Comments on: A Surprisingly Common Cause for High Energy Bills

By: daniel

daniel — Sat, 30 May 2015 13:48:42 +0000

I had much the same problem.
I had much the same problem. SO, I got rather a lot of 240v baseboard heaters (surplus and wayfair sales) and ran them on 120v, knowing that they'd produce only 25% of their rating and be a LOT safer to use (no furniture arrangement troubles). These I hooked up with either Honeywell disc type thermostats or digital thermostats (with fan mode engaged so its either on or off). I used many of all of the above so that nothing could possibly overrun considerably. The thermostats are mounted in short depth boxes, surface mounted at floor level so as to do really relevant measuring.
The electric bill fell by 75%.
The inconvenience is that changing the temperature means visiting each station. That was an initial challenge until everything was set. Afterwards it has maintained suitable temperatures all year long without any additional labor.
An additional limitation is that if the heat is shut off for vacation, the house will not reaheat quickly and may take more than a day (were it not for some help from space heaters and the oven); however, were that not the case, indeed the 25% powered baseboards with high accuracy thermostats will hold up in the very worst winter conditions down to 38 below without varying the room temp more than 1 degree.
Apparently, physical bulk and heat at floor level are key factors for resistance heat. Of course, heated floor could have been more efficient, but I wasn't really motivated to replace all of the floors.
Physical bulk could be in the form of my undervolted baseboards or modern radiant panels or heated floors, all of which are far more efficient than anything with a blower.
In my opinion ductwork with resistance heat is a request for horrid bills and whatever you do, just don't do that.
It is notable that the shoppers at amazon have been routinely using the 600W big panel heaters along with plug-in digital thermostats, and I see that the heaters are positioned low enough to suck cold air off the floor, meanwhile the thermostats are on typical outlets low-positioned close to the floor, which almost guarantees fair accuracy. Not surprisingly, it takes a lot of units and their bills fell dramatically.
Resistance heat operates efficiently when it is at least 2% of the room's total bulk, when there is no blower involved and when the sensors are close to the floor.
So, by all means, disable the heat-strips in those awkward ductwork systems.
That is all.

By: Barbara

Barbara — Fri, 10 Apr 2015 17:56:17 +0000

Update. HVAC guy is coming
Update. HVAC guy is coming back out again today. He's been here off and on 3 times since I last posted. It is getting better. The heat pump and air handler power consumption is now only about a third more than it should be. He got upset with me and bought the tools to test static pressure. (aren't they supposed to have these tools?) My static pressure is way off. Changing out the reversing valve.... again.

In the mean time, by utilizing my TED unit, I found two major massive power draws and "house burn down" problems. The main breaker (outside disconnect), was melted and burnt. It couldn't be seen without the meter pulled. And I found a wire going to the outside lights that had melted the supply, neutral and ground wires together. It was pulling 1.5kw per hour. I'm a very lucky person that it didn't catch fire.

My power bill went from 2800kwh down to 419 this month with the AC off.

By: Regina

Regina — Fri, 10 Apr 2015 08:48:32 +0000

I have had this exact same
I have had this exact same problem. My house wasn't going below 85 and it was unbearable. I'm curious if I am just doing something wrong or if there is a loss of connection. Thanks for the article.

By: David Butler

David Butler — Tue, 07 Apr 2015 02:14:58 +0000

@Stephanie, there's no way to
@Stephanie, there's no way to diagnose in a forum like this, but it's possible the heat pump may be configured to shut down when the electric furnace turns on, perhaps at a pre-set outside temperature.

A lot of hvac techs think this is the correct way to configure a heat pump, but it only leads to much higher energy bills.

At 0F, a 2006 vintage heat pump is still approx 2x more efficient than an electric furnace. But it doesn't have enough capacity to keep your home warm at that temperature, thus the need for supplemental heat.

The other possibility is that your heat pump has a problem. Now that the coldest part of the winter is past, you can easily test this by having the tech temporarily disconnect the electric furnace. If there's a separate breaker for the electric heat elements (vs. the air handler) you can simply turn off that breaker until it drops below freezing again.

The heat pump should be able to keep your home warm when it's in the 40's or above outside. That way you can be sure your heat pump is working properly.

