Faulty Thermostat lead to high bills?

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Tyler23

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Hi -

I recently replaced a 30 year old, 80 gallon electric water heater with a new Rheem 65 gallon. I replaced it on the same day as my meter is read in April and seemed to be working fine, until I got my next bill and it was $100 higher than my one from the year prior (mild winter for us, no differences in water usage, etc.).

Called Rheem and they walked me through testing the unit with a voltmeter. The upper thermostat is bad so they are sending me a new one. I asked the tech why this would be causing such high bills and he seemed stumped.

The thing is, the water is not too hot so it doesn't seem to be overheating it. Both thermostats have been set to 120 degrees. We have no re-circ pump or anything else unique about this set up.

So my question is: how can a faulty thermostat cause such a spike in usage? It seems like it would make sense if the water was coming out way hotter than what it was set to as it would be constantly heating the water; but that's not the case (temp at the closest tap is 118). If anything, I am finding patches of cold or lukewarm water sometimes.

Any insight would be appreciated. I don't want to get my hopes up that this is going to solve everything. Frankly, I'm missing my old one right now.

Thanks,

Tyler
 

Reach4

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Look at four electric bills. See if one or both of the readings involved an estimated bill for the month in question or the month before. Also, you use electricity for heating -- at least to run the blower or pumps. Your usage could have changed.

Also, compare KWH usage rather than dollars.
 

Tyler23

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Look at four electric bills. See if one or both of the readings involved an estimated bill for the month in question or the month before. Also, you use electricity for heating -- at least to run the blower or pumps. Your usage could have changed.

Also, compare KWH usage rather than dollars.

Yes, I used 2010 Kwh for the month of April in 2014; in 2015 I used 3390. I used dollars because our rates haven't changed in three years. I estimate my own usage by taking readings throughout the month and plugging it into my Excel worksheet (though I've gotten out of the habit until now). It's usually within $5 of my actual bill.

Yes, I have an electric heat pump for heating, but our weather is actually milder this year than last. Obviously something is not right. So I'm wondering how a faulty thermostat on my new water heater could lead to such high usage.

Thanks for your feedback.
 

Jadnashua

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If the water is not getting excessively hot, only two things I can think of: the insulation on the new one is crap (unlikely, the new ones must meet higher standards than those of old), or you potentially have a leak somewhere. Take a look at your water meter while nobody is using water in the house. See if it is moving. Do your water lines run underneath a slab, or are they all exposed? If under a slab, if you have any pets, do they gravitate to certain areas, or do you notice any areas where the floor seems warm?

Electric WH work the top element to help you get the last out of the tank and to provide some quicker hot water, then, once satisfied, switches to enable the bottom element. That means that a faulty top element, the bottom one would never get enabled, and you'd have no hot water. So, unless that current is leaking somewhere and not putting that energy into heat in the tank, you're either using a lot of water, or something is electrified that shouldn't be.
 

Tyler23

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Thanks Jim. We are on a well, so no meter to look at. There are no leaks that I can see around the WH itself and there is a slab but no water lines go through it. The reason that I think it's the water heater itself that is the issue, is because the increased electrical usage started right when I installed this. The old one I removed was working fine at the time and it was a straight swap out: no new electrical or anything else. My usage for the month prior to the swap was in-line (less actually) with the year before.

Rheem is sending a technician to put in the new thermo, so I will be picking his brain on this too.
 

WorthFlorida

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I would be very surprised if the upper thermostat is bad. There are a few things you can do, or have an electrician if you are afraid of electric, to check your loads. While the water heater is presumed to be on, place your hand on the circuit breakers in the electrical panel and feel for heat. Excessive heat is not good and you need to have that circuit looked into. Most of the breakers should be at room temperature and a heavy load like a water heater might be just slightly warm but maybe no more than a few degrees. Excessive heat could be a bad connection at the breaker or even a bad breaker.

You'll need a clamp meter to check the current to the water heater. Most likely you have a 4500 watt heating (2) element at 220-230 volt. Only one element is on at one time. The current draw will be around 8.5 amps per leg (120 volts). To test this it is best to remove the circuit breaker panel and check the current from there and you can inspect the connections. Also check it at the water heater connection.

Also check that the water heater is wired with 10 gauge wire and you have a 30 amp breaker. A thirty year old home it should. But do check the voltage at the water heater while it is heating water to be sure you have full voltage. A big voltage drop could mean the heating elements are not getting hot enough but your wires or a connection is getting very warm burning power.

In S. Florida with A/C running most days, electric water heater and dryer, only in the summer do I get above 2000 kilowatts for the month. If you have a smart meter as most people do in Florida, it displays your daily load within 24 hours. If you do have one, turn off the water heater for the day and check your meter reading the next day. Or look at your meter spining, turn off the water heater and check the meter. If it really slowed down it can point that there is no other load in the house drawing a lot of power.

