Posted by: @johnmo

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As discussed on another thread you could get in a situation where it's rubbish in and rubbish out.

You mean like happens with the current method! 

Posted by: @johnmo

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You taking my money and everyone else's money via a grant, you may want a house at 16 degrees, but the next owner of your house may be wants a more constant 21.

Actually in my case the next owner will almost certainly demolish the house but... its a fair argument that the grant should have a minimum lifetime.  Perhaps a clause requiring it to be paid back if the system is removed within 5 years (currently it can be removed immediately, sold, and a gas boiler reinstalled so far as I am aware!)

Posted by: @johnmo

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Your gas consumption data is of little use generally.

Why is that.  The heat loss of the house is the heat loss of the house.  The gas boiler is of a known vintage and the flow temperature is known, so a fairly good estimate of efficiency can be gained.  WC is essentially irrelevant.  The only real unknown is the heating profile, except that it isnt because its revealed in the 30 min smart meter readings.  A simple questionnaire to the customer could readily determine if they have set the temperatures at a figure way different from ~20C, which they could be required to sign and be liable if they were materially incorrect.

Posted by: @johnmo

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MCS isn't perfect, if you don't like it don't take the £7500, self fund - just like I did

Good for you.  However (whether you agree with it or not) the grant is is about combatting climate change and stimulating an industry, not funding (or not funding) your (new?) build or my retrofit.   

You are basically making an argument for totally ignoring some useful and readily available data, and solely using data which is, in many cases, known to be wildly inaccurate.  That's just madness.    I'm not arguing to ignore the spreadsheet method, Im merely arguing that there is additional data which could (in my view should) be taken into account.

I feel you may be allowing your own declared feelings about the grant, and maybe the fact that, in your own case, it doesn't matter if the sizing is way out (whereas for most retrofit cases it does) to get in the way of calm, logical discussion.  Thats a little disappointing from someone who is normally pretty calm and logical about these things.

@bontwoody There’s one thing for sure then, my wife and I would not conform! We both have medical needs requiring what MCS would regard as an elevated temperature. Furthermore, as the kitchen does not have ‘conventional heat sources’ as we use an induction hob and the nearest we get to an oven is a combi microwave cooker and the freezer and heat pump tumble dryer are out in the utility (garage) area, an estimate of 19 degrees C just ain’t going to cut it for us! Regards, Toodles.

Posted by: @toodles

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@heacol And how many of those 900 pumps have you lived with through a full winter please? Regards, Toodles.

Posted by: @heacol

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@jamespa There are many theories that may or may not help with heat loss, however, in reality, in a new build property, it is irrelevant as 80-85% of the actual heat loss is ventilation, which is the greatest elephant in the room and very fairly delt with. In addition to that, the insulating properties, of any insulating material follow the laws of diminishing returns. 75mm of any insulation gives 90% of its insulating value, the next 25mm gives another 5% and a further 100mm gives another 1%, and so on. The 2 big cons in the building trade ventilation and insulation.

 

In reality, when doing heat loss on a new build, (from 1980 onwards) unless it was a self-build and you speak to the builder, the heat loss assumptions are always worst case scenario due to the terrible building standard in this country. Prior to that, the properties were generally built by craftsman, and you know exactly what you get. It is much easier to get an accurate heat loss in a building built prior to 1920, because you know exactly what you are getting, there are no surprises

Your comments on insulation are well taken and fair,

My comments, as I have said from time to time, relate to retrofits not new build.  Older retrofits (such as the pre- 1920 properties you speak of, but also much more recent properties form the 30s to the 80s and even later) will likely have had miscellaneous fabric upgrades/improvements, some of which wont even be visible.  How are these, which can make a massive difference, taken into account (answer - by at least some in the industry, they aren't).

Posted by: @heacol

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@JamesPa, I agree, but what is the efficiency of the boiler? Ofgem have found a variance from below 50% to above 90%, using the gas usage as a metric, like any metric, is only of value if all the variables are known or quantifiable. As we have no idea what the efficiency of the existing boiler is, is it of any use?

I would have thought you can get a pretty good idea from vintage and flow temperature, almost certainly good enough to act as a sense check for the spreadsheet method.

Posted by: @heacol

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 In a nutshell, the success of a heat loss calculation lies with the experience and intuition of the person conducting the survey and the informed, or ill-informed decisions they make. It has very little to do with the software or anything else.

No surprise there!

Posted by: @heacol

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My calculator is very simple, only 4 wall types, 1 window type, 2 floors, and 3 roof types. It produces lower heat loss requirements that any other commercial one, and complies with BS EN 12831:2003

very sensible IMHO

Posted by: @heacol

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but in over 900 installations, I do not have a cold customer and an average SCOP of between 4 and 5.

