Category Archives: Bogus claims

Condensing boilers (not)

The exhaust from a natural gas appliance contains about 0.15 litres of water per kWh of gas input, and about a tenth of the thermal output is lost because that water is emitted as vapour. Condensing boilers are a good idea in theory because they can condense the vapour and recover latent heat from the products of combustion, boosting output by around a tenth.

In practice, too few condensing boilers achieve their potential because they cannot cool the flue gas below its dew point (around 59C ). Result: plumes of vapour outside. This one resembles what you’d see boiling a 2-3 kW kettle in the open air, and that’s a measure of how much energy is being wasted.

The truth is that so-called condensing boilers need to be installed in heating systems with low return water temperatures. Underfloor heating, or systems with oversized radiators for example. Only then will they get sufficiently-low temperatures in their heat exchangers to get the exhaust vapour to condense.

 

Nice try, but…

A recent issue of the CIBSE Journal, which one would have thought ought to have high editorial standards, recently published an article which was basically a puff piece for a certain boiler water additive. It contained some fairly odd assertions, such as that the water in the system would heat up faster but somehow cool down more slowly. Leaving aside the fact that large systems in fact operate at steady water temperatures, this would be magic indeed. The author suggested that the additive reduced the insulating effect of  steam bubbles on the heat-exchanger surface, and thus improved heat transfer. He may have been taking the word ‘boiler’ too literally because of course steam bubbles don’t normally occur in a low or medium-temperature hot water boiler, and if they did, I defy him to explain how they would interfere with heat transfer in the heat emitters.

But for me the best bit was a chart relating to an evaluation of the product in situ. A scatter diagram compared the before-and-after relationships between fuel consumption and degree days (a proxy for heating load). This is good: it is the sort of analysis one might expect to see,

The chart looked like this, and I can’t argue that performance is better after than before. The problem is that this chart does not tell quite the story they wanted. The claim for the additive is that it improves heat transfer; the reduction in fuel consumption should therefore be proportional to load, and the ‘after’ line ought really to have a shallower gradient as well as a lower intercept. If the intercept reduces but the gradient stays the same, as happened here, it is because some fixed load (such as boiler standing losses) has disappeared. One cannot help wondering whether they had idle boilers in circuit before the system was dosed, but not afterwards.

The analysis illustrated here is among the useful techniques people learn on my energy monitoring and targeting courses.

Kinetic plates

When this “kinetic plate” was installed in 2009, the Guardian published an article which suggested that it would harvest up to “30 kWh per hour” of “green energy” from the traffic passing over it. Rubbish, of course. Firstly (as was acknowledged in a muted disclaimer at the foot of the article) it wasn’t free energy; it was contributed by the passing drivers. But what about the 30 kWh per hour claim? That’s the equivalent of harnessing the output from engine of this Peugeot and running it flat out for 15 minutes in the hour.

Really? We can do some quick sums on this. Say the car, with its driver, weighs about 1,400 kg. Suppose that it depresses the plate 10mm (0.01m). If we take gravitational constant as 9.8 N/kg, the energy imparted by the car as it drives onto the plate is 1,400 x 0.01 x 9.8 = 137.2 joules (watt-seconds). That is only 0.000038 kWh. In other words, you’d need getting on for eight hundred thousand cars an hour to achieve 30 kW output, even if the mechanism were 100% efficient, which it won’t be.

Along similar lines the IMechE published an article about a kinetic pavement in 2015. This related to a system for capturing energy from pedestrians, and rather usefully it included some statistics: that 54,267 steps had generated 217,028 watt-seconds. I hope all my readers can confirm for themselves that this equates to a mere 0.06 kWh.

Unethical sales of so-called energy saving product

The BBC’s Watchdog programme (series 38, episode 1) did an excellent job exposing the activities of a company called Energysave, which was caught training its salesmen to use high-pressure sales techniques on vulnerable customers. They were claiming, outrageously, that their product, a water-repellent coating for masonry, cut heat loss by a third. (Although their website says conductivity “decreases enormously with dampness”. Whoops)

Warning sign: an iIlliterate promotional video

You can catch up with the episode on BBC iPlayer. The relevant material is in two parts at 16’04” and 32’53” with the final confrontation scene at 51’52”, but the episode also includes stuff on defective smart meter installations.

