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RegGuheert
Posts: 6229
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 11:55 am

iPlug wrote:We're debating whether we would need a back-up natural gas furnace (dual fuel) if we change our AC to a heat pump. Do you find that your heat pump can keep up with your low temps or do you go to resistance or natural gas heating at that point?

It only gets as cold as the mid 20s for a few hours, <5 times a year here, so don't know if a backup natural gas furnace is worth the investment. Not sure the HVAC guys would even agree to tie in our old natural gas furnace if upgrading the AC to a new high efficiency heat pump system.

A Trane 5 ton XV20i 20 SEER / 10 HSPF unit looks pretty sweet.
Our Trane 5-ton unit is a bit older: XL19i 19 SEER / 8.2 HSPF. It is rated to stay off of the resistive backup furnace down to the low teens. I would expect a newer unit with an HSPF of 10 to get you down to about 10F.

The real trick with a heat pump is the ramp rate. We drop our temperature by 6F at 7:00 PM each night in the wintertime and ramp it up slowly in the morning. The issue is that on cold and/or windy mornings, the ramp may be too fast for it to make the setpoints in time, which kicks on the resistive heaters. As such, I just turn off the breakers to the electric backup furnace this time of year when I don't expect the temperatures to get below about 20F.

In your case, I certainly wouldn't install a gas furnace, but if you have enough electricity at your panel, you might want to add in a resistive furnace. That way you can have heat if/when the outdoor unit has issues.
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

iPlug
Posts: 108
Joined: Thu Apr 28, 2016 6:47 pm
Delivery Date: 25 Apr 2016
Location: Rocklin, CA

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 12:40 pm

RegGuheert wrote:...In your case, I certainly wouldn't install a gas furnace, but if you have enough electricity at your panel, you might want to add in a resistive furnace. That way you can have heat if/when the outdoor unit has issues.


Thanks for the advice. That makes me feel a lot more comfortable with going without a gas furnace.

Our house was built in 2002 and we have a Square D 30 space 200 A service panel. All 30 spaces are currently taken. Besides the usual house electrical demands, our PV solar, HPWH, 2 electric charging stations, spa, and pool pump got us to that point.

We could add quad breakers to accommodate additional devices, but the electrician who did the HPWH wiring (our last addition to the panel) says our service panel bus is near capacity. So we would probably have to upgrade to a 400 A service panel for that reason to accommodate a resistive furnace. Also this would probably be needed to meet building code at least, even if we never need to use the resistive furnace.

Besides, that would give us an excuse to finish adding PV panels to our one remaining PV panel-free roof slope, and the service panel upgrade would qualify a part of the 30% federal tax PV credit as it would be needed with simultaneous installation of more PV panels. :D
2016 Leaf SV (leased) + 2012 Plug-in Prius (own), 11.43 kW Solar PV (16 MWh/yr actual production), Clipper Creek Level-2 7.7 kW charging stations x2, 20.5 SEER/13.0 HSPF ducted air-source heat pump, 3.70 UEF heat pump water heater

LeftieBiker
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Location: Upstate New York, US

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 1:33 pm

Our house was built in 2002 and we have a Square D 30 space 200 A service panel. All 30 spaces are currently taken. Besides the usual house electrical demands, our PV Solar, HPWH, 2 electric charging stations, spa, and pool pump got us to that point.


Because the pool pump and resistive furnace wouldn't be used at the same time, I wouldn't worry too much about panel overload. Put that pump and another moderate or low load on half space breakers.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
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goldbrick
Posts: 150
Joined: Tue Aug 01, 2017 3:33 pm
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Leaf Number: 311806
Location: Colorado front range

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 1:50 pm

LED lights everywhere, 18" of blown-in cellulose in the attic (HUGE difference), open windows at night, closed during the day (summer time temps in house are usually in 60's). Outdoor mounted on-demand gas water heater for hot water and we retro-fitted a radiator into our existing forced air heating system that uses this hot water as well. Induction stove. We get rated #1 by our local utility for our neighborhood and our average electric use for the last 12 months was about 220kWh per month. It's a bit of a problem since I want to get panels on the roof but the utility limits the amount of generation you can do to 120% of your recent usage. That limits me to a really small system and since our house is about 2400 sq ft I could fit a lot more. I'm thinking I need to start charging the car at home instead of the free charging I get at work. I might still install the bigger system although I may never recover the money from the excess power generated. Maybe I'll install an EVSE outside and charge my neighbors to use it to recover the expense. :mrgreen:

iPlug
Posts: 108
Joined: Thu Apr 28, 2016 6:47 pm
Delivery Date: 25 Apr 2016
Location: Rocklin, CA

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 2:11 pm

goldbrick wrote:LED lights everywhere, 18" of blown-in cellulose in the attic (HUGE difference), open windows at night, closed during the day (summer time temps in house are usually in 60's). Outdoor mounted on-demand gas water heater for hot water and we retro-fitted a radiator into our existing forced air heating system that uses this hot water as well. Induction stove. We get rated #1 by our local utility for our neighborhood and our average electric use for the last 12 months was about 220kWh per month. It's a bit of a problem since I want to get panels on the roof but the utility limits the amount of generation you can do to 120% of your recent usage. That limits me to a really small system and since our house is about 2400 sq ft I could fit a lot more. I'm thinking I need to start charging the car at home instead of the free charging I get at work. I might still install the bigger system although I may never recover the money from the excess power generated. Maybe I'll install an EVSE outside and charge my neighbors to use it to recover the expense. :mrgreen:

Nice!

