What to do? 2 50-gal hybrids or 1 80-gal electric water heater

11 years ago

We originally planned for 2 water heaters, one per level. We liked what we have read about the GE GeoSpring Hybrid water heaters, & we can get them with a significant enough discount. The max. size for the GE hybrid is 50 gallons.

Our GC was originally on board, & then he recently backed off & said we need one 80 gallon electric for the entire house, due to the downstairs bathtub. We have explained we are not bath people. No one in the house will probably ever take a bath (I might pop in once/year, if that). He still wants to put the single 80 gallon heater in the garage, despite what we have told him. I would like to put one hybrid in the garage & one up in the attic on the second floor (with a drain leading outside in the event of a leak - I also like the fact it will partially cool this space).

Looking at our plan, red is where hot water will be most vital & pink will be not as vital (house will be approx. 4,500 square feet total). DH showers first thing in the a.m. I shower after the kids are off to school. Kids shower in the evening. Laundry is done throughout the day, usually when no one is at home using other water & hot water is only used on approximately 2-3 loads/week. The dishwasher runs at night, usually around bedtime. Knowing all our water usage, does our original plan make sense? Will we still have issues on the ground floor with hot water?

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david_cary

11 years ago

I personally think your plan is fine. While there is the tub issue, you don't really use pure hot water for a bathtub (or at least most people don't)

Worthy - the payback is less than 2 years usually on the upcharge.

I keep forgetting where Worthy lives but his water temp must be freezing and his electric hot water tanks were nearly dead to have a 8 hour recovery time. I have a vacation home where I shut off the electric tank and am always amazed how quickly we have hot water - and the heat is off and I am talking about the winter. So 8 hours is crazy - more like 45 minutes from 60 to 120.

Now - your real issue is hot water wait times. The garage length to the master shower is horrible. Have you planned for that? Has someone spelled out to you what size plumbing run it is and how long it will take with your shower head?

Your other issue is the airflow around your heat pumps (or a/c it doesn't matter). Sure the units aren't pretty but they need as much air flow as possible to be efficient. I don't know if this meets manufacturer's specs but I also wouldn't use their bare minimum as a goal.

Where are you building and are you building on a slab? Is the downstairs plumbing run in the slab? Is it insulated?

I'm making the assumption that you don't have NG and are located pretty far south.

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Comments (14)

worthy
11 years ago
Hybrid heaters save on heating bills, but the initial costs are multiples of conventional electric water heaters.

Recovery time would be key for me. We once had an 80Imperial gallon heater servicing a home with four adults two children, two clothes washers. We would constantly run out of hot water till I added another tank. Now, with just a 50 Imperial gallon conventional natural gas tank, two-three adults and three children do just fine. The electric tanks had eight hour recovery times; the natural gas, just an hour.

I've run multiple tanks in other homes too. I connect both to the entire system, not segregating them by floors.
User
11 years ago
The location of the water heater is sub-optimal regardless of which brand you use. The upstairs hall next to the closet looks like it would have room for it to be located there. At least it would be more central. Also, if you have gas, consider a large capacity tankless if your incoming water temperature is warm enough to get the proper temp rise. It's also smaller and won't take up nearly as much room as tanked models.
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Saltidog, Dude, chill. I was respectfully saying you had a different opinion - not what your opinion was or that it had anything to do with the heating elements. You can disagree without being disagreeable. I do understand thermodynamics very well, thank you. There is no "trend" and no misrepresentation. Yes, the units have resistive elements as backup, for high demand situations, and when the ambient temperature gets low enough that enough heat can't be extracted using the heat pump (for geospring unit that's 45 degrees F) Saltidog, I don't know what you are getting your panties in a bunch about... yes, I understand your heater works well for you. I would expect that. It's installed in a basement that's at least 700 cubic feet of space. Because it's underground it will maintain a temperature of around 50 - 55 degrees or more if there are other heat sources in the basement. That's enough to allow the heat pump to work just fine. The water heater will work in almost all situations / applications where one would normally install a tank heater. It will even run on the heat pump in most situations. The question is when you have the water heater in a fully conditioned space (not basement) and that space is being heated. At that time, one is shifting the heating load of the water heater to the furnace - which may or may not be more cost effective. I think the water heaters are great - esp if they can work out the reliability problems (which I think are teething pains, not inherent problems). I stick by my assertion that there are three applications whereby they produce the most system efficiency / cost effectiveness.
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auroraborelis
11 years ago
I have no idea at all - I just wanted to say it is nice to see your final floor plan!
wishiwasinoz
Original Author
11 years ago
Thanks Laura! It's getting there!

Ugh, I don't like what I am reading. We are in northern FL (slab). I would say our biggest priority for hot water is in the kitchen, master shower, & the kids' showers. I don't mind waiting a few minutes for the shower to heat up in our shower, but I do mind wasting all that water while I wait. Should I just have a bucket waiting in the shower & use that to water my plants every day?

