solar thermal expansion tanks and valves specialists …€¦ · 100 sun & wind energy 9/2010...
TRANSCRIPT
Sun & Wind Energy 9/201098
Solar thermal expanSion tankS and valveS
Safety valve by Orkli
Safety valve by Watts Industries
Air separator and air vent by Voss
Air vent cylinder as part of the air separator and air vent by Taconova
Air separator and air vent by Spirotech
Mixing valve by Watts Industries
Safety valve by Barberi
Air vent by Watts Industries
Mixing valve by Caleffi
String controller valve by Orkli
Looking into the solar thermal exhibition halls of Intersolar, shimmering blue collectors catch the eye. Between the collectors are rows of stands,
their displays stacked high with innumerable small parts. They sparkle with brass and stainless steel. Mo-ving closer, one can recognise in the inconspicuous metal parts highly specialised valves and air vents used in solar and heating circuits. Without the highly precise performance of these parts, solar thermal sys-tems would not be able to do their work.
Italian fittings specialist Caleffi S.p.A., Switzer-land‘s Ostaco AG with its Taconova brand, Orkli, S.Coop of Spain and Watts Industries Europe B.V, for in-stance, all offer full solar hydraulics product lines and, in addition to individual components, also carry com-plete solar stations. Others actually produce just one, or a handful of components (see table 1). Giacomini presented its valves for the first time at Intersolar in Munich this year. For 10 years the Italian company has been active in the solar market, a segment which com-prises some 5 % of its business. Spain’s AC-fix has been producing valves in China for the solar market since 2009. It has been manufacturing fittings for plastic pipe for some ten years. The company is also present in the solar market with its AC-FIX Solar prod-uct line and plans to expand its product offering for that market to include other components. One exam-ple of a highly specialised company is Italy’s Varem, which produces expansion tanks. The company is
Ever more heating system fittings manufacturers are
making special components for solar thermal systems.
SUN & WIND ENERGY provides an overview of which
companies offer expansion tanks, air vents, and valves.
Mixing valve by TA
String controller valve by Barberi
Specialists abound
Mixing valve by Orkli
String controller valve by Caleffi
String cont-roller valve Watt Flow
Mixing valve by TaconovaString
controller valve by Taconova
Air vent by Orkli
Photos: manufacturers/Wilhelm Breuer (3)
Sun & Wind Energy 9/2010 99
from the metal tank and storage tank industry. The German-Italian Zilmet Group, headquartered in Italy, is another leading expansion tank company. Voss Ent-lüftungs-Armaturen GmbH of Germany has traded ex-clusively in heating system air vents for over 35 years.
Letting the air out
After all, one element not at all welcome in heating sys-tems is air. That is where air vents and microbubble separators come in. They are built into the solar circuit and show unwelcome guests, moving about as air bub-bles or microbubbles in the system, the way out. One has to distinguish between air from the filling process and air from normal operation of the system.
The first time the system is filled, the air vent en-sures that no air gets into the system, but rather that it is completely displaced by the solar liquid. Air escap-ing from the water/glycol mixture also builds up as the system operates. This is handled by air separators which trap air bubbles in fine mesh or screens and capture them in an air pocket, which is then emptied through an air vent.
