Motorised Valves

www fiorentina it mazda diesel beyond paradise temi sull illuminismo ddr pc2100 cl2 5 the king of fighters 2002 venezia albergi monster sumo comune di copparo eos 350 d kit ef s 18 55mm canon rc belluno immagini video e dettagli per dragon quest viii luomo verde in dvd regioni lettori dvd dvx imballaggi in carta e cartone reel 50 kit decoder motorizzato hey mama back eyed peas storia di hitler grafismo testina canon bjc 85 vali barbulescu www campeggi ungheria it occhiali briko kartika luyet savi agriturismo loano jeans rogers dolby 5 1 sony spyware cleaner video sender hotel palace milano un tentativo sentimentale level 42 live at wembley chat con chicas de la india drinu ultima estrazione superenalotto telefono con cuffia vientiane cose fare videogioco monopoli in pc hotsex tastiera ibm nuova fiat panda 4x4 auto nuove scambisti a genova western 200gb ninna nanna brahms piastra capello delle gorette camping singoli donne richard wagner tristan und isolde fiat stilo 140 cv scherzi per compleanni slow food venezia condotta opinio communis doctorum epa w a gov not without us ram corsair 3200 il silenzio inno militare madame sousatzka corsi post diploma www porca madonna it il derviscio casse home theatre senza fili foot job conserva pietro cavo rca 3 futur whirlpool - awo8126 sesto senso lettera ad un amico morto cd key numa yey lu rusciu judo boy vol 04 atlante letteratura dale don dale ottavio barbieri stipel borsa dimage kit 5 1 dare da bere sottomarina di chioggia iron en flame oreste del buono marie gillain ca pha thanh da ulead cd dvd picture show poltrona benessere ristorante la strega schede notebook los roches stefio princess mixer gevers marie philips fisio 625 mdr 700 opel astra sw 1999 katica mulino il- sony kv-29cs60 foxconn 754 neffa aspettando il sole tripp trapp stokke norte eminem the show cd musicali job service project live in texas xbox controller s lenca roma mano armata film dvd vernice bicomponente trasparente techsolo 70 nilo bianco cd la forza dell amore luomo che uccise se stesso sony tv 16 hit mania dance 1996 midi filer scheda madre asus k8v x asus p5nd2 www maurizia paradiso com incasso piano cottura ariston lupin 3 ps2 so in love with you texas video maroon monitor 17 lcd fujitsu siemens play boy sesso calcio 5 video del decapitado singole catania occhi di gatto vol 6 travelmate 4601wlmi back-ups es 350va ultra 8gb pianoforte digitale locale b isdn los prophets saab 22 tid mercedes e 250 diesel sw lana asciugabiancheria testina canon 250 sony cybershot dsc programma scaricare mp3 cheb abdou cori juventus gayboy pic www bancaroma www mp3raid com anna tatangelo dimmi dimmi amd opteron 200 midi ci sarai mouse 500 foto donne violentate motorcicle bose gs promotional product www crociere m s c vendita ufficio crotone la chiamata dei tre libri assicurazione cagliari wintv pvr 150mce imac g5 17 combo denon a1xv sony cyber-shot dsc p200 lampada alogena frontale jonathan team massa macchine digitali fuji briefe die neueste literatur segretarie sexy arco passeggino pin up si sta facendo notte www intervalworld com www orariotreni it garbage bleed like me facile one touch road to lisbon lettori dvx prezzi microtransfer surplus loves brother riscaldamento a gas il dubbio dellanima para jose de bere note suoneria fuck it obiettivo minolta zoom 300 ombelico faltoyano rita to co w zyciu jest wazne leslie amin mp3 aleksandr solgenitsin www canzone zucchero it nelly fourtado sailing porto sant elpidio mentre adamo dorme panjabi m c san giorgio s g f albergo venezia soggiorno This article is about motorised valves used in Central Heating systems. Motorised valves are a type of electrically actuated valve (others include solenoid valves and valves using electrically-generated thermal effects).

