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Pipe run for heat dump

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6:24 pm
22 April, 2009

Tallent

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I'm currently building a house and of course installing solar panels . I am going to oversize the system to get the most out of it in winter. The heat dump is going to be an old boiler coil submerged in a manmade well. I am going to run the plasticpipe through a soil pipe buried in the ground.

Will I need to do anything else to protect the pipework? It will be about 30m long run.

Also there won't be any access once filled in, it is quite a way from panel so heat shouldn't be a problem over this distance should it?

4:43 pm
28 April, 2009

Ecologics

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Hi Tallent,

There are two things I'd mention from your mail:

1. You say you will be using plastic pipes in your solar heat dump, as temperatures can get up to 120 degrees or so in pressurised solar systems there is a chance that these pipes will be exposed to these temperatures and melt. Without knowing the ins and outs of your system completely I would say avoid using plastic altogether and go with copper or stainless steel particularly if you won't have access to the pipes once the system is installed.

2. Your heat dump sounds like it could be a very long pipe run, there may be a problem in terms of the ability of the solar pump to push fluid around your dump and back up to the solar panel when the dump circuit is activated. I've seen this happen when some systems have tried to use underfloor heating circuits as a dump load but when the dump is activated the solar fluid never makes it back to the panel in time and the system stagnates anyway. This may not be an issue with your system but Imention it just in case..

Out of curiousity why are you dumping into a well – is there an advantage to this?

4:58 pm
25 December, 2009

heinbloed

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You do not have to oversize your ST collectors to get the most out of them in Winter, this would be a waste of resources, of energy.

It is propably illegal to interfere with the natural ground water system by heating it up. The ground water is protected by EU legislation. Even though the Irish State gives a damn about this fact (there is no official control on whatsoever is dumped into and taken from the ground water table) the ecological builder should be aware of this problem.

A correctly sized ST collector needs no 'heat dump'. Get a speciallist in and get the project guaranteed in writing, calculations etc..

10:26 am
5 January, 2010

Ecologics

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heinbloed said:

A correctly sized ST collector needs no 'heat dump'. Get a speciallist in and get the project guaranteed in writing, calculations etc..

Hi Heinbloed, We recommend heat dumps particularly with vaccuum tubes in residential DHW solar for three main reasons:

1. To ensure antifeeze is not denatured by the high temperatures reached during stagnation. To quote from a safety document from Tyfocor a leading antifreeze producer: "Tyfocor® L begins to undergo irreversible chemical changes at temperatures higher than 200 °C, with the result that the reliability of the equipment may be endangered." All solar systems have the potential to stagnate particularly in residential situations when the occupants are on holidays or absent. A heat dump will make sure the panels do not stagnate and the antifreeze remains active for the winter months.

2. There are no accessible insulation materials that can guarantee prolonged exposure to stagnation tempertaures of 200 degree plus. This results in the eventual degradation of the insulation materials around the pipe work directly attached to the panels. A heat dump aviods these temperatures and prolongs the lifespan of the insulation.

3. If a system goes into stagnation the emergency shutdown function on most controllers is activated when the panels reach 140 degrees. On a summers day this means the whole system will not come back into operation until the panels cool down which is often not tilll night time. This is a potential waste of energy should the cylinder be in a position to accept heat later in the day.

Essentially a heat dump allows a system to operate without stagnation which increases the longevity of the components and maximises efficiency.

8:59 pm
6 January, 2010

heinbloed

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Well, drain-back systems do not overheat. They need no anti-freeze. At a temperature set at the solar station they empty automatically. This is used as an over-heating control set at ca.95 degrees Celsius as well as a freezing control mechanism when set at ca. 5 degrees Celsiuis.

There are now several systems listed on the ESTIF home page, bearing the solar keymark and neither over-heating nor freezing. Without glycol they work, just tap water. And since neither the collectors nor the pipes are pressure stressed when in operation the components last much longer.

The thermal storage tank made from cheap plastic, safing hundreds or thousands of Euros alone, depending on the size.

The collectors as well as the plumbing can be choosen from the cheaper range. The thermal insulants last longer as well when not exposed to high temperatures.

Another method to avoid boiling is the correct sizing and installation of the collectors.

Putting them NOT at the maximum harvest angle (exposed to the Summer sun at midday at an angle of 90 degrees) but a bit over the maximum possible Winter harvest.

This positioning does not need a dump.