You mentioned that you have a heat pump, does the air handler have auxiliary electric heat? A common problem is usually when the A/C is running, the contactor for the electric heater is burned closed and therefore the A/C and heat are running at the same time. If you do check that the heat pump alone is running and the aux heat is off. A clamp meter would be helpful here. It could be just a coincidence that something else went bad.
 

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Dana

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Yes, I used 2010 Kwh for the month of April in 2014; in 2015 I used 3390. I used dollars because our rates haven't changed in three years. I estimate my own usage by taking readings throughout the month and plugging it into my Excel worksheet (though I've gotten out of the habit until now). It's usually within $5 of my actual bill.

Yes, I have an electric heat pump for heating, but our weather is actually milder this year than last. Obviously something is not right. So I'm wondering how a faulty thermostat on my new water heater could lead to such high usage.

Thanks for your feedback.

There's almost no way for a faulty T-stat on a hot water heater to add $100 to a monthly bill at WA type electricity pricing without noticing the steam explosion or pressure & temperature valve piddling away endlessly. The energy going into the tank has to be coming out somewhere, and it would be pretty obvious. At typical electric hot water heater uses 3500-6000 kwh per YEAR depending on your hot water usage- and extra 1300 kwh in ONE MONTH would be dead-obvious if it was the hot water heater.

But there are MANY ways heat pump fault can add up to another 1300kwh/month without noticing.

If your heat pump has auxilliary heat strips that come on at backup or are programed (often at the heating thermostat) to come on at some at some prededermined outdoor temp, a faulty ROOM thermostat or a stuck relay keeping the strip heaters active on all calls for heat could easily add $100 or even more to the heating bill despite milder outdoor temps, and without being obvious. A slow refrigerant leak could also result in significantly lower heat pump efficiency, which adds up to more kwh usage.

Methinks you've been barking at the wrong appliance.
 

Tyler23

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Thanks Dana. Nothing apparent with our heat pump (rooms/zones not doing what thermostat calls for). I just checked the board and the heat strips are not on. Everything there looks ok.

That's what's confusing about this. The higher bills coincides exactly with the new water heater, but there are no water leaks anywhere (I checked under the house) and it's not like the water heater itself or pipes are energized. When Rheem had me test it, I was getting 240v on the upper panel of the WH, but the thermostat was not (hence the reason they sent me a replacement).

I'm stumped. Either it's something having to do with the WH or I've got a major "leak" somewhere else....and I have no idea what to do.
 

WorthFlorida

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Be sure all faucets are turned off and check the water meter. If there is a leak it will show water flow.
 

hj

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quote; check the water meter

He said he was on a well, therefore, no water meter. High bills without extremely hot water would normally indicate a broken hot water line under the floor. If the upper thermostat were REALLY defective, you woul not have had ANY hot water.
 

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Could be a hole in the drop pipe in the well causing the pump to run a lot. So turning off breakers and seeing the effect on the electric meter could be informative.
 

Dana

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Thanks Dana. Nothing apparent with our heat pump (rooms/zones not doing what thermostat calls for). I just checked the board and the heat strips are not on. Everything there looks ok.

That's what's confusing about this. The higher bills coincides exactly with the new water heater, but there are no water leaks anywhere (I checked under the house) and it's not like the water heater itself or pipes are energized. When Rheem had me test it, I was getting 240v on the upper panel of the WH, but the thermostat was not (hence the reason they sent me a replacement).

I'm stumped. Either it's something having to do with the WH or I've got a major "leak" somewhere else....and I have no idea what to do.

I don't normally recommend instrumentation this expensive for one-off diagnosis', but if you're burning through a mystery 1000 kwh+ /month it's probably going to be worth the expense . By data-logging the power use on any & all suspect circuits you should be able to zoom in on EXACTLY where the power is going in a matter of a few days. It shouldn't be too tough to narrow it down- 1000 kwh/month is about 1400 watts of continuous draw, 1300kwh/month is almost about 1800 watts. If the parasitic power draw is intermittent it would show up as huge spikes well in excess of that, at times when nothing should be pulling power. It's a LOT of power, which would normally show up as quite a bit heat somewhere if it's being dissipated indoors. There's no way the water heater is draw that much parasitic power unless it always feels like a sauna in that room.

You could sell the TED on craigslist or something when you're done if you don't think you'll need it again, but keeping it as a monitor for the heat pump might be worth it to catch performance problems early.

