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Most efficient method for water heating?


johnnyboy
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Well it seems nothing much changes in forum land.

I don't intend to do anything more to guide either you as clearly that is a lost cause.

But for anyone else out there who might be considering such things, know that when you calculate something like this, the best results will be gained considering ALL the factors not just the one to get the outcome you expect.What has just been illustration in the posts above is the way NOT to make a fiscal analyis of heating technology.

If cost/payback is the only issue in the deliberation for what ever the system should be,  then add Installation + (running costs x compound increase over the rest of your life) + maintenance + possibile replacement cost of both systems and at least then a realistic comparison might begin to emerge.For reference, the result you should get is something between 3 to 6 years. Mine was a big system and has just now reach its amortisation point after 5 years.

That'll do I think.

O

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I don't understand your comment "nothing changes in forum land". You bought the subject up so it is open to debate.

You made some comments which I and another have called in to question. You say they are wrong but offer not alternative. I am not saying this form of heating is a bad idea, in fact the opposite, but you do have to take certain things in to account. There are lots of negative myths about solar water heating but there are also lots of positive myths from manufacturers as well.

An excellent source for these systems and energy saving in general is the Energy Saving Trust (EST). Their financial calculations will not be quite the same as in France die to electricity costs, 'grants' and installation costs.

They will tell you as will any expert in this field that the first place you should spend money is on insulation. The better your insulation the more money you save.

From their website they claim based on your system being installed by a properly registered installer is that you get payback at seven years but they have been wrong in the past. I can imagine that this time will be quicker if DIY installed but then you will loose ether the five or ten year guarantee, or so they say. Also installing this type of system may well be beyond the skills of many forum members, in fact beyond many people in general but then I know some people in the UK who can’t even wire a 13A plug and that’s just the blokes.

Running costs - well there is a little on a non passive systems which uses a pump because it is electric.

Installation of a system and that of replacing an existing electric water heater in France will be dramatically different.

Because of the chemicals (anti freeze) used in solar heating systems both on the EST and other websites that specialise in these type of systems recommend that apart from watching for leaks all other maintenance be carried out by an approved installer/service company.

Maintenance of a typical French electric water heating system is simple, just bleed it using the vent at the bottom. Anything else should be done by an approved electrician/plumber. We still have the original water heater installed in 1983 running as well as the rest installed in 2001 and no problems. I note that a replacement solar panel costs from £200 (239 Euros) upwards (excluding fitting) although in non passive systems the pump is the weakest link which according the EST will set you back around £90 including fitting. A complete new electric hot water heater will cost you 175 Euros plus fitting but a complete new solar system will cost you 2,500 Euros excluding fitting (less as the pipe work would be there already).

From an environmental perspective i.e. carbon production you also have to take into account that 80.4% of French electricity is nuclear and only 3.1% is carbon based the rest is renewable. France is in fact the third lowest carbon producer in the world way less than all but one European country. An interesting thing I discovered is that when solar water panels are manufactured to ensure they are manufactured to the highest quality and efficiency they are ‘washed’ in Nitrogen Trifluoride several times. Nitrogen Trifluoride is 17,000 times more damaging to the atmosphere than Carbon Dioxide which means in short that the claim they don’t give off greenhouse gases is in fact not true. It’s a bit like electric cars and their batteries. However personally that would not put me off buying them if I thought I was going to get my money back in double quick time and then go on to save me a shed load of money.

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Pertinent comment about insulation and a well thought out reply in general. I simple cant believe the difference in energy consumption and comfort a well insulated home offers. Our new house carries the RT2005 energy label, with added 300mm of "laine de rouch" in the attic and all new double glazed windows with a special gas in-between the pains of glass. We heat the 'insert' wood burner for about 4 hrs during the evening heating the house up to around 28C in the lounge and 24C in the other rooms (all doors open of course). This heat stays in the house for a full 24hrs, dropping to around 21C by 20.00 the next night Given that i cut most my wood, this is the first year we heat during winter almost for free! I'm currently building a new house with the RT2012 label, which believe me, is extremely tough and effectively makes the house practically energy positive (if renewable energies are used).
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[quote user="Quillan"]

One hot water tank in my house runs only at night. The current price, (looking at my most recent bill) is around 6.5 cents per Kwh (including taxes). My tanks have 2kw heaters so thats 13 cents per hour. [/quote]

Q, is that correct?  From EDF's website they quote figures after tax at Peak 0.1467 off peak 0.1002.  No time to post the link but that is what it says and before the January price hike.

