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Wiring A Heatmiser IQ+ For ErP Suspended Heater

wiring a Heatmiser IQ+ Diagram

Wiring A Heatmiser IQ+ Controller To An ERP Compliant Suspended Heater

Wiring a Heatmiser IQ+ Controller – Updated 27th May 2018

What Is ErP And Lot 21 And What Is An ERP Compliant Heater?
“The Energy Related Product Directive” (ErP For Short).

ErP Directive (2009/125/EC) is a European Council Regulation that implements a series of measures to reduce greenhouse gas emissions. Lot 21 of the Directive implements changes to warm air heaters.

Lot 21 has three different phase in dates which force increases in seasonal efficiency and the lowering of Nox emissions contained within the flue gasses.

How Does This Affect Wiring A Heatmiser IQ+ with a new Warm Air Heater?
In simple terms, it means we need more wires.

For many years, the gas burner control system has simply been an on / off control. It turns on when heat is demanded and turns off when not required.

Under ErP, when heating a space for occupancy comfort, on / off burners and controls can no longer contribute towards the required seasonal efficiencies.

The Heating Industry has responded and Hi / Lo burner controls is now the standard basic method of control supplied from the factory. Fully modulating is still preferable over Hi Lo.

Hi / Lo control is not new, its been available for many years but due to the increased costs of a Hi / Lo capable burner, most end users were choosing the cheaper On / Off options.

To enable use of Hi / Lo control, we need to use an additional relay in the Heatmiser IQ+ and program the controller to support Hi / Lo operation.

As the space temperature begins to rise, when it reaches the Hi / Lo differential setting inside the controller, a relay is opened and the heater’s burner is instructed to reduce its firing rate.

This lower heat input into the space is often enough to reach and maintain set point. Overshoot of set point is generally avoided, less heat energy is used and as a result, less combustion gases are introduced to the atmosphere.

When starting up the heater, we need to instruct it to turn on in Hi Fire mode, then allow it to drop back to Lo. As always we can easily achieve this with the IQ+.

Wiring A Heatmiser IQ+

Click on the image to view a large PDF version.

wiring a Heatmiser IQ+ Diagram

Consider the wiring overview above.

When wiring a Heatmiser IQ+, two switch fused spurs are used to satisfy the requirements of BS:7671.

The first spur provides power to the heater and also provides a low level point of isolation / mechanical lock off. As the second spur is fed from the first this gives one point of isolation. If the heater is isolated, so are the controls.

The second spur provides protection to the IQ+ Controller as it requires much less current than the actual heater. Fuse the IQ+ at 5A and the heater either 5A, 10A or 13A depending on current draw.

Select a suitably sized cable to allow for current and voltage drop. Generally a 1.5mm cable is suitable for most smaller suspended heaters, but you may need a 2.5mm in some cases.

Fix the spurs to the wall and connect using a 20mm conduit coupler and two bushes. A Coupler and bushes can be used to fix the Controls spur to the IQ+. Take care marking the IQ+ Controller plate and hold it in place when marking. The alignment is tight to get the hole just right.

When wiring a Heatmiser IQ+, ensure all electrical supplies are turned off and safely isolated with a lock off kit if required. Always make sure the supply is turned off using an approved voltage indicator.

The customers supply should be fed into the Heater spur and terminated to the IN terminals. Provide a Live, Neutral and Earth. Ensure a back box bond is fitted to the spur front.

If using NYYJ cable, stuffing glands can be used to terminate the cable neatly at both ends. SY type cable must not be used for fixed electrical installation. If using SWA or other type of wiring system, ensure that the armour is earthed correctly at both ends. Also make sure the correct type of gland is used for the cable type.

Wire the heater supply cable to the “OUT” or “LOAD” terminals in the heater spur. At the same time route a separate Live, Neutral and Earth from the SAME terminals, to the next spur. Singles can be used here.

In the second spur, wire up the Live, Neutral and Earth (from Heater Spur) into the IN terminals.

Wire from the “OUT” or “LOAD” terminals directly into the Heatmiser IQ+ PCB.

A 7-Core control cable is taken from the top of the second spur and taken up to the heater. Ensure the use of correct terminations as previously discussed. Again, we suggest the use of NYYJ cable.

A length of 2” cable tray fixes the wiring into position extremely neatly and can easily be mounted right up to the heater.

Cut the 7-Core cable a little longer and strip back to the gland. Feed into the spur and route through the bush and coupler, then into the IQ+ controller.

Now would be a good time to take an R1+R2 reading for each of the cables and carry out an insulation test. These can be recorded on the installation certificate and will satisfy dead testing. Take the incoming connections out of the IQ+ before testing. Following dead testing, we can continue wiring a Heatmiser IQ+.

We need to install a few links inside the IQ+ Controller to make things work.

