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Energy efficiency Questions

Posted by ajsmama (My Page) on
Tue, Mar 10, 09 at 14:17

We have geothermal heat with electric backup in 18 month old 2700 sf Colonial and we just used 77 kWh/day this past month (avg temp 29 same as last year according to my bill). Last year it was 74. I am on GW a lot more now with old computer running, but not sure why we're using so much (more this year!) electricity. We have Energy Star (though LG claimed it was better than it really is) fridge and DW. Hot water is electric, though it's prewarmed by the heat pump that's not saying much this time of year. Usage is around 40 kWh/day during the non-heating season (even in the cooling season our heat pump is pretty efficient, bill doesn't change much from May - Oct, jumps in Nov when we turn on the breaker for backup heat). So on average we are still paying $265/mo for electricity all year round!

Windows are Andersen 400 series thermopane, we have 2x6 framing and R-22 insulation in the exterior walls, basement is insulated (not sure R value of fiberglas batts but have 2x10 joists so it's deep, at least R-19). Attic has full soffits and ridge vent but have R-38 in attic floor, also walls on either side of attic and basement stairs are insulated (R-22?). House is modular so we were thinking may not be sealed/insulated well b/t floors?

The only other things we could think of were to replace our 3-yr old non-Energy Star washer and dryer (electric) with front-load washer and a clothes line, and to maybe put foam gaskets on the outlets. Don't want to make the house too tight though - we haven't tested for radon, but sometimes we get sewer smell from Studor valve in attic and somehow from basement (along untrimmed sides of stair stringer, so not sure how much good it did to insulate interior DR, foyer walls along stairwell). So we know we are sucking air from unfinished sections of the house b/c the rest of the house is so tight. ERV was $2600 option we didn't get, think it can be installed afterwards so that's why we put it off but I'd like not to spend the $ at all. Any suggestions? Worth paying electric company $75 for an energy audit?


Follow-Up Postings:

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RE: Energy efficiency Questions

A couple thoughts,

First, 77 KWH per day isn't too bad for an all electric home of your size. A better index of 'how cold was it?' than the average temperature per the power company is a calculation of Degree Days. There are many sources, one link is below.It will give you a better measure of the heating demand on your system.

You might see if you heating contractor can 'tweak' your geothermal unit to use the backup electric plenum heater less- it takes 3-4 times as much electricity per unit heat as the geothermal unit.

I'd sure hesitate to replace a 3-year old washer and dryer. Are you using energy-efficient light bulbs?

How can you breathe without an HRV unit? Don't you have terrible condensation problems in the winter? We just moved into a new house with geothermal heat that's configured pretty much like yours. Even with the HRV running pretty much full blast, we had condensation and freezing on the inside of our windows when the outside temp got too far below zero.

Here is a link that might be useful: Degree day calculator


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RE: Energy efficiency Questions

Thanks for the link - I'll check it out. DH says there are a number of people at work who have about same size house who spend as much as we do on electric even though they have oil heat and in some cases oil HW too.

HVAC guy said to leave thermostat set steady not program it b/c even 2 degree rise could kick in Aux heat and it would cost more to bring temp back up than it would save by lowering it at night. How else could we use it less (other than setting temp lower)?

I guess we've got some leaks. Below zero some nights (lots of nights in that 77 kWh month) highs in teens, 68 in house, less than 30% RH and no condensation unless I run humidifier in kids' rooms and leave blinds drawn to sills. I found I can get it to about 40% RH w/o condensation if I leave shades up or pull them down over sills so some air gets in the sides at the bottom.

All recessed lights in kitchen are CFLs. We have 10 yr old TV that's on quite a bit, old computer on GW all the time but we don't tend to use lights much. I do leave stair light on for dd for an hour or sometimes more at night - 40 W incandescent sconce at top of stairs and 2 CFLs in flush mount at bottom on same switch (not my idea). DH has 60W in lamp on "his" end of couch that can be on a few hours/night, my side has CFL. Sometimes kids turn on halogen track lighting in FR but it's not like it's every night. Only light that gets left on all day (and sometimes night) is single CFL over sink.


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RE: Energy efficiency Questions

I try to shut off the printer when not using it (but eats up toner). Computer does not hibernate - I turn it off. Not sure how much power DSL modem and wireless router take.