There are calculator tools available telling us how much energy will be harvested at which positioning. Any excess heat (in case the tank temperature reaches 95 degrees Celsius in Winter) can be fed directly into the building's central heating system.Most heating systems would be happy with much less….

Safing space heating energy and the energy to manufacture the anti-freeze as well as the energy needed for shorter intervalls to service the system.

Making ST economical viable without subsidies.

Heating-up the ground where the natural existing organisms responsible for cleaning the water NEED the natural ground temperature to survive will kill these organisms. Not only living organisms will be killed by the heating-up but the chemical structure of the ground will be altered as well.

This causes demage to the ground water, to the water quality, to us. Most bacterias and micro-organisms living in the ground water have a life-span of decades, some get over 100 years old. Provided they live under stable conditions like temperature and nutrient supply, gass concentrations and chemical/ph conditions.

Warming up the ground by only a few degrees Celsius for a short period kills them. Allows for sick-making bacterias used to warmer temperatures and a higher nutrient concentration but less oxigene to take over the reign.

Think about what happens to food if not stored at stable, cold temperatures.Water is our most important food.

All this can be avoided by using logic when installing the ST system. No digging, cheaper equipment, less installation work. Less energy consumed, less money spend. Longer life span and more thermal energy in Winter time. More usefull energy.

Just by changing the angle of the collector and by allowing free gravity energy to be exploited.

6:24 pm
7 January, 2010

heinbloed

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Hi!

(Excuse my impersonal earlier post, no greetings, no “hello” ect.)

The latest issue of “SUN&WINDENERGY” 1/2010 has a list of 20 drain-back systems published, incl. 6 of them running on pure water. The article runs from page 54-61 and is written by Joachim Berner, titled ” Safe from to much sun”. The list of system manufacturers is published at page 56-57.

http://www.sunwindenergy.com/swe/content/aktuellesheft/popup.php?ausgabe=01%20/%202010&pic=ainhalt/swe-2010-01-1.jpg

Incl. a British company (Atmos) , 2 Dutch Companies ( IthoBv and ZEN International) and 1 USA companie (Solar Hot). And the Germans of course, Rotex and PAW.

All 20 on a market overview showing drain-back manufacturers selling 'systems', complete packages containing tanks, pump stations and collectors.

The big players from China are not listed, there the drain-back systems are state of the art, see my last post.

Drain-back ST installations can be installed by any competent plumber using everywhere available materials, one doesn't have to rely on packages, systems.

So there is no excuse to dump energy anymore (smiley) or to install expensive, overdimensioned ST systems costing more energy then they safe.

Good luck

5:09 pm
8 January, 2010

Quentin

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This is a rather unusual way to do a heat dump, and I am not convinced it is any cheaper than the normal option which is a radiator, adequately sized, either in a north-facing bathroom, or on a loft, or even outside the house under the roof eaves.

There is no big deal about this. All that is required is a three port motorised valve and a radiator. Alternatively, some installers use the top coil to circulate the surplus heat into the central heating, but that means twice the electricity useage as two pumps are running.

Drainback systems are not a panacea. They require a higher pressure pump, as it must pump a head height from the coil to the panel (whereas your normal circulation pump is just circulating). You are still left with a panel going to its stagnation temperature which may damamge insulation in close proximity to the panel. You also leave the panel sitting at a high temperature and while the coating may be designed to take stagnation, this can accelerate the aging of the butyl rubber seal.

Drainback systems must ideally use a panel that drains properly, and this is not possible with most vacuum tube systems, in which case residual water will boil. You should only really use a drainback system with a panel designed for such use. That usually means no vacuum tubes, if they happen to be your preferred option.

In terms of designing a system so that it will never go into stagnation, that doesn't take into account summer vacations, or times when for one reason or another the householders don't take a bath two nights in a row, leaving the cylinder starting the next day already close to its temperature.

Overall, I would always recommend a heat dump. The extra component costs are just a few hundred euro, and if this means prolonging the life of the system, it is money well spent.

6:25 pm
8 January, 2010

heinbloed

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Well, Quentin, some 100 million systems using drain back methods have already been installed.

Here is an Irish system using vacuum tubes, installed in Youghal and working since 2 years:

http://www.4shared.com/dir/22533121/14e77a6b/sharing.html

At picture IMG_0704.JPG you can see the pump station including the pump (enlarge the image for details). It is the weakest pump available on the market, there is simply no smaller one. A "Laing ecocirc Typ D5 solar ", so small that it can run on PV. It demands 8-24 Volts, has a min. start consumption of >1 Watt and a max. consumption of 22 Watts.

