Installation advice for heat pump water heater

[SageBrush]

That’s right - once beyond net zero consumption. Prior to the net zero mark, PG&E credits us full peak rates which are as high as $0.491/kWh

OK, I think I am following.

For now, your excess generation is worth the prevailing TOU retail rate up to a 1:1 net metering. What will happen after your current rate schedule is closed ?

 

[iPlug]

OK, I think I am following.

For now, your excess generation is worth the prevailing TOU retail rate up to a 1:1 net metering.

That's right.

What will happen after your current rate schedule is closed ?

Starting next year I remain on the same E-6 rate plan except the peak hours shift deeper into the evening. In 2022 a bit further deeper into the evening again. In 2023 I have to leave the terminating plan altogether and pick a then existing rate plan.

 

[SageBrush]

Starting next year I remain on the same E-6 rate plan except the peak hours shift deeper into the evening. In 2022 a bit further deeper into the evening again. In 2023 I have to leave the terminating plan altogether and pick a then existing rate plan.

Awesome ... for the next two years, anyway.
If you were a new PV customer today, do any of the schedules still allow generation credit greater than 3.5 cents a kWh on a TOU schedule, or do you really have to self-consume to make PV a money saver ?

 

[iPlug]

Awesome ... for the next two years, anyway.
If you were a new PV customer today, do any of the schedules still allow generation credit greater than 3.5 cents a kWh on a TOU schedule, or do you really have to self-consume to make PV a money saver ?

To my knowledge and prior reading, all PG&E rate plans pay surplus generation at the same rate which is signed off by the CPUC.

If the primary driver is maximizing money savings, one would want to self consume PV as much as possible. We've dipped into net surplus to offset some of our non-home personal carbon footprint such as air travel.

 

[miimura]

To my knowledge and prior reading, all PG&E rate plans pay surplus generation at the same rate which is signed off by the CPUC.

If the primary driver is maximizing money savings, one would want to self consume PV as much as possible. We've dipped into net surplus to offset some of our non-home personal carbon footprint such as air travel.

California is all net metering at retail rate until you are a surplus generator. If the total of your generation is greater than the total of your consumption, you will get Net Surplus Compensation, which varies around $0.03/kWh for your surplus kWh.

 

[SR22pilot]

I have noticed that if you switch to a mode that engages resistance heating, they don't necessarily turn off immediately when you switch to heat pump mode. So could be related to what you noticed.

You will see a difference in energy consumption using heat-pump-only mode compared to energy saver, the question is whether or not heat-pump-only mode is enough to keep water temperatures hot enough for you. For me, it is nearly all the time. When it isn't, I usually just wait 30 minutes to an hour.

The manual is confusing. It lists efficiency for heat pump mode as high and for energy saver as very high. Hence manual says energy saver is more efficient.

 

[SR22pilot]

I have noticed that if you switch to a mode that engages resistance heating, they don't necessarily turn off immediately when you switch to heat pump mode. So could be related to what you noticed.

You will see a difference in energy consumption using heat-pump-only mode compared to energy saver, the question is whether or not heat-pump-only mode is enough to keep water temperatures hot enough for you. For me, it is nearly all the time. When it isn't, I usually just wait 30 minutes to an hour.

I have the 80 gallon model and there are just two of us. We never run the tank more than a third down.

 

[iPlug]

The manual is confusing. It lists efficiency for heat pump mode as high and for energy saver as very high. Hence manual says energy saver is more efficient.

Saw that. At the same time it also says the recovery time is much faster with energy saver mode and slow for heat pump mode.

My best guess for why they (dubiously) claim very high efficiency with energy saver mode is that the energy saver mode has a maximum temperature limit.

 

[iPlug]

From their manual on-line:

One could surmise carelessness in filling the cells, witness poor proofreading with periods in a couple cells. Energy saver should show ~"medium" under efficiency. The rest of the matrix looks ~legit (except vacation mode for which the device consumes no energy as it is off).

 

[SR22pilot]

From their manual on-line:

View attachment 576360
One could surmise carelessness in filling the cells, witness poor proofreading with periods in a couple cells. Energy saver should show ~"medium" under efficiency. The rest of the matrix looks ~legit (except vacation mode for which the device consumes no energy as it is off).

it seems to me Energy Saver should be named Hybrid. When I first shifted to Heat Pump the app admonished me to go back to Energy Saver. I went back to Heat Pump again and this time there was no warning. I’ll look over the next few days to see if it makes a difference.

 

[iPlug]

Yeah, Rheem really seems to be pushing that over “heat pump only” mode.

I suspect the reason for this is that the typical consumer is not someone like a TMC energy/efficiency enthusiast who understands the limits of the heat pump and that if planning poorly will be stuck with slow recovery time and cold showers. The average person would not likely know what is going on and be upset and think there was something wrong with the water heater. “Energy saver” mode mitigates most of that.

 

[SageBrush]

Yeah, Rheem really seems to be pushing that

They are missing out on a upsell opportunity ..

"Cold water ? Yeah, that sucks."
"We have the larger tank that you need on sale, today."

 

[arnolddeleon]

An update on my install.

I got the app working. A few things I learned.