Thanks to newsletter reader Istvan Sereg for the tip-off.

Fuel savings from system water treatment: limits of plausibility

Just how big a saving is it possible to achieve with a product which improves heat transfer in a ‘wet’ heating system (one which uses circulating water to feed radiators, heater batteries or convectors)?  It is an important question to answer because suspect additives claiming to reduce losses through water treatment are becoming prevalent, making claims in the range of 10-20%, while air-removal devices have been claiming up to 30%. It is possible to show that the plausible upper limit is of the order of 7%  and that this would be achievable through good routine maintenance anyway.

To work this out we first break the system into its two major components: the heating boiler (which in reality may be two or more plumbed in parallel) and the building, which represents the heat load. The first thing we can say is that if the heating in the building is maintaining the required temperatures, the thermal load which it presents to the boiler will not be affected by internal heat transfer coefficients. If heat transfer in the heat emitters is impeded, then either the circulating water temperature will rise or control valves will be open for a greater percentage of time in order to deliver the required heat output, or both; either way, the net heat delivered (and demanded from the boiler) is the same.  So water treatments will not affect the heat demanded from the boiler; their only effect will be to improve the efficiency with which the boiler converts fuel into useful heat.  Let us consider how this can be done. Consider the routes by which energy is lost in the boiler:

  1. Standing losses from the boiler casing and associated pipework and fittings;
  2. Sensible heat loss in the exhaust gases. This is the energy that was needed to elevate the temperature of the dry products of combustion (i.e. excluding latent heat);
  3. Latent heat losses, e. the energy implicitly used in converting water to vapour in the exhaust (it is this heat which is recovered in a condensing boiler);
  4. Unburned fuel (carbon monoxide or soot).

Which of these could be affected by water treatment and which would not?  Standing heat loss is sensitive only to the extent that the external surface temperature of the boiler might differ with and without water-side scaling. As such losses would only be about 2% of the boiler’s rated output in the first place, we can safely take the effect of variations to be negligible. Latent heat losses would not be affected because they are solely a function of the quantity of water vapour in the exhaust, and that is fixed by the chemistry of combustion and in particular the amount of hydrogen in the fuel. Unburned fuel losses will not be affected either. They are determined by the effectiveness of burner maintenance in terms of air/fuel ratio and how well the fuel is mixed with the combustion air.

That just leaves sensible heat losses.  Two things can cause higher-than necessary sensible heat loss. One is to have excessive volumes of air fed through the combustion process, and the other is having a higher-than-necessary exhaust gas temperature.  Excess air is self-evidently totally unrelated to poor water-side heat transfer, but high exhaust temperatures will definitely occur if the heat transfer surfaces are dirty or scaled up.  With impaired heat transfer the boiler cannot absorb as much of the heat of combustion as it should, or to look at it a different way, higher combustion-product temperatures are needed to overcome the thermal resistance.

Elevated stack temperature, then, is the only significant symptom of water-side scaling.  So how high could that temperature go, and what are the implications?  Most people would agree that an exhaust temperature of 250°C or more would be highly exceptional and values of 130°C to 200°C more typical.  Now let us suppose for the sake of argument that the exhaust gases in a reasonably well-maintained boiler contain 4% residual oxygen in the exhaust and have a temperature of 130°C, with (to make it realistic) 200 parts per million of carbon monoxide. The stack losses under these conditions will be:

4.2% sensible heat in dry flue gases

11.2% enthalpy of water vapour

0.1% unburned gases.

This leaves a net 84.5% as “useful” heat but we should deduct a further 2% for standing losses, giving 82.5% overall thermal efficiency as our benchmark.

Now let’s suppose that the same boiler had badly fouled heat transfer surfaces, raising the exhaust temperature to 300°C —  way in excess of what one might normally expect to encounter.  Under these conditions the stack losses become:

10.4% sensible heat in dry flue gas

12.7% enthalpy of water vapour

0.1% unburned gases

So we now have only 76.9% “useful” heat which, after again deducting 2% standing losses, means an overall efficiency of 74.9%, compared with the 82.5% benchmark.  The difference in efficiency between the dirty and clean conditions is

(82.5 – 74.9) / 82.5 = 6.8%

and this figure of about 7% is the most, therefore, that one could plausibly claim as the effect of descaling a heating system whose boilers are otherwise clean and reasonably well-tuned. In fact if the observed stack temperature before treatment is lower, the headroom for savings is lower too.  At 200°C the overall efficiency would work out at 81.4% and the potential savings would be capped at about 3%.