LeftieBiker wrote:Because the pool pump and resistive furnace wouldn't be used at the same time, I wouldn't worry too much about panel overload. Put that pump and another moderate or low load on half space breakers.

I'm ok with that, it seems very unlikely that in any reasonable scenario we would exceed the ratings of the service panel as a couple appliance uses are mutually exclusive. Additionally, although on breakers to support much higher demand, we only run the HPWH in heat pump mode which only seems to run max 0.5-0.6 kW despite on a 30 A breaker (in case using resistive heating), and our EV charging stations are on 40 and 50 A breakers - but one of these is for our Plug-in Prius which only charges at max ~2 kW.

However, when we installed the last appliance, the HPWH, our city made us do a load calculation worksheet and we barely made it without having to upgrade the panel. If the resistive furnace uses no more than our old 10 SEER AC, it might still work for the city load calculation requirements.
2016 Leaf SV (leased) + 2012 Plug-in Prius (own), 11.43 kW Solar PV (16 MWh/yr actual production), Clipper Creek Level-2 7.7 kW charging stations x2, 20.5 SEER/13.0 HSPF ducted air-source heat pump, 3.70 UEF heat pump water heater

User avatar
RegGuheert
Posts: 6229
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 2:42 pm

iPlug wrote:Our house was built in 2002 and we have a Square D 30 space 200 A service panel. All 30 spaces are currently taken. Besides the usual house electrical demands, our PV solar, HPWH, 2 electric charging stations, spa, and pool pump got us to that point.
A few thoughts on this:

- Put the breaker(s) for the solar on the OPPOSITE end of the panel from the mains. That way the current from the solar is not additive with the mains. (I know: that doesn't change the code requirements, but it DOES change the physical reality.)
- If you run your HPWH on "Heat-pump Only" mode, it will only draw about 600W, so it is not a big deail in that case. (Again, it doesn't help with codes, but it can help in reality.)
- Put the breakers for the charging stations and the spa near the mains so that the amount of resistance (and therefore, heating) is minimized for those.
- Nowadays the bus bars are rated for at least 225 A in a 200 A panel, but I don't know if that was true in 2002. Do you know what the rating is for the bus bars in your panel?
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

Zythryn
Posts: 1023
Joined: Fri Jun 04, 2010 4:49 am

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 3:11 pm

We recently started from scratch to build as efficiently as we could.

Lots of insulation and excellent windows.
Heat pump technology for our heating, cooling, domestic hot water and clothes dryer.
PV with batteries.

We also have a very small amount of turf. The rest of the yard is rain gardens and drought tolerant plants. After the first year, getting the turf and plants established, we expect to use no irrigation. Just what the rain brings.

We also designed our house with lots of windows on the south side, with an overhang designed to shade the windows in the summer, and let in the winter sun.
Floors and counters in south facing rooms are dark tile or countertop. These absorb heat during the sunny hours, preventing the home from overheating. In the evening, the tile releases that heat, lessening the need to heat the house.

No natural gas at all. We don't even have a meter. Even though we have nothing that produces carbon monoxide, we still put in CO detectors, because it is in the building code :lol:
Previous owner of Prius, Volt, Leaf & Model S
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iPlug
Posts: 108
Joined: Thu Apr 28, 2016 6:47 pm
Delivery Date: 25 Apr 2016
Location: Rocklin, CA

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 4:03 pm

RegGuheert wrote:A few thoughts on this:

- Put the breaker(s) for the solar on the OPPOSITE end of the panel from the mains. That way the current from the solar is not additive with the mains. (I know: that doesn't change the code requirements, but it DOES change the physical reality.)

Yep, that's how we have it setup.

RegGuheert wrote:- If you run your HPWH on "Heat-pump Only" mode, it will only draw about 600W, so it is not a big deail in that case. (Again, it doesn't help with codes, but it can help in reality.)
- Put the breakers for the charging stations and the spa near the mains so that the amount of resistance (and therefore, heating) is minimized for those.

That's how we have it setup.

RegGuheert wrote:- Nowadays the bus bars are rated for at least 225 A in a 200 A panel, but I don't know if that was true in 2002. Do you know what the rating is for the bus bars in your panel?