A defective meter is possible, a simple error reading the meter would be caught and resolved in the accounting. If you use the TED on the power mains into the house to measure the whole house power use for a few days, reading the meter yourself, if the meter disagrees with it by more than a few percent, suspect the meter.
 

Tyler23

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Thanks Dana and others. This tech Rheem is supposed to be sending out is turning out to be flaky.

Regarding the meter, it was by happenstance that the PUD sent out a tech the day I received the higher bill to do an audit to make sure the meter matched what is relayed wirelessly to the truck that drives around each month. He said it matched up. I know it doesn't address whether the meter itself is defective though.
 

Dana

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It simply can't be the Rheem, whether the tech is a flake or a superstar.

An "extra" 1400 watts is a ~4800BTU/hr space heater. Even if the water heater is in an uninsulated garage it would be pretty toasty in there with that much heat being dissipated 24/7. If that much heat is being dissipated the inside of the tank 24/7 it's got to be coming out of the tank, either the temperature & pressure valve, and the t & p output plumbing would be scalding hot, with scalding hot water going down the drain (or all over the floor, if it's not plumbed to a drain). If it's a leaking hot water tap or pipe would be a steady dribble, not just a drip, and the hot water distribution plumbing would always be hot.

If you've completely ruled out hot water leaks as well as stuck strip heaters on the heat pump (which is really suspect #1) and that the heat pump itself is working up to snuff without engaging the strip heaters (suspect #2), and there are no warm/hot spots in the house indicating some other random 1400 watt load, my money is on the meter being defective.
 

Tyler23

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Yeah, I know Dana...I was just getting frustrated that he was being flaky. He came today and swapped it out. There are no water leaks at all. He also checked the breakers, listening for noises and feeling for anything hot. He was stumped as well.

So I guess the only thing left to do is call the electric company about the meter. I will check my heat strips tonight to make sure those are ruled out.

Question: if it is my meter, should I expect to see it still turning if I shut off both my panels? Is it that simple to figure out if that's the problem?
 

Jadnashua

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There should be absolutely no power consumption if you shut the main panel's main breaker off. I'm assuming that the second panel is a sub-panel...if so, then you only need to turn off the main breaker.

As said, though, if the WH was using all of that power, things would obviously be quite toasty. Try shutting the water off to the WH and watching the meter after say 1/2-hour or so. By then, with no hot water use, all elements should be off, and it should not be drawing much of any power (and unless it has some digital control, no power at all). THen, turn the shutoff back on, and see if the electric meter starts to show a spike in power usage. If there is a hot water pipe leak, a constant draw could cause that much of a rise. Is your pump running more often than previously?
 

Dana

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A meter defect would usually show up as a calibration error. Even a 300% error (a meter logging 3x the amount of power that was actually being used) would show up as zero power consumption if the main breaker was off, since 300% of zero is still zero. It's extremely unlikely that it would still be turning with the main breaker off, but it's easy to test that.

Monitoring the main power feed with a TED datalogger and comparing it with what the meter was logging would easily flag an error as large as the one you think is there.

A heat pump that's low on refrigerant could still heat the place during shoulder-season weather without engaging the heat strips, but at a much lower efficiency/much higher power consumption. I read an account of one mini-split heat pump installation in WA that was still heating the place with a coefficient of efficiency less than 1, which means electric baseboards would have been more efficient. With the proper refrigerant charge it deliver a COP of about 3, using less than 1/3 the amount of power it was using before the refrigerant charge levels was corrected. What make/model heat pump do you have?

With a TED you can figure out exactly which circuits are drawing which amounts of power (and when), which will steer you toward the real power hogs, and it can verify whether the meter is way off. If diagnosis drags on for a month or two, at $100/month of excess power billing/use, it would pay for itself.
 

Tyler23

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Hi all. Because I didn't want to be "that guy" who starts a thread and then disappears (not like you're all waiting around for this, but....) thought I'd let you know what ended up being the issue.

I had the power company come out and I worked with the tech by shutting off certain high-use breakers while he timed the meter spin. It turns out the well pump was running constantly. Got a well company to come out and test the pump, but it was fine. It ended up being a leaky pipe between the well and my house (220'). I was losing on the order of 8 - 10 gals/minute.

Had a directional boring guy come in and run a new pipe and electrical usage returned to normal. Because of the distance, the unknown depth of the pipe (turned out to 5' down), the age (1968) and the fact that the pipe likely went under both my driveway and landscaping (not to mention having no idea where the leak was), running a new pipe made the most sense as opposed to trying to fix it. It was $2,500 I didn't want to spend, but if it had gone on much longer, I likely would have burned out my pump (another $2k likely) and that would have been two problems.

Anyway, I appreciate the replies/feedback, especially Dana and Reach4 (who pretty much called it).
 
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