Previously, air vents with shut-off valves were lo-cated on roofs, while microbubble separators were at-tached to pipes in the basement. Now, however, new products have been developed which can serve both functions. Dutch company Spirotech offers a large au-tomatic air vent in its product line. The Spirotop Solar is suitable for eliminating air resulting from filling, as well as venting air generated in normal operation. It can remove large air bubbles from a system and is in-stalled on the roof like conventional air vents. The com-pany‘s other product is a microbubble separator, the Spirovent Solar. In a discussion at Intersolar, Volker Hafner of Spirotech voiced his opinion that air separa-tors and not just air vents should be located on roofs. After all, the venting point should always be placed as high as possible, where the pressure is highest and
CompanyExpansion tanks
Safety valves
Mixing valves
String con-troller valves
Air sepa-rators
Air vents Solar stations Website
AC-fix Global Piping Systems x x x x www.ac-fix.com
Afriso-Euro-Index x x www.afriso.de
Barberi Rubinetterie x x x www.barberi.it
Caleffi Armaturen x x x x x x x www.caleffi.de
Elbi x www.elbi.it
Esbe x www.esbe.se
FAR Rubinetteria x www.far.eu
Flamco Wemefa x x www.flamco.de
Giacomini x x x x www.giacomini.com
Heimeier x www.heimeier.com
Honeywell x x x x www.honeywell.com
ICMA x x x x x x www.icmaspa.it
MFC Solar x x www.mfcsrl.it
MUT Solar xwww.mutmeccanica.com
Orkli, S.Coop x x x x x x x www.orkli.com
Oventrop x x x x www.oventrop.de
PAW x x www.paw.eu
Pneumatex x x www.pneumatex.com
Reflex Winkelmann x x www.reflex.de
Spirotech x x www.spirotech.de
TA x www.pneumatex.de
Taconova x x x x x www.taconova.de
Tiemme Raccorderie x x x x www.tiemme.com
Tuxhorn x x www.tuxhorn.de
Varema x www.varem.com
Voss Entlüftungs-Armaturen x www.purgomat.de
Watts Industies Deutschland x x x xwww.wattsindustries.com
Zilmet Deutschland x www.zilmet.de
Table 1: Overview
Source: manufacturers’ information
Expansion tanks by Varem, Zilmet and Pneumatex. Photos (3): Wilhelm Breuer
Sun & Wind Energy 9/2010100
Solar thermal expanSion tankS and valveS
Source: manufacturers’ information
the temperature lowest. Placing the Spirovent Solar at such a location allows it to vent air when the system is filled and afterwards continuously release air from the system. In the air separator, the fluid flows through a spiral structure. The tiny bubbles rise to the top, collect in an air chamber, and are released through an air vent. The air separator can be installed either a hori-zontally or a vertically in the pipe system.
The Spirotech product has a special, patented au-to-close function on the air vent or air separator. A part in front of the float can distinguish between air and steam. If vaporised solar fluid tries to escape through the valve, it automatically closes. According to the company‘s information, the patented function elimi-nates the need for a shut-off valve or ball valve to pro-tect the solar-thermal system from overheating at high stagnation temperatures. Once the system cools, the valve opens again. The air separated from the system can then escape unimpeded again.
The Voss Purgomat 150 „Hitze“ automatic solar air vent is equipped with a laser-welded stainless steel float. A leak-proof cap with hygroscopic seals prevents a dirty valve seat allowing fluid to escape through the air vent. This lock prevents solar fluid escaping the system when steam builds up. In addition, Voss recom-mends a ball valve, heat-resistant to 200 °C, as an op-tional cut off for the air vent. The Purginox 2000 auto-matic float air vent has a higher venting capacity than other vents and is thus suitable for larger systems.
Companies, such as AC-Fix, Caleffi Solar, MFC Solar srl, Pneumatex, Orkli, Tiemme and Watts Industries of-fer air vents, which in any case are to be combined with a shut-off valve on the roof to prevent an overheating of the system. An alternative approach combines the air separators installed in the basement with an air vent and thus replace the air vent on the roof. The air separator can be installed either horizontally or verti-cally. Such valves can withstand temperatures of be-tween 110 and 200 °C, depending on the supplier (see table 2 and 3).
