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Argument over heat load

Posted: Mon Oct 17, 2011 4:16 am
by kenneal - lagger
[Bandidoz - split from a previous thread on WTs]

If you dislike wind turbines so much inspector perhaps you should drastically reduce your electricity use as I am preparing to do. Electric heating is definitely an extremely wasteful no, no so perhaps you should ditch your extravagant refrigeration unit.

I know that a lot of people are worried about global warming but to try to cool the outside environment using a giant fridge unit and to store the heat in your house is a bit silly!! Especially when your heat store is so inadequately insulated and that it leaks the heat back outside so quickly. I thought an highly qualified engineer would know that.:D :D :D

Posted: Tue Oct 18, 2011 9:14 am
by An Inspector Calls

As my house has a heating requirement of 1.5 kW, exactly the same as your elaborately, expensively lagged house, I don't see what you have to crow about.

And my house is old housing stock with stone walls off the gas grid - I haven't created the massive CO2 emissions involved in new build. I didn't 'give up' and move on to a convenient, new build, but thought through how I could achieve a low cost heating solution for this old house.

This is the cheap, engineering solution: a balance between economic insulation and modern technology; a much better approach than that favoured by Neanderthal laggers.

I wonder why some Passivhauses have heat pumps in their recirculation systems?

I await your next witticism/cartoon on the subject . . .

Strange that this heat pump causes you so much angst? Quaint!

And I should point out that you're diverting the thread away from windmills, which might make you a TROLL!

Posted: Tue Oct 18, 2011 12:40 pm
by kenneal - lagger
Oooooooooooooooooooooooooo! Sensitive are we???

Last time you posted your house had a heat load of 6kW? Been lagging recently or are you not sure of its exact heat load? I could calculate it for you but it would cost you about £150!! :D :D :D

And you're right, let's get the thread back to the OP - Wind farms. Windmills are such beautiful things but are dated technology now.

Posted: Tue Oct 18, 2011 7:43 pm
by An Inspector Calls
kenneal wrote:Oooooooooooooooooooooooooo! Sensitive are we???

Last time you posted your house had a heat load of 6kW? Been lagging recently or are you not sure of its exact heat load? I could calculate it for you but it would cost you about £150!! :D :D :D

And you're right, let's get the thread back to the OP - Wind farms. Windmills are such beautiful things but are dated technology now.
Are you taking something?

The 8 kW heat load (I've never claimed 6 kW) was my simple calculation of conduction and ventilation losses with no allowance for insolation. Yes, I see you're a member of the noble profession of SAP assessors - well you have to earn money somehow, and you probably have the qualifiactions for it. The SAP assessor I had pre heat pump installation was useless, which I suspect is par for the course.

But the SAP I got, after three tries, (the first SAP calculation involved the idiot using the external dimensions for the house) allowed for insolation, and other heat sources such as electricity consumption (the great thing about electricity is that you get to use it twice). I'd never bothered with that, so the reports I've submitted are pre those adjustments. But looking at my total consumption figures for heating and hot water (the latter entirely heat pump with no aux. heat) the house load has come to 1.5 kW.

You see, the same as your magnificent, expensive, lagged house, at a fraction of the cost.

There's more than one way to crack a problem.

But then, as a simple, happy lagger, you wouldn't understand.

Posted: Wed Oct 19, 2011 12:02 am
by kenneal - lagger
If your heat load is only 1.5kW why on earth did you put in an 8kW heat pump and a wood burning stove? You could have got away with the woodstove and a 1kW immersion heater. I presume there are only two of you in the house so your hot water requirement isn't going to be large. Could have saved yourself about £8k and reduced your current lecky bill. Who's simple now?

Happy Lagger.

Posted: Wed Oct 19, 2011 8:54 am
by An Inspector Calls
very thick lagger

Are you daft or stupid? This is approaching the level of care in the community . . .

Because, the 1.5 kW heat load is post (that means after) fitting the heat pump.


