waved before our very eyes.

Earlier this month, he threw more buckets of money at the so-called Boiler Upgrade Scheme (BUS) to ensure that homeowners who want to make the leap from gas boiler to heat pump will have ready access to grants worth up to £7,500.

Without the grants, heat pumps would be out of the financial reach of most households (more on this in a minute). Even with them, they remain an option that only a minority of households can afford.

He also announced that planning rules would be relaxed to ensure that nearly everybody who wants a heat pump installed on an exterior wall of their home will soon be able to go ahead – irrespective of the fact that the pump’s noise could well keep the neighbours awake for most of the night.

Cities could soon be turned into ‘cacophonous’ heat pump farms, according to one respected commentator. Ear plugs at the ready for the heat pump raves.

Mr Miliband wasn’t finished. He also said that the boiler tax will return from next April – a fine paid by boiler manufacturers unable to meet unachievable heat pump sales targets – and passed on to buyers of gas boilers in the form of higher prices.

It will be a modest fine to begin with, but is likely to be cranked up every year while green Labour (green in so many other ways) remains in power.

Mr Miliband has supporters. The grandiose Energy & Climate Intelligence Unit followed the announcements with a ludicrous press release that played the patriotic card.

It said heat pumps would help wean the UK off foreign imported gas – without squaring the circle by admitting that most heat pumps are manufactured in Asia and then imported into the UK. 

Even manufacturers here assemble heat pumps primarily from components brought into the country on container ships sailing the seven seas.

Yet there are more discerning experts who believe that the Government’s belief in a heat pump future – with its target of 600,000 installations a year by 2028 (more than ten times last year’s installation figure) – will end in failure.

Yesterday, Gordon Hughes, a former senior adviser on energy and environmental policy at the World Bank, told Money Mail that the 2028 installation target is not credible, even if larger subsidies were handed out to buyers of heat pumps. 

He also said that even at an installation rate of 600,000 a year, it would take 45 years to convert all houses to heat pumps – way beyond the country’s legally binding commitment under the Climate Change Act 2008 to reach net zero emissions by 2050.

Mr Hughes added: ‘Almost everyone with practical knowledge of the energy sector knows that current heat pump targets are both daft and unachievable.

‘But policies are a matter of religious faith, and few are willing to be cast out for saying the emperor has no clothes.’

Money Mail searches for the answers to the key questions facing households thinking about joining Mr Miliband in his heat pump crusade.

How much is it going to cost?

It depends on the type of heat pump installed – air pump or ground source.

The air source pump sits on the outside wall of a home – and looks like the air conditioning units that you see outside many industrial buildings. 

This pump is painful on the eyes (an eyesore), ears (it’s noisy and gets noisier as it ages) and wallet, costing an average of £13,200 to install.

In basic terms, it sucks air from the outside which then interacts with a refrigerant – a chemical substance – to produce heat which can be used to warm radiators and create hot water.

Then there is the grander ground source pump which, through the laying of underground pipes (typically in the back garden), draws upon natural-occurring heat stored in the ground to ultimately heat radiators and water in the home.

These can cost anything between £15,000 and £30,000, which makes them the Louis Vuitton of heat pumps.

But this government – and Mr Miliband in particular – is desperate for households to wean themselves off gas boilers and buy these expensive pumps. So desperate, in fact, that it offers grants of £7,500 to those who get them installed (properly).

These are provided through BUS (gov.uk/apply-boiler-upgrade-scheme) and available to households in England and Wales (other energy-efficiency grants are on offer in Scotland and Northern Ireland).

So that takes the price of the respective pumps down to a more reasonable £5,700 (air) and £7,500 to £22,500 (ground).

To put these sums into perspective, the cost of replacing a gas boiler is around £2,500.

So, should you buy a pump?

Mike Foster, chief executive of energy trade association the Energy and Utilities Alliance, says that if people want a heat pump and can afford it, ‘they should go out and get one’.

Yet a survey by consumer group Which? indicates that cost remains a big issue – 71 pc of respondents who know about heat pumps say they are out of their financial range.