Taking the pressure off
Once the solar liquid is able to move freely through the system without the interference of air, the next danger looms – extreme high pressure due to the very high temperatures generated within the collector. That is
The inner workings of the air separator and the float air vent with auto-close function by Spirotech. Photo: Spirotech
Table 3: Air vents
Manufacturer ProductMax. operating temp. [°C]
Operating pressure [bar]
AC-fix 8001 Series 180 10
Caleffi Solar Quick vent 200 10
Caleffi SolarHigh-performance quick vent Discal Air
200 10
Flamco Wemefa Flexvent Top Solar 180 10
GiacominiAutomatic float air vent R99S
150 10
Honeywell EA122 110 6
Honeywell E121 110 10
ICMA Art. S111 160 10
ICMA Art. S110 130 10
MFC Solar MFC 3000 200 10
OrkliAutomatic solar air vent
150 6
Pneumatex Zeparo ZUT 160 10
Spirotech Spirotop Solar 180 10
TiemmeAutomatic solar air vent
180 10
Voss Entlüftungs-Armaturen
Automatic solar air vent Purgomat 150
150 10
Voss Entlüftungs-Armaturen
Automatic float air vent Purginox 2000
150 16
Watts IndustriesAutomatic quick vent MV 10 sol
160 12
Manufacturer ProductMax. operating temp. [°C]
Operating pressure [bar]
Afriso-Euro-Index Air separator combination Solar LKS 160 6
Barberi n/a 110 10
Caleffi Solar Micro bubble separator Solar Discal 160 10
Flamco Wemefa Flamcovent Solar EcoPlus 200 10
ICMA Art. S740 n/a n/a
Orkli Air separator 150 6
Pneumatex Zeparo ZUV 160 10
Reflex Winkelmann Reflex exair solar 180 10
Spirotech Spirovent Solar 180 10
Taconova Air scoop Airscoop 160 ’8
Voss Entlüftungs-Armaturen Air separator Micropurg 150 Solar 150 10
Table 2: Air separators
Source: manufacturers’ information
why a membrane expansion tank is such an important component of the solar circuit. Some of the leading manufacturers of such tanks are Zilmet, Varem, Pneumatex and Elbi. The central element of the expan-sion tank is the membrane. Most companies use butyl or EPDM membranes, which on average can withstand temperatures from 70 to 90 °C. Zilmet uses a butyl-based material, the details of which the company does not wish to elaborate on, which can withstand a tem-perature of 110 °C. When too much pressure builds up in the circuit, the liquid is pushed out of the system and into the expansion tank, thus relieving pressure on the system. Generally, the membrane within the tank has a convex shape. Pneumatex uses a bubble-shaped membrane. Rather than dividing the tank into two halves, the Pneumatex membrane is suspended in the tank like a balloon, expanding as the temperature increases. At the moment of expansion, the bubble does not have to move as much as the hemispheric membrane when subject to loading. This is easier on the membrane, says a Pneumatex representative ex-plaining the advantage of the balloon-like membrane. Zilmet, too, has an expansion tank which uses a bubble construction. This design enables the membrane in Zilmet’s Solarplus TM to be replaced. Elbi’s AS/SC and AF/AFL series tanks also have replaceable membranes. The membranes in the Pneumatex products are only replaceable in expansion tanks larger than 1,000 L.
VDI guidelines specify that intermediate vessels should be installed when the possibility exists that temperatures in the expansion tank could exceed the approved temperatures for the membranes. Such a danger is present in roof-mounted central distribution systems with short pipes, but Zilmet points out that there is still a risk even in pipes over 20 m long. The in-
Sun & Wind Energy 9/2010102
Solar thermal expanSion tankS and valveS
String-rEgulAtiOn vAlvES
Company Product Max. operating temperature [°C]
Barberi n/a 140
Caleffi Solar Setcal Solar 130
Honeywell Kombi 3 plus (V5000, V5010) 130
Orkli n/a 110
Oventrop Hydrocontroll STR 200
Taconova Setter Bypass SD Solar HT 185
Watts Industries Watt Flow Sol 160
Mixing vAlvES
Company ProductMax. operating
temperature [°C]
Temperature adjustment range [°C]
AC-fix 8005 seriess 100 30 to 65
AC-fix 8010 seriess 100 35 to 55
Barberi Art. PO4/PO5 110 30 to 65
Caleffi Solar Mixing valve 110 30 to 65
Caleffi Solar Mixing valve 100 35 to 55
Esbe Esbe Basic 90 35 to 60
Esbe Esbe Premium 90 48
Esbe Solar seriess VTS520/S550 110 45 to 65
Esbe Solar seriess VTS520/S550 110 50 to 75
Esbe Solarkit seriess VMC300 90 35 to 60
FAR Rubinetteria Solar-FAR 120 27 to 70