[quote user="Quillan"]

An excellent source for these systems and energy saving in general is the Energy Saving Trust (EST). Their financial calculations will not be quite the same as in France die to electricity costs, 'grants' and installation costs.

They will tell you as will any expert in this field that the first place you should spend money is on insulation. The better your insulation the more money you save.

From their website they claim based on your system being installed by a properly registered installer is that you get payback at seven years but they have been wrong in the past. Running costs - well there is a little on a non passive systems which uses a pump because it is electric. [/quote]

Why when you quote them as an "excellent source" do you then not believe the 7 years comment, it seems you just select points that you want to agree with which maybe what Oracle means by nothing changes in forum land.

 

[quote user="quillan"]

An interesting thing I discovered is that when solar water panels are manufactured to ensure they are manufactured to the highest quality and efficiency they are ‘washed’ in Nitrogen Trifluoride several times. Nitrogen Trifluoride is 17,000 times more damaging to the atmosphere than Carbon Dioxide which means in short that the claim they don’t give off greenhouse gases is in fact not true. It’s a bit like electric cars and their batteries. However personally that would not put me off buying them if I thought I was going to get my money back in double quick time and then go on to save me a shed load of money.

[/quote]

Whilst the chemical itself is damaging, it would be your generation that found this out only after damaging our environment.  We used to wash metal components in the same system and it was estimated from each tank 1 tonne of this was evaporated into the atmosphere each year and we had 6 of those wash tanks!  One of my projects was to cut this to save the company money but I also wanted to reduce the damage this would be causing.  It is now prohibited to allow these chemicals into the atmosphere and companies now by plant that condenses 99% of the wash agent back into the tank as it saves a lot of money. 

I do agree that there is a lot of "green wash" out there but seriously PV panels are now at 50% of their previous price and solar hot water should be a must right after the insulation installation

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I only know a little about RT2012 but it is defiantly the way to go. I am very interested in going the "Passivhaus" route for my "retirement" house. I call it that as it will probably be the last house I will ever live in. My aim is to build the most energy efficient house I can because lets face it you don't want to spend all your pension just keeping warm (or cool in the summer). A Passivhaus, in case people have never heard of it. is a house that is 90% or more energy efficient. There are some brick ones now but the majority are built of wood. There are currently only two certified houses in France but they are very expensive to build. I am not an architect so the structure design will be down to professionals but what I am interested in is designing system using existing equipment rather than pay a fortune for specialised and very expensive equipment. Needless to say it will have solar water heating not to mention solar panel (and possibly wind) electricity generation although my aim is to store the electricity rather than sell it to ERDF. Neither of these things I consider to be good value for money if you are installing them into an existing house because of cost but when building from scratch it is much cheaper to install.

A person I have known ever since coming to France (they are the people we rented from when we first came here) are trying to build such a house at present. One area of significant saving is heat exchanging. These houses are basically airtight so air is taken in from the outside, circulated then expelled but the heat (or cold) is removed via a heat exchanger (recovery) and applied to the incoming air. Specialised equipment is quite expensive so he has decided to use a single inverter a/c unit but in 'reverse'. He has drilled a well and uses water from it and a recovery tank to run showers, toilets etc. Rather than buy an expensive water filtration system he is experimenting using a filter system designed for medium sized fishponds. He is not looking to drink the water so as long at it looks clear it is not a problem.