Installation costs are also not necessarily the only financial hit. Heat pumps are not effective in homes where windows are single glazed (as opposed to double glazed), or where walls are not insulated.

According to the Energy Saving Trust (EST), the cost of fitting A-rated windows (the most energy-efficient double-glazed windows) for a semi-detached house typically cost £15,000, while cavity wall insulation will cost £2,700. 

If you have solid walls and want them insulated, the EST reckons that will set you back £7,500 if fitted internally, or £11,000 externally. 

In short, fitting a heat pump in a solid-wall, semi-detached house with A-rated windows and external wall insulation will set you back £39,200 – £31,700 net of the £7,500 grant.

Running costs will still be more than that of a gas boiler, too. Mr Foster says: ‘You may hear from supporters of heat pump technology that it is three times more efficient than a gas boiler.

‘What they fail to mention is that the average unit price of electricity is four times higher than that for gas. This means a heat pump works out slightly more expensive to run over a full year than a gas boiler.’ 

For the 50 per cent of homes that use gas for cooking, Mr Foster adds that a conversion to heat pumps will mean the need for electric cooking appliances – yet more cost (typically, £250 for an electric oven, £225 for an electric hob, and £250 for installation) on top of the £39,200.

Mr Hughes agrees. He says the differential between gas and electricity prices makes it financially ‘daft’ to replace a gas boiler with a heat pump. 

He adds: ‘Electricity prices would have to be less than half their current level – with gas prices not changing – to even make a heat pump a consideration.’

Is the boiler tax a game-changer?

From April next year, the Government’s Clean Heat Market Mechanism (CHMM)

will impose swingeing taxes on boiler manufacturers if heat pumps represent less than 6 per cent of all domestic heating installations.

For every heat pump installation short of their target, the manufacturers will be hit with a £500 fine. But Mr Miliband’s zealotry towards heat pumps means the sky is the limit in 12 months’ time.

The tax will be passed on by manufacturers to buyers of gas boilers in the form of higher prices. 

Based on the current demand for gas boilers and heat pumps, Mr Foster estimates that it is likely to add £25 to the average cost of a gas boiler when fines are set at £500.

But if Mr Miliband were to impose a more onerous heat pump installation target and bigger fines, the gap between heat pump and gas boiler installation costs would start closing. 

If the Secretary of State demanded a 24 per cent installation target – similar to the electric vehicle targets imposed on car manufacturers – and a fine of £5,000 per heat pump short of the target, Mr Foster says this would result in a boiler tax for customers of £1,000.

Peter Thom, founder of energy efficiency specialist Green Heat, says the financial mathematics for households aren’t changed by CHMM.

He says: ‘My advice would still be to replace a failing gas boiler with another gas boiler.’

But he adds: ‘I would ensure that any new installation works effectively at a lower temperature – which may mean putting in higher-output radiators. I’d also make sure that the heating controls are upgraded.

‘This would mean your heating system is heat-pump ready for when the dice is loaded so heavily against gas boilers that heat pumps are the way forward.’

Could better tech drive down prices?

Not according to Mr Foster. He says heat pumps are already sold in their millions worldwide (especially in the Far East) and their basic design has not changed much. 

Yes, he says, they could become quieter – but that will come at a price.

Unless a vicious boiler tax is introduced, a gas boiler will always be cheaper than a heat pump.

Is the funding sustainable?

No. Mr Thom says the installation target of 600,000 heat pumps per year by 2028 will cost the taxpayer £4.5 billion annually (assuming the BUS grant remains at £7,500).

If the annual target of 1.6 million new heat pumps is achieved in 2035, it will cost £12 billion a year.

He adds: ‘This is like being at the Mad Hatter’s party on Fantasy Island.

‘I also question the moral compass of a government which is providing grants of £7,500 to help essentially wealthy people install heat pumps while, at the same time, taking away the winter fuel allowance from millions of pensioners – with some four million people now in fuel poverty.’

A damning comment.

• Are you a heat pump sceptic or a zealot?

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