I run it at around 10 Watts and 12 volts when on grit, using an oversized transformer consuming more energy then the pump itself.

I always run it on max. possible output of about 7 liters/minute.

And on PV at around 16 Volts, I don't the wattage there.

I have it most of the time on PV, only when the weather is to dark and the PV doesn't deliver enough energy the grid has to kick in.

There are many myth's with everything that hasn't been seen before.

Fact is that these systems do work. There are more evacuated tube collector systems installed then flat panel systems around the globe, for economical reasons most run as open,quasi drain-back installations.

And one does certainly not protect the rubber butyl sealant of a flat panel collector when dumping surplus heat (smiley). The sealant is air cooled, being exposed to the fresh air. As the glas pane and the frame.

The incompetence of the plumbing industry and their greed to maximise profits is the only reason why drain back systems are not further known in the northern part of the EU – so "SUN&WINDENERGY". This is also my experience.

In southern Europe they kick in big, Spain and Italy and Greece are now going for it.In Spain the open drain back systems are running since decades. Without butyl rubber destruction.

SolaHart, the Australian pioneer, is using flat panel collectors in drain-back versions since 50 years. In Australia, and no destruction of the butyl rubber, no heat dumps…..

Mineral wool insulation is not destroyed by heat/high stagnation temperatures. Sure, the more expensive, more profitable foam is…

Any flat panel can be used in a drain-back system, again it is a question how competent the plumber is.

It is a big deal for the plumbers to rip-off their clients, selling surplus equipment, offering expensive works and maintenance.

Imagine a ST system costs only 20-40% of the end-price of what clients are used to. That would ruin most installers and make ST systems in the current subsidy enviroment for free.The subsidised household would get a net income with each installation.

A boost for the energy conscious consumer. But it is not in the interest of the plumber to deliver a good deal to the client, it's the interest in his own vallet what keeps him in the profession.

Therefore it can't be what shouldn't be….

Have you ever seen a drain-back system working?

Quote:

"Overall, I would always recommend a heat dump. The extra component costs are just a few hundred euro, and if this means prolonging the life of the system, it is money well spent. "

Sorry, but for a few hundred euros you can buy an entire ST system. Incl. the tank and the evacuated tubes, see the ecologics system from China. And incl. the drain-back/overboil function.

If water boils away in an open tube system it will be replaced. No problem, no costs.

The system you can see at the provided link is working now, I still have to switch it off. After dark. Delivering many kWh per day. Heating the house. A drain back system without glycol, without antifreeze. Last night we had here in Youghal minus 9 degrees Celsius, no breakage, no freezing. Starting happily this morning on it's own , driven by the sun's energy only.

And the only heat "dump" being the thermal storage plastic tank and the atmosphere.

Would you like to see it in situ as well ?

There is a British company using drain-back systems as well, no heat dump, no glycol, no overheating, no butylrubber destruction, cheap plastic tank etc.. Atmos.

They might use the more resistant, cheaper, food-grade silicone rubber sealants however, as I do.

"sun&windenergy" offers free issues. If you contact them.

Try to get hold of the issue 1/2010. Or simply order it for a few €s.

Plenty of information and some critical words about incompetent plumbers. And about other parts of the renewable energy industry as well.

Again: You're welcome to have a look. And no, I have nothing for sale.

5:25 pm
14 January, 2010

Ecologics

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heinbloed said:

Well, drain-back systems do not overheat. They need no anti-freeze. At a temperature set at the solar station they empty automatically. This is used as an over-heating control set at ca.95 degrees Celsius as well as a freezing control mechanism when set at ca. 5 degrees Celsiuis.

Hii Heinbloed,

There are two issues here:

1. This still means the panels will stagnate regularly and reach temperatures above 200 degrees particularly if using vacuum tubes – from our experience and from conversations with manufacturers and other suppliers this is not a recommended situation. Flatplates left to stagnate will endure degradation of the rubber seal that weathers the joint between the glazing and the panel body. In vacuum tubes the insulation materials on the pipework adjacent to the panels are only usually capable of enduring temperatures up to 150 degrees and not for long periods of time. In the interests of durability we recommend that these temperatures are avoided if possible.

2. You recommend a u-pipe vacuum tube – how can these be used in a drainback system as the fluid within the u-pipe will remain within the panel when the pump shuts off.? If no antifreeze is used in the system then this would be at risk of freezing in winter.