Three points need to be stressed here. Firstly, just measuring the flue gas temperature will tell you accurately the maximum that a boiler-water additive alone could conceivably save. Secondly, you cannot be sure the problem is on the water side anyway: it may be fireside deposits. Thirdly, all these potential savings should be achievable just with good conventional cleaning and descaling.

 

Meaningless claims

MEANINGLESS CLAIMS No. 9,461

Seen in a product brochure for a control system: “The theory states that if you allow the indoor temp to vary by 8ºC in a commercial or public building the heat saving will be 80%. In practice a span of 3-4ºC is usually more realistic (20-24ºC is common) resulting in heat savings of 20-40%. The use of a temperature range does not mean that the indoor temperature will change 3-4ºC over 24h, the average change in indoor temp over 24h is less than 1ºC, which is enough to utilise thermal storage. If no range is allowed, none of the excess free or purchased energy can be stored in the building.”

MEANINGLESS CLAIMS No. 9,462

I recently reported the new fashion for describing boiler-water additives as ‘organic’ to make them sound benign. As I pointed out, cyanide is an organic compound. Now here’s a new twist: a report on the efficacy of a certain boiler water additive says “[it] is 100% organic so the embodied carbon is 0.58kg of CO2 per bottle”. Er… How do they figure that?

MEANINGLESS CLAIMS No. 9,463

The same report cited another which said that a certain programme of domestic energy-conservation refits had yielded “up to a 42% increase in living room temperature”. Cold comfort indeed if your room started at zero degrees Celsius; 42% of zero is zero. Oh wait: what if you had used Fahrenheit, where freezing point is 32°F? A 42% increase on 32°F gives you 45.4°F (7.5°C). So it depends what temperature scale you use, and the truth is you can only talk about a percentage increase in temperature relative to absolute zero (-273°C). If we start at an absolute 273K (0°C), a 42% increase takes us to 388K or 115°C. To be honest, that doesn’t sound too comfortable either.

Refrigeration nonsense

The vapour-compression cycle at the heart of most air-conditioning systems consists of a closed loop of volatile fluid. In the diagram below the  fluid in vapour form at (1) is compressed, which raises its temperature (2), after which it passes through a heat exchanger (the “condenser”) where it is cooled by water or ambient air. At (3) it reaches its dewpoint temperature and condenses, changing back to liquid (4). The liquid passes through an expansion valve. The abrupt drop in pressure causes a drop of temperature as some of the fluid turns to vapour: the resulting cold liquid/vapour mixture passes through a heat exchanger (the “evaporator”) picking up heat from the space and turning back to vapour (1).

normal_loop
Figure 1: the vapour-compression refrigeration cycle schematically and on a temperature-entropy diagram

The condenser has two jobs to do. It needs to dump latent heat (3->4) but first it must dump sensible heat just to reduce the vapour’s temperature to its dewpoint. This is referred to as removing superheat.

It has been claimed that it is possible to improve the efficiency of this process by injecting heat between the compressor and condenser (for example by using a solar panel). Could this work?

solar_loop_true
Figure 2: showing the effect of injecting heat

The claim is based on the idea that injecting heat reduces the power drawn by the compressor. It is an interesting claim because it contains a grain of truth, but there is a catch: the drop in power would be inextricably linked to a drop in the cooling capacity of the apparatus. This is because we have now superheated the vapour even more than before, so the condenser now needs to dump more sensible heat. This reduces its capacity to dump latent heat. The evaporator can only absorb as much latent heat as the condenser can reject: if the latter is reduced, so is the former. Any observed reduction in compressor power is the consequence of the cooling capacity being constrained.

The final nail in the coffin of this idea is that reduced power is not the same as reduced energy consumption: the compressor will need to run for longer to pump out the same amount of heat. Thus there is no kWh saving, whatever the testimonials may say.

View a vendor’s response

Fuel treatment products recalled

Dateline April 1, 2016: Endomagno Ltd has ordered a total product recall of its bolt-on fuel-treatment magnets after two serious incidents at customers’ premises.