No TIVO, but we do have DVD player with remote, old VCR (remote doesn't work but I think it still stays powered up if it's plugged in), and new converter box that has remote. Plugged into power strip but we'll have to remember to shut that off. Of course have coffeemaker with clock, MW with clock, programmable thermostats. Ds has clock radio. We probably have quite a few phantoms - any idea how to calculate how much?

I only use hot water about every 2-3 weeks for bleach load - always use cold rinse. Use warm for jeans & towels 2-3x/wk and cold for "dress" clothes (other cottons, knits, synthetics) other 3 loads. Top loader uses a lot of water. At least DW doesn't have heated dry (though I think it has booster heater). Main thing is that washer doesn't spin out jeans/towels well - I've already had it serviced last year but no better. So it makes the dryer work harder/longer.


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RE: Energy efficiency Questions

$75 for an energy audit? Yes, you should do it.

With modular, there is the possibility of gaps where the sections of house join. A little foam can fix that leak. The audit (assuming blower door test is done) will also tell you if you need an HRV for proper ventilation and indoor air quality.


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RE: Energy efficiency Questions

We were thinking the same thing, though we didn't know how to fix it if there were a gap b/t the upper and lower modules. GT installer was supposed to do a blower test and Manual J calcs but I don't know if he ever did - I wasn't around all the time (living 100 miles away during construction, part of the reason we did modular) and I never saw results. I'll call him tomorrow.


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RE: Energy efficiency Questions

Hi,
I agree on the energy audit -- you will likely get your $75 back in savings quickly.
If the audit includes thermal imaging, that would be a good way to locate any bad joints from the modular home construction, but if they put it together carefully, it does not seem like it should be a problem.

A handy gadget to have to figure out how much power things are using is a Kill-A-Watt -- you plug the Kil-A-Watt into the wall, then the thing you want to measure into the Kill-A-Watt, and it tells you how much power its using -- very handy.
www.newegg.com usually has them for about $15 to $20.

Gary


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RE: Energy efficiency Questions

Your numbers seem reasonable to me, maybe just a little high. Assuming you average 37 kwh/d for heat when it is 29 (average outside), that is 37 kwh/d x 3413 btu/kwh x 3 (heat pump eff 300%) / 24 hr/d = ~16,000 btu/hr head load. I have a comparable size house and I averaged ~14,000 btu/hr when it averaged 26 outside one month (closest comparison). I would say my house is insulated above average. If your heat pump efficiency is higher than I assumed you probably have some leaks to get under control.

good luck


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RE: Energy efficiency Questions

Thanks Chris. Climatemaster specs assuming full load is 32*F, COP would be 4.0, capacity 37,500 BTUh. What is your insulation?

I emailed installer, he did not run blower test - says electric company can do. He recommends waiting til we get all the window/door casings up (though I thought house wrap should prevent air infiltration, shouldn't rely on caulk and wood!). We drop temp 1* upstairs at night, bring it up 1* 6am, drop it 1* during day, back up 1* at kids' bedtime. Downstairs we drop 3* at night and creep it up 1*/45min starting at 5:30am. he suggested just leaving contant temp setting (like 67) so only operating in 1 stage. He said also since attic is unconditioned we can add to the R38 insulation in the floor/ceiling where some of the ductwork is run, and definitely insulate ductwork in the kneewalls where no plywood, ductwork sticks out over top of insulation. Said electric company has even had them use "bluebeard (blueboard?) b4 in unconditioned spaces. Ducts are "using 26-gauge galvanized sheet metal wrapped with the code required 3"inch thick FSK insulation for the main ductwork and R-8 3"inch thick flexible ductwork ducted to the individual supply and return air grills located thru the home" according to contract, but I don't know R value of 3"FSK.

He also suggested scheduling preventive maint. check (for a fee of course) to make sure operating "at its best."

Any other suggestions?


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RE: Energy efficiency Questions

How about a new thermostat? If you're having to be that fussy w/ the settings to avoid using aux heat, it either needs some settings changed or you need a smarter stat. I'd go w/ one of the Honeywell Vision Pros (either standard or the IAQ one, esp if you get a HRV).

