ASHPs Energy Saving Trust(EST) Phase 2 trial report

Cardew

After the EST published their Phase I trial report of both ASHP and GSHP, which by any standard gave a most disappointing set of results, this thread was started:

https://forums.moneysavingexpert.com/discussion/2968958

Well the EST have now published their Phase 2 report here:

http://www.energysavingtrust.org.uk/Organisations/Working-with-Energy-Saving-Trust/The-Foundation/Our-pioneering-research

The report deals with both GSHPs and ASHPs. The various interested parties investigated these poor results and a series of what the report terms ‘interventions’ were carried out to improve the installations.

Personally I again find the results and conclusions to be disappointing. This extract from their conclusions sums up the performance of the systems.

How do heat pumps perform in UK homes? The evidence obtained through this study indicates that correctly installed and operated heat pumps can perform to a very high standard in UK homes. Our methodology focused on measuring the efficiency of the monitored heat pumps by calculating Seasonal Performance Factor (SPF). This is simply defined as the amount of heat the heat pump produces compared with the amount of electricity needed to run the system (including auxiliary, immersion heaters and circulation pumps).

The average SPF for an air source heat pump was found to be 2.45. For ground source heat pumps it was found to be 2.82.

So the bottom line is that the average SPF(usually termed COP on these forums) for ASHPs is 2.45.

It is perhaps worth examining those ASHP results in more detail(they are shown in Figure 9). Of the 15 trialled:

qty 3 had a SPF of 2.0,

qty 5 of 2.2,

qty 3 of 2.4 and

qty 1 each at 2.6, 2.8, 3.0, and 3.6.

So only one above 3.0; yet read the manufacturers brochures!

So what is your definition of an acceptable SPF? For me the single property(with underfloor heating) achieving 3.6 is good; 2.0 would be unacceptable.

This was posted in the earlier thread:

When considering the COP(SPF) of ASHPs firms never take into account that the heat produced when occupants are out of the property, or in bed, is wasted.

For instance it might be necessary to keep the ASHP running 24/7 because of the inability of the system with low temperature water to quickly bring the house up to temperature. It might be that, say, 30kWh will be produced when occupants are out, or in bed.

With gas/oil CH with water at 80+C there is no need to heat the house when occupants are out/in bed, as 20-30 minutes will bring a house up to heat. Yet in the inevitable comparisons of running costs, the 'unwanted' 30kWh is always used to swing the comparison in favour of heat pumps – and still fails!

Although the EST have acknowledged elsewhere that principle is correct, the report fails to mention this important aspect.

The report again stresses the crucial need for installers to use all the new and improved MCS guidelines for installation.

However to my mind the most disappointing aspect of the report is that there is no rigorous regime proposed to ensure that MCS installers do fully comply with all the guidelines(not regulations). An installer can still purchase a heat pump from a manufacturer and fit it to a house.

Can anyone seriously think that many firms, contacted by a prospective customer, would refuse to fit a heat pump to a unsuitable house? We need some organisation along the lines of the NHBRC to oversee and inspect heat pump installations

We still are in the position where customers are expected to pay often well in excess of £10,000 with no guarantee of performance; essentially take pot luck. Not good enough!

Discuss.

matelodave

Whilst I tend to agree that the efficiency is somewhat less than the "optimised" data given out by the manufacturers even an average COP of the heating system of 2.45 equates to about 4.9p a kw at 12p a unit. Even the lowest COP of 2.0 equates only 6p/kw which is better than oil or lpg and without the hassle

Some as you pointed out were significantly better, a COP of 3 or better makes reduces the cost of a kw down to less than 4p

So if you can get a correctly designed and installed system and learn how to use it properly the running costs are getting close to or can even better the cost of mains gas - especially if you take the inefficiencies of gas into account as well.

The up front costs are significantly higher but in the longer term if it's done properly there is a saving.

I would agree though that there should be better policing of the industry and no one should be allowed to configure, sell or install systems unless they are properly trained & certified.

