The first phase, which concludes with recommended technical and regulatory adaptations to permit legal, safe use of plug-in batteries, is scheduled to run for 8 months.  

There is a second phase the outcome of which is "Recommend technical and regulatory adaptations to enhance the safety of indoor installations of domestic batteries."  This appears to relate primarily to electrician installed systems and runs until March 2028.

Assuming that plug in can be legalised after the first phase and the contract starts 25th November, so that takes us to June 2027 for this phase to complete.  When the same exercise was done for plug in solar it then took 2 further months to develop the technical standard/product specification.  This was against a background of a public ministerial commitment to an accelerated timescale, its quite plausible therefore that it will take longer for the 'battery' spec to be developed, consulted on, published and legislated for.

Thus I think this tells us that plug in batteries will not become legal until Q3, p2027, possibly even Q4 2027.

If anyone has a more optimistic interpretation I would be delighted to hear!  

Firstly I have attached some screen prints of my set-up, could you advise if my settings correct.  I am trying to achieve:

Internal Temp: 22C
Curve: 0.2
Manual setting
24 hrs run time

Secondly.  My flow temperature is a lot higher than the target being set by the Heating Curve.  Its 17C outside at the moment so I should see a flow temp of 25C according to the curve, but the app, sensocomfort, and my temperature probes are seeing 27C.

Some addition data that may be relevant:  Typical power 400 watts consumption, compressor running at 25%. HP is cycling every 2hours (which is to be expected).

Disclosure: This forum thread is not sponsored, funded or paid for by tepeo. It has been created as an independent community resource, with RHH retaining full editorial and moderation control.

Whether you’re considering your first system, comparing installation quotes or already have one and need a little help, post your general questions here. We’re interested in the everyday experience as much as the equipment like how comfortably it heats or cools your home, what it costs to run and whether you’d make the same choices again.

If you want more focused replies to your particular project please start a new deviated thread instead. Give us a little background about your home and what you’re hoping to achieve, along with the make and model if you already have a system or quotation, so members can offer more useful replies.

And if you’ve been living with air-to-air for a while, please share what you’ve learned here. Your experience could help someone else make a much more confident decision.

If you’ve had a Heat Geek installation, please share your experience, good, bad or somewhere in between. We’d particularly like to hear about the design and quotation process, installation quality, disruption, promised and actual performance, flow temperatures, aftercare, performance guarantees and how any problems were resolved.

The aim is to build a fair, balanced and useful discussion based on genuine homeowner experiences, helping others make better-informed decisions.

Please keep contributions factual and respectful.

So when running pure weather comp, is the weekly planner NOT active?  Screen prints of my set up attached.

(PS note.  Only trying to running a time schedule such that I can use overnight peak rates, house only needs 4/5 hours a day/night in the shoulder months, so will run 24/7 once winter is here.)

This contraption mixes water with compressed air and injects it:

The water inlet is taken before the house's pressure regulator, so it comes in at 7 bar, which compensates for the pressure drop in the red PEX pipe. With only 3 bar supply it would have been necessary to use 20 or 25mm pipe to get proper flow.

It is followed by a 4-way valve to allow flow in both directions.

Besides the compressor (which I already had) and the flex hoses (which came out of the old heating system) this is not expensive to implement. Probably less than €100.

It worked wonderfully. It pulled a ton of crap from the loops.

Compressed air helps a lot. I rinsed with with water until it came out clear, then turned on the air: brown stuff immediately came out, and kept coming out. I let it run for several hours, reversing flow direction every five minutes, one UFH loop at a time.

Air bubbles create a sort of water hammer effect which works really well for dislodging crap. Also air flows through pipes easier than water, so an air/water mix can flow at surprisingly high speeds through UFH loops, several meters per second at least. I used a feed pressure of 2.5 bar.

Drain pipe must be firmly secured. It did its best to get out of the washing machine U-bend.

Once this is done, it's time for chemicals.

I got a 200l polyethylene bin from a local farmer, and reused the filter and pump from the old groundwater heat pump system. The previous contraption is now partially disassembled, keeping only the air injector.

UFH loops are flushed with compressed air, then the bin is first filled with Sentinel X-800 cleaning agent diluted to spec in 40°C water, then the pump turned on. Again, reverse flow every five minutes and do each UFH loop in turn.

Feed pressure at the pump outlet is 3-4 bar depending on length of UFH loop being cleaned, flow is 2-3 m3/h water plus air, so velocity in the UFH loops should reach 5-10 m/s. The whole thing is shaking and kicking.

