If the circulator control and high limit switches are closed, the circulator and burner come on. All of the end switches in a system are wired in parallel. This ensures that the circulator and burner are powered when any zone calls for heat.
The circulator and burner shut down when all the thermostats are satisfied. Note: The following troubleshooting procedures are intended to familiarize you with some basic types of systems. Also, try to move the valve stem assembly by hand to be sure that the paddle is free. Some exceptions will be where a plunger will have to be pushed down manually to see if it is free, as these types of valves do not employ the paddle-type valve system. For these systems, the preferred valve is a two-position open or closed straight-through valve, such as the Honeywell V These valves are standard for residential applications.
The exploded view of a typical Honeywell straight-through type zone valve Figure 1 shows how it is designed and constructed. Its main components are:. All the end switches in a system are wired in parallel so that a call for heat from any zone powers the burner and circulator. Diverting valves operate the same way, except that the ball closes the alternate port when the valve opens. For proper operation, it is important to install the zone valve so that the water or steam flows in the direction of the arrow on the valve body Figure 3.
The compact design allows these valves to fit under the covers of most baseboards. The complete powerhead can be replaced without disturbing the valve body, and does not require breaking line connections or draining the system.
The rubber plug is rotated by water movement and the closing action against the seat. In domestic situations, there are two types of Zone Valves - two port and 'mid-position' zone valves.
To test if your zone valve is working is very easy. Lets say your central heating is not working, but you have plenty of hot water. To test if your zone valve is working, switch off demand for your hot water you can do this via the timer - set Hot Water to Off. Now create demand for central heating - turn up the thermostat and make sure the timer is set to 'On' or 'Continious'. Identify your Zone Valves - they will typically be in the airing cupboard or close to the pump.
A two port Zone valve is on the left and the mid position valve is on the right below. If you have 2 port valves, you will have two or three of these valves, one for each heating zone and one for the domestic hot water identify which one is connected to your hot water cylinder. The V Motorized Zone Valve provides two-position open-close control of supply water for baseboard radiation, convectors, fan-coil units, etc.
It uses a two-wire, volt control circuit and requires a SPST thermostat. Integral end-switch models permit the sequencing of auxiliary equipment. Quick Fit actuator provides easy snap on and off connection to the valve assembly. And I agree you'd need to look at thermostats and wiring if changing the zone valve type as a normally-open zone valve requires a reverse-acting thermostat as you indicated. It is possible to simply change the actuator heads from the D model to one of the other models - changing wiring and thermostats as appropriate, leaving the actual valve body installed.
A thermostat wired to operate a normally-open zone valve NO valve will need to be re-wired if it supports operating a normally-closed NC valve.
Otherwise the thermostat will need replacement. Before you would change to a "normally closed" zone valve which is more common at least in residential installations we'd want to understand how your heating system was designed to work.
The installer surely had a reason for the "normally-open" approach. Is this a residential building? Are there some special heating needs or applications? Honeywell VG - PN normally closed has as an end-switch. Some writers opine that in some buildings we install a normally-open zone control so that " But you could argue that in the event of loss of heat but not loss of power, you'd gain that advantage. What I understand is with the normally open valve power is required continuously keep the valve closed.
I think that this could cause extra heat build up in the motor and cause premature failure along with more power usage. The normally closed valve only uses power to open the valve when heat is called for. The application that we have is residential, but was originally installed when the house was built 29 years ago.
It's a good system but we are trying to improve costs and new procedures develop with time. There are no special heating needs or requirements. Thanks for all of the information it will help us in making a decision. Probably one thermostats at a time. Dennis: thanks for the follow-up. As I noted, unless the valve mechanism itself is damaged, you can just change the power head - leaving the actual valve assembly in place.
Quoting the product literature:. Easy servicing because the entire powerhead assembly can be replaced without removing valve body from line. Optional accessory fittings can be provided to facilitate convenient removal of the entire zone valve unit. When changing the thermostat, there are some models that can be wired to operate either type of zone valve: normally closed or normally open. It's not clear to me that the added heat from the 40VA transformer wiring that powers this zone valve would normally be sufficient to contribute to the product's failure in the field.
