Rednecktek
Solar Wizard
You only say that because you're not here taking cold showers.
Groundmount water heater discussion
- Thread starter Rednecktek
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Solarcabin Channel
Solar Addict
Is that by choice or no water heater?You only say that because you're not here taking cold showers.
Rednecktek
Solar Wizard
The on-demand I had plugged in (until earlier today) was a weeeee bit undersized for the ground water temp. The new one should be much better.
Solarcabin Channel
Solar Addict
I use a propane OD with a preheat tank in the cabin. That preheat really saves on time and energy/fuel used.
Rednecktek
Solar Wizard
Yeah, I'm using the shower to test run models and performance to eventually replace the propane water heater in the cabin. It eats a LOT of propane.
The electric ones I looked at want 60A at 240VAC. I suppose that it would actually save power over a standard heater depending on frequency of use, but that seems like a very high demand.
Brett V
Mad Scientist
Have you looked at heat pump water heaters? I have one and it's extremely efficient on power.
Hedges
I See Electromagnetic Fields!
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Why would an electric instant water heater save power over a tank-type electric resistance water heater?
True, that should save 1/2 to 2/3 of the power.
It will draw the power it wants, so draw down battery or leave some PV production unused.
Enable AC powered resistance water heater whenever battery is no longer taking charge, perhaps based on current sensor in PV/SCC wire?
There are PWM controllers for water heaters that implement MPPT, PV direct, using dedicated panels.
But maybe your HPWH, enabled for a reasonably long cycle when battery is full, would deliver more heat even though some PV goes to waste.
Been there done that. Among other things, we also don't miss the open air outhouse when it's below freezing, nighttime AND the wind blowing +30 mph. Now living in a 5th wheel on all electric while we build...going to do another winter in it but this time with 5.460kw vs last year's 400w. Should be better...You only say that because you're not here taking cold showers.
Hope for a lot of sunny days.
Rednecktek
Solar Wizard
I looked into those a while back and it really depends on the location. For my old place when you combine the low cost of power and the winter temperatures, the warranty would expire a couple years before it paid for itself. Out here at the cabin it's so cold for so long and the place spends so much time unattended that it would rot out its tank and anode before it broke even.
Plus, they still require 240v and I only have a 3Kw 120v inverter.
I converted to a tankless, propane and uses 120v. It takes a while before water gets hot but when it does you never run out of hot water. It saves me from keeping the water hot when I don't need it and I notice the savings. It don't use much propane to even notice.
timselectric
If I can do it, you can do it.
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Because it only heats the water that is used.
Instead of constantly keeping a tank warm.
But, it's not good for off grid. Because of the high instantaneous load.
I agree if it is an all electric model.
Nobodybusiness
Solar Sponge.
Yea like 36kw by itself. They are a huge load.
Can’t use gas heater because we don’t have any so its a HPWH for me.
Hedges
I See Electromagnetic Fields!
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Can you quantify that in kWh savings per day?
How does it compare to the lower efficiency of delivering high current to instant water heater, including I^2R losses in wire and inverter components?
If someone with a 40 gallon electric water heater uses 40 gallons per day, what increased percentage of kWh consumption to keep water hot?
"keeping water hot" doesn't use any energy.
It is only the energy lost through insulation, and through the connected water pipes (insulating a few feet of pipe should help.)
My gas bill is about $8/month, for a water heater and the stove. To me, any losses are trivial, don't justify changes to save energy. And that's with gas heat exchanger, which should constantly cause convection through the flue (mine doesn't even have baffle with actuator like higher efficiency models.)
But gas is cheap, and off grid PV has a different budget.
Solarcabin Channel
Solar Addict
My propane OD with preheat tank uses pennies per shower. A 30# tank lasts me 3 months in summer and that is for cooking and OD water heater.
In winter I go through about a gallon a day for heat, cooking and hot water.
We don't have NG lines in my neck of the woods so propane is next best thing and reduces the size solar power system I would need.
Well, if you can't get a propane tank, I would not bother with the electric tankless. You probably better keep the tank style and put a timer on it. A normal ele., water heater tank usually takes a 30amp breaker where as a electric tankless may need a 60 amp but for a propane tankless, you only use may be 15 or 20 amp. It's plane as day. Being off grid requires you to think of ways to conserve.
Nobodybusiness
Solar Sponge.
Propane is expensive and hard to get around here.
We had people calling empty a couple years ago and they did without for almost a month.
It’s just another thing to tie you to the system.
I have a Heat pump water heater.
Uses electric and considerably less than a tank heater
I had a Takagi years ago when I had NG.
Worked ok but if you have well water with any minerals then You are flushing that thing all the time.
Solarcabin Channel
Solar Addict
Can you repair that system yourself and get replacement parts off the shelf if it breaks down?
Those are factors I consider living off grid with just a small town available.
timselectric
If I can do it, you can do it.
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I can't.
But have seen many comparisons in the past.
It is all about the losses of heat. And the wasted energy to combat it.
I'm not a thermal Engineer, but I did stay in a holiday Inn express last night.
Nobodybusiness
Solar Sponge.
No but I also don’t have to buy propane or NG either.
It has a Mylar heat blanket around it like the old one did.
Plus we live 30 miles from a Lowe’s / Home Depot.
I still have my AO Smith that used 4500 watts to heat water if needed.
Solarcabin Channel
Solar Addict
I still have my wood stove with water tank jacket and 12 volt pump if needed.
Each person's situation is different and suggesting one over another without knowing that situation leads to disagreements.
I am a small system off grid homesteader so my suggestions are for like minded people.
Propane is kinda a monopoly. Several places will keep there prices the same. What I did is bought my own tank, a large tank say 500gal. Then shop around for the lowest price in the early summer months when price is the lowest. Fill it up and make it last till the next summer. I paid 1.33 this past summer which is higher than last yr. At the same time the big boys charges 1.80 gal. Usually a family owned company will give you a lower rate if you buy just from them as I have found.
I do have a Takagi and with well water. Every thing is filtered twice and softened before it reaches the WH. But as with any thing if you want it to last you need to maintain it.
Nobodybusiness
Solar Sponge.
Last time I had Propane I was paying $2.80 a gallon.
That was 2008-2012.
We had a 500 gallon in ground tank.
Prices must have come down a lot since then which seems counterintuitive.
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