I don't think the MCS scheme is stringent enough, something like Gas Safe or the Electricians scheme should be implemented and people should be able to get recompense if a system doesn't even come close to it's design performance.

However that said, many of the problems with systems can also be attributed to the customers or users. Without a proper understanding of how it works (or taking away the opportunity to fiddle or tweak) can have a significant effect on the operational efficiency of a system.

You state that 30kw of heat produced is wasted, possibly, but it only takes 8-12kw to produce it (depending on the COP) so it's not quite as wasteful as it first seems. I'd also challenge the assertion that gas/oil will bring a house up to temperature in 20-30 mins.

Cardew

We need to differentiate between putting an ASHP in a 'new build' house, or a retrofit.

On a new build the economics of running costs can make a lot more sense - assuming a correct installation.

Nearly all the posts on MSE have been for retrofit and figures of £10,000+ have been bandied about.

What annual savings would an ASHP, with an average SPF of 2.45 make over oil in a normal house? £200 a year? Take a long time to get back £10,000!! Especially if you could invest that £10K and get 2%-3% in a long term investment. 5%(4% after tax) is currently being offered - see Martin's blog. That would give an income of £400pa.

However we agree on the main point that there simply isn't any effective policing of heat pump installation firms. Being MCS registered simply means you have exhibited the knowledge, not that you will apply that knowledge.

It is absolutely certain that some firms like 'Bodger and Sons' will not turn down a chance to install a system on a totally unsuitable house.

To my mind the manufacturers should get far more involved. Firms like Mitsubishi and Daikin should sell the product to the customer, using their own team of installers(obvious they would sub-contract) They - the manufacturers - then would have the responsibility for satisfactory performance.

P.S.
On the Phase 1 trial installations had an SPF as low as 1.2. If that could happen on a monitored trial, how many others have been installed in UK with the same, or worse, results - and absolute disaster. Yet what is being done about the situation? - nothing! Buyer beware!

matelodave

Mines a retrofit - a Daikin 11kw split system which including installation & commissioning cost me 6k (£7.5 if you include the pressurised hot water cylinder), an 8.5kw Ecodan monobloc with pressurised hot water cylinder was quoted at just under £7k although I'm sure it would have been too small.

The other costs I incurred were for the actual central heating system - in my case underfloor as that was my choice but could just as easily been radiators etc which would be similar whatever the heatsource.

So some of the quotes of £10k plus should actually be put into context to actually establish the extra cost of the heatpump over a conventional system. We should also know whether they are properly designed and costed quotes or wet-finger guesstimates.

The extra cost of a heatpump unit will be quite large if you compare it to an in situ mains gas boiler installation but if you have to get mains gas to your property or are installing an oil boiler, tank, base, oil supply lines and possibly a flue then the differences are reduced by quite a bit. Likewise the installation of LPG tanks, bases and pipework can add a fair amount to the basic installation cost of a boiler.

On top of which you have to arrange for supplies and in some cases pay up front to fill the tanks.

I'm not saying that they are the ultimate answer because for a lot of people they won't be. But they do work and can be cost effective but only on a properly designed system - even in older properties.

A lot of heatpumps were sold to replace existing boilers (gas, oil or even lpg) and bunged onto a heating system that wasn't designed to work at the lower temperatures and so didn't perform satisfactorily. Starting from scratch and correctly executed then they are fine

[Deleted User]

Hi,

Cardew thanks for posting this. Had a quick skim through and already noticed a couple of minor improvements I could make to mine

The only reason our retrofit was north of £10k was the wife wanted glass designer fancoils, 16 of them :eek:. No to mention an expensive towel rail and UFH for the bathroom. She would have chosen something alarmingly expensive no matter the fuel.

As were were starting from scratch even oil would have been expensive. The old LPG system was dumped as part of renovations, rads, tanks, boiler, pipes all ripped out along with floor boards, joists, plaster off the walls...

As it was the LPG system for CH/DHW was £200pm plus £35 pm for electric.

Now three years later after latest electricity price rises £93pm for everything.