I think one thing that is highlighted here is that there is a difference in perspective from a homeowner with the ability to install and manage their own system like yourself and a company like Ecologics who have a responsibility to ensure the safety and longevity of the systems we install for the general public. We endeavour to strike a balance between affordability and effectiveness with the aim of making renewable energy easy to install and available to as wide a portion of the public as possible without compromising on quality. In terms of the bigger picture of sustainability and climate change we feel that this is imperative and we are making progress.

3:12 pm
17 January, 2010

heinbloed

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Hi Admin!

My English seems to be very bad…

To an open system stagnation doesn't matter. The water can boil-off/evapourate at 100 degrees Celsius. And will be replaced when demanded.

A drain-back system doesn't boil at all. The water drains back into a storage tank before it boils, reaches a temperature above 95 degrees Celsius.And before it freezes as well.

Think about a roof, a raindrain, a water barrel and a pump with a gardenhose: The water in the barrel is pumped up to the roof where it is warmed up when running down over the slates. It runs down into the barrel. From where it is pumped up again.

As soon as the pump is switched off the circulation stops. No freezing, no boiling. Plain and effient.

So there is no temperature of 100 degrees Celsius at the pipe work, the sealant rings ect..No expansion barrel. No Glycol. No emergency valve. No metal tubing/pipes. Nothing but collector, plastic pipes and a storage tank plus pump.

The thermal loss of a vacuum? Eta 0. Eta zero. So no need for thermal sensors. A timer at the pump. No cables from and to the collector.

Plain.

This makes the ST system based on an open drain back method easy to install and gives a very long lifetime with no maintenance involved. An efficient investment for everyone. Without subsidies, cheaper then any other method of using renewed energy.

About evacuated glas tubes:

( "2. You recommend a u-pipe vacuum tube – how can these be used in a drainback system as the fluid within the u-pipe will remain within the panel when the pump shuts off.? If no antifreeze is used in the system then this would be at risk of freezing in winter.")

Not all vacuum tubes hold surplus clutter in them. Like U-pipes or heat pipes.The vacuum is the best insulant mankind knows.

I never recommended U-pipes or heat pipes, just the oposite. I consider these as trash. Inefficient, expensive. Leading to overheating and pressure, reducing the efficiency of the investment. Millions of households and industries use vacuum tubes with nothing but a vacuum and water in them. Like me for example.

Only the horizontal collector pipe-where the vacuum tubes end in- is drained to a certain amount, about 2/3. Not the vacuum tubes themself. Why should they? The vacuum holds the water in the tubes above freezing temperatures after all.

The recent winter showed temperatures below minus 12 degrees Celsius here in Cork. No freezing in the tubes. These ST systems are guaranteed for Wisconsin/USA with minus 32 degrees Celsius. No problem. Pure water, no antifreeze.

The combination of two methods, namely drain-back plus open, is far more efficient then anything else.

2.7 m2 of collecting surface (4m2 total surface) for €700.- incl. the stand. Or around € 600.- at e-bay. These are consumer prices and incl. VAT

They're the only ones where a pay-back/ammortisation can be expected. Because of their low costs and their long life time.

All the other subsidised ST systems never pay-back. An open secret of the trade. Therfore subsidies are needed.

The Chinese have no subsidies for private energy consumption. They must see a pay-back when going for ST. Therefore technical clutter has no chance there. Only the open systems using evacuated tubes are a market sucess in China.

You're welcome to watch such a system working in Ireland.

3:26 pm
17 January, 2010

heinbloed

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Imagine you can get € 800.- subsidies for an evacuated tube collector (according to the list of ecologics) but the collector costs only € 700.- …incl. the VAT.

You don't need much phantasy for this.

THIS IS REALITY !!

A waste of taxpayer's money. Well the exchequer can have €150 back on this, the VAT (smiley).

Under these conditions the pump station is payed as well, the insulated pipe work included. " Free " energy. Thanks to the subsidies.

Why not going for it, ecologics?

You would be the first company in the world able offering "free" energy, thanks to the mad subsidy politics of an incompetent gouvernment.

The Irish Farmers dump "free" milk powder in Africa ruining the local farmers there, so why not ruining the fossile energy industry here in Ireland ?

Killing the fossiles like Shell and ESB with their own arms. It's in your hands.

I can provide you with the knowledge and you do the "dirty work" (pressing the 'ironic button' hardly !).

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