For electricity he using solar panels but we (I have helped him on this) have designed a system using four second hand submarine batteries and a Mastervolt four step charger and pure sine wave inverter with built in battery management. All he then needs is the smallest possible EDF electricity supply to supplement the charging should it ever be required.

The only form of heating for winter is a single small wood burner. The house is 'upside down' ie living upstairs and bedrooms downstairs so upstairs is a comfortable 22 deg and the bedrooms 18 deg. The house was 'fired up' last week for the first time and whilst it is no where near completion internally the systems appear to be working as expected but it is yet to get 'super cold'. The electricity seems to work but because of the amount of work still being carried out it requires an outside power source at present but once finished and all the building equipment removed it should work rather well.

All this designing is nothing really to do with being 'green' it is all about building a cost effective highly energy efficient home whose running cost will be next to nothing.

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Théière

Electricity prices - I am using my bill for 2013 and taking into account that the time of the year when solar heating is at its most efficient which equates to between 8 and ten months and that the tanks only heat at night then the rate is 0.041 kWh. I rounded it up to 0.06 to take into account tax etc. If you want I can scan the bill and email you a copy.

EST - Most people in the UK consider them to be an excellent source. 'O' said 3 to 5 years and they claim 7 but I did say that is when installed by professionals and it would be quicker if you DIYed the installation. I also pointed out however that this sort of equipment installation that would be beyond the abilities of the average home owner.

Chemicals - A lot of these panels are made in countries where there is little or no regulation on their use nor on the well being of the workers who manufacture them. The ones built in the EU probably meet all the requirements for health and safety plus the environment. PV panels are for electricity and we are talking solar heating but the price of their manufacturing has possibly reduced as well especially with cheap Asian imports. Yes I agree with your last comment but only after you have applied all the insulation you can. Unfortunately because you can't see insulation many people don't even think about it seriously which of course they should and that’s where you should be injecting most of your money. I still believe that all these solar system for electricity and water are much cheaper to install when building from scratch rather than retro fitting afterwards. Therefore by being cheaper to install the money you save and the payback time is quicker. Would I personally install them, yes but only when building a new house.

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Hi Peeps,

Just a small update on our little saga. The bozo's came back last week and after a minor flood in the atelier ( no drain valve fitted to system, so drained by loosening the lowest connection!). They then proceeded to try and flush the system with fresh water, the only problem being that there was no flow around the system. Several hours later after flushing all the pipes successfully, we now find that the panels themselves are blocked. I had worked that out for myself, when they showed me the air bleed valve at the top of the system was gummed up with a blck substance (boiled fluid)!

They then cleaned up and left , himself saying that he will contact Buderus, reference cleaning out the panels. I for one think that this will be impossible due to the viscosity of the gummy substance. I stand to be corrected, but I don't think we will be seeing any further movement on this before the new year now. Which is a shame, as here in Limousin at the moment we have bright sunshine and 7.0 degrees, the temperature at the sensor on the roof showing 117 degrees C.

Will update further if and when!!

Johnnyboy

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  • 4 weeks later...
Another update! Well it appears that our solar water heating panels are blocked with a Tar - like substance, the Air Purge Valve was brought down for inspection first, which is where I saw this substance. After 3 days the Marx brothers had determined that it is the panels themselves that are blocked, not the pipework in the system.

They then put in a fluid on recommendation from the manufacturers, to try and clear the system. That was over three weeks ago and no idea other than a vague "we'll return in early January" of what they propose next.

Have been in touch with UFC Que Choisir over this matter and to date they have been helpful, but still no definitive result. At least its comforting to know that they are aware of entreprises such as this one and are prepared to help to try and get a result on our behalf.

The Expansion Tank was found to have a leak on the air side of the diaphragm, which seems the most likely cause of poor circulation in the first place and consequent dumping of fluid overboard via the PRV. Also , Mr D**khead has informed us of the need to replace the fluid every 3-4 years, not very helpful as he filled the system originally over 5 years ago and never mentioned before! Anyone know if this is a requirement, as the only info I've located on the web, is to check the fluid every 2-3 years for the anti-gel content?