Daisy chain from the Neutral incoming connection, and take this to the N terminal of the “Lock Out Relay” terminals, then feed to the C (Common) terminal of the “Lock Out Reset Relay”. Keep the stripped insulation short and two 1.5mm wires will easily go into the terminals neatly.

These two Neutral jumpers allow the lock out indicator and reset circuitry to work. Lock out reset is normally done with a switched Neutral, so be careful you get this right.

Next in a similar way, daisy chain from the Live incoming connection into relay 1 (Fan) then relay 2 (Lo Fire).

This provides a live feed to the relays so when they operate, a control signal is generated.

Wire earth of the 7-Core inside the spur, there are two connection points and sufficient room to install neatly.

Following the wiring diagram:-

  • Cable 1 to the Fan relay
  • Cable 2 to the Lo-Fire relay
  • Cables 3 & 4 to the Hi-Fire relay
  • Cable 5 to the Lockout indicator
  • 6 to the Lockout Reset

Check over all the connections carefully and note they may not follow number order.

Close off all the spurs and replace the cover of the IQ+, ensure the ribbon cable is pushed home both ends. This completes wiring a Heatmiser IQ+ controller.

At the heater, terminate both cables off neatly and appropriately.

Connect the L, N and E conductors from the 3-Core cable to the incoming mains terminal block.

Join the E conductor from the 7-Core cable into the main Earth terminal in the heater, alongside the supply E.

Using the chart above, terminate the remaining six cores to the heaters wiring terminal strip.

  • Cable 1 provides a manual fan signal, generally called FAN or SUMMER
  • Cable 2 provides the signal for heat, generally called HEAT ON or CALL FOR HEAT
  • Cable 3 & 4 provide the Hi Heat circuit, generally called HIGH or Hi Fire
  • Cable 5 provides a signal to the IQ+ if the heater enters lock out.
  • Cable 6 provides a signal to rest the heater, following lock out.

Check all the cables are tight and routed neatly through the heater by giving a gentle “tug test”.

Now would be an ideal time to take relevant Earth Loop readings (Zs) for the installation certificate.

Once you are satisfied that the electrical installation is completed, we need to make some modifications to the IQ+ controller.

Wiring A Heatmiser IQ+ Controller Programming

Turn on the power and allow the controller to boot up.

Lets make some changes to the configuration of the controller first.

Enter Engineer Configuration Menu

Press the [PROG] button, enter the Engineer password “6 3 4 3” followed by the [ENTER] key.

Turn On Optimisation

Lets turn on the Optimisation feature by pressing button [4] on the keypad.

Remember, when you set up the times later on we will be entering “Opening Times” as the controller handles the actual on / off times on your behalf.

Optimisation allows the heater to turn on a little earlier or later, depending on how cold the room is. During the winter months the heater comes on a little earlier. As things warm up, it comes on a little later.

Press [1] to enable Optimisation mode and press [ENTER].

Next we need to enter the rate of change figure. Leave this as 20. This figure is the amount of time it takes to heat the building by 1.0 Degree. 20 Minutes is a good starting point. As the controller is self learning, it will adjust this figure automatically. Press [ENTER] after making changes.

Next set the maximum number of hours the heater can come on, before occupancy time. Generally a figure of 2 Hours is sufficient. In some extreme cases increase this to 3 hours.

Press the [ENTER] key and you should drop back to the main engineering menu.

Setup Controller As Hi / Lo Configuration

Next, press [4] to enter the SETUP menu, then press [1] to enter CONFIG.

Press [1] to select Hi / Lo operation and press [ENTER] to move on.

Press [1] to enable HIGH FLAME BOOST and press [ENTER] to move on.

High Flame Boost closes both the “Hi” and “Lo” relays at start up. After 60 seconds, the controller checks to see if both relays are required. If the temperature is within the differential band the “Hi” relay will then turn off.

Enter the Hi / Lo Differential. If you set this at 4 Degrees and say the daytime temperature was set at 21 Degrees. As the room temperature reaches 18 Degrees, the heater would drop to Lo fire and continue to operate until it reaches 21 Degrees. 4 Degrees is a good starting point for this value.

When the value is input, press the [ENTER] button again.

Press [0] for Double Ignition to disable then [ENTER].

Do the same [0] and disable the proving switch, then hit [ENTER].

Next you can set a “User Temperature Limit”. If the controller is programmed with a day time temperature of 21 Degrees, entering 02.0 [ENTER] into this box would allow staff to increase the room temperature to 23 Degrees.

When you drop back to the menu, press the [RUN] button until you drop back out of the menus. The screen will read “Adjusting Setup”.

The user settings can now be set as required for the heater.