Posted: Thu Oct 20, 2011 4:57 am
by kenneal - lagger
Your English is not very good or you didn't read what the other Inspector in the IMEE Troll Department wrote, the one who took over when you went on a tea break or something.
But looking at my total consumption figures for heating and hot water (the latter entirely heat pump with no aux. heat) the house load has come to 1.5 kW.
As my house has a heating requirement of 1.5 kW, exactly the same as your elaborately, expensively lagged house, I don't see what you have to crow about.
By the way, the 6kW heat load of my previous house was calculated as your 8kw was, the long hand way with paper and pencil and a calculator. SAP wasn't invented in 1975.

Posted: Thu Oct 20, 2011 8:54 am
by An Inspector Calls
very, very, thick lagger

You're definitely on something.

Just what is the IMEE? I think you trying to come up with IEE, nka IET. Please get your attempt at insults correct - nothing worse than sloppiness.

As for the rest, this sounds like biff at his best.

I assumed your 6 kW was the fag packet method, as was original 8 kW. I do know when the SAP farce started. Just that I've never modified my calculation of 8 kW with factors such as insolation and secondary heating - the SAP inspector man did that prior to the fitting of the heat pump, which appears to have reduced my house heat load to 1.5 kW.

All of which still leaves me trying to understand the basis on which you claim wondrous skills as a lagger, when, it appears, your results were reportedly so poor and expensive.

And biff will be seething as you've trolled his thread so far from a serious discussion on the aethestics of windmills.

Posted: Thu Oct 20, 2011 3:09 pm
by Bandidoz
Good point - split the "heat load" discussion to another thread...

Posted: Thu Oct 20, 2011 4:54 pm
by kenneal - lagger
Inspector, fitting a heat pump won't affect the heat load of the house. The house requires a given heat input, the heat load, to achieve a certain internal temperature, normally 21C at a given external temperature, normally 0C, at a given ventilation rate, usually 10 air changes per hour for an unimproved house but could be 5 for a draught stripped house or below 1AC/hr for a very, very good modern draught stripped house.

A medium sized house with 10AC/hr would have a heat load for the ventilation alone of about 1.5kW so either you have got it wrong, you live in a tiny house or it is superinsulated to PassivHaus standards making you a very, very thick superlagger.

I wouldn't allow for insolation on a heating installation unless the house was very well insulated, had a significant amount of south facing glazing and a significant amount of thermal mass as the usual time for the maximum heat load to occur would be at night when the "sun don't shine" as they say.

I too am not a great fan of SAP as I find that it is biased towards gas heating and solar eco bling.

And thanks, Bandidoz, for splitting the thread.

Posted: Thu Oct 20, 2011 5:12 pm
by Bandidoz
I think you are both arguing in agreement but taking different viewpoints on where the "system boundary" is.

Seems to me as though the "heat load of Inspector's house" is IRO 6 to 8kW, the use of a heat pump meaning that only 1.5kW of leccy supply being needed to meet the demand.

Posted: Thu Oct 20, 2011 6:00 pm
by kenneal - lagger
I still have a problem there, Bandidiz as that implies, for 8kW output, the heat pump is working at a COP of 5.3 which is in the excessive to impossible range. Even if the HP is a 6kW GSHP model a COP of 4 might be possible during the summer/autumn but towards the middle/end of winter, unless the ground has running water in it, or the collector field is exceptionally large, the ground will have been cooled considerably and the COP is likely to drop to 2 or even lower giving him a neat input to the house of 3kW max.

To obtain the higher COP numbers the inspector would need a low central heating flow temperature in the 35C to 45C range. He would need either very large radiators or underfloor heating or very high levels of insulation or a mixture of two of those to maintain a comfortable temperature range in the house. With these flow temperatures he would have to use an immersion heater to boost the Domestic Hot Water (DHW) to 55C to 60C, using extra electricity in the process.

As he lives in a rural area, he would probably have access to gas if not, he is liable to power cuts at the worst of times and with the likely future loss of generating capacity he is very vulnerable to loss of electricity supply when his heating is entirely electricity based. The cost of supply is also likely to remain high and get higher.