More will follow, if and when anything happens.

Johnnyboy

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One other thing came to mind this morning, we have "Juridique" cover under our insurance. So the idea from UFC was good, ie, contacting insurance to get an expert to examine and advise on the problem. However, on contacting them we find that there is no cover for Solar Panels or PV panels due to so many cowboy outfits who installed systems then disappeared overnight apparently. No mention of this in the pamphlet as far as we can see, have booked an appointment with the bank manager who sold us the policy (16th Jan) to try and find out any further info.

So we are left trying to find someone who could inspect/advise ourselves, anyone have any ideas on where please?

Johnnyboy

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I am not certain by any means but I beleive the insurer will instruct the expert as that is someone who they would regularly work with.  Still following your thread as I like the updates and info on outside temp and panel temp which is helpful.  Good luck with this, it's annoying when companies "learn on the job" and customers end up knowing more than installers which is something that should never happen unless the customer has a degree or better in the subject.

 

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Thanks T,

Insurance Juridique does not cover solar water panels or PV panels. The reason given to us was that in the beginning there were so many cowboy outfits involved in the installation side of things which then disappeared overnight, that they refused to give cover in this instance. There is a catch phrase in the exclusions that covers this type of installation.

As for learning on the job, although I have an engineering background through the aircraft industry I do not claim to be any kind of expert on heating/solar systems. I do however read and digest any info I can find, the latest being why are the middle and lower temp sensors in the hot water tank in the same pocket? Which I noticed this morning! Looking at the info I have, it suggests to me that the lower sensor should be alongside the pipes going into the tank from the solar system.

As for the panels being blocked, it is caused by the glycol seperating into its constituent parts, water and sugars (brown to black in colour) and the sugars sticking to the inside of the system. A process termed "Candification" , this should be cleaned out by the fluid added recently apparently. Hope this is correct, as the pipes in the panels are only (10mm) dia.

This info came from a very helpful guy at Worcester Bosch in the UK, as Buderus france just kept giving us the run-around and saying that we should speak to the installer!

The workmen have just arrived as I write, will update with any news later.

Johnnyboy

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Reckon you're right Lehaut, the panels are coming off the roof at this very moment as the cleaning fluid did not work as advertised! I did wonder quite how the fluid was going to percolate round the tubing when its only 10mm diameter, even under 2 bar pressure.

Must go and have a look for myself now.

Johnnyboy.

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The other panel was removed today and the whole area re-covered with roof tiles, so we're obviously in for a fairly long waiting period!

The latest idea is to try and force hot water through them, but now I am informed that the pipes are 5-6 mm diameter they think. So we'd best not hold our breath then!! The top and bottom pipes are probably about 10 - 11 mm dia and seem to be clear, its just the heating tubes within the panel which appear to have the problem. They are tee'd off a small way inside the panel apparently then snake their way up from the bottom to the top tube.

Cannot add any more for the mo.

Johnnyboy.

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  • 2 weeks later...
Ok T, guess it'll be a couple of days before I get anything meaningful out of the system though. Also have to sort out whether the temp sensor for the lower part of the tank is in correct place, at the moment its in the same pocket in the middle of the tank as the sensor for the boiler. I personally do not think this is correct, looking at the schematic drawing for a similar system (albeit, a different boiler part number). Cannot find anything showing our boiler (Buderus G125 Oil Fired), must try and get hold of that very helpful guy at Worcester Valves again.

Keep you posted,

Johnnyboy.

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Its German manufactured and came with a load of pamphlets in french and several other languages, all except english!!

Have found literature in English for some of the other components online, but nothing about the boiler itself.

Just had himself come in to say they have finished now, so just have to wait until the sun comes out again!

Johnnyboy.

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Don't talk about gaskets to me! Our pellet stove had it's yearly check etc early December. We smelt smoke shortly after - it took two visits to discover that one of the flue gaskets had been split. So far - it is still on order...importer out of stock... time of year ...etc !!!!

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