Good to hear, but you aren't the only person in the industry, and SCOP isnt the whole (possibly not even the main) issue.  An oversized heat pump will likely be physically larger and more intrusive, may trigger the need for planning permission (which might not be obtained), may trigger unnecessary pipework upgrades and radiators which don't fit or are ugly.  And of course an undersized heat pump will leave the homeowner cold.  Apart from the last these things don't matter much to the installer, but they do to the customer!

I'm not arguing to drop the spreadsheet method.  Im arguing to use in addition the other data which is available, at the minimum as a sense check!  Who in their right mind ignores completely the only experimental data available about a key design parameter, in favour of theory which is known to be based on dodgy data!  

I'm sorry to be cynical but I fear that the slavish adherence to the spreadsheet method alone is for the convenience and protection of installers (and MCS) not the customer, and as a result the industry is closing its mind completely to alternative or complementary methods.  Whilst you doubtless have the intuition and experience to use it sensibly, its readily apparent that others in the industry don't.  

Posted by: @jamespa

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Why is that. 

For exactly the same reason I gave in my example. As installed my boiler used twice the expected amount of gas. Main reason was too many thermostats, boiler short cycling. Same as many houses in the UK and possibly my last house, gas was cheap so never bothered looking, So in the above case using gas data to size a heat pump, would end up being twice the size it needs to be.

Other way to run the house on the cheap at 16 degs, very unlikely the heating runs very long, so data looks like a well insulated house, you end up with a heat pump way to small.

Posted by: @jamespa

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You are basically making an argument for totally ignoring some useful and readily available data,

As said 99% of the public have very little understanding or interests in house heating. They just expect to be warm when they want to be.

Posted by: @jamespa

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to get in the way of calm, logical discussion.  Thats a little disappointing from someone who is normally pretty calm and logical about these things.

Certainly not wanting to be arse, if that's the way it came across.

Grant money needs a consistent method of heat demand sizing. Generally gas or oil consumption doesn't get that. It may in a limited set of circumstances but not enough to say it's foolproof. Currently used surveys and calculations are 100 times better than a plumber rules of thumb, where you end up with a 40kW boiler with little or no modulation in a 4kW house.

@johnmo We had a 24 kWh gas boiler and it was, by default installed and left set to 16 kWh; we thought that BG knew what they were doing, after all, they carried out a survey first. But did they??? Our 8 kWh heat pump more than coped with -7 or -8 degrees C last December and we have an elevated temperature requirement these days. My feeling is that surveys then (about 2008) paid lip service and a wet finger figured in the guestimated rating. Regards, Toodles.

@jamespa I would have thought you can get a pretty good idea from vintage and flow temperature, almost certainly good enough to act as a sense check for the spreadsheet method.  Possibly but unfortunately experience is still best, however, believe it or not, for most installations, you can get a pretty good sizing by taking the floor area divided by number of floors, square root the answer, and put that in the calculator. I use that as the check.

An oversized heat pump will likely be physically larger and more intrusive, may trigger the need for planning permission (which might not be obtained), may trigger unnecessary pipework upgrades and radiators which don't fit or are ugly  possibly but unlikely trigger panning, I have never r-piped a property, even with 8mm microbore, never installed a buffer tank and most radiators are of similar size with 1 or 2 extra panels. Not as bad as it is made out the be when on open zone.

I'm sorry to be cynical but I fear that the slavish adherence to the spreadsheet method alone is for the convenience and protection of installers (and MCS) not the customer, and as a result the industry is closing its mind completely to alternative or complementary methods.  Whilst you doubtless have the intuition and experience to use it sensibly, its readily apparent that others in the industry don't.  Agreed

@Johnmo  I agree with most of what you say.

Posted by: @heacol

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(quite from @jamespa) "An oversized heat pump will likely be physically larger and more intrusive, may trigger the need for planning permission (which might not be obtained), may trigger unnecessary pipework upgrades and radiators which don't fit or are ugly  possibly but unlikely trigger panning"

 

I have never r-piped a property, even with 8mm microbore, never installed a buffer tank and most radiators are of similar size with 1 or 2 extra panels. Not as bad as it is made out the be when on open zone.

It sounds like you pay more attention to the consequences of a sizing and think more about the design options than most of the muppets I encountered two years ago when I embarked on this journey, and some (albeit fewer as a percentage) that I am encountering even now!  

I note you agree with the comment I described as cynical.

It seems like you are saying that correct sizing/ interpretation using the current method (and making the correct design decisions thereafter) is an art dependant on the skill of the installer.  That feels like an argument for a sanity check given that installers vary!

Or maybe just scrap MCS so the bad installers are no longer protected and the good ones can take over?  Do the good installers, or the public, need MCS?