So thats a saving of £142 pm, £1704 per year... Nuts eh!

If RHI happens then so be it but with these savings i'm not bothered...

Not for everyone but works for us

matelodave

I've just been reading the reports and I wonder if some of the gas & oil installations that are around would stand up to the same sort of scrutiny that they've put heatpumps through.


Do their efficiencies, include how the systems are used (water flow temperature, heating temperatures, hot water tank temperatures and other system losses) like they've done with HPs.


What about the electrical inputs for pumps, control boards and gas/oil valves, burners & fans all of which contribute to the energy consumption of the boiler. I'd guess that system pumps for gas or oil central heating are no more efficient than those on a HP system.


There are also comments about the energy used for legionella sterilisation - that's only on a for an hour or so a week unlike gas or oil systems where the temperature is usually kept at 60 degrees or more and is mixed with cooler water so that it can be used. System losses will be significantly higher if you heat water to 60 degrees and store it at that temperature all the time rather than heating & storing at 45 and just boosting it to 60 for an hour once a week.


Perhaps arrays of heatmeters, gas consumption meters & electricity consumption meters around Mrs Miggin's gas or oil system in her three bedroomed bungalow in S!!!!horpe might show up quite a few inefficiencies as well. The quoted 90% for gas or oil might be significantly lower when some of these factors are taken into account.


As the study points out, its the whole installation & how it's used that's critical, gas and oil and even storage rads don't get the same amount of scrutiny or criticism. They are mostly bunged in using "rule of thumb" guesstimates and are usually oversized so probably not as efficient as they could be either.


Most people feel that their system is working better if the radiator is red hot rather than lukewarm and it was evident from the study that those who's systems were designed for lower temperature running had better efficiencies than those who had the wick turned up. It wasn't obvious in the reports whether those systems that were least efficient had been designed from the outset or if the HP had been installed on an existing system. Likewise it was difficult to acertain how the systems were being used - eg were they families, single people, were the houses heated all day or just mornings/evening and weekends. Those who used a lot of hot water had lower efficiencies but that was mainly because they were heating it above 50-55 degrees and in some cases even higher so that an immersion heater kicked in. Even an efficiency of 1.5 is better than heating hot water direct from an immersion heater.

Cardew

You need to read the detailed DECC 123 page technical report for a breakdown of each system. This from that report:

Comprehensive monitoring was carried out at 83 households for Phase I. Detailed analysis investigated the factors that affect performance was published in March 2012. As a result of this detailed analysis, the Microgeneration Certification Scheme
installation standards for heat pumps were improved and the new
version came into force in March 2012.


For Phase II of the trial, 38 of the heat pumps from Phase I were selected for a range of interventions, from major (for example, re-sizing the heat pump) to minor (for example altering control parameters). Six new heat pumps, sized and designed according to the new MCS MIS 3005 Issue 3.1 standards, were also monitored.

My overall point was the results - a 2.45 SPF average for ASHPs - were achieved with the manufacturers carefully monitoring each system and in some cases making major interventions - like re-sizing the heat pump itself - being carried out. Despite this scrutiny some systems achieved just a SPF of just 2.0.

If, despite all that scrutiny, an SPF of only 2.0 is achieved, it is a racing certainty that some people will be getting a lower SPF.

One of the 'killers' of Heat Pump efficiencies is the defrost cycles.

Agreed that people with ASHPs need to be better educated on how to operate them correctly. However many people simply cannot/will not grasp the technicalities involved - my wife(with an MA so not thick!) would be one such case - we had an ASHP in a house abroad.

My criticism is that ASHP manufacturers still sell a heat pump to 'Bodger and Sons' who can fit it to unsuitable houses with absolutely no guarantee of performance for a system that can cost in excess of £10,000.

P.S.
I certainly agree with you about the 90+% efficiencies of condensing gas/oil boilers not being achieved in practice, but I have read trial reports where overall efficiencies in the mid eighties are routinely achieved.

The point about oil/gas boilers is they have large outputs to cope with the heating/hot water demand without resorting to electrical back-up.