JUMPINGSPIDER.CO.UK – blogging at its jumpiest

Six Heat Pumps! Now we’re getting a Gas Boiler

Last year (2023) the Government decided to give away £7500 of Public money to anyone who replaced their gas boiler with a heat pump. Sounds like a great deal so why has the take up of this grant been so abysmal?

Well, there are a few caveats to qualifying for the Boiler Upgrade Scheme (BUS) as it’s known:

1. It has to be installed by a MCS certified installer
It’s they who will actually pocket the £7.5k grant. MCS installers will already have spent considerable time and effort gaining certification and they will be looking to recoup this cost. One way is to over-specify systems and then charge the full retail price for the hardware.

2. You’ll need a full Heat Loss Calculation for the house.
This is a lengthy process, it sounds like science and is supposed to caclulate how much heat the building loses at a winter temperature deemed normal at your location: -3°C possibly. The problem is, it’s likely done by guessing the construction of the house and thermal conductivity of the hidden materials.

The process ignores or makes all kinds of assumptions about:

The warm bodies inhabiting the house
The heat generated by all your appliances
The solar gain that you may get on a clear crisp February morning
The number of pets in the house
Curtains, carpets or blinds
Ventilation rates (probably based on the year the house was built)
Shading from nearby trees
Exposure to the wind and rain
The state of your cavity wall insulation

The Heat Loss Calc is compulsory even though previous years’ gas bills probably give a more accurate indication of the house’s requirements. If the calculation (rounded up just in case) shows you need a 8kW heat pump – MCS suggest you try to find one to match but in reality your installer is a fanboy of Vaillant or Daikin and will just go up to the next largest available unit which might be 12kW. Putting on another jumper on the three coldest days of the year is not an option.

3. The system has to be sized to provide ALL your home’s heating for 363 days of the year. 
Any existing heating is disregarded completely. And in fact the MCS advice is to go a little bigger—just in case; continuing with the mindset of every gas fitter last century. It would make much more sense to have an appropriately sized system for 360 days of the year and put on some supplimentary heating or jumpers for the few days when it might be that cold. Especially on the South Coast where the weather is dramatically different from say the Scottish Borders.

4. The heat pump has to be an air-to-water heat pump supplying all the heating AND hot water for the house.
This almost guarantees the installation will be massively more complicated. Combi gas systems will need to go back to having a 200l water tank in the airing cupboard. The tank will need a drain to the outside for expansion. You’ll likely be told your radiators need upgrading or you need underfloor heating because the lower flow temp of ASHPs won’t work. Higher temperature heat pumps are not encouraged because they are deemed less efficient. 

5. Air-to-Air heat pumps are excluded.
A2A units (usually called air conditioning) which are arguably even more efficient at heating the house are considered luxury items and not eligible. Even though they can be installed in a tenth of the time and for a fraction of the cost. If MCS allowed Air Conditioning heat pumps and continued use of the gas boiler for DHW our country’s gas consumption could go down so much faster.

6. You must have an Energy Performance Certificate for the house.
This should guarantee the house is well insulated but the industry generally agrees that the EPC scheme is woefully inadequte. For instance you are marked down for having mechanical ventilation with heat recovery; trickle vents on windows are considered better! And the inspector may recommend spending thousands of pounds to save £40/year on energy costs. 2024 update: you no longer need to have insulation in your loft or cavity walls!!!! What the fuck!? Without that you are certain to need bigger radiators, a bigger heat pump, larger pipes, and more expense. With higher running costs.

Note: You can run the ASHP on electricity from a coal or gas fired power station if you like—probably running at 40% efficiency!
The Boiler Upgrade Scheme is to encourage take up of renewable energy and reduce the UK’s carbon footprint – even though there’s no stipulation that you must run the Heat Pump on green electricity.

I just couldn’t see the sense in any of that. I couldn’t understand what internal walls have to do with calculating the heat losses of a house when the ‘lost’ heat is just going into another room.

The whole process is a continuation of Britain’s house building scandal, where they are still building some of the worst housing stock in Europe. Period features are more highly prized than half decent construction and insulation. Why are we subsidising heat pumps and not Insulation which lasts a lot longer, is cheap, easy to install and makes a huge difference no matter what heating system is used?

In Britain the dream house for most has a kitchen with an Aga running all day long and an open fire in the lounge sending all the warm air straight up the chimney. Thirty years ago we bought a 10 year old Swedish kit house in Sussex, it came as standard with mechanical ventilation, triple glazing, airtight construction and decent insulation. British standards are still lagging worefully behind – new builds in the UK still have gas boilers or even electric radiators running at 100% efficiency, double glazing and for ventilation, window trickle vents, catflaps and letterboxes.

With the sudden increase of energy prices last year, I started looking at what could be done. Our gas boiler was ancient but we used so little gas (£250/year) there was no financial incentive to change it. But in 2022 prices rocketed and I started taking notice. I realised the pilot light was using over 4kWh of gas every day!

So this Summer we turned off our gas and had two Panasonic 3.5 kW air conditioning units installed – they required no changes to the plumbing in the house and were installed in one day by one f-gas fitter for a grand total of £3510. That’s about 80% cheaper than a MCS A2W installation but of course there’s no public funding for it. We used the immersion heater for hot water and it worked out at about the same cost as the pilot light.



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