When you adjust the on and off times of the controller, remember to enter the opening time rather than the heater on time. The controller will automatically bring on the heating early as we set up Optimisation.

You can download the “IQ+ Quick Start Guide”, together will the full manual below in PDF format.

The “Quick Start Guide” explains most of the controllers functions on one sheet.

If you need any further help wiring a Heatmiser IQ+ controller, or wish to buy any Heatmiser products, please contact us or click here to visit Heatmiser products in our store.

You can visit Heatmiser by clicking here.

Heatmiser-IQ+-Full-Manual-Thumb    Heatmiser-IQ+-Quick-Start-Thumb

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Upgrade A Powrmatic NV Heater To Brahma Controls

Powrmatic NVx Heater


During service life, it may become necessary to replace the control electronics to earlier Powrmatic NVx heaters containing a separate PCB in conjunction with a plug in Pactrol control box.

Upon receiving the modification kit from Powrmatic, read the instructions carefully. They are well written and document the procedure from start to finish in an easy to understand manner. Do not attempt to carry out the modification unless you are a qualified engineer, mistakes carry heavy consequences.

We began by isolating the gas supply to the Powrmatic heater. One of our Gas Safe engineers isolated the gas supply to the heater, plugged it off and made sure it could not be turned back on again. Next we isolated the electrical supply to the heater by turning off the fused isolator and removing the fuse. Using a test meter we proved that the electrical supply was off and therefore safe to work on. We will be removing the power cord that supplies the heater so a safe isolation is essential.

We checked that there were no electrical feeds being provided by the Powrmatic Powrtrol controller to the heater, supplied elsewhere. We confirmed that the Powrtrol mains supply was sourced from the heater after the isolation point and safe to proceed. We have found Powrtrol units fed from alternative supplies resulting in some control wires still being live inside the heater, even with the heater switched off. If this is the case, trace the supply to the Powrtrol and isolate it, lock it off and hang a warning sign from the isolator. If necessary, remove the wires from the supply point to prevent unauthorised switch on.

We then identified the Powrtrol wiring. The Live, Earth and Neutral feed to the controller was wired into the mains supply terminals inside the heater. There were also two additional wires which we identified and labelled as heat and summer. The heat signal starts the heater running when the controller calls for heat and the summer signal turns on the main fan when a switch is operated on the controller. Next we labelled up the supply cable correctly using coloured sleeving. The supply cable had been left with the colours brown, black and grey. We re-labelled them as green/yellow for earth, brown for live and blue for neutral in compliance with BS7671.

The whole chassis containing the PCB and Pactrol control box needs to be removed so we removed all the wires as indicated in the manual. The mains supply cabling and Powrtrol cabling were removed since we have identified the wires. There are flexible cables that provide power to the gas valve, main fan and combustion fan. Remove the connectors from the PCB and move the cables out of the way. The probe and ignition wires were removed from the old control box and leads carefully tied out of the way then the tube was removed from the pressure switch. The cabling to the overheat stat and neon was also removed from the stat and discarded as a new cable is supplied in the kit. The link between the neon indicator and the stat remains in place.

The chassis is held in place with four self drilling screws. They were removed using a nut spinner and the old chassis withdrawn and discarded.

There are specific details of how to mount the new chassis. We identified the position requirements for the NVx70 and marked the mounting holes using a pencil. We installed fixings back into some of the holes as required by the instructions. This plugs unused holes in the heater chassis. We used a small 3mm pilot drill and drilled the centre holes of the marked holes, this will assist in the self drilling screw locating. With the electrical chassis offered into place we installed the new self drilling fixings to hold it into place.

The supplied cable was installed between the controls and the overheat thermostat. The wire was installed to the terminal strip and then the connectors plugged onto the overheat thermostat. The terminals were easily identifiable on the rear of the stat and the wiring diagram shows the connections clearly. We needed to clean the back of the overheat thermostat to read the terminal markings aided by a small flashlight.

The flexible cables that supply the gas valve, combustion fan and main fan were connected back to the relevant connections on the terminal strip. The cable already installed to the main fan was of sufficient length and did not require replacing with the spare one supplied in the kit. We had to cut the Lucar Crimps off the wires and strip them back to install into the terminal strip. The cables can be made to run up the centre of the compartment and form a neat loom.

The ignition and probe cables are connected onto the Brahma control box directly. Ignition goes towards the bottom of the control box and ionisation probe towards the top. They use different sizes to identify the probes so check to avoid damage.

Next we re-wired the incoming mains supply cables into the mains terminal block and also connected in the power supply cables that feed the Powrtrol unit. The heat and fan circuits were wired back into the terminal strip.

All that remained was to push the flexible hose back onto the new pressure switch, connecting it to the – port, the + port remains unused. We followed up with some cable tie work and generally neatening up inside the panel.

