Changing to electric hot water?

[h2ofun]

2 years ago when my water heater died, my solar guys said I should just put a gas water heater back in. No idea why, but that is what we did.

but now that I have SO much excess solar, and looks like NEM2 for a long time, I am just wondering if there is any payback at all to replacing my gas water heater
with just a 100% electric, and not give as much free energy to PGE? Would hope they could give my gas water heater to someone in need for free.

 

[Laketime]

You can, but just understand that they are very slow to make HW. Do not expect your SO to take a nice shower and be able to then take one yourself. I had a traditional 65 gal twin element heater in my lake house and it would take forever to get ready for a second shower. We recently changed to a top of the line Rheem hybrid 65 gal electric heater and while being better it still runs out of water after the first longer shower. There is just no way to make that much hot water with 2 electric elements on a 30amp line even with an inverter based heater. At my other house we have an 80 gal super stor indirect WH and it can make 450 gals of HW an hour- that's more than the street can provide. I literally can't run out of HW unless my boiler goes down. I would stick to gas for comfort.

 

[Ampster]

My. solution to the hot water recovery time is to raise the tank temperature and use a tempering valve. That increases the effective number of gallons at the shower head.

 

[h2ofun]

You can, but just understand that they are very slow to make HW. Do not expect your SO to take a nice shower and be able to then take one yourself. I had a traditional 65 gal twin element heater in my lake house and it would take forever to get ready for a second shower. We recently changed to a top of the line Rheem hybrid 65 gal electric heater and while being better it still runs out of water after the first longer shower. There is just no way to make that much hot water with 2 electric elements on a 30amp line even with an inverter based heater. At my other house we have an 80 gal super stor indirect WH and it can make 450 gals of HW an hour- that's more than the street can provide. I literally can't run out of HW unless my boiler goes down. I would stick to gas for comfort.

THANKS for the input! I had not idea. So, solves that issue, Would rather pay a few bucks that run out of hot water, period. And since I have a solar hot water setup also, during the summer it gets really pre heated, so not using as much energy as the normal person.

I just love this group, so much knowledge!!!!

 

[darhall993]

My. solution to the hot water recovery time is to raise the tank temperature and use a tempering valve. That increases the effective number of gallons at the shower head.

@Ampster is spot on, we have a 50 Gallon Rheem heat pump unit set at 140 degrees at our Beach house because of size constraints and we have the tempering valve, works well with several folks taking showers. I leave the unit in heat pump mode 100%. If you have company visiting you can always toggle the unit to use the full resistance element in “High Demand” mode, this works great and also pumps cold air into the attic during hot summer months.

 

[Electrph]

THANKS for the input! I had not idea. So, solves that issue, Would rather pay a few bucks that run out of hot water, period. And since I have a solar hot water setup also, during the summer it gets really pre heated, so not using as much energy as the normal person.

I just love this group, so much knowledge!!!!

i suppose having a hybrid water heater must def be a ymmv thing ... we have a 65 gallon rheem hybrid (heat pump water heater) through trial and error is set to 130 all the time / as well as set to high demand mode for few hours each weekday AM .. we have 2 adults 3 children (2 are teenage females !) and we do not normally have issues with running out of hot water .. it has happened a few times when running dishwasher / laundry in AM .. but never unbearably for last person .. will def agree water heater has nowhere near the recovery of our previous ng 50 gallon model .. rheem does claim it has a faster recovery than a non hybrid straight element due to elements and heat pump working simultaneously .. we are not all trained on taking quick showers either btw esp myself haha

 

[h2ofun]

@Ampster is spot on, we have a 50 Gallon Rheem heat pump unit set at 140 degrees at our Beach house because of size constraints and we have the tempering valve, works well with several folks taking showers. I leave the unit in heat pump mode 100%. If you have company visiting you can always toggle the unit to use the full resistance element in “High Demand” mode, this works great and also pumps cold air into the attic during hot summer months.

I have a tempering value on my setup now. Since what I have is already installed, sometimes better to just leave stuff alone and find other ways to use more electricity. I just want a person who says they would pay for a EV charging setup in my garage, and in exchange, they can charge for free.

 

[EVRider-FL]

I’ve never had problems getting enough hot water from our electric water heaters, so don’t assume that one person’s experience is representative of all electric water heaters.

 

[83girl]

We replaced our 80 gallon electric hot water heater with a gas on-demand hot water heater before we got solar. It's nice having endless hot water. I would never go back to electric. But to each their own I guess.

 

[dailo]

I recently switched to a heat pump model and amazing how efficient they are, but definitely doesn't heat up as fast as the gas one. Hasn't been a problem for my family so far, but during the winter the water heater maybe uses 5-6 kWh a day and summer probably less so will prob make a small dent compared to your production.

 

[orbit2020]

My experience with Rudd HPWH is great. 80 gal tank on Heat Pump is adeq for 2 people in winter. If we need more, then I just switch it to ‘High demand or Electric mode’. Which is rare in my circumstance, with the pandemic. The power consumption is awesome, 6kw/day in winter, 4kw/day in warmer months. My garage is cooler. No need for ducting in my garage. And you can also get a rebate upto $2000 from your utilty in some places.
I found getting someone reliable and good to do the replacement the hardest. It is surprising, that even today, in silicon valley, most plumbers are not well informed with heat pump heaters. The ones that are, act like it is a niche product and tend to charge more for installation. But well worth the effort imho.