Water came out clear at the previous step, but the cleaning agent still pulled a lot of crap out of the pipes.

These flakes are quite large (the fitting is 1" for scale), I wonder how that got through the circulator...  Well, it died, maybe that has something to do with it...

This is what the filter caught:

...I only put the filter in line when I switched from plain water to Sentinel cleaning agent, so who knows how much of this stuff got flushed into the sewer.

Some of these flakes are large enough to match the internal diameter of the UFH pipes, I guess the compressed air helped break them up.

Next, I rinsed with clean water plus air.

The reverse osmosis rig is currently filling the big blue tub with demineralized water, so tomorrow I'll pour some inhibitor in it and use the pump to flush and fill the loops.

Conclusion: I'm very happy with this DIY powerflushing stuff. It makes a mess of course, but I save 5-800€ per manifold, and I have 3 of these manifolds. Not bad for assembling a bunch of fittings, setting a timer to switch valves every five minutes, and mopping the floor afterwards.

Background

The Boiler Upgrade Scheme is paid for through general taxation. It provides grants of £7500 for Air-to-Water (A2W) and £2500 for Air-to-Air (A2A) heat pumps when they are installed as a replacement for a gas boiler. BUS grants are also available for replacing oil boilers and direct electric boilers, however, here we focus on gas.

Existing electric supplementary heaters are permitted to stay in place e.g. electric towel rails, electric immersion heaters, etc. The output of the heat pump must cover the full space heating requirements of the property, and together with any supplementary appliances, it must also cover the space heating and hot water requirements of the property.

The full regulations are here:

How the scheme could be improved

Technology agnostic

At present, the amount of the BUS grant depends on the technology used rather than only on the desired outcome, i.e. low carbon heating. This situation should be avoided since it leads to a poor use of public money. As an example, consider a property with two viable alternatives: (i) an A2W system including hot water heating at a total cost of £10500, and (ii) an A2A system again including hot water heating at a total cost of £6500. In a free market (no subsidies) option (ii) would be the most economic choice. However, with the current subsidies, the household assuming that they are indifferent to the technology choice would choose option (i) as the cost to them is £3000, rather than £4000 for option (ii). In this case, the difference in subsidies creates a distortion that wastes £5000 of public money to make the householder £1000 better off, with no benefit with respect to the outcome.

The solution to this issue is to provide the same incentive independent of the technology used and hence achieve the desired outcome, the adoption of low carbon heating, at the lowest overall cost. The subsidy provided should aim to only create a market distortion with respect to gas heating, and not one between different heat-pump based systems. Air-to-water, air-to-air, air-source or ground source does not matter; they are all heat pumps capable of providing low carbon heating. If they can meet a sufficiently high SCOP, currently just 2.8, then the subsidy should be the same. This would ensure that the most cost-effective technology is deployed and that taxpayers get the best overall value for money and hence the total funds for the BUS grant go further, achieving larger reductions in CO2 emissions.

A variable grant rather than a fixed one

The BUS grant currently provides a fixed subsidy of £7500 or £2500 depending on the technology used to replace a gas boiler. The grant is the same irrespective of the size of the property, the size of the system that is replaced, and the efficiency of the technology used. This leads to the situation where the BUS grant is both over-generous and under-generous at the same time.

For a small property, replacement of a gas boiler with an A2W system might cost £8000 of which the BUS grant pays £7500 and the householder just £500. However, the householder may well have gone ahead anyway even if the cost to them was £2500, less than installation of a new gas boiler at around £3000. As a consequence, £2000 of public money has been wasted on something that would still have happened if the grant were £5500.

For a larger property, replacement of a gas boiler with an A2W system might cost £14000 of which the BUS grant pays £7500 and the householder £5500. In this case the house holder may have been willing to pay £4000 but decides that paying nearly twice the cost of a replacement gas boiler simply isn’t worth it and therefore does not go ahead. An opportunity to install low carbon heating is missed.

An additional problem caused by the price distortion is the effect on the amount of due diligence that some householders apply and the choices that they make. Three quotes of £8000, £9000, and £10000 where all the money comes from household funds needs serious consideration in terms of quality, checking installer reputation, equipment used etc. However, after the BUS grant, the costs to the householder are £500, £1500, and £2500, which may well create a race to the bottom. It would be easy to fall into the trap that the lowest price quote at 1/3^rd the cost of the middle one and 1/5^th the cost of the most expensive is the one to go for. By not caring because it is so cheap, £500 and a huge £7500 in grant, the householder sets themselves up to be exploited by cowboys out to make a fast buck. The result is a poor quality system that does not meet the householders needs, something they may come to regret in future.

