Electric bill

Discussion in 'General Discussions' started by TuffToodle, Nov 29, 2018.

  1. TuffToodle

    TuffToodle New Member

    Oh - and our set back is only from 71 during the day to 68 in the evening. I also only started using the setback this year - and this is year 4 of this recurring issue, so I know it's not the problem - it might not help, but it's not the answer.
     
  2. ChrisJ

    ChrisJ Active Member Forum Leader

    You won't know what that point is unless the heat pump is allowed to carry the load by itself. Somewhere in the system is a way to adjust that outdoor temp setting.
     
  3. SR

    SR New Member

    Please try this experiment this weekend when you are not out of town: Leave your t-stat at 71 continuously. Go to your electrical panel and look for the circuit breaker(s) labeled "Duct Heater" or "Elec Coil" or "Heat Packs" and turn them off. There should be one or maybe two of them and they should be 30 amp, 40 amp or maybe 50 amp 2-pole breakers. Do not turn off your heat pump circuit breaker. Once you do that we will know for sure whether or not your GSHP can carry the entire heating load by itself, as ChrisJ noted above. If you can turn them off and your house does not get chilly this weekend, we have your solution. If your house gets chilly, then you have to add insulation, seek out a manual J, hire a lawyer, etc. But it won't come to that.
     
  4. Noobie

    Noobie New Member

    OP, what I know about geothermal fits in a thimble, but having lived in two leaky houses, including my current one that we are insulating, don’t underestimate the effect of leaks. 5% of the attic being under insulated will have more effect than you would think.
    We insulated half of our cathedral ceiling to R60+, but until we do the other half, it doesn’t “average” out to R30.
     
  5. TuffToodle

    TuffToodle New Member

    I'm sorry it took so long to get back to you SR - we had a busy weekend - I am going to dig up the manuals this week and do some reading, If I can figure out how to disable the aux I will report back.
    Noobie - I am happy to insulate and air seal, my only concern is the cost/benefit. Our insulation contractor projected an $80 savings / year (my own projections come out closer to $290) - but the expense of insulating our attic roof to create a conditioned space for the duct work was quoted at 16K !!! - It would take 30+ years to recoup that investment. Now, granted this is a home we plan to stay in, but there are many other items on my to-do list that would come first if those savings projections are accurate. We are also considering doing it ourselves at this point- from what I have heard it is relatively straightforward - just a royal pain to do yourself.
    I'll report back as soon as I have more information!
     
  6. TuffToodle

    TuffToodle New Member

    Unfortunately, all our circuit breakers were labeled "geo" so it will require a bit more detective work
     
  7. nc73

    nc73 Member Forum Leader

    You could just go the easy route and get a regular heat pump. They aren't as efficient but at this point, it will be more efficient than the geo. Less things to go wrong with an air sourced heat pump! I went with geo because I like to tinker. Non tinkerers should really stay away from geo.
     
  8. TuffToodle

    TuffToodle New Member

    Sorry nc73 - that ship has sailed - I will just have to become a tinker-er lol
     
  9. IsItForMe

    IsItForMe New Member

    Could you please elaborate on your reasoning for repeating this sort of recommendation so often?
     
  10. TuffToodle

    TuffToodle New Member

    Ok, I am up to my eyeballs in manuals, but so far no way to turn the aux off to let it run. I have been keeping an eye on the thermostat and have not seen the aux come on at all over the past week - so my guess is that is operating as it should - we've had some cold and snowy days/nights and no sign of needing the backup heat. So that's good news I guess. I'll keep you all posted as I find out more.
     
  11. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Lets do the math here: a dual stage 4 ton system should use between 2.7-2.8 KW when running. Lets say 3 KW just for round numbers, in stage 2.
    72 KWh per day, 2,160 kWh per months, at 0.15 $/kwh it is $324/month. This is 24hours/30days OP claims it is $700/month.

    I would say it is a save bet that the aux heat is engaged, unless something else does not add up.
     
  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Yes, if your strip heat comes on, you can see bills like that. You already told us you are having uninsulated ductwork in the attic, which means you are heating the outside.
    While the manual J allows you to calculate the envelope based on certain assumptions based on heat flux (insulation) and air tightness (cold air infiltration), it is more a guesstimate since it is very difficult to check what is really in the walls of an existing house.
    If you have clear and obvious holes in your thermal envelope, including non insulated ductwork in your attic outside the thermal envelope, you are obligated to fix that, or pay the price of higher heating costs. You cannot simply blame your HVAC contractor for your high heating bills. It is not his fault that your house uses more energy.
     
  13. TuffToodle

    TuffToodle New Member

    Well when you put it like that it just makes so much sense lol . So if the aux is engaging that much - how do I fix it? Is it the Geo system that needs tweaking or my leaky house?
     