Motorised valves generally comprise:

a synchronous electric motor
gears to reduce the speed and increase the torque output of the motor

The motor and gears are often combined in a package known as a Synchron motor.

a linkage from the output gear to the hydronic part of the valve
one or more switches (usually microswitches) actuated by, for example, a cam attached to the output linkage
a spring: see below

the above components usually comprise one module, often known as the 'head', which may be detatched from the parts below for repair or replacement.

a valve controlling flow of water in the hydronic system, actuated by the head: this part is often known as the 'body'.

Configurations of motorised valve

Valves are commonly found in the following configurations:

2-port

The valve has 2 pipe connections (ports) and permits or blocks flow between the ports depending on whether it is actuated or not. Flow is permitted when the valve is actuated and blocked in its resting state.

3-port

The valve has 3 pipe connections, in a T formation. The centre leg of the T is the inlet and the two short arms are the outlets, usually referred to as ports A and B. Actuation controls whether the flow from the inlet passes to the A or B port. In the resting state flow is to the A port.

Honeywell 3-port mid-position spring-return valve Probably the most common type and make of valve found in domestic CH systems.

There are two types of 3-port valve:

Diverter valve: This is a simple change-over version of a 2-port valve: when the valve is actuated all flow is diverted to the B outlet.

Mid-position valve: In this type of valve there is a stable state in which flow from the inlet can pass to both (A and B) outlet ports simultaneously. This type of valve is commonly found in domestic central heating systems where it controls flow of hot water from a boiler to hot water and radiator circuits in a Y-plan system configuration.

Types of motorised valve

Spring return valves

In these types when power is applied the motor and gears act against the force of a spring to operate the valve. When power is removed the spring returns the valve to its resting position. In a 2-port valve this is the closed position. In a 3-port valve the resting position is where flow from the inlet passes to the A port.

These types of valve consume power whenever they are open (and, in the case of 3-port valves, often even when they are not). In 2-port valves the motor runs until the valve is fully open and then stalls as the actuator mechanism cannot move any further. 3-port valves are more complicated: a description can be found in the uk.d-i-y FAQ and here is a diagram showing a 3-port valve in a Y-plan CH system

Motor On / Motor Off (MOMO) valves

In these types of valve the motor is used to drive the motor from one position to the next. Switches in the mechanism stop the motor when it has reached its desired position.

Since the motor only runs whilst the valve is changing from one state to another there is a saving in energy compared to valves where the motor runs continuously while the vale is open. Such valves may also be more reliable since the motor and surrounding components will run cooler.

2-port

This type of valve changes from it closed (off) to its open (on) position when power is applied to one terminal, and from open to closed when power is applied to another terminal.

                   ENERGISE                ENERGISE
                   TO CLOSE                TO  OPEN
                       |                       |
                     white                   yellow
                       |                       |
                       o                       o
                       /                       /
                     o/   o                  o/   o------- orange ----> TO BOILER
                     |                       |
                     |                       |
                      ----------- -----------
                                 |
                              -------
                             |       |
                             | MOTOR |
                             |       |
                              -------
                                 |
                                blue
                                 |
                              NEUTRAL
       
         Switches are shown in their non-actuated states which occur
             when the valve is neither fully open nor fully closed.
         The switch on the left operates when the valve reaches its closed position.
         The switch on the right operates when the valve reaches its open position.

These types of valves are occasionally found in domestic central heating systems: usually as Satchwell or Sunvic valves with grey plastic heads. Sunvic manufacture both MOMO and spring-return valves in similar casings.

If a motor-open/motor-close valve is replaced by a spring-return valve, or vice-versa, the controls wiring must be modified to suit. In the case of replacing a spring-return with a MOMO valve this requires change-over contacts at the room thermostat (or progstat) and an extra wiring conductor between the 'stat and the valve.

This type of valve is also found in non-domestic installations.

Industrial 2-port motorised valve
The large orange box on the right houses the motor and gears.
The smaller orange box on the left contains the switches.

3-port

Sunvic's SDMV series 3-port valves are motor-open/motor-close types but are wired identically to spring-return valves.

These Switchmaster valves with bright blue plastic heads are found in some older domestic installations. The author is unsure whether the wiring of these differs from that for spring-return valves.