Giacomini Thermostatic DHW mixer R156 85 38 to 60
Honeywell TM200-3/4A 90 30 to 60
ICMA Art. S100-102, S107-109 100 30 to 60
ICMA Art. S103, S112 85 20 to 65
MFC Solar MFC 3070-3074 110 n/a
MUT Series RA 85 30 to 60
Orkli Solar model 130 40 to 50
Orkli High temperature model 130 50 to 70
Oventrop Brawa-Mix 90 45 to 65
Oventrop Brawa-Mix 100 35 to 50
TA TA-Therm 90 35 to 65
TA TA-Therm HT 90 45 to 80
TA TA-Mix 100 35 to 65
Taconova MT 52 mixing valve Universal HC 100 20 to 70
Taconova MT 53 thermostatic mixing valve 100 45 to 65
Taconova MT 53 thermostatic mixing valve 100 35 to 75
Taconova MC 52 mixing valve Compact 100 30 to 70
Tuxhorn Tubra Therm mixing valve 90 35 to 65
Watts Industries Thermostatic mixing valve Solar 110 30 to 65
SAfEty vAlvES
Manufacturer ProductOperating tem-
perature [°C]Operating pressure [bar]
AC-FIX 8004 seriess 160 10
Afriso-Euro-Index Membrane-safety valve 160 6
Barberi Safety valve 150 3 to 10
Caleffi Solar Safety valve 160 4 to 10
Esbe Series VSB 100.300 95 to 120 16
Flamco Wemefa Prescor Solar safety valve 160 6 to 10
Giacomini Safety valve R140C 200 4
Honeywell SM152 95 6 to 10
Honeywell SM120 120 2.5 to 3
ICMA Art. S120/Art. S121 160 6
Orkli n/a 160 3 to 10
Watts Industries Solar safety valve 160 3.5 to 10
Source: manufacturers‘ information
Table 4: Valvestermediate vessel allows the medium to cool down be-fore it reaches the membrane. The VDI guideline recommends an upstream tank when, “the volume within the pipes between the collector field and the ex-pansion tank is less than 50 % of the fluid storage ca-pacity of the properly measured expansion tank.” Zilmat developed a product for such cases a few years ago. The Solarsafe plus combines the intermediate vessel and the expansion tank in a single container. Elbi has been offering intermediate vessels since last year. Elbi’s products are sold in Germany by SferaTec Gebäudetechnik Vertriebs GmbH.
The expansion and contraction of the membrane in expansion tanks is a normal part of solar circuit opera-tion. The tank provides space to equalize excessive pressure. If, the operation of the system gets out of control through excessive stagnation, however, a safe-ty valve is used to limit the pressure in the primary cir-cuit. The valve relieves excessive pressure. Most man-ufacturers‘ valves can withstand temperatures of 150 to 160 °C.
A further increasingly important component is the string controller valve. The valves are responsible for hydraulic balancing within a system. These valves are especially important in systems designed for multi-family dwellings and commercial buildings. Because such systems are increasingly important on the solar market, these valves are gaining greater significance. Caleffi Solar, Oventrop, Orkli, Taconova and Watts In-dustries are among the companies that offer string controller valves in various designs. When used within the solar circuit, these components come in contact with a glycol-water mixture. Most manufacturers say that their materials are designed for 50 % glycol solu-tions.
The right mix
All of the components described above ensure smooth operation of the solar circuit. Solar systems easily ca-pable of generating temperatures in excess of 90 °C need an important component in the domestic hot wa-ter system, the mixing valve or mixer. The valve mixes hot water with cold water to reach the consumer’s de-sired temperature. The temperature of the water exit-ing the tap can generally be set within a range of 35 to 65 °C. Some companies, such as Esbe, Orkli, and Taconova, offer mixing valves that can be set to 70 °C. A good setting to prevent scalding is 60 °C. Valves manufactured by Caleffi, Taconova, and Watts Indus-tries all have integrated scalding prevention devices. If the cold water supply is interrupted, the valve closes immediately, preventing hot water exiting the tap as well. Taconova‘s MT 53 valve and Esbe’s Solar-series valves can be set as high as 75 °C for legionella-pre-vention rinsing in hospitals and retirement homes, for instance. Such valves can withstand temperatures of anywhere from 85 to 130 °C (see table 4).
While expansion tanks and safety valves can han-dle the high temperatures in solar circuits, mixer valves ensure the proper temperature of the final product, the heated water from the tap. Katharina Ertmer
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