I'd also get a blower door and poss. duct blaster test done to see how leaky the house is and where. Fine if part of a larger audit.

If parts aren't finished, that greatly increases the number of places that you can exchange conditioned air w/ unconditioned.


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RE: Energy efficiency Questions

I have R-49 in the attic and R-13 in the walls, in a 20 yr old colonial.

I would think the casings/jambs should make little difference. This area shouls already be sealed with a low expanding foam or similar.

I do like the honeywell vision thermostats too, I have one on our forced air system.


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RE: Energy efficiency Questions

Chris - so we have more in the walls and less in the attic. The windows just have fiberglas stuffed in. I have 9 window casings up that DH says we are not pulling off now that they're finished. Other 18 (roughly) plus slider and front door have either casing loosely tacked or no casing at all. I am planning on using foam in those. The rest of the envelope is finished (just no tile or sinks/faucets/toilet in master bath and no sink in powder room - supply and drains capped off).

We have the Honeywell VisionPro IAQ and basically the installer told me not to use it. Just set it (to 1 temp) and forget it! We also shouldn't have spent the $ on second zone upstairs (though modular company wired for thermostat location so I figured we should use it). We had oil HWBB in last house with programmable thermostats so I figured we needed programmable in new house. Looks like we should have spent the $ on HRV instead - now HRV price has gone up $400 in 2 years!


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RE: Energy efficiency Questions

I disagree with your installer and I'm tempted to call him various derogatory names.

If the IAQ is set up properly, it should recover from setbacks without calling for auxiliary heat. The 'Intelligent Recovery' feature will learn how the house responds and start running the system before the time that the next part of the program starts in order to use the HP only.

With as many different settings as there are in the IAQ setup programming, I'd be slightly worried that the installer set the stat up in a way that wouldn't take advantage of the smart features of the stat.

And I know it'll suck, but I'd go back and foam the rest of those windows.

FWIW, we have a dual-fuel setup w/ a HP. I just changed out the control so that the Vision Pro controls the switchover between the HP and gas furnace. Beforehand, a mechanical thermostat at the HP controlled whether it ran or not, based on outside temperature. I never trusted the accuracy of this dual fuel kit. And I've seen our gas bills go down, despite the cold weather this winter, which I think is a result of the Vision Pro running the HP down to a solid 30F instead of whatever temp the other switch was locking it out at.


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RE: Energy efficiency Questions

thull - We only set the temp back 1* to 67 at 8am, up to 68 at 6pm (maybe can change that to 7pm?) in time for the kids to go to bed at 7:30, down agian to 67 when we go to bed at 10pm, up again to 68 at 6am. Downstairs we set to 65 at night (10pm), up to 66 at 5:30am, 67 at 6:15, 68 at 7am. He initially told us 2* swings could trigger Aux heat. But it seems like once the night time lows get well below freezing, the GSHP can't keep up, so for the 2 winters we've been in this house we've turned on the breaker for Aux heat around Tgiving and then it runs every night (and in Dec starts running during the day) until early April.

How would I be able to set the IAQ (it does say when it's running in Recovery mode on the display) so that the 15kW heater doesn't kick in (so much)? Are we keeping our house too warm (sometimes it's 60* difference, or even more, during Feb)?

I'm trmpted to foam all the windows but DH says no way are we pulling the finished casing off (probably ruining it in the process) now that it's up. So if we find any leaks around those 9 windows, we'll have to carefully caulk. I really don't want to have to finish it again - I've got enough to do (I'm the wood finisher in the house - wish I knew enough and had the tools to be the woodworker, but I'm paying my cousin the carpenter $15/hr to do the things I can't or just don't want to do).


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RE: Energy efficiency Questions

You'll quickly get out of my depth, but here's what I can suggest. The link below is the installation guide for the 9421 thermostat. Page 2 shows you how to get into the installer setup.

The adaptive recovery setting is in register 0530, 1 is the default, which turns this on. Registers 0350 and 0360 will tell you whether the HP is locked out below a set external temperature. This would be counterintuitive, I think, for GSHP.

If the recovery setting is turned on, it may be that your system is undersized for those <10F times. At that point, assuming the HVAC is running as it should, I'd start looking at the building envelope for leaks. May not 100% correct the problem but it could help. And it'd answer your question about whether all those windows are leaking around the jambs.