• Rheem has reachable support!
• I knew that Google Pixel phones are notorious at working with provisioning systems but I eventually got it to work.
  • They will automatically disconnect from a WiFi connection that has no internet. The only way to disable this is catch the notification for it.
  • A random MAC address is used (don't know if this ended up mattering), this can be disabled
  • A non Pixel specific thing, I use Cloudflare's 1.1.1.1 service to protect my DNS queries. Need to disable this for setup
• I thought I would get around some of the Pixel challenges by using a non Google tablet. That turned out to be a blind path. Even though I had relatively modern Lenovo Android tablet the Play store would only give me an old version of the EcoNet app
  

I see the discussion of scheduling, that was going to be my next question. Would I gain significant benefit in raising/lowering the set point to follow my TOU hours. This property is on a grandfathered E-6 rate. Currently it is set at 120 degrees, heat pump only 24 x 7. I'm limited to heat pump only until the electrical work is done.

 

[iPlug]

I see the discussion of scheduling, that was going to be my next question. Would I gain significant benefit in raising/lowering the set point to follow my TOU hours. This property is on a grandfathered E-6 rate. Currently it is set at 120 degrees, heat pump only 24 x 7. I'm limited to heat pump only until the electrical work is done.

If this home is not net zero on electricity use, then yes, you could set the heat pump only to run during E-6 plan off-peak rates to save money. But you may want to consider at least a couple things:

1) Unit may forget schedule:
At least once a few months ago our HPWH just decided to forget the schedule and wife calls me at work to tell me she and our boys had cold showers. Was able to hop on my app and set things straight.

With rental tenants, that may be even more problematic. Might be nice to have a 240V inline switch that you can remote restart the unit if your run into that issue but can't get the app to resolve the problem.

2) Temp set point may be insufficient:
A water temp set point 120°F may not be high enough in the setting of running the heat pump only during off-peak hours. To compensate for this, you can increase the set point to as high as 140°F, in theory. But I am not sure if there are legal implications, especially as this is a rental unit for setting temp >120°F. You may want to consider a mixing valve in that case.

In the summer, under our E-6 schedule, we set our 65G HPWH as low as 124°F. 4 occupants standard, each two showers a day + laundry and dishwasher. In peak winter (gets significantly colder here than the bay area but significantly warmer than most of the U.S.), set to ~130°F and as high as 136°F if guests staying with us. During winter, E-6 only has 3 hours a day that are not off-peak and only on week days, so that helps.

 

[SR22pilot]

I set my water heater to heat pump mode but the app keeps telling me to change it to Energy Saving mode for maximum efficiency. I would think that heat pump mode would be the most energy efficient. I find Rheem’s information confusing.

 

[SageBrush]

the app keeps telling me to change it to Energy Saving mode for maximum efficiency

What is the exact wording ?
And what does the app mean by "efficiency" ? (That is a rhetorical question.)

I'm willing to place a small wager that many (perhaps a large majority) of consumers buy a tank of the same size that they are replacing and find that heat pump only mode does not satisfy their hot water consumption wants. Off they go to complain. In that situation, ask yourself what the company would recommend.

I'm not even sure that the company is giving poor general advice. Depending on the implementation, if the heat pump operation keeps the water above whatever threshold is set then resistance heating is never called on and is equivalent to heat pump only mode. If the water temp falls below the threshold then the person in the shower (or the next one waiting) would flip on resistance heating. I think the Rheem way limits the resistance heating to as low as possible in contexts where people shower when they want, not when the tank is ready for them.

 

[iPlug]

I set my water heater to heat pump mode but the app keeps telling me to change it to Energy Saving mode for maximum efficiency. I would think that heat pump mode would be the most energy efficient. I find Rheem’s information confusing.

They introduced this misinformation “bug” many months ago. As long as you’re not running out of hot water, would recommend ignore it:

Feel free to play around with all the different settings and see what your energy use reports say on the app and/or at your meter if you have that data. Have played around with those things on my end and definitely heat pump only mode is the most energy efficient.

 

[miimura]

I think in this case "Efficiency" is referring to the magnitude of customer service complaint reduction.

 

[SR22pilot]

They introduced this misinformation “bug” many months ago. As long as you’re not running out of hot water, would recommend ignore it:View attachment 579492

Feel free to play around with all the different settings and see what your energy use reports say on the app and/or at your meter if you have that data. Have played around with those things on my end and definitely heat pump only mode is the most energy efficient.

Thanks!!, it makes sense that heat pump only is the most efficient. However, the admonition to be more efficient by shifting to Energy Saver and the blue leaf icon for energy saver send a different message. I was wondering if it was a lower power heat pump mode.

I have the 80 gallon model and so far it has only lost one green bar after use. Also, it barely cools the small room (HVAC room) it is in. It doesn’t run that much. Other than the above confusion, I an very happy with the unit. It has allowed me to tell the gas company to disconnect the service. That was over $40/month just to heat water due to high base charges.

I do have the adapter for the intake and may put in a return vent to take air from an adjacent room. That will ensure warmer intake air when running.

 

[nwdiver]

Get on the 100% electrification heat pump train! ALL Aboard!!

Let's Ride These Heatwaves With Heat Pumps