Such magnets are commonly claimed to improve consumption by aligning the gas molecules, and the incidents appear to involve the alignment effect being so strong that the gas has actually crystallised in the burner. Why this has started to happen now is not clear (the product literature points out that the Romans used lode-stones to improve the heat output of hypocausts) but my theory is that it relates to the introduction of new microcrystalline neodymium magnets in what the company describes as “a certain configuration”. Chaos entanglement theory says that these may interact with quantum nanoparticles in the gas stream in unpredictable ways.

The product recall presents a significant logistical problem for Endomagno. Although the magnets are easy to attach using gaffer tape, they cannot be removed by the customer without invalidating the product’s Korean patent. This means sending a technician to every site and as a market leader in magnetic fuel treatment they have nearly seven users.

Endomagno’s marketing director, Frank Lee Beaugusse, told me that the company is urgently investigating two alternative technologies. The most promising is a unipolar magnet, which only has a north pole, but they are also testing more conventional magnets with east and west (rather than north and south) poles. Comparative evaluation and testing will be carried out by Laboratoires Garnier.

Does faster warm-up save much energy?

There is a class of product that claims to save energy by enhancing the output of central heating radiators. These are usually small fan units, but one product I have seen is just a metal plate stuck on with double-sided tape which passively increases the radiator’s surface area. Then of course we have those additives which improve heat transfer on the water side.

These devices are commonly sold on the basis that you will save energy because the room “will heat up faster”.  In principle, there might be some truth in this, but savings would only arise if you optimised the start time of the heating to take advantage of the shorter warm-up period.

How big is this saving or lossradiator_boost_profiles likely to be? The picture on the right shows a simulation of the diurnal temperature variation, mid-day to mid-day, in an intermittently-heated space.
This profile is reasonably representative of a building with moderate thermal performance.

When the heating goes off at A, the temperature falls rapidly and first and then progressively more slowly until B, where the heating comes on again and boosts the temperature back up to point C. This simulation shows the effect of (a) boosting the heater output by 50% and (b) optimising the start time, in which case the heating now comes on later, at B’, because the radiator can raise the temperature faster and reach point C as before.

The height of the bars represents the difference between inside and outside temperature (which is held constant here to simplify the analysis) and because heat loss is proportional to the inside-outside temperature difference, the shaded area of the chart is a good proxy for daily heat loss and thus fuel consumption. The small triangular area CBB’ represents the daily energy saved by the change. It amounts in this case to 3.4% of the total, and this proportion will probably be the similar across a range of outside air temperatures; less in milder weather, and more when it is colder.

So if you would need to increase radiator output by half to save only around 3% on fuel, it is hard to see how the marginal increase in output from a stick-on booster is going to make a perceptible change. And remember, if you don’t optimise the start time, increasing the output will cause the room temperature to rise faster, achieving target temperature prematurely, leading not to a saving but to an equal, albeit negligible, loss.

Twelve hallmarks of bogus claims for energy-saving products

Some energy-saving products and techniques always work: fitting a properly-sized high-efficiency electric motor, for example. Some, like condensing boilers and voltage reduction, only work in the right circumstances. Some will work only if properly commissioned and operated (automatic lighting controls are a case in point). Some products, like those based on automatic control algorithms, may be perfectly good from some vendors but not others. Certain products, however, will never save energy under any circumstances because they are bogus. The Advertising Standards Authority ruled in 2013, for instance, that Blue Carbon Ltd must not claim that their “current optimization” device saves energy, because its claims could not be substantiated. But how is the hard-pressed environmental manager, facilities manager or works engineer, who may have little grounding in the subject, going to make the judgment about something which just feels wrong?

From the advertising literature that I have seen, there are a dozen hallmarks of suspicious products, which I elaborate on below. Unfortunately, the boundaries are not clear. Apart from bad science (which can be difficult for the lay person to judge), no single factor will definitively identify a bogus offering, and some (like ease of installation, testimonials, and high percentage savings) could be perfectly genuine. But if four or more of the following apply, there may well be a problem:

1. Failure to adhere to the known laws of science is a sure sign, and pseudo-scientific jargon should raise suspicion. Usually spurious claims can be debunked with basic school science, but not many people will remember their physics and chemistry lessons all that clearly in later life and most will just be left with that vague feeling that the claims sound wrong. Help may be needed from a trustworthy source like the UK Association of Energy Engineers, which operates an “Ask the Expert” service for its members, and is free to join; and I offer a free on-line basic science course  for energy managers elsewhere on this web site.

