Hydro Quebec Flex D Rate - Controlling Clothes Dryer with Insteon EZIO relay

We're just over half the peak demand season in Quebec, so far, so good. Will write up some articles on what I've done so far. On one demand management period a few weeks ago, someone in the house started the clothes dryer, I caught it after it had been running for about 10 minutes. One of the problems with the whole energy management / peak demand implementation is that it is difficult to get everyone in the house on the same page. I understand that at $0.50 per kW-hr - running the dryer for an hour ends up being an expensive proposition. It's harder to get the two 12 year olds in the house to understand. 

LG Clothes Dryer - Cover Off, Control Board back left of the photo. Relay will go close to control board

For avoiding future problems with the dryer, I decided to implement an interrupt to prevent the dryer from starting during a peak demand event. We have an LG dryer with an electronic control board. I didn't want to get into switching the power feed to the dryer - it's a large circuit. I decided to try interrupting the door open switch, effectively putting a second switch (relay) in series with the door open switch. 

Opening the cover of the dryer exposes the wiring and control board. Cut the power before opening the dryer cover for obvious reasons. The wiring diagram was attached to the inside sidewall of the dryer, and still quite legible. 

LG Dryer Wiring Diagram

The dryer switches 120V (one leg of the 240V), and it switches the connection to neutral. When open - it provides the neutral connection for the lamp inside the dryer, causing the lamp to come on. When closed, it provides the neutral connection for the control board. I decided to interrupt the neutral connection to the control board, in a fail safe fashion. My relay will be normally closed on the neutral circuit to the control board, so that if there is no control system, no connection to the relay power - the dryer will function normally. The interrupt feature will require 24VAC from my control system. 

Wiring in the relay with a relay base was quite simple - 4 connections. 

Relay with base installed on a short braket - no interference with top cover

The wire to the control board was a yellow wire according to the wiring diagram - very easy to identify. I simply cut the wire, crimped in two extensions to take the connection over to one of the relays normally closed pair of terminals. I use heat shrink crimp connections for a neat installation.

Connections made on the NC relay terminals - interrupt yellow wire (neutral to control board)

I ran a control wire down into the basement next to the dryer vent line - very easy in my case - and over to an automation panel where I had a pair of existing Smartenit EZIO 4x2 Insteon relays. I just selected one of the relay output terminals, and used 24VAC from the transformer in the cabinet. When going through the dryer case - I was careful to run the cable through a rubber grommet to avoid any shorts in the future, and ensured my cables were well attached to the dryer frame with zip ties. 

I just finished testing the connection. It works perfectly. When interrupted - the electronic control panel stays powered up, all the control lights are illuminated, but when you press the start button, nothing happens. The control board thinks the door is open and won't initiate the drying sequence. All good. This project was surprisingly quick and easy - took about 2 hours in total. Feel free to ask any questions down below. 

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Hydro Quebec Flex D Rate - Peak Demand Project

Hydro Quebec, my provincial electricity utility, is trialing a dynamic pricing model this winter. It hasn't been rolled out to all residential consumers yet, it's in a trial phase. I applied for the trial and was accepted to participate. I figured that dynamic pricing is inevitable with Quebec's push towards electric cars, so I might as well jump in and see how it goes. My home is already extensively automated, so I should be able to come up with protocols to deal with the peak demand events with a minimum of manual intervention.

The base electricity rates in Quebec are tiered. The first 40 kWh per day are charged at 6.08¢/kWh (1st tier). The remaining energy is charged at 9.38¢/kWh (2nd tier).

The "Rate Flex D" is a dynamic rate where electricity is cheaper than the base rate in winter, except during peak demand events, when it’s more expensive. From December 1st to April 31st of the following year, outside of peak demand events, the price of electricity is below the base rate, so you can save money (4.28¢/kWh for the first tier of 40 kWh/day, and 7.36¢/kWh for the 2nd tier). During peak demand events, electricity is billed at a high price (50¢/kWh). The day before a peak demand event, you receive a notification.

I've been through three days of peak demand events so far. In this post, I'll describe some of my preparation, and how things are going so far. 

First, here are some characteristics about my house.

• Large, two story house with full basement. Electrically heated garage on an elevated concrete slab, with basement space below the slab. 3/4 of the basement is finished, 1/4 is utility space housing the fan coil, most of the zoned ductwork, the electrical entrance, and storage space under the garage;
• 400A electrical entrance, with three 200A breaker panels. One panel is designed for critical loads and is connected to a generator transfer switch. There was a generator installed at one time at the house, it has since been removed. 
• Principal heat source is a Carrier Infinity Greenspeed 4 ton heat pump with variable speed indoor fan coil, with three stages of backup electric resistance heating. The heat pump can maintain a constant temperature in the house, without electric backup heating, down to about -14C. Below that temperature, the heat pump needs help. The heat pump thermal efficiency drops to 1 at about -20C, where it no longer is effective.
• The forced air ductwork is zoned, with a separate zone for each level of the house - basement, main floor and 1st floor. I upgraded the Infinity system to full zone control this year, and can now control the temperatures on each floor independently. 
• There are supplemental electric resistance heaters in most of the rooms in the basement for comfort. These are controlled by programmable thermostats. Now, since the zone heating upgrade, I haven't bothered turning those circuits on since I can effectively control the basement temperature from the principal heating system. Our offices are in the basement, and with COVID confinement, a comfortable working temperature in the basement was one of the prime drivers to do the zone heating project.
• I have extensive Insteon control over lighting. Virtually all lighting in the house, on all levels, is controlled by insteon switches and dimmers. 

More to follow in this series on Rate Flex D Peak Demand.....

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