David, NG isn't an option, & LP is too pricey to do the whole house. No one has spelled out what size plumbing run it is & how long it will take with the shower head. All GC has said is we will have no issue with getting hot water to the master. Should we consider a LP tankless for just the master bath? I guess that is an option, but I don't like the expense. All in, what would something like that cost (including the tank & propane lines)?

Also, I will discuss the a/c air flow issue w/GC - thank you! We have the big, bad ARB to contend with!

Just when you think you have things done & as perfect as it's going to get... What am I smoking? That will never happen! :-/
zone4newby
11 years ago
Even if you don't ever plan to use the tub on the main level, the next owners might, and if there isn't enough capacity in the system for someone to take a comfortable bath in it, you may need to disclose that when you sell. I'd be pretty unhappy if I bought a house with a bathtub that couldn't be used as a bathtub. So I think you should either remove the tub or account for it in the sizing of your hot water heater.
david_cary
11 years ago
Zone4 - you might not be happy but disclosure wouldn't apply here. There is no code requirement that applies (that I know of) and so there is no breach.

It would seem that installing LP for that purpose alone seems a little extreme.

One option - which has cheaper run cost and install than the LP tankless option - run a recirc loop from that bathroom to the tank. Have it on a switch. You turn on the switch and the line fills with hot water. The pump is $200, electric should be $200 and extra plumbing is $100. You won't waste water and as long as you shut it off, you won't waste electricity to heat the water. My $100 charges of course are guesses and the plumbing in the slab might be more. The $200 electric is what it would cost me in NC. You can of course put the kitchen sink on the same loop and install a switch at that location too.

Recirc loops are done all the time but where you need to be careful is the energy loses because they are usually left on nearly all the time. By having them on-demand with switches, you counter most of those losses.

To help with some of this, I would definitely insulate the slab plumbing lines.

Another option would be to do solar for the hot water and use a 80 gallon tank. If the incentives are there, solar can be reasonable. I paid less than $2000 all in which is about the cost of your 2 50 gallon heat pumps.
wishiwasinoz
Original Author
11 years ago
I got some clarification. GC is having the hot water circulate through the pipes continuously only during the peak times that we set. He said it will not run all the time. We did discuss this early on in the planning process, & it slipped my mind.

He said we will never have to wait more than 10-20 seconds for hot water in our master shower.

Should we still consider the two hybrids? We can get them at a considerable discount, & I like that they pay for themselves after a relatively short period of time & the fact they are more environmentally friendly. Solar isn't an option with the location of the house on the lot & the solar panels.
Beth Parsons
11 years ago
Our lifestyle/schedule is pretty much exactly the same as yours (except that I LOVE soaking in the tub & have probably 7 loads of laundry/week) - we have a 4300 sq/ft house (5 bathrooms total) with an 80 gallon electric tank located in the garage with the master bath a good deal away on the opposite side of the house. We've been in our house for 3 weeks now and haven't run out of hot water once though it does take several seconds for the hot to reach the master bath.
david_cary
11 years ago
Is he insulating the pipes. Top of my build regrets was not insulating the recirc loop better (I did it a little by myself). Peak hours tends to be 16 hours a day because the wait with a deactivated loop is way too long - 2 minutes in my house.
Annie Deighnaugh
11 years ago
We put in 2 tankless hot water heaters....one for the east side of the house where the powder room, guest bath, kitchen and laundry are....one on the west side for the master bath....we didn't want to have to let the water run for 20 min before the hot water got to the tap, and I wanted to be able to take a shower without any hot water supply interruption should anyone want to run the DW or washing machine or anything...
david_cary
11 years ago
Just so we are clear - a heat pump tanked system is far more efficient and cheap to operate than a comparable tankless system (since NG is unavailable).

And modern DW and washing machines don't come close to interrupting anyone's shower.
wishiwasinoz
Original Author
11 years ago
We hashed it out with our GC a little while ago. The loop will be well insulated & on a switch with a timer. He said if we are having large amounts of company, just click it on & we will have no issues. He said with the tub, we should be okay enough for our needs with the (2) 50s (one up & one down). I think he would have rather us used the 80 gal, but I am digging in my heels on this, as I really want the hybrids. GC said it's no biggie for a future homeowner to change out the water heater for future needs.

David, thank you so kindly for all your helpful comments & suggestions! It is very much appreciated!
Annie Deighnaugh
11 years ago
david cary, at our old house anything would interrupt our shower and it was most unpleasant...I'm delighted I don't have that problem any more...though I am still unhappy with the wait for the hot water to come, but it's much better than if we had only one hot water heater. A hot water recirc system was discussed but it was not a green enough solution for our purposes.

We don't have NG available either and use LP instead which also feeds our gas fireplace and generator.

What to do? 2 50-gal hybrids or 1 80-gal electric water heater

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