There will be a problem nationally if we go over to large numbers of heat pump installations and electric cars with being able to generate enough capacity without building a large amount of nuclear. Apart from the environmental problems of this, there is the problem of where we will get the money in the current financial climate to build out ten or twelve new nukes.

The cheapest way long term of satisfying our heating demand is to lose it and the easiest way of doing that is, as Mobbsey says, to put on a hat and coat. That won't be satisfactory for most people so insulation, lagging to quote the inspector, is the next most efficient way. Neither of those ways will satisfy his troll masters' desire for growth so he will poo poo the idea as he has always done.

Posted: Thu Oct 20, 2011 8:04 pm
by An Inspector Calls

You're simply having trouble keeping up with all the hares you've set loose.

My 8 kW heat load, like your 6 kW heat calculation, was a simple calculation of conduction and ventilation heat losses. No allowance in both cases for (a) insolation and (b) secondary heating from lighting/cooking/hot water heating, etc. (You always get to use your electricity twice).

Now, I've had an SAP done which is an interesting exercise but I rather think it over eggs the claims of accuracy. The proof of the pudding is in my annual heat pump consumption figure (and remember it's doing heating and hot water). And that indicates an average heat load of 1.5 kW. The average CoP (I have a heat output meter fitted - but I don't hold too much store as to its accuracy as flow measurements are notoriously difficult to do accurately, esp.if you want them cheap) is 3. So that might imply that the house heta load is ~ 4.5 kW post secondary heating and insolation. But that's not important: the 1.5 kW average heat load is the only figure that matters.

As to your other points:
(a) The ground loop is generous, and is on sloping ground below an extensive marshy area (not our land) which drains through our field.

(b) I went to a great deal of trouble to increase the area of radiators (they don't look excessive as you imply), aiming for a maximum ouput temperature of 45 C. Indeed, the heat output curve of the pump is set to deliver a maximum output of 45 at 0 C outside air temperature. The absolute block is set to 47 C.

(c) Most of the time hot water is entirely heat pumped, targetting 55 C. That's perfectly adequate. Looking at spring months, when there's little heating required, mostly hot water, and the ground loops are at their coldest, the CoP in those circumstances is regularly ~2.5. That's the lowest it gets.

(d) And before we have a lecture on Legionella (albeit, why this is a concern when the water is in a tank and not exposed to air, and is circulated quite frequently, I don't know), it is set to boost the hot water to >60 C periodically. This consumes very little electricity.

(e) I don't have gas. There are occasional electricity cuts - perhaps 2 a year, lasting perhaps 2-3 hours. They don't fall exclusively in winter and have dominantly been planned, notified outages for maintenance and alterrations to the local circuits. They're irrelevant. We can fall back on wood burning stove if required. And in no way am I setting out to plan for some coming Armageddon (in your case I think hoped-for) when we all have to take to the woods with our axes (and machine guns).

(f) Yes, fit heat pumps and nuclear. Great solution. c.f. McKay.

(g) I've never poo pooed the idea of insulation as you'd like to pigeon hole me. Always been keen. But an unconsidered application of it, as you advocate, with no regard to cost is stupid. A heat pump is an elegant, simple, cheap solution, especially for those off gas grid and in stone walled houses.

(h) As for a desire for growth, my view on that is that growth is a misnomer. It's really alterration. Each generation peeing on its own walls, and shifting the chairs around (on the Titanic, if you will). Every generation wants, and will do it. You certainly seem to be doing your fair share.

Posted: Fri Oct 21, 2011 4:14 am
by kenneal - lagger
You are the one confusing things. You are confusing my peak heat load with your average electricity consumption. Are you trying to confuse the people reading this who might be trying to make an important investment decision on their house? I can assure you that I am not trying to confuse anyone. But thank you for confirming my estimates of your system and its performance.
AIC wrote:And that indicates an average heat load of 1.5 kW. The average CoP (I have a heat output meter fitted - but I don't hold too much store as to its accuracy as flow measurements are notoriously difficult to do accurately, esp.if you want them cheap) is 3. So that might imply that the house heat load is ~ 4.5 kW
You can't have two average heat loads. You have an average electricity use of 1.5kW indicating an average heat load of 4.5kW with a peak load of 8kW. That would give a peak electricity demand for heating alone of about 3.2kW when the COP is 2.5. So last December you were using 3.2kW of electricity continuously for about three weeks. If you fitted a heating system to deal with an average heat load you would spend much of the year with a very cold, uncomfortable house.

