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Frequently Asked Questions

Multizoner Temperature Controls

1- Standard Controls - Programmable, Individual Thermostats and Multizoners Centres

Where do I need individual room thermostats?
Individual room thermostats are only required in rooms with imposed temperature changes, such as the kitchen, rooms with solar gain, and rooms which are not used often. The thermostat, in underfloor heating, acts mainly as a high limit cutoff. Thus avoiding overheating in such rooms.

What about rooms that are not used often?
You could turn down the temperature of these rooms at the manifold but it is unlikely you would remember to turn them on, in time for the rooms to be occupied or to provide adequate frost and damp protection. A room thermostat with set -back is preferable in the, say, spare bedroom.

Why do you leave at least one port without actuator on the Pexatherm UFH manifolds?
The main programmable thermostat used per manifold or area zone is situated in the area of the open manifold circuit. This is usually the coldest area or room for this zone (Entrance hall). Once the prog. 'stat is satisfied in this area the whole manifold is shut down by the pump and or valve. This arrangement avoids the need of pump pressure regulating valve and the consequent cost and complications. This valve can create a bypass to the UFH manifold and consequent loss of heat in the rooms.

Do I need 3 or 4 wires to the Pexatherm room thermostat with night setback switch?
One wire supplies the live to the thermostat. Another wire supplies the live to the actuator from the thermostat and the third wire is the neutral. Refer to your dossier wiring diagrams.
The Pexatherm thermostat has a switch for night set back position. For this to work, a fourth live wire for the setback heater in the thermostat can be made live by bridging the incoming live or by sending a separate switchable live from the master programmer.

When should the thermostat orange light come on?
Only when the thermostat is in the setback position. This is to warn you that the thermostat is working at 5 oC lower than normal.

When should I use the Pexatherm programmable thermostat?
The Pexatherm programmable thermostat (prog. 'stat for short) can be used for individual room control or for controlling several rooms at a time or for the control of the whole area covered by the underfloor heating manifold. Such as ground or first floor.
The prog. 'stat turns on one or two (up to 6) actuators in the case of room control.
The prog. 'stat switches on the underfloor heating pump and the motorised valve (where needed) when used to control the underfloor heating manifold for the area.

Is it true the Pexatherm programmable thermostat requires only 2 wires?
The clock and the flip relay in the Pexatherm prog. 'stat is battery operated. So it does not need a live and a neutral.
Therefore one connection is needed to the live supply and the other to the actuator live or pump and/or motorised valve. See above answer. Refer to wiring diagram in your dossier.

How do I connect 2 Pexatherm programmable thermostat to the boiler?
Each prog. 'stat brings on the pump and opens the motorised valve for each manifold, say on separate floors. The micro (end) switch on each motorised valve energises the boiler. This way any prog. 'stat in the off position does not switch on when the boiler is fired by the other prog. 'stat. This is the concept behind the standard 'S' plan used in conventional radiator central heating. Refer to wiring diagram in your dossier.

Multizoner wiring centres help solving the above wiring problems by providing labeled connections to all the input thermostats and the outputs to pump valves boiler and actuators.

Why do you have two different boiler connections in the Multizoner?
The 1st pair of connectors are zero voltage. This means you connect room thermostat terminals at the boiler here. Combi boilers prefer this connection so that the domestic hot water heating is still available when space heating is off. The other set of connection is live feed to the boiler and suitable for boilers with little or no control built into them. These three terminals, effectively, replace plugging the boiler to a live socket. You can also use this connection to run either the boiler pump or the UFH pump.

Can the underfloor heating pump and its zone motorised valve be connected to the same output at the Multizoner?
Yes. Pexatherm UFH manifolds and mixers are designed in such a way that the UFH pump will always have a bypass whatever the position of the valve.

How do I wire the two wire, battery operated, thermostats operating manifold actuators in the Multizoner?
Wire to the live (L) and switchable live (SL) and ignore the neutral (N).

I have UFH in new extension. The existing radiators cool down sometimes when the UFH switches on. Why?
The UFH pump draws water from the boiler and from the existing radiators at the junction where it connects to the central heating system. Fit a non return valve between this Tee and the radiators to solve this problem.

You offer 3 Multizoners MZ1 and MZII. Which one do I need?
The MZ I is designed for all types of central heating including underfloor heating. The space heating is controlled by up to 6 prog. 'stats or individual thermostats. The prog. 'stat can be placed in an area such as one on the ground floor and another on the first floor while the room thermostats can be in a conservatory, kitchen or spare bedroom. The choice is yours.
The digital clock on the MZ I controls the timing of the hot water cylinder heating and the bronze secondary circulation pump separately. You can use this second channel to time the heating of towel rails.

The MZ II is a heating only wiring centre and can be an extension to MZ I. It connects up to 8 prog. 'stats individual room thermostats. As an example it is used to connect up to 8 individual room thermostat on large underfloor heating manifold.

The MZ 0 is a wiring centre for up to 4 thermostats. This could be 2 programmable thermostats in an ordinary central heating system. One in the bedroom area and the other in the living area. The other two thermostat could be one for hot water cylinder and another say in a conservatory or an extension with radiator or underfloor heating. MZ 0 can also be used as an extension for MZ I and MZ II or with a small underfloor heating manifold up to 5 heating circuits.