Posted by: @johnmo

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So in the above case using gas data to size a heat pump, would end up being twice the size it needs to be.

er.. just like the spreadsheet method!

Hence why I am arguing for the consumption to be used as a sense check at least!

Posted by: @johnmo

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yes I am, how would an installer know if it's good or bad data when he comes to visit your house in July and cannot see the heating system being used, then have to justify the heat pump sized based on rubbish data, that he cannot verify.

er - just like an installer cant tell the quality of the double glazing, about the presence of internal or external wall insulation, about floor insulation or the air change value

Posted by: @johnmo

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As said 99% of the public have very little understanding or interests in house heating. They just expect to be warm when they want to be.

 

true, which is why the industry should be using all the data available.  In another thread heacol has essentially told us (I think) that the current method depends on the skill of the installer.  Since the public has, we agree, little interest how are they supposed to judge that?

Posted by: @johnmo

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Grant money needs a consistent method of heat demand sizing. Generally gas or oil consumption doesn't get that. It may in a limited set of circumstances but not enough to say it's foolproof. Currently used surveys and calculations are 100 times better than a plumber rules of thumb, where you end up with a 40kW boiler with little or no modulation in a 4kW house.

Agree we need better than plumber rule of thumb.  But we also need correct (to a reasonable degree) not just consistent output.  The current method does not (and arguably cannot) deliver that.  Hence the debate about additional information which could be brought to bear.  If the suggested information isnt good enough then we need to extend the debate to find something that is rather than closing our minds to the issue.

There are other methods, how many would want this? 

A rapid overnight test is carried out that essentially heats up your property overnight. Then internal and external temperature sensors measure how long it takes to cool back down again.

No one can be in the property when this is happening – the home must be completely ‘at rest’. If this is not possible, a longer, three-week test is available. It uses similar data but requires additional information from your energy meters and the property can remain occupied.

First methods pack the family off in a hotel and the equipment, analysis etc. could see those costs racking up. Second easier but long winded. Hired equipment installed in the house for 3 weeks.

But both are repeatable could be applied to any property, but the already MCS install, just got more expensive. But can only be done in the heating season.

Posted by: @johnmo

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There are other methods, how many would want this? 

A rapid overnight test is carried out that essentially heats up your property overnight. Then internal and external temperature sensors measure how long it takes to cool back down again.

No one can be in the property when this is happening – the home must be completely ‘at rest’. If this is not possible, a longer, three-week test is available. It uses similar data but requires additional information from your energy meters and the property can remain occupied.

First methods pack the family off in a hotel and the equipment, analysis etc. could see those costs racking up. Second easier but long winded. Hired equipment installed in the house for 3 weeks.

But both are repeatable could be applied to any property, but the already MCS install, just got more expensive. But can only be done in the heating season.

I agree that this is not a particularly attractive method.  

However that doesn't justify relying on a method with known failings and ignoring other data.  If these aren't good enough then the industry needs to fess up (internally at least) and think hard about what i,s or even sponsor (or persuade the government to sponsor) some research!

Has anybody, for example, thought about what data could be mined by a multi dimensional analysis of say a years worth of half hourly meter readings (with weather information and maybe IAT.  I rather suspect its a lot more than meets the eye or could be done with a simple spreadsheet.  Cross correlation of rates of change, taking into account the pattern of high/low readings to determine heating pattern etc may be quite powerful.  Just bear in mind that Google can (for example) determine what ads to serve us (and make money by doing so) from information gleaned from our browsing.  I stress however that this is just one example, the basic point remains that the only real source of experimental data is completely ignored and the method used has known significant flaws.

Or is the industry just content because the current method more or less completely protects installers, notwithstanding any effect it may have on the customer?  The cynical side of me says it is and that, from an industry point of view, keeping quiet is the best strategy!  Presumably similar forces were at work when the industry made a big fuss about selling us condensing boilers, and then set them up not to condense!  This industry, it seems to me has 'form'.

@majordennisbloodnok 

Fraud?

Thermal Conductivity :

My House was initially to have been heated by a Warmflow 6.5 Kw Heat Pump to meet an estimated requirement of ~5.6 Kw .

My Installer then installed a 5 Kw Samsung saying that "his Buyer had seen the 5 kw Samsung and that this would be ideal".

My installer then adjusted the "Thermal conductivity" of my Walls  to justify the 5 Kw output from the Samsung.

NIC Inspection:

My installer was later asked by an NIC Engineer to justify this "adjustment " of the Wall Thermal Conductivity.

Failing to satisfy the NIC Engineer my "installer" was , yet again Stuck Off by the MCS/NIC.

Conclusion:

Surely,  "installers" adjusting  Wall Thermal Conductivity undermines  credibility in the entire Power requirement process.