So looking at your installation, not only did you have the cost of the heat pump, you had the cost of installing larger radiators and a larger area of collector. Make a note of that if you are looking at an installation quote from a heat pump salesman now. Does the quote include those extra costs? You are also in the fortunate position of owning a large area of land with a high and moving water table which means that your heat source is conveniently replenished. Even so your COP goes down to 2.5. What COP is your heat pump salesman quoting? Without the benefit of a moving water table most peoples COP could well go down to below 2 for late winter/early spring when the heat is needed most.

I agree with you on the Legionella point.

Regarding Armageddon, I think it would be sensible to plan for a crash worse than the 1930s. Mervin King, the Governor of the Bank of England, said that there is one on the way soon. If it's good enough for him, it's good enough for me. And remember that it took WW2 to get the world out of that recession.

Once again you mention that I specify insulation with no regard for cost. Builders have been telling me that for thirty five years. Clients, however, have been enjoying the comfort and savings bought about by insulating their homes to more than the economic thickness of the time. The 100mm of cavity wall insulation that was uneconomic in the 70s and 80s is now the requirement. The client who put 50mm of external insulation on there solid walls in the early 80's is now regretting that they didn't put more on back then because their savings would have been greater. It's the economics which are wrong not the insulation. In my lifetime the "economic" thickness of loft insulation has gone from 50mm to 100mm to 200mm to 270mm as fuel costs have risen. Are they suddenly going to stay the same?

The u-value for walls has gone from no requirement to 0.6 to 0.45 to 0.35 to 0.3 so why not just jump to 0.12 - 0.15 when you reach the point where reducing the heat loss any further is just not practical because the insulation thickness to increase the u-value by a significant amount then becomes so thick that the embodied energy in the insulation wouldn't be saved. There are limits, I do agree. At these limits a central heating system is not required. Most people would be saving 80% or more of their current heating bills.

The Green Deal is a good idea as far as it goes in allowing the insulation costs to be spread onto future owners who will also benefit from the insulation installation. But it doesn't allow for sufficient spending even though the government have admitted that fuel costs will continue to rise. As I have written elsewhere what is needed is a National Insulation Scheme instead of more Quantitative Easing paid for by the government printing money and taking it back over a long period. That would do more for the economy than putting more money into the banks.

Posted: Fri Oct 21, 2011 9:00 am
by An Inspector Calls
Well, I'm not interested in semantic smart-arsing through the first two of your paragraphs. My heat load/electricity load for my house, with heat pump is an average 1.5 KW. Same as yours.

But then there's more of the same, telling me, retrospectively, how to cost the installation of my heat pump and heating system. Well.I'm not particularly interested in thrashing through the costs of the heat pump installation with you. I've been there, done that, you haven't. Getting the correct area of ground loop is a design process: the impact on installation costs is insignificant - it's rather like the decision you have to make when you decide whether to have gold plated taps or chrome. But I would encourage every heat pump installer to err on the side of as large an area as possible on the basis that, (a) once the JCB is on site they might as well, for example, drop in another loop, and (b) the conducting pipe is piss cheap.

I'm quite aware of what I had to pay for radiators, and, amazingly, I did note that this was an extra cost before the event! And I thought that aspect through without you telling me! But then, all of the radiators I replaced were over 40 years old so it simply became another process of careful design rather than significant additional costs.

My heat pump salesman was rather devoid of bullshit and made no silly predictions of CoP. Rather, he explained how the CoP could be affected by various factors and together we went on to explore how my installation might achieve as high a CoP as possible (and here's the novel bit) on an economic basis!!!

You statements, otherwise, about CoP are rubbish.

But I'm pefectly happy for you to continuing lagging across the home counties. Just piss off try to tell me, and other people, that heat pumps are a silly solution because you're making yourself look like a fool.