IMT350w Power Options

How to power your wireless networked Proliphix Internet Managed Thermostat (IMT).

Overview

While the thermostat is wireless from the perspective of how it connects to your network, it is still wired to your HVAC system in the same manner as any standard 24v interfacing thermostat. For a typical heating and cooling system you would have wires that are used to supply 24v into the thermostat on the RH terminal and then switch that 24v back out the W1 heat control wire, Y1 for cool, G for fan. (W2 Heat stage 2 and Y2 Cool stage 2 if you have a dual stage capable system). If you have a heat pump there would be additional wires for your reversing valve and possible an auxiliary heat source and lastly an additional compressor control wire if your heat pump is dual stage capable.

There are three methods to power your IMT wireless thermostats described below.

1. Using a Common wire

Historically for many commercial grade thermostats there has been a need to provide an amount of power that is not practical using standard battery technology. To solve this problem there is an additional wire that is connected to the HVAC system’s 24v transformer which is known as the “Common”. By using a wire that is connected to the Common terminal on the transformer, you can complete a power circuit and use the 24v HVAC transformer as the source to power your IMT.

Your current thermostat may or may not have a wire connected as a Common. If it is available, then you are all set and can use the HVAC Common method to provide power to your IMT wireless networked thermostat. It is possible to still use this method if you have either a spare wire in the HVAC wiring bundle that is not currently being used or you might be able to pull an additional wire from the HVAC system to your thermostat and use that as the Common.

Note: Any wiring required to add a common wire in your HVAC system should be done only by a qualified professional. Please consult with your HVAC technician or your local electrician for further assistance.

If you cannot provide a Common to your thermostat then you will have to look at the alternative method of powering your thermostat using either a EPA (Ethernet Power Adapter) or a HPA (HVAC Power Adapter).

2. EPA (Ethernet Power Adapter)

While the EPA is primarily used for IMT models that have hard wired Ethernet connections, there is no restriction that would prevent you from using the EPA as a local power delivery mechanism via a Cat5/5e/6 run of cable i.e. a power source only, no networking connection. The main advantage of this using this method is that installation can be done by positioning the EPA near the closest power outlet and using a short run of Cat5/5e/6 to carry power from the EPA to the IMT wireless networking model. There are two models of EPA, the EPA-20 which can power two IMT’s or the EPA-60 which can power up to six IMT’s. This power option is often installed by the property owners and does not require any specific technical skills except for running a cable from the thermostat to the EPA location.

3. HPA (HVAC Power Adapter)

The HPA is a device that will take the fan wire (G) from your existing thermostat wiring and reuse it by making it behave as a Common. What this means that that your fan will be tied to your Y1 Cooling relay so that when the call for cool starts a single relay (Y1) would energize the air conditioner compressor and the fan together. Detailed installation instructions for the HPA can be found in the HPA Installation Guide.

The advantage of this method is that it can provide power to the thermostat when you are not able to provide a Common in addition to your existing wiring if you have a fan control wire (G). The disadvantage to this method is that you will lose independent control of your fan meaning you will not be able to turn the fan on or off without turning on your air conditioning.

Note: Installing an HPA should be done only by a qualified professional. Please consult with your HVAC technician or your local electrician for further assistance.