Why do I need hot water priority control in MZ I ?
Heating the water in the cylinder rapidly requires the full boiler output for a short period of time (typically 20 to 30 min. from cold). Having the space heating off for such a short time is not noticeable in a well insulated home and specially with underfloor heating. Otherwise the boiler will not be able to heat the water and the heating system if it had to supply both at the same time in the cold weather. Over sizing the boiler to do both is also energy inefficient. The MZ I has hot water priority heating feature built in. Once the cylinder thermostat calls for heat the Multizoner shuts the space heating valve or pump and opens the cylinder valve while turning the boiler on if it is off.

So too the IPPEC's Quickheat boilers. The sensor from the boiler to the cylinder detects the demand for hot water and the 3 port valve in the boiler diverts the output solely to the cylinder until the water reaches the set temp.

Where do you place the Multizoner wiring centres?
They are positioned near the manifold or near the boiler and cylinder in the case of the MZ I.

Can I use the Multizoner with any boiler?
The Multizoner wiring centre can be used with any boiler - gas, condensing and oil fired. Make sure what type of connection the boiler require and where to connect in the boiler.

Can I use the Multizoner with your advanced Delta controller?
You only need the MZ II with the Delta to control a multitude of prog. and individual thermostats. See wiring details in your dossier.

How do you wire the Multizoner I to the Pexapipe unvented cylinder? Two wires from the cylinder thermostat are connected to the MZ I cylinder sensor terminals and ditto for the high limit cylinder thermostat. The motorized valve and or pump are connected with 3 wires to the cylinder heating output terminals. It is that simple.

How do I wire together several Multizoners?
The common output is that to the boiler. Therefore the Multizoners can have separate or common live neutral and earth. The boiler outputs of each Multizoner must be connected in parallel to the boiler.

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2- Advanced Controls - Delta

Do I need the Pexatherm WG100/200 enclosure with the Delta?
Yes. The connection strip and the diagram explaining these connections are required. This enclosure panel makes the wiring of controls much easier. All the sensors are wired to the left side of the panel and outputs to boiler, pump etc. to the right side of the panel. Refer to WG100/200 accompanying the Delta instructions.

How do I wire the boiler to the Delta's enclosure panel?
The Delta opens or closes a relay across T1 and T2 (the boiler terminals). Therefore you can wire zero voltage across these. This means you bridge the thermostat positions at the boiler or preferably frost thermostat position if available via the Delta.
Alternatively, you can send a live signal to fire boiler from T2 and bridge T1 to the permanent live terminals of the WG100/200. This way the boiler is supplied with live mains from the the Delta enclosure. The boiler neutral and earth are also connected to the appropriate terminals at the Delta enclosure.

How do I wire the PEXAPIPE cylinder motorised valve to the Delta?
The output from the Delta to cylinder pump or valve is sent to high limit thermostat to cylinder thermostat and then to motorised valve. It is also connected to pump if used. There is no need to connect micro-switch of MV wire to boiler as this is handled by the Delta. This way, if high limit thermostat or cylinder thermostat opens the valve closes as a safety feature. See wiring diagrams in dossier.

How do I wire the Pexatherm programmable thermostat with the Delta?
The UFH heating pump output at the Delta sends a live to the Pexatherm programmable thermostat. Then the switchable live from the prog. 'stat opens the valve or/and turns on the pump at the UFH or radiator manifold on the first floor. See Delta and pro. 'stat wiring diagrams in your dossier.

How do I wire the Multizoner wiring centre with the Delta?
See the Multizoner section FAQ's above.

How do I check that everything is working properly with the Delta?
When the switch on the WG100/200 is pressed to manual, the sensors are disengaged and all the outputs are switched on. This way the boiler, pumps should come on and any valve opens. The Delta will not operate properly if any of the sensors is wired incorrectly when the Delta is switched back to the automatic mode.

The heating pump seems to run all the time.
The heating pump is designed to run for long periods at a time. To reduce this long running use the economy setting. This way the Delta is in frost protection mode rather than set back mode at night or in the 'off' position. Also you can turn down the setting of the outside high limit found on the bottom side of the Delta. Refer to Delta manual.

The boiler comes on and then switches off immediately.
The Delta is designed to control large boilers too. In this case the minimum boiler temperature can be set to avoid energy wastage. However most domestic boilers do not need this setting. Turn down to a minimum the low boiler limit found on the bottom side of Delta. The boiler and heating pump come on together. Refer to Delta manual.

Delta stays too long in domestic water heating mode.
There are several reasons for this situation. First, turn down the pump overrun to a minimum and the dT to a maximum at the buttons found at the bottom of the Delta. See Delta manual. If this does not help, check the sensor position on the cylinder. This should be situated near the cylinder thermostat and in direct contact with the cylinder metal body. Set the hot water temperature at the Delta to no more than 45 oC. The water at the top of cylinder would still be 50 to 55 oC.
The hot water mode remains on longer if the boiler is cycling. Check for reduced flow from boiler to cylinder.
Use PEXAPIPE high recovery cylinder. The large coil in the cylinder dissipate the heat rapidly from the boiler.
Connect towel rails to boiler flow and return to help dissipate heat from the boiler when heating cylinder.

What does the 'E' setting mean on the selector knob?
This means economy or 'Eco' mode. The Delta is still in automatic mode but at night the heating is off unless the outside temp. drops to 5 deg. C.(or the set min. outside temp.). Then the heating comes on up to the setback temperature. Choose this setting for a well insulated house where the temperature decay, during the night, is very slow.

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