The solution here is to make the grant a percentage of the overall cost up to some maximum value. This is what is done in some other European countries. As an example, the percentage could be 75% and the maximum say £10,000. This would work for the small and large property examples described above. The proportionate cost to the householder would also lead to better due diligence, since the cost to them of the different options in the example above would be proportionate to the overall costs, i.e. £2000, £2250, and £2500 in this case. Now a high quality install with better equipment appears to be what it in fact is, much better value for money.

Note, in changing to a variable rather than a fixed amount for the grant, there should also be some restrictions on what can be included in the figure that the grant is based upon. For example, the cost of radiator replacements or underfloor heating should not be included when these are at the discretion of the householder rather than an essential requirement. Only the costs necessary to install a heat pump and achieve a SCOP of at least 2.8 would qualify with respect to the grant.

The perfect is the enemy of the good

No support is currently available to install low-carbon heating alongside an existing gas boiler. It’s all or nothing as far as the BUS grant is concerned. Unfortunately, this is an example of the perfect being the enemy of the good.

Over 10 million homes have gas boilers that are less than 10 years old, i.e. potentially less than half of the way through their lives. There are ways in which partial de-carbonisation can be achieved which are of great benefit in terms of carbon emissions, without replacing the existing stock of relatively new gas boiler.

A small grant, call it the Boiler Enhancement Scheme (BES) could cover 50% of the costs, up to a maximum of £1000, of installing an A2A heat pump alongside existing gas boilers. The uptake of such A2A systems would likely be very high, since they cost as little as £1600 fully installed for a single-split system. Such a system could provide at least 3000kWh of heating in a property that has the Ofgem average gas consumption (9500 units of gas, about 8550kWh of heat). This would reduce the property’s CO2 emissions by around 1/3^rd. This is a far more efficient reduction in CO2 emissions per £1000 of public money compared to the existing BUS grant for A2W, which costs £7500 to remove 3 times as much CO2 emissions. On those figures, the BES grant would be 250% more effective than the BUS grant for the same amount of taxpayers’ money.

Would households actually use A2A for space heating? A2A systems have easily achievable SCOPs of over 5. Currently, the gas price is about 7.97p per unit and electricity 26.32p per unit. Assuming gas boiler efficiency of 0.9, an A2A heat pump with efficiency of 5 costs just below 60% the price of gas per kWh of heat delivered. People don’t need an incentive to make the maximum use of an A2A system for heating, as it is already there in the existing spark gap. They only need consider their bank balance! In Jan 2027, the argument will become even more compelling. The latest forecast based on 30^th Sept figures for wholesale gas prices put the price of gas at 9.76p and electricity at 30.28p from 1^st Jan 20207, so A2A heating will then cost only 56% the price of gas.

By introducing households to heat-pumps via the A2A route, they are much more likely to be fully onboard with an A2W replacement for their gas boiler when the latter reaches the end of its life.

Conclusions

I think there are good economic arguments for reforming the BUS grant so that it is technology agnostic, pays a variable rather than a fixed amount based on the essential upgrade cost, and also encourages hybrid upgrades as well as complete ones.

I’d be interested to hear what others think about these suggestions both for and against. What do you think of the existing BUS grant? Is it fit for purpose? Could the same amount of money be spent in a better way to encourage the transition to low carbon heating? Is a grant for hybrid / partial low carbon heating a good idea? How do you think the use of taxpayers’ money could be improved to encourage more people to make the transition to low carbon heating?

The pipes still need insulation but it's flushed and bled, now holding 0.4bar pressure after two leaky unions.

I've still got a completely new circuit to three radiatorors to connect on, but I thought it would be better to flush the old pipework through first; it also makes leak checking easier.

Time to wire up the control panel 

Heat Geek have obviously built a very distinctive brand around making heating engineering more accessible and less corporate, and there’s no question they’ve been successful at creating an identity people recognise.

But where does the line sit when that branding moves into the actual technical paperwork a homeowner receives?

Personally, I can’t quite decide whether this is clever and memorable, or whether the slogans and graphics make a heating-system design feel slightly less serious than it should.

Maybe I’m just getting old.

Interested to know what everyone else thinks. Great branding, harmless fun or slightly juvenile for a professional design document?