I suspect that, if you were really enterprising, you could rig up your own 'blower door.' With the right fan, set up to depressurize the house, you could tell pretty easily where the leaks were. Not scientific or calibrated, by any stretch, but it help you see what's going on.

FWIW, friends of ours used to live in an Earthcraft-certified home in suburban ATL. I'm all for the program, but they complained vehemently about the AC in that house not keeping up. Even doing all the input/modeling for a proper system sizing, it's still possible to goof.

Here is a link that might be useful: IAQ install manual


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RE: Energy efficiency Questions

I went to Advanced settings last year and checked that IAQ was on. Our manual doesn't have settings 0350 and 0360 listed. It does have setting 0400, but that doesn't display - and I just checked, 0350 and 0360 don't either - goes right from 0320 to 0500. Any way to enter code? I've got honeywell on the line now - on hold.


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Honeywell won't work with me

Honeywell won't tell me anything - says I have to work with installer. I did get more Advanced Functions by pressing the 2 blank keys (instead of just the 1 that Owner's Manual tells about). They never set system up for Auto Changeover. I could set it, but have no way of setting deadband (function 0310). Also, Honeywell confirms that we have internal humidistat, but won't tell me how to configure it (function 0370 not available even in the "Installer" mode I went into). Last but not least, I can't even see function 0200 (electric/fossil aux heat), 0350 or 0360 (lockouts). Is there some special code an installer has to enter that isn't mentioned in the above manual? Otherwise I have to wait til summer for "maintenance" (filter replacement and they gave us too-small filter last year, but we're required to keep contract for 3 years), or pay for a service call.


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RE: Energy efficiency Questions

Fortunately, it's a smart thermostat. It won't let you change registers that aren't applicable based on some of the earlier/basic system settings.

If 0342 is set to 0 (no outdoor sensor), then you won't be able to adjust 0350 or 0360. But a GSHP isn't really affected by the outdoor temp, since the heat exchange pipes are buried just for that purpose (to be unaffected by cold temperature).

If you want to change 0300 for auto changeover, it will let you set the deadband in 0310 once you turn on changeover. Personally, I've never used this. We 'let it ride' when the temperature's moderate.

On the 0200 setting, what's the setting in 0176? If it's '1,' then the stat isn't running the aux heat and you won't be able to change 0200. This could be the case if a control board at the air handler is determining when to turn on the strips. I'm guess that this could be your problem- another control that's running the aux heat rather than wringing the last bit of heat out of the GSHP.

That would also defeat the use of the intelligent recovery feature of the stat. All that the air handler sees is a "run heat" signal, then it decides which heat to provide. The alternative, likely possible by landing extra low-voltage wire(s) at the interface box (unused strand(s) of thermostat wire that's already run) and changing some jumpers at the air handler, is for the stat to call for the GSHP as the primary heat and then call for staged electric strips as one or more backup heat sources.

The alternative is that intelligent recovery is turned off in 0530, which you didn't mention in your response.

It's kind of analogous to our problems with the dual fuel kit outside at our air-source heat pump. I added the outdoor sensor to the stat and took the dual fuel kit out of the loop to get more precise control over when the aux heat (gas in our case) runs.


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RE: Energy efficiency Questions

0530 is 1 so Recovery is on - we can see on thermostat when it's running in that mode. I don't remember if they set it or if I did last year.

0200 isn't showing so I have no idea what it's set to. Neither is 0176.

0342 is set to 1 (we do have a remote sensor) but I can't see 0350 or 0360 so have no idea if any lockouts are set.

Have't heard back from installer on how strips are wired and t-stat is set - guess he got tired of all the ?s yesterday.

We have 6-degree difference in heat/cool settings - we like it 68 when we're heating and if it gets above 74 we turn the A/C on. So I guess I could do a changeover with 6 degree deadband? What do you mean by "let it ride"? Looks like 3 degrees is the default.


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RE: Energy efficiency Questions

We manually change over our system from heat to cool. If it's warm enough during the day to maybe need cooling, but still cold enough at night to run the heat, I'm not paying for both. So we won't switch the AC on until its consistently warm enough or humid enough to really need it.