  14. TuffToodle

    TuffToodle New Member

    Just to be clear, the Attic is under insulated, but the duct work is insulated. So, based on what you're saying, I should just assume the original insulation projections were low and that once I tighten up the house these crazy bills should resolve? I'm not looking to place blame. I just need to figure out the root cause and fix it before I'm screwed lol
     
  15. Tamar

    Tamar Member Forum Leader

    Hello all, I just popped in to see what's new.

    TuffToodle, I'm a homeowner, not a geo expert, but I have learned a lot on this forum. I want to make a few plain English suggestions that might be helpful. I noticed up the thread that you say you have 2 thermostats and you also mentioned that one was on the counter so that your son could play with it. Is that correct?

    Do you have the option of leaving your lower level thermostat at your comfort temperature (no setback! that's a geo no-no), and setting the upper level thermostat lower? I'd try that.

    Also, your thermostats should be on interior walls; I hope they are. Let us know if they are not. The comment about your son resetting it has me seeing visions of the "great" thermostat that our first geo installer wanted to give us that we could carry through the house and it wirelessly transmitted the temperature, which is a supremely stupid idea.

    Third, your aux heat can be disabled by simply disconnecting a wire that's currently connected to your thermostat I know it's probably not a great suggestion for you to pull the thermostat off the wall and figure out which wire is for aux heat, but maybe a friend could help? (EDIT: ignore this suggestion if aux heat is controlled by a controller...see geoxne's better suggestion below)

    In the long run, at the very least you need to either figure out how to allow for more "droop" (temp drop) before the aux heat kicks in, or you need a different stat.

    for more in-depth advice...Doc will not steer you wrong, so when he asks for more information you'll be paid back in spades if you can provide it. :)
     
    Last edited: Jan 20, 2019 at 12:26 AM
    Marsman likes this.
  16. geoxne

    geoxne Active Member Forum Leader

    Your Arzel Zone Panel is in charge of staging your 2 stage HP and aux heat. Staging can be adjusted during setup based on a number of settings. Depending on which model you have, these adjustable settings include % zone weights, leaving air temps, outside air temps and even ground loop temperature on one model.
    https://www.arzelzoning.com/products/

    It is very possible your zone panel is staging on aux heat unnecessarily. It is very important that you find a trained Arzel technician that is familiar with the performance of your geo HP and how it needs to be controlled to set up your zoning properly. Also beware of any Dual Fuel setting. This will turn off the compressor when aux heat is called. This setting is only needed when the aux heat source is upstream of the HP coil (ex, gas furnace with HP coil) as HP can not heat already heated air.

    All this assumes your HP is performing to specification. This can be confirmed by calculating the heat of extraction and comparing to published capacity charts.
     
  17. Marsman

    Marsman New Member

    I would avoid set backs. I assume your T-stat is seeing the differential when going to 71F and aux is coming on. I have breakers on my panel and a box on my wall going to my coil box. I turned off the wall box. The only time I have it on is if I am away and I need the back up . When I moved into my home , my power bill was higher and I read on this forum to disable Aux and if you do not disable it leave it set and/or only set back a degree or so
     
  18. TuffToodle

    TuffToodle New Member

    Tamar - I did as you suggested - I have the upstairs thermostat set at 70 and in the evening goes back only to 68 - the downstairs is now at a constant 70. Initially, I set them both back because I had assumed the hot air from downstairs would travel upstairs and it would cause the downstairs to run more at night. I have done a lot of reading about doing setbacks on geothermal systems and the consensus seems to be that it is fine to do if it will be for a period of 8 hours or more and if it is less than 3 degrees difference - so that's what we have here. We didn't have much of a choice it was just too hot at night and too cold during the day. The thermostats are both on interior walls, but they are wireless, so there is no cord that connects to the aux heat to disconnect :(
    geoxne - Obviously I don't have the know how to go plugging around in the zone panel, but we have had a few days here in PA below freezing (8 degrees last night) and the few times I checked the thermostat I didn't see the aux sign - I do know we are still using a lot of electricity though, so I am inclined to think we are just hemorrhaging heat. While the geo may be performing perfectly, if it's running constantly I imagine that's where the bills are coming from? How would I calculate the heat of extraction like you mentioned to see if the HP is functioning properly? I really love our geo installer and I am inclined to believe him when he says things are set up properly - especially after having a competitor check out the system. We've strated to make small air sealing improvements, but things like attic insulation are just going to have to wait for the tax return.
    Thanks again for all the help guys - I'll keep you posted. January-February are always our worst electric months!
     
  19. Tamar

    Tamar Member Forum Leader

    Okay, just one more thought and then I'll turn it back over to the experts. Does your fan run constantly, or only when the Geo is running? If it runs constantly as opposed to cycling with the geo (assuming the geo cycles) that could contribute to a higher energy bill.
     

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