Technical inconsistencies may give the game away. The ASA’s ruling on Blue Carbon’s advertising drew attention to contradictory assertions in relation to magnetic fields. Purveyors of magnetic fuel enhancers used to pooh-pooh each others’ claims depending on whether they used permanent magnets or oscillating fields. And the vendor may inadvertently tip you off: one stated on his web site that his invention was not a perpetual-motion machine. Why would he need to say that?

A related trick is to misuse scientific truths. For example, it is true to say that when water boils in contact with a hot surface, heat transfer is greatly impeded if, rather than having discrete steam bubbles forming, they coalesce into a film; however, it is not correct to claim that this phenomenon will occur in a normal heating boiler. The term ‘boiler’ is a misnomer because the water in contact with the heat transfer surfaces remains liquid. Were steam bubbles ever to form because of localized overheating or inadequate water flow you would get popping and clanging noises (“kettling”) caused by detached steam bubbles condensing and collapsing abruptly in the water away from the surface.

2. Implausible percentage savings claims: more than anything, it is claims for savings of 20% or more which prompt people to become suspicious and contact me for my opinion. The problem is that some established technologies do achieve that (and more), so what is really at issue is the nagging question “if this is so good, why isn’t it fitted everywhere?”. Taken on its own, this is not evidence enough, although it is sometimes possible to show from engineering calculations that a claim is unlikely to be feasible. I return to this theme later but the enemy are not all stupid and there is a new breed smart enough to make a subtler pitch. Nobody would think a claim for six percent was suspicious.

3. Extreme ease of installation: it has to be just a simple additive, bolt-on, or electrical connection for two reasons. Firstly the salesman needs to put as few obstacles in your way as possible. Secondly it needs to be cheap for him to install and easy to remove (or abandon) when a diligent customer discovers it does not work.

4. Being dismissive of established test methods or expertise: snake-oil merchants sometimes rubbish conventional wisdom, and when I argue with them, they point out that scientific knowledge is always advancing, that they have superior qualifications to me, that people once thought the earth was flat, etc., etc.. But however novel a product may be, its effect on losses and efficiency will be indistinguishable in kind from other products that achieve the same thing. For instance, anything which improves the efficiency of a properly-maintained heating boiler running under full load will reduce its exhaust temperature (it cannot change the residual oxygen content because that will already have been optimized). In general, if a product gives poor or no results with realistic tests, it will give poor or no results when installed.

One web site said this about people who questioned the technical basis of their claims: “they are wrong because they do not have the knowledge and technology we do”. A compelling argument indeed.

5. Analysis based on indirect measurements like reduced running hours: it is not safe to infer that reducing running hours reduces energy consumption. If you turn your heating off for ten minutes in every hour, for example, you will have an intermittent drop in space temperature and each time the heating system runs it will use extra fuel to restore the desired temperature. Remember in this case that heat is flowing out of the building all the time (even when the heating is off) and over the course of a day or a week, all the heat lost must be balanced by heat input, regardless of how intermittently it is supplied. In fact, to maintain the same minimum inside temperature with intermittent heat input, you would use more fuel by having to maintain a higher average.

Similar considerations apply to voltage reduction, in that any reduction in current, while proving a reduction in instantaneous power, does not take running hours into account. A thermostatically-controlled electric heater in particular will run for longer in order to deliver the required quantity of heat, negating any apparent savings inferred from a spot check.

According to the ASA adjudication, Blue Carbon had their product laboratory-tested in Austria using a method based upon the time taken to boil water. Really? One has to wonder why. Be skeptical of any proposal which seems to dodge the more direct and rigorous option of measuring total energy consumption before and after installation

6. Secret ingredients or principles of operation: claims based on secrets are by their nature hard to assess in principle, so secrecy is the perfect cloak for trickery. However, if you are looking for a way to deter a persistent salesman, you can use secrecy against them. Just fall back on a health-and-safety argument. Ask for toxicity and materials-compatibility tests on any chemical constituents. And if somebody tries to sell you a magnetic device so powerful that it can affect oil or gas, ask for information about its effects on human tissue and body fluids.

