Jennifer Runyon, RenewableEnergyWorld.com and Chris Williams, Heatspring
February 26, 2014 | 22 Comments
Is it typical to have your electricity use to significantly increase after an installation? If so, why?
Yes, electricity costs will often increase after the installation of any heat pump, including a ground source heat pump.
Keep in mind that we're not so concerned with the fact that his electricity bill increased or how much, it's a more nuanced question. We're concerned with how much of that increase is directly attributed to the geothermal system itself and how much he would have had to pay to heat his home to the same temperature with another fuel source.
In general, the amount that a homeowner's electricity bill will increase depends on a few things.
If electricity use is significantly higher, what could be wrong?
This is hard to say, there's a few more questions we would need to answer that could help to deduce the problem. The only real solution is to monitor the system in real time. The good news is that this technology is now cheap and accurate.
I asked Matt Davis and Ground Energy Support to help me answer this question. Matt's an expert in real-time monitoring for geothermal heat pumps and specializes in helping homeowners monitor their geothermal heat pump systems so they can be 100% confident they're running well and identify the exact problems with a system if it's not. He's published a guide called The Homeowners Guide to Investing in Geothermal Heat Pumps.
Matt said he would want to get answers to a few more questions to determine more specifically what could be going wrong. Those include:
Here are some of the most common system problems that we'd be able to find with real time monitoring. The most common type of ground loop is a closed loop, so I'll assume it's a closed loop system.
Spot Checking Versus Performance Monitoring
Spot-checking of the system means a technician checks a few temperatures and readings in a single instance. The problem with spot-checking is that it doesn't provide very useful data about a system performance because it only provides a single snap shot in time.
In Matt's experience, spot-checking system performance is inadequate.
"He says that his installer came to visit and said it was working fine. What about when his installer left? You need to do monitoring if you want to see how it is working in the middle of the night during the coldest part of the year. Your installer is probably not sitting there watching it then. Snapshots of performance can be misleading with a GSHP system as they do not track if and when auxiliary electric is coming on, how long it is on, and should it even be on or is it compensating for some deficiency. [A monitoring system] tracks cost savings using local and up-to-date comparison fuel costs based on actual heating load so the homeowner doesn't need to do adjustments for price variations, variations in degree days, or changes in behavior. [Monitoring can] track BTUs, what they cost for geo and what they would have cost for other fuels."
Chris Williams is the on the executive committee for the Massachusetts Clean Heat Bill, which will create a production based incentive for renewable thermal technologies and is the Chief Marketing Officer at HeatSpring, you can find him @topherwilliams.
Matt Davis is the co-founder of Ground Energy Support, which provides real time monitoring for geothermal heat pump systems to homeowners that want to make sure their systems are operating efficiently.
Lead image: Electric meter via Shutterstock