 

[ptdusn]

@h2ofun You can always check out an electric tankless heater. They heat pretty quick

 

[DHevey]

THANKS for the input! I had not idea. So, solves that issue, Would rather pay a few bucks that run out of hot water, period. And since I have a solar hot water setup also, during the summer it gets really pre heated, so not using as much energy as the normal person.

I just love this group, so much knowledge!!!!

I have a solar hot water setup, too, with a Sun Earth 45 kW electric hot water heater. I've never noticed slow heating. It's the perfect use of my excess solar energy.

 

[nwdiver]

@h2ofun You can always check out an electric tankless heater. They heat pretty quick

But not very future proof. Gonna be a bad day if your utility decides that demand fees are the way to go. Tankless electric usually uses ~18kW. If you decide you want to take a shower at 8pm during peak hours that could add ~$200 to your electric bill just for 1 15 minute shower.

Also terrible if you want the ability to have hot water during a power outage. You'd need 4 powerwalls just to power the shower!

The best solution is a larger tank of water heated by a heat pump. Or get two water heaters and run them in parallel, I had a co-worker that did that because they kept running out of hot water.

 

[Laketime]

i suppose having a hybrid water heater must def be a ymmv thing ... we have a 65 gallon rheem hybrid (heat pump water heater) through trial and error is set to 130 all the time / as well as set to high demand mode for few hours each weekday AM .. we have 2 adults 3 children (2 are teenage females !) and we do not normally have issues with running out of hot water .. it has happened a few times when running dishwasher / laundry in AM .. but never unbearably for last person .. will def agree water heater has nowhere near the recovery of our previous ng 50 gallon model .. rheem does claim it has a faster recovery than a non hybrid straight element due to elements and heat pump working simultaneously .. we are not all trained on taking quick showers either btw esp myself haha

Teenage kids are the death of hot water. A standard shower is me yelling one of the them to get out at the 15 minute mark. Today with the same HW heater you have my 17yr old took a longer shower (probably 13-15 min) followed 20 min later by my wife who ran out of water 5 minutes into her shower. It is set to 135 degrees and high demand mode. I had to skip my shower when after an hour the water temp was up to 115 degrees but the app still showed red for availability (typically that means the top of the tank is hotter but the rest is still cold). 3 hours later the compressor is still cycling on and off as the tank tries to stabilize. With 1.5 showers we have used 8kWh so far today. I am extremely unimpressed- I should have just done a propane instant and been done with it.

 

[nwdiver]

Teenage kids are the death of hot water. A standard shower is me yelling one of the them to get out at the 15 minute mark. Today with the same HW heater you have my 17yr old took a longer shower (probably 13-15 min) followed 20 min later by my wife who ran out of water 5 minutes into her shower. It is set to 135 degrees and high demand mode. I had to skip my shower when after an hour the water temp was up to 115 degrees but the app still showed red for availability (typically that means the top of the tank is hotter but the rest is still cold). 3 hours later the compressor is still cycling on and off as the tank tries to stabilize. With 1.5 showers we have used 8kWh so far today. I am extremely unimpressed- I should have just done a propane instant and been done with it.

..... do you not have a shower head? A shower head reduces the flow rate to 2.5gpm. Even if you had 135F water coming out that's ~26 minutes of flow.

 

[Laketime]

..... do you not have a shower head? A shower head reduces the flow rate to 2.5gpm. Even if you had 135F water coming out that's ~26 minutes of flow.

Yes- we have a shower head and the well water pressure is set to 50psi. But hot water doesn't work like what you are saying. It is coming out of the ground at 45 degrees (what we are experiencing upstate NY during this cold winter) so you need a 90 degree water rise. That takes time to overcome. As soon as the hot water hits a critical low point you have to go full hot while showering. That just craters the temperature in the tank as it can't make HW as fast as the water coming in thus dropping the temp in the tank by the second.

 

[nwdiver]

Yes- we have a shower head and the well water pressure is set to 50psi. But hot water doesn't work like what you are saying. It is coming out of the ground at 45 degrees (what we are experiencing upstate NY during this cold winter) so you need a 90 degree water rise. That takes time to overcome. As soon as the hot water hits a critical low point you have to go full hot while showering. That just craters the temperature in the tank as it can't make HW as fast as the water coming in thus dropping the temp in the tank by the second.

Water heaters are designed to prevent mixing. Cold water and Hot water also don't like to mix. You can't exhaust 65 gallons of hot water from mixing. If anything colder incoming water should make the hot water last longer since 135F and 45F water REALLY won't mix. It should last at least ~26 minutes unless you have an absurdly high flow rate.

Is it possible your hot and cold lines were installed backwards (swapped) on your water heater? That would cause what you're describing....

 

[Laketime]

Water heaters are designed to prevent mixing. Cold water and Hot water also don't like to mix. You can't exhaust 65 gallons of hot water from mixing. If anything colder incoming water should make the hot water last longer since 135F and 45F water REALLY won't mix. It should last at least ~26 minutes unless you have an absurdly high flow rate.

Is it possible your hot and cold lines were installed backwards on your water heater? That would cause what you're describing....

It's installed properly. If you check the plumbing and HVAC forums it's the single biggest issue (aside from app connectivity).

 

[ptdusn]

..... do you not have a shower head? A shower head reduces the flow rate to 2.5gpm. Even if you had 135F water coming out that's ~26 minutes of flow.

First thing I do to those low flow shower heads, get a 1/8" drill and drill baby, drill!