It is important to note that the ignition and probe leads should not be cable tied or allowed to come into close proximity of other electrical cables inside the heater. The heater design is good and the leads remained towards the left hand side of the tray naturally. Avoid close proximity to the burner manifold.

Using a continuity tester on the ohms setting we next ensured that the earth connections from the gas valve, combustion fan, main fan, Powrtrol and the chassis were all reading low. This is an essential safety check and should not be avoided. Fully investigate high readings.

The most important step now is to check your work. I checked it from start to finish, hold each wire connected to every terminal, follow it to its destination and confirm that its connected to the right place. A colleague learning the replacement procedure then checked my work for me.

Once we were happy with the wiring, we put the fuse back into the isolator and turned back on the supply. The red neon on the chassis tray came on to signal the heater was locked out. We then confirmed that the supply polarity was correct and the supply earth was present.

With the gas supply still turned off, we set the Powrtrol to call for heat and held the reset button momentarily, the control box reset and the combustion fan started to safety purge the system with fresh air. After a short wait, the ignition electrode sparked to life and the gas valve opened.

After a couple of seconds the control box failed to prove the burner was lit and turned off the ignition and gas valve. The cycle continues several times and eventually the heater locks out and the red neon rocker switch lights back up.

Our Gas Safe engineer then reinstated the gas supply, carried out some safety checks and then informed me it was safe to test. The flue gas analyser was turned on and a manometer made ready to test and adjust gas pressures if necessary.

The lockout button was pressed again and the heater began its start up sequence. Almost as soon as the ignition electrode sparked to life, the six burners ignited on the manifold.

Our Gas Safe engineer then carried out various tests and measurements and printed out a flue gas analysis. He serviced and cleaned the heater and then gave the customer a Gas Safe service record.

Most warm air heater manufacturers are now using Brahma control boxes and they are working very reliably out in the field. We have only experienced two failures this year, both caused by energy management system engineers connecting the lockout reset wrongly. In all cases, the lockout reset should be switched to Neutral. Applying a live connection to this terminal will permanently damage the control box beyond repair.

If you need a control upgrade for a Powrmatic NVx heater, a full appliance service or even a replacement heater, please contact us by email or call us.


Philip Hamer

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How To Connect A Heatmiser IQ+ Controller

Heatmiser IQ+

This document will explain how to connect a Heatmiser IQ+ controller to a warm air heater.
One of the most common questions we receive regarding the Heatmiser IQ+ Controller is how to correctly wire the unit to operate with a warm air heater, so hopefully this will help with the basics.

Click on the pictures to see a full size image.

Heatmiser IQ+ Wiring Diagram
Wiring Diagram

First go ahead and firmly mount the unit to a flat surface at the desired location. We generally remove the PCB from the enclosure whilst mounting the unit to prevent damage, retain the screws carefully.

Install a run of 7-Core SY flexible armored cable between the heater and the controller. We use cores sized at 1.5mm csa which is suitable for most applications and the relay rating inside the IQ+. Use the correct glands to terminate the cable correctly and pick up a cross bond to the earth tag as required.

If you bring the power supply to the IQ+ from the heater, adjust the wiring to the L and N terminals (1 & 2) as necessary, don’t forget to install a fused spur for the controller.

First we will install the power supply to the Heatmier IQ+ from the fused spur. Wire from the spur to the terminals marked Live, Earth and Neutral at the bottom of the controller board.

We need to install a couple of jumper wires inside the controller to make things work. Jumper from the incoming Live terminal and pick up one terminal each of Relay 1, 2 and 3. Make the links carefully and fully open the cages to the terminals. Use a pair of long nose pliers to push the wires fully home, with some care they will fit correctly.

Next jumper from the incoming Neutral terminal to pick up the Lockout Neon and then to the C (Common) terminal for the relay. This Neutral connection to the relay assumes that the lockout signal requires N to be applied to re-set the control box so check first. All the equipment we install uses N lockout!

Core 1 – Live feed to the heater so wire this directly into the Live output of the spur.
Core 2 – Neutral feed to the heater, again wire this from the Neutral output of the spur.
G/Y – This is the earth cable which should be wired to the Earth terminal of the spur.
Core 3 – This provides the signal to the heater to provide “Heat”.
Core 4 – This provides the signal to the heater to turn the “Fan” on only.
Core 5 – This provides a Live signal from the heater to the control box to signal it has locked out.
Core 6 – This provides a Neutral signal from the controller to the heater control box to pull it out of lockout.

Wire the remaining cores into the heater to correspond to the relevant terminals.

Powrmatic heaters are well labeled. Click on the pictures below to see wiring connections for Powrmatic and Benson.

Heater Wiring Diagrams
Wiring Terminals To A Powrmatic NVx Heater

Wiring Connection Terminals