Yes, our bus bar is 225 A.

Thanks for the input. You are probably right, there seems no physical/electrical reasons why a heat pump HVAC/electric resistance furnace upgrade would not work using our our same panel.

Zythryn wrote:We recently started from scratch to build as efficiently as we could.

Lots of insulation and excellent windows.
Heat pump technology for our heating, cooling, domestic hot water and clothes dryer.
PV with batteries.

We also have a very small amount of turf. The rest of the yard is rain gardens and drought tolerant plants. After the first year, getting the turf and plants established, we expect to use no irrigation. Just what the rain brings.

We also designed our house with lots of windows on the south side, with an overhang designed to shade the windows in the summer, and let in the winter sun.
Floors and counters in south facing rooms are dark tile or countertop. These absorb heat during the sunny hours, preventing the home from overheating. In the evening, the tile releases that heat, lessening the need to heat the house.

No natural gas at all. We don't even have a meter. Even though we have nothing that produces carbon monoxide, we still put in CO detectors, because it is in the building code :lol:

Zythryn, you are way ahead of the curve. Lot's of leading edge stuff, enjoy keeping up with your progress.

For those who are not aware, check out his website at: http://netzeromn.com
2016 Leaf SV (leased) + 2012 Plug-in Prius (own), 11.43 kW Solar PV (16 MWh/yr actual production), Clipper Creek Level-2 7.7 kW charging stations x2, 20.5 SEER/13.0 HSPF ducted air-source heat pump, 3.70 UEF heat pump water heater

iPlug
Posts: 108
Joined: Thu Apr 28, 2016 6:47 pm
Delivery Date: 25 Apr 2016
Location: Rocklin, CA

Re: Share Your Home Electrification/Efficiency Improvements

Wed Apr 04, 2018 4:12 pm

Zythryn wrote:...Heat pump technology for our heating, cooling, domestic hot water and clothes dryer...

Over in PriusChat, I think you mentioned a couple years ago that you got a ventless Whirlpool model? Any issues with the dryer? We have been hoping there would be more competition joining the fray of heat pump dryers, but not really any new players in the last couple of years. When our electric dryer goes, we definitely would like to go heat pump and probably Whirlpool if they remain one of the few games in town.

Zythryn wrote:PV with batteries.

Everything running smoothly with the PowerWall batteries? I think you mentioned there were some bugs to work out initially. Really nice to have that buffer/storage.
2016 Leaf SV (leased) + 2012 Plug-in Prius (own), 11.43 kW Solar PV (16 MWh/yr actual production), Clipper Creek Level-2 7.7 kW charging stations x2, 20.5 SEER/13.0 HSPF ducted air-source heat pump, 3.70 UEF heat pump water heater

GetOffYourGas
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Joined: Tue Dec 20, 2011 6:56 pm
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Location: Syracuse, NY

Re: Share Your Home Electrification/Efficiency Improvements

Thu Apr 05, 2018 5:21 am

Very nicely done, Zythryn. I love that you use both passive and active methods to increase your efficiency!

Zythryn wrote:We also have a very small amount of turf. The rest of the yard is rain gardens and drought tolerant plants. After the first year, getting the turf and plants established, we expect to use no irrigation. Just what the rain brings.


I'm always surprised at how many people water their lawn. I guess I'm just spoiled by all the rain we get. Watering is rarely a problem, it's the flooding you have to be careful of. I have no problem keeping a lot of grass growing. I have a problem keeping it mowed. When it does stop raining, the grass doesn't dry out fast enough before it rains again!

Zythryn wrote:We also designed our house with lots of windows on the south side, with an overhang designed to shade the windows in the summer, and let in the winter sun.
Floors and counters in south facing rooms are dark tile or countertop. These absorb heat during the sunny hours, preventing the home from overheating. In the evening, the tile releases that heat, lessening the need to heat the house.


My undergrad Alma Mater (Clarkson University, in upstate NY) had built their entire campus like this decades ago. They built in as much passive energy savings as they could. The real shame is that they basically abandoned those buildings, built a new campus just outside of town, and neglected to do any of these things. There's even a rumor that one of their buildings was designed for the desert heat. It basically has cooling fins on the outside, and is designed to create an updraft of air to help cool the building. Not so great in a climate that sees months at a time below zero (F).

Zythryn wrote:No natural gas at all. We don't even have a meter. Even though we have nothing that produces carbon monoxide, we still put in CO detectors, because it is in the building code :lol:


This was going to be my ultimate goal. Unfortunately you have to be really dedicated to get there in an existing house. As I mentioned earlier, going to electrical heating would be a nightmare for cost and looks. To put it into perspective, the quote I got for the heat pump system was about 40% of the price I paid for the house! I've all but given up on the dream of ditching the gas meter in my house. If I built a house from scratch, I would design it to be 100% electric.
~Brian

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