Motorised Valves

rafael dropulic planet camper elezioni italia paul simon aspirapolvere daewoo hii brytny spears commento al libro il piacere time for us barbecue griglia paradiso interpretazione letterale flat 29 daewoo foto j lo situazioni eccitanti foto donna incinta roms per snes screensaver del signore degli anello foto orrori passat tdi stago jeanette rockin on heaven powershot a75 hd seagate 120 hard disk e floppy skijump amare chi non ti ama motorola batteria v635 lyricas de daddy yankee impianti basket ministero difesa concorsi informatore medico sul farmaco raffineria vascorossi www patente web it maglie maniche lunghe dolce gabbana uomo le piu belle foto di johnny depp prodotti per unghie epson 6200 usb gamepad boley latino traduzione hs1c nokia la chapelle jean de sissi libri player mp3 dagostea din testi dell album let go di avril lavigne x800 pro vivo www generali it la tetanic pley boy siemens cordless gigaset c250 guantanamo rss 2 0 samsung sm913v el rojo televisore 42 pollici crash ctarina geosat 2 5 compact old furore ford cougar 1999 laky luke nuova opel tigra auto nuove cori di cavalli ombrello add site lui dotado securefile 20 tritatutto frullatore iran air visura catastale on line birken siegmund von lente advance accessori console pc amd sempron 3000 everio jvc dil dhoonde answer net www totalstay com business web hosting vespro siciliano car kit gps e accessori offerte lavoro provincia asti low cost londra la sanita in italia marble prestito caltanissetta get ready roachford formula 2005 sony dsc s80 immagini e audio per halo 2 cicco voli amburgo pantom planet california o c giustiziato abiti lunghi donna nokia fm mmc centrino fujitsu antec cooler hp laserjet 4300 immagini decapitazioni in irak grossisti ceramiche artistiche kia kehna amd sempron 2800 box duomo testimonianze di angeli cant t take my eyes off you router zyxel radiazioni b x distruzione uomo xmann dawnloads films hard voli roccaraso diamante lobo frittella di riso wireless media center club ati 9800 harry potter 2 radice metano caldaie e scaldabagni canon ef 28 200 videocamere mpeg 4 palmari hp ipaq gps fantastici4 www lotoo it case editrici tu malattia woolrich roma bogota biglietti aerei lettori dvddvix the general steamboat bill jr merda della merda www directline com turismo sicilia renault 19 hd sata western walter scott gigabyte gak8ns killing zone hermann hesse lazio net prenotazione albergo berna mustek scanner p3600 uccisione americano in iraq usb firewire hdd esterno la rondini schwartz delmore ruslana remix codici seca viaccess ralph lauren polo elenco albergo venezia michele bubble lettore di compact flash toner 1600 walking away craig david la primera guerra mundial offerta regali cagliari gioco di ieri il natale fiabe diffusore scaffale kristen kruk inni inter mp3 uomini nudisti la donna dei faraoni centrale jamo unreal tournament demo schermo plasma philips nvidia quadro 3400 tracheostomia villaggio turistico costa azzurra black boobs dowload su cellulare western digital sata 120gb macro canon videos mexicano videos gioco delle bevande stampanti multifunzione per cd canon powershot 4 0 samsung ml1520 tegole per copertura giovannini corinna uccelli di rovo film esecuzioni americani iraq cum swap poltrona letto de felice franco vendita dvd cremona volo napoli sharm el sheikh adattatore firewire usb nuova toyota aygo auto nuove articoli monouso nuove immagini per wanted guns jet raider the i inside pc h6340 collane di perle adattatore dvii copertina avril lavigne under my skin el mago de oz lofra 65 cucine benjamin britten peter grimes toner d418 rasoio panasonic ricaricabile 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.