By: Stephanie

Stephanie — Tue, 07 Apr 2015 01:14:17 +0000

Hi, I'm looking for any
Hi, I'm looking for any advice or suggestions regarding my current energy situation. My family moved into a house that was built in 1974 in December 2013. The previous owners had put in a Lennox Electric Furnace & heat pump in 2006. We are in South Dakota and our winter months getting pretty cold. In the first few months we moved in our electric bills ranged from $700-$1000 each month. We had several techs out that couldn't find anything wrong, and the 3rd person that came out said the unit had wires that were connected wrong. This wasn't until April 2014 that this was found and by that time the weather was getting nicer. Our summer bill usage averaged last summer around 1600 kwh each month. Once winter hit again the monthly kwh usage went from 6,404 to 7,479 to 8,444. I had another tech out this month and he found a wire was burnt out, but said everything else looked good. I'm wondering if this seems unusual to anyone else for an electric furnace or if there are any other suggestions on what I could do? We have a 2 story house (2,000 sq feet) and an unfinished basement (750 sq feet). We also replaced all of our lighting with LED bulbs, and have brand new energy star kitchen appliances and washer/dryer.

By: David Butler

David Butler — Wed, 11 Feb 2015 00:37:40 +0000

@Donna, amplifying on Curt's
@Donna, amplifying on Curt's comment, you didn't say if you have a heat pump (which is the topic of the article here). If's you're not sure, check to see if the outdoor unit is operating during heating calls.

By: Curt Kinder

Curt Kinder — Tue, 10 Feb 2015 23:50:45 +0000

Long distance guess - system
Long distance guess - system is straight cool and so relies on electric aux strips as sole cource of heat, OR it is a heat pump with a major problem such that the compressor won't run properly in heat mode

I would also look for a gross duct leak in an unconditioned space...you could be trying to heat all outdoors!

By: Donna

Donna — Tue, 10 Feb 2015 22:55:16 +0000

I'm having extreme
I'm having extreme electricity usage when my electric heater is running. I've narrowed it down to that by looking at my smart meter data. When no heat is being used (turned off)my daily usage drops to about 10-12 kWh a day (I'm frugal)and jumps to 115 and over when heat is on. I live in Houston and it has not been that cold here!
I've had two HVAC calls and a number of friends take a look and no one has found a problem. Any hints to guide me as to what to do? It's tough to pay HVAC as I have to pay the high electric bills and that leaves me broke. It is warm enough now that I can leave the heat mostly off but I'd like to get this fixed.

By: bob

bob — Sun, 08 Feb 2015 22:48:54 +0000

Just turn off one of the
Just turn off one of the breakers at the air handler to cut the AUX heat in 1/2. One will have the blower also, so be sure to get the correct breaker.

By: David Butler

David Butler — Sat, 07 Feb 2015 21:52:50 +0000

@Barbara, as Curt said,
@Barbara, as Curt said, neither the thermostat, nor white wire at the stat, have anything to do with defrost operation. The defrost control on the outdoor unit will independently energize the strips, so disconnecting the white wire only solves part of your high load problem.

It's hard to say which one (defrost, vs. supplemental heat calls) represents the largest contributor to your high energy bills, but you need to have strip heat during defrost calls.

Also note that the defrost controller operates on a timer, when outside temp is below a pre-set limit. It has no way to know if there's actually any frost on the coil. So it's not unusual for defrost cycle to start when there's no frost. BUT, in that case, the cycle shouldn't last more than a minute or so. If that's not happening then either your unit has a poorly designed defrost control, or the liquid line sensor is defective. Typically, there's a sensor on the liquid line that terminates the defrost cycle quickly when there's no frost.

Also, you do NOT need 20kW of strip heat during defrost cycles. A strip kit that large will have more than one stage (possibly a 7kW first stage?). So the control sequencer shouldn't allow the full 20k in the beginning of a call for strip heat. In any case, I suggest having your hvac tech disconnect the 2nd stage, as I doubt seriously you'll ever need it in your climate.

One final comment, if your defrost is energizing when temps are in the 50's, then you either have a poorly designed defrost control or a defective ambient temperature sensor. Those things sometimes need to be calibrated.

This discussion is getting way too detailed and technical for an online forum. Contact me off-list if you'd like further assistance.