Toronto hydro is making it easier to get off of gas and go all electric.
You’ve heard of heat pumps, right? You know, those cool ultra efficient all-electric boxes that can replace your methane guzzling, greenhouse gas emitting, climate change contributing gas furnace with a sleek, low emission heating and cooling system. Problem is, you don’t have enough electrical power for one of those, right? WRONG! We have seldom, if ever, encountered a situation where there hasn’t been more than enough power for a heat pump to replace a gas or oil furnace either on the existing main service, or in some cases of larger homes, with an upgrade to a 200A service if you don’t already have that. Most newer homes come with 200A service as standard, btw.
The myth that you need to upgrade your electrical service was born from a lack of information about the real loads most homeowners use. The Electrical Code – that bible that keeps us safe and our houses from burning down from shoddy wiring is a really handy document. It contains all sorts of rules and tables including ones that tell your Electrician how to estimate the size of service that you’ll need based on the things in your home that use electricity. As it’s goal is safety, there are large margins of error in each standard load, which is a pretty good idea.
Here’s the thing, though. If I add up those theoretical loads ‘by the book’, the result is often a number so large that I need a larger incoming service to meet the predicted load. Helpfully, a little over a year ago, the Electrical Safety Authority (ESA), the good folks who regulate all things electrical in Ontario, including how to size incoming services, issued a technical bulletin (8-3-15 for those who like to know these things) that spells out another way to determine if your existing electrical service is going to be good enough to handle the extra loads from a new heat pump. It is shockingly simple (I had to squeeze that pun in somewhere). You look at your highest hourly peak demand from the past year, then add a safety factor (always) of 125% to arrive at the safe maximum demand for your current usage (another good electrical pun). In the case of my house, with an existing 125A main service supplying a 1450 sq.ft. main house and a 350 sf garden suite, my hourly peak load in the past year was 9.39 kWh which using the formula from that ESA bulletin:
Peak demand (Amps) = ((highest LDC supplied value in a hourly interval kWh) X 125%) X 1000 / 240 V
Works out to about 50 Amps of current. So, with a 125A service, I have gobs of electricity to spare.
Now, we have been able to make these calculations in the past IF we can get the hourly load data. Which in theory we could, but in practice it was only available in a format that special software (that mostly doesn’t exist anymore) could read – called ‘Green Button Data’.
Recently, the good folks over at Toronto Hydro have stepped in and made it really easy to get really really good data on your actual electrical usage.
Login into your residential Toronto Hydro Account here
Click on the “Track my energy use” Icon
Click on “Hourly Usage” on the ‘My usage’ banner
3. Click on “Download hourly usage
4. Specify the Start date and End date (Maximum of 24 months from current date)
5. Click the “Download” button to download the *.CSV file
6. Then open this in a spreadsheet, and ask someone who likes Excel to help with the last few steps – or give the data to your Designer to help.
Bonus track – for Excel users
The data will appear in Column ‘B; so using the formula =MAX(B:B) you can quickly find the highest peak hourly load for the past year. Multiply this by 1250 and divide by 240. Voilá – your peak demand current in Amps, with a 25% safety margin. Compare to your nominal service size (typically 100A, 125A, or 200A), and the difference is how much capacity you have for you HVAC designer to work with when choosing equipment for your home.
See here how the good folks at Toronto Hydro are helping
For questions and support, please email climateaction@torontohydro.com.