You've reached the end of what I can tell you about the Honeywell. You might get help at doityourself.com, but you'd need to make a complete list of your settings in all the registers in the Honeywell. And likely give them more info on your air handler and HP. They have some pros who answer lots of thermostat questions.

Asking or doing more research there may help. You might also consider posting on the HVAC forum here. I don't think as many folks in the know on systems are reading the Renewable Energy board.


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RE: Energy efficiency Questions

Thanks I did post on HVAC but no answers from anyone familiar with this t-stat. I can't see all the registers so don't know if doityourself could help. I think I'm stuck with getting installer to scroll through settings and explain things to me when he comes out to change filter. Climatemaster site was no help in ?s about staging and best settings.


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RE: Energy efficiency Questions

You shouldn't be able to see all the registers. As I said before, some of the basic settings lock out the later ones so you aren't fiddling with ones that aren't applicable. My problem is that I'm not totally clear on how yours is set up.

If you're following the instructions to get into the installer setup, make a list of all the registers you do see and their settings. The DIY forum folks may be able to help just with that.


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RE: Energy efficiency Questions

ajsmama

sounds like your installer did not do his job.

maybe post his name and where from so others can avoid him


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RE: Energy efficiency Questions

FWIW, I spent a few minutes the other day looking at some of Climatemaster's info. It looks like there are options for how your electric heat can be staged. I'll admit that I didn't understand the dip switch settings relative to that staging. Probably something you'd have to be looking at in person to have a eureka moment. I guess the worst case for you would be if it was set up as all one stage (15kW on as the only option).

Anyway, good luck with it. I'd do my homework and be ready with a lot of questions about how your system is set up and how they could better optimize it to use less energy.

Don't discount envelope/windows/etc as potential causes for your problems. If you can do some diagnostics on whether you have air leaks, it certainly can't hurt.

Here is a link that might be useful: Climatemaster electric heater manual


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RE: Energy efficiency Questions

Well, I certainly am getting a lot of leakage from my range hood. Supposed to have a backdraft damper on it (factory installed) but I wouldn't put it past the modular factory to have removed it (as for ductless installation) since they screwed up a lot of other things. Thanks thull for the link, I didn't see that on Climatemaster website. I'll have to check the jumpers and DIP switch settings. Maybe the HVAC did wire it for factory settings (5kW in stage 1) and just didn't use all the settings the t-stat is capable of.


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RE: Energy efficiency Questions

OK, didn't pull the cover off to check DIPs, but downstairs t-stat settings are:

0172 (system type) - 2E (HP with Auto Discover)
0174 (cooling compressor stages) - 2E (2 stages, AD?)
0176 (heating compressor stages) - 1E (1 stage, AD?)
0190 (changeover valve) - 0 (O/B terminal controls valve in cooling - what's that?
0200 (backup heat) - 0E (electric, AD)
0220 (stage 1 compressor cycle rate) - 3E (3 CPH, AD?)
0230 (stage 2 compressor cycle rate) - 3E (3 CPH, AD?)
0240 (Stage 1 heat cycle rate) - 5E (5 CPH, AD?)
0300 (auto/manual changeover) - 0 (manual - should I change this?)
0342 (outdoor sensor) - 1 (remote) - not sure why this doesn't say E as well, since the other functions with AD do.
0350 (HP compressor lockout) - 0 (none - good? Manual says if we have remote sensor, should select lockout)
0360 (HP Aux lockout) - 0 (none - I think we should set this, so if outside temp is above certain point, only HP runs? But what's reasonable?)
0365 (discharge sensor) - 1 (yes)
0370 (Indoor humidity sensor) - 0E (disabled, but should autodiscover? - Honeywell told me there was one)
0400 (ventilation control) - 0 (none)
0530 (Adaptive Recovery) - 1 (on)
0580 (compressor off time) - 5 (minutes)
0600 (heat range temp stop) - was 90, I changed to 75
0610 (cool range temp stop) - was 60, I changed to 65
0650 (extended fan time heat) - 0 (off)
0660 (extended fan time cool) - 0 (off)
0680 (heat temp control) - 2 (factory setting)
0690 (cool temp control) - 2 (factory setting)

Do these look reasonable for cold New England?


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