7. Reliance on being patented as proof of effectiveness: have a look and see where the product is patented (if indeed it really is; sometimes vendors lie). If it is patented in the UK, at least it is probably based on accepted scientific principles. If the product is only patented in the United States or some other jurisdictions, it could be spurious because not all national patent offices are equally rigorous. Most importantly, a patent does not imply, let alone prove, that something works; it shows that it can be made, and how. From which it follows that if the patent refers to secret or even unspecified materials or arrangements, you can be sure you are looking at a dud because the essence of a proper patent is that it discloses enough about the invention to enable somebody with relevant skills to reproduce it.

We have recently seen a growth in references to products having been granted ‘global’ patents. There is no such thing as a global patent, so you can draw your own conclusions about anyone who says they hold one[1].

8. Heavy reliance on testimonials: I have to be careful here because good products are promoted on the basis of testimonials too. On the whole, testimonials that are purely qualitative (“the installer came at the promised time and cleaned up thoroughly afterwards”) can be believed. Quantitative ones (“we saved 30% off our gas bills”) are weak. Very few end users have the measurement and verification skills necessary to make such a claim credible. Could I just thank the hostages who smuggled out the truth in their testimonials: “the savings were unbelievable”.

Fraudsters are canny. They can harvest true testimonials from cases where there are apparent savings while ignoring the cases where there was no effect or where consumption increased. And they can blackmail their customer: who wants his boss to learn that he would not endorse a product on which he had forked out a large amount of his employer’s money? In the 1990s one case was reported to me where employees of blue-chip companies were even offered “access payments” (bribes in other words) to show prospective customers their installations.

9. Literature plastered with ISO9001 and other certification logos:sometimes it seems only the 25-yard swimming certificate has been left out.

One of the things which seemingly lends credibility is a reference to the International Performance Measurement and Verification Protocol (IPMVP). Just remember, though, that IPMVP cannot be used to validate a technology in general. It strictly covers the evaluation of a specific installation. Therefore any generic claim of savings based on IPMVP should be treated as misleading. Furthermore, under IPMVP the findings of an evaluation are valid only for the duration of the post-installation test: as soon as measurements stop, any further savings can only be presumed. They are not proven.

10. Dense academic research reports: aware of the skepticism which greets their pseudo-scientific explanations of secret (and yet patented) technologies, vendors sometimes add scientific research reports to the mix.

Of course to most prospective buyers, pages of indecipherable formulae and diagrams can do no more than create the impression of rigour and—paradoxically—increase rather than reduce their suspicions. So the reports’ authors are often (a) professors and (b) held out to be “world-leading” authorities, just to reassure you. But physics is physics and maths is maths and if such a report falls into the hands of someone independent who knows these subjects, flaws may become apparent (lines of magnetic flux do not bend abruptly; the heat transfer process in a low-temperature hot-water boiler does not include film boiling; and so on). Pointing out errors in a paper with a “world-leading” professor’s name on the cover causes indignation, online abuse and sometimes threats, but of course the vendor cannot risk going back to the professor, because the professor (even if they exist and signed the report) will agree that their junior research assistant made those fundamental errors which had survived world-leading professorial scrutiny.

11. Name-dropping: watch out for product literature embellished with superfluous references designed to reinforce their credibility. Fair enough to say that a product has been evaluated using degree-day; but why data “from Oxford University” especially? Another favourite of mine is a product “discovered by an ex-NASA scientist”.

12. Pincer-movement sales tactics: victim energy managers can find themselves under pressure from two directions: a salesman on one hand, and a top person from their own organization who has been groomed by a director of the sales company. Often the senior contact is made socially (the “funny handshake on the golf course” approach) and it is designed to exploit the fact that senior people usually know little if anything about technical details. The energy manager is then put in the potentially difficult position of having to explain to his or her boss why the idea they are being told to follow up is stupid. This indirect bullying is a pernicious tactic because it undermines both the credibility of the energy manager and the trust between them and senior management.

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[1] There is a pilot scheme called the Global Patent Prosecution Highway but that is actually an administrative process whereby patents granted in one country will have their applications accelerated in other participating jurisdictions. The name signifies a global prosecution highway for patents, not a prosecution highway for global patents.