Watch out : however, for wiring errors, short circuits, or a misbehaving low voltage transformer. Those defects could contribute to zone valve failure, as might corrosive or mineral-laden water in more rare cases. On by mod replacement Sparco PowerTrack zone actuators from Honeywell. Trevor, Forgive the slow reply - we've been swamped with questions. If the failure is the actual valve and not the motor then to repair these you'll need to - cool down the heating system turn it off and wait - drain off pressure and water from the lines enough that the piping in the area of work is empty so it can be soldered open the boiler drain, using a hose to direct water to a safe drain location - disconnect andlabel the zone valve wiring connections - with POWER OFF - cut out and sweat in new valves - re-fill the heating system assuming it's a water-only system - get the air out of the heating pipes so you won't be air-bound Search InspectApedia.
On by Trevor - how to replace Sparco PowerTrack zone actuators broken into pieces. Here is another pic of the system, any insight someone could provide on changing my zone valves and the steps I need to do to pull it off would be so appreciated! I have 4, old, Sparco PowerTrack zone actuators on my system that are literally broken into pieces. I have no experience with boiler systems but no how to sweat and do copper plumbing. Can I just cut out the old actuators and install the new zone valves on my own?
Jon Green, Thanks for pointing out the operation of the WR Zone Valve About the "why" of requiring electrical energy to close the valve when the thermostat is satisfied, I'm embarrassed to pretend to second guess WR's engineers who certainly know more about it than you or I, but maybe the idea was to make an inexpensive zone valve that would close more-reliably than a spring-operated valve.
Among zone valves are models that are NO - Normally-Open, and use a current to close the valve NC - Normally-closed, and use a signal to open the valve and the WR type zone valve that uses current both to open and to close the valve.
This excerpt describes the operation of the White Rodgers As the thermostat calls for heat, the valve motor is energized and begins to open the valve. This contact provides a holding circuit to prevent the valve from stopping part way through its cycle if the thermostat is changed to the satisfied position.
When thermostat is satisfied, the valve motor is again energized. These valves require thermostats to send current to the valve to turn it on,, but then the valves require current to the opposite wires to turn the valve to the off position.
Just stopping current to the "ON" position will do nothing as the valve stays open. Therefore a simple 2 wire thermostat will not work without a relay to send current to the off wires when the thermostat turns off, or a special thermostat that sends current one way when heat is on, and current through another wire to turn the valve off. Why would anyone want a valve like that, instead of a spring or mechanism that just turns the valve automatically to the off position when the thermostat turns off?
On by mod - diagnose zone that sometimes does not open. Anonymous, I would look first for a loose electrical connection and second I would consider replacing the zone valve actuator or motor that may be sticking or failing. I have 3 separate zone valves in my home. At times it seems to be working normally; but at other times It will not call for heat until I turn the thermostat up for another zone valve.
I have made the mistake of removing and tossing a part whose function I couldn't understand. Usually people don't go to the trouble of installing a valve or control unless it was needed. But yeah, there can indeed be a "left-over" control from discontinued equipment or devices.
I have a boiler in an extension that provides hot water to the kitchen and extension. Home » 5 things installers need to know about fitting zone valves. Tameson looks at 5 things installers need to know about fitting zone valves for heating systems.
Central heating systems with zone valves are becoming more prevalent due to the increase in efficiency and comfort they can provide. They effectively give the building owner more control of where and when an area gets heated.
By using individual thermostats to control separate zones, a building owner has greater control of where and when an area gets heated. For example, a home owner can heat the bedrooms at night and the common areas during the day.
When installing zone valves for central heating systems, an installer needs to keep in mind the following 5 things: 1 Valve Type An electric ball valve is the most efficient valve type to be used as a zone valve. They have a lower power consumption, have a long operating life and close slowly to prevent a water hammer.
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