Electric HW - On-Demand or Tank?

AdmiralYoda

My water heater is coming up on replacement.  It's currently gas fired but I'm thinking of changing it over to electric.

We are a family of 4 people and have low flow faucets and a single low flow shower.

Absolute worst case, I'm looking at a need of 4GPM...washer is filling, doing dishes, someone showering.   Typical worst case is 3GPM.  

With my current electrical service I can handle a 27kw-ish heater.  I'm in the Northeast and my water is 40 degrees in the dead of winter.

The 27kw heater has a roughly 65 rise at 3GPM so I should have plenty of hot water.

What's the general opinion on electric on demand?  I like the idea of space savings and not having to vent it.

TAG

Nothing is as cheap and simple as a gas storage tank water heater -- I always use Bradford whites in my rentals. My beach house uses an on demand gas for the outdoor shower ..... it's sized properly for that single use and is great as there can be almost constant shower use at different times when groups come back from the beach. We also did an electric on-demand to replace an electric storage that supplied the water for a large tub and nothing else. The tub was rarely used and it was crazy to keep a huge tank of hot water for something used a few times a year.

I'm not a fan of any on-demand for whole house use -- they keep getting better .. but -- there is a wait and the water temps always seem to bounce around initially . Maybe a house with home run PEX is the best choice if going on-demand.

Is you current vent a problem?

AdmiralYoda

No vent problems.  We just had solar panels installed and "should" have some surplus energy, so I thought maybe I could go to an electric water heater and have my solar panels pay for it.

Also....electric seems to be cheaper.  I have nothing bad to say about a gas water heater.  The one we have now is a 10yr GE boiler from the big box stores.

It has a standing pilot and is 13 years old.  If I were to stay with gas I'd want a fancy one with electronic ignition and a vent damper.

Intplm.

Solar Panels !!? Then yes! Go electric. And while you are at it, why not install a hybrid electric water heater?

AdmiralYoda

Intplm. said:

Solar Panels !!? Then yes! Go electric. And while you are at it, why not install a hybrid electric water heater?

To be honest I'm not too familiar with them.  Those are the ones with a heat pump correct?  Got one you'd recommend?

ethicalpaul

Traditional electric I can't believe would be cheaper than gas. But the Rheem Marathon is the best of that type IMO. Well-insulated plastic tank that will never rust out.

But a hybrid (heat pump) water heater like @Intplm. mentioned blows them all away and there are often cash incentives to install them. I love mine.

Intplm.

A.O. Smith is a good company. Bradford White is a great water heater manufacturer.
There are others too. Look into a professional installer that backs up their product.

AdmiralYoda

@ethicalpaul which hybrid water heater do you have?

Jamie Hall

27 KW? Not from your photovoltaic panels. Presumably you are thinking in terms of the grid connected variety. Also that presumes you have a 200 amp service in place.

A hybrid will probably do you well enough, if the tank is big enough. The recovery is painfully slow if they stay in heat pump mode -- and they are no better than straight electric when they shift to fast recovery mode.

Depending on where you are, you need to compare your electric rates per BTU with your gas rate -- per BTU. In some parts of the country, electric is indeed competitive. In others, such as the northeast, it is not -- even with a heat pump.

AdmiralYoda

@Jamie Hall you are correct, we are tied to the grid and have a 200A service.  The 27kw units requires a 200A minimum, anything larger requires 300A.

I want the most efficient option without breaking the bank.  Gas or electric.

A condensing gas water heater is still an option....the PVC venting is the issue.  No convenient way to vent it.

Jamie Hall

I applaud this: "most efficient option" -- but I urge you to consider overall efficiency, not just efficiency in your home. How is your grid electricity generated? If it is natural gas or coal, that is no more than perhaps 35% efficient overall. A gas water heater is about 80% plus...

Larry Weingarten

Hi, I'd definitely be looking at a large heat pump unit. That way the slow recovery basically doesn't matter, and it operates more efficiently in HP mode. Also, there may be rebates. look at https://www.dsireusa.org/ . These units make good dehumidifiers and can do a little cooling, so if you can get a ducted or ductable unit, you can do some fun things with it in addition to slowly making hot water.

Yours, Larry

JUGHNE

One point to consider with a house of 4 people,
if you lose utility power you lose heat.
If you do have a standard NG water you would at least always have hot water, have at least a hot shower or tub soak.

Any thing without a tank will not produce hot water.

ethicalpaul

My heat pump heater has a tank

It's this one @AdmiralYoda : https://www.homedepot.com/p/Rheem-Performance-Platinum-65-Gal-10-Year-Hybrid-High-Efficiency-Smart-Tank-Electric-Water-Heater-XE65T10H45U0/312741511

They go on sale, and as has been said, look for rebates. I even got the rebate installing it myself.

TAG

In the north east -- hot water, stove and dryer. Bills are often under $25 for gas in the months not heating the house .... how much will all the fancy stuff save you ?

The new water heaters have electronic ignition.

On a side note -- the GE water heater is one of the greatest marketing moves in history .. IMO. My memory says this had to be late 90's .. HD did a survey of households. What kind of WH do you have? ... a huge number said ...GE. Next question .... do you have favorable view of the current WH? -- most said yes. Most import ....Would you buy another GE .. most again said yes.

Only problem -- GE did not make water heaters. HD went to GE and they teamed up -- GE got a payment per sale plus the GE service number on all of the units. I think they went to Rheem to have them manufacture

ethicalpaul

Jamie Hall said:

I applaud this: "most efficient option" -- but I urge you to consider overall efficiency, not just efficiency in your home. How is your grid electricity generated? If it is natural gas or coal, that is no more than perhaps 35% efficient overall. A gas water heater is about 80% plus...

But since heat pump water heaters have about a 3.5 energy factor (compared to .8something for gas) you're still better off overall.

TAG

They are popular in hot climates with nice rebates .... people place them in the garage. I know more than one who has placed them in an old north east house basement only to discover they make the space even colder (naturally) ... also -- my guess is the units don't like the colder spaces as those same people say they are loud.

My guess is they would like sitting next to an oil fired boiler -- lots of free BTU's around.

AdmiralYoda

The condensing gas units won't make much sense for my application.  No good venting options.

It's probably down to electric heat pump vs electronic ignition gas.  On demand looks good on paper....but in reality I'll probably kick myself for it without a 300A service.

ethicalpaul

Mine is happy next to my boiler and is as loud as my refrigerator, which is quiet

Zman

Did you put so much solar on the roof that you think you will need to add load in order to offset?
Your 27KW heater will require 112.5 spare amps on your service. Keep in mind you really should not go all the way to 200 amps.

I would recommend a gas heater with electronic ignition and a built-in vent damper. It will be cheaper to install and run than anything electric.

AdmiralYoda

@Zman the solar is oversized a little for our annual usage.  So at the end of the year the electric company should cut us a check for $200 or so.

The thought was to ditch gas and use that overage to use an efficient electric water heater.

I'd save about $20 per month from May-Sept by not using gas to heat my water AND use the solar overage to cover the efficient electric water heater.

Zman

In most markets, nat gas cost 4 times as much as electricity. Do you know your local rates?

AdmiralYoda

Zman said:

In most markets, nat gas cost 4 times as much as electricity. Do you know your local rates?

I haven't broken down the costs of each yet.  I'm in the Northeast and electricity definitely isn't cheap.

EBEBRATT-Ed

Stay with gas. If your in the NE gas is much cheaper than electric. The hybred are fine until they brake and cost a fortune to fix.

It's not just the fuel your paying for it's the cost of the equipment and the equipment's longevity and replacement cost