color me stupid somebody want to edumacate me?

[time2roll]

heat pump was first choice, but its too cold here in the winter. I can by top of the line japanese HPWH used 2-3 years old for about 1000 USD each (especially with the current yen to dollar rate). i was originally thinking of getting two to heat the tank, but investigations among the locals, and talking with some members here on the forum put the kibosh on that idea.

1st world problems, I know.

Ultimately if the heating element is 4500 watts that is all the energy there is to heat the entire place. Or about 15k BTU. Is that enough?

I get the heat pump issues as it still needs to pump the heat out of the structure if space heating.

 

[Daddy Tanuki]

This should work very well If you have enough excess. How much excess can you reasonably expect?

with current panels in the winter, about 25 kw after batteries are at float. which by my calculations is not enough. hence i want to add some west facing panels on my shop, another 2 or 3 kw of panels vertical facing west to give me a few more hours.

With my new banks added in I have a 70kWh bank of which I rarely use more than about 10-12kWh through an entire 24 hour period so I can even draw some from my bank, but that will be a net loss as I have to replenish it the following day.

lastly I will have a waste oil burner attached to the tank for the coldest months. How much energy will it produce I am unsure of as of yet, as I am still making it. but when running the unit dry with no water, it was enough to make the 1/2" thick walls of the Co2 cylinder i used to make the main chamber glow red hot so it takes a few BTU's to do that. this is all one huge time consuming experiment to keep me busy on my off hours. if it does not work initially I will add as many elements and panels as needed until it does.

 

[Daddy Tanuki]

There is another way. One can run a 2nd 30 amp circuit to your water heater like I did. I have two 5500 watt elements, each with thier own thermostat and 30 amp circuit.

*why did I do that?* because I needed 11kW of heating, 5.5 wouldn't do it.

Other than a few winter months I am net positive so I take a hefty credit into December. For years my radiant infloor system relied solely on a wood boiler but this oldish fart is getting tired of that so last winter I made some changes. I replaced my 18 year old water heater with a new one and ran a 2nd 30 amp circuit to it. "Two birds with one stone" Now I use up that credit before my COOP takes it at the 12 month true up and have nice warm floors without having to deal with the wood heat.


See my response above.

I will mention that those Grundfos "pumps" aren't pumps. They are circulators that are not designed to work in a non-pressurized system, trust me, I've fought it for years on my personal system. Anything less than 12PSI on the suction side and they are very likely to cavitate and loose prime.

wonder what the pressure is from a 2 meter elevation change? my property is on a a slope and this thing is going to the back of the house on the slope so it will be at least 2 meters higher than the circulators... wonder if that will be enough, or if I will have to spring for something more robust.

 

[Partimewages]

Just remember 1 watt only = 3.412 btu's. 4500 watts = 15354 btu's.

 

[Daddy Tanuki]

Ultimately if the heating element is 4500 watts that is all the energy there is to heat the entire place. Or about 15k BTU. Is that enough?

I get the heat pump issues as it still needs to pump the heat out of the structure if space heating.

good question. I currently have no way of measuring that as I burn wood in a fairly inefficient woodstove, and it bakes us out if we do not throttle it all the way down.

thats one of the reasons I was thinking about adding more elements, rather have overkill then not enough. the house is now well insulated and sealed where it was not before (new siding, under cladding and some real insulation. along with tyveck, and caulked seams for all the under cladding.

 

[Daddy Tanuki]

Just remember 1 watt only = 3.412 btu's. 4500 watts = 15354 btu's.

yep see above, hence my desire to add more elements but not sure of the way a US water heater works. I am using US elements as I had not been able to find any locally. they have the old style electric water heaters, but they are becoming scarce with HPWH's Solar vacuum tube water heaters, and the current crop of super efficient gas on demand units, the old style ones are hard to find, and even if you do they do not want to sell you parts, they want to sell you complete units.

FYI I can spend about 1200 USD per year on this project (or any combination of years to get there), as it originally cost me 1200 USD in kerosene to heat the cabin just on the weekends for one whole winter season. This was prior to the remodel and new insulation. have not used kerosene now in over 7 years as I got into the whole wood burning thing, but as I age, that will eventually become a non starter as well.

for the first years experiment if I only get free hot water and can warm the house during the shoulder seasons that will be enough initially

 

[OzSolar]

wonder what the pressure is from a 2 meter elevation change? my property is on a a slope and this thing is going to the back of the house on the slope so it will be at least 2 meters higher than the circulators... wonder if that will be enough, or if I will have to spring for something more robust.

2 meters of water on top of the inlet gets you to less than 3PSI so I think you're still going to struggle to not lose prime. I ended up using a pump I salvaged from an espresso machine in my atmospheric system. "Fluid-O-Tech"

 

[Daddy Tanuki]

2 meters of water on top of the inlet gets you to less than 3PSI so I think you're still going to struggle to not lose prime. I ended up using a pump I salvaged from an espresso machine in my atmospheric system. "Fluid-O-Tech"

thanks, i will keep that in mind... thats more power out from the batteries at night, not a deal killer depending upon how much the pump I find uses.

 

[gotbeans]

how does a normal US water heater wire the elements? i know they have separate thermostats but do they end up in parallel using 9000 watts, or do they end up in series using about 2000 watts?

Water heaters virtually never activate the top element. It's only used when you're out of hot water
the hot water outlet is from the very top of the tank
the cold inlet goes from the top all the way to the bottom via a pipe and the hot water heater has a split of cold / hot due to heat rising via gravity
the bottom element is always used because it's colder on the bottom
when you run the hot water slowly the bottom element can't keep up, at some point when the cold water is like 80% of the tank, the bottom element turns off and the top element will turn on to keep the heat closer to the top which increases the longevity of your hot water as it's only heating the top portion of the tank so you'll have hot water for a while longer until it's all ran out.

you can also buy lower wattage elements for your hot water heater if you don't care if it takes a long time to heat up. Personally I use 1500 watt elements instead of the 4500 they come with

 

[Hedges]

wonder what the pressure is from a 2 meter elevation change? my property is on a a slope and this thing is going to the back of the house on the slope so it will be at least 2 meters higher than the circulators... wonder if that will be enough, or if I will have to spring for something more robust.

2 meters of water on top of the inlet gets you to less than 3PSI so I think you're still going to struggle to not lose prime. I ended up using a pump I salvaged from an espresso machine in my atmospheric system. "Fluid-O-Tech"

Roughly, 2' = 1 psi. 30' depth equals 1 atmosphere.
So 3 meters would be just about 3 psi.

Fun fact, a water nozzle connected to bottom of a tank squirts with velocity (neglecting friction) sufficient to reach water level in tank (neglecting air resistance.)

So I use that to estimate water velocity for a Pelton wheel (something I've never implemented.)
I understand loss due to drag in pipe is quite significant. Would need large diameter, low flow, to minimize that.

That drag would also affect your circulator.

I will mention that those Grundfos "pumps" aren't pumps. They are circulators that are not designed to work in a non-pressurized system, trust me, I've fought it for years on my personal system. Anything less than 12PSI on the suction side and they are very likely to cavitate and loose prime.

Pressurize with captive air tank?

 

[Zwy]

During coldest parts of winter, you plan on heating with used oil. Why not just get one of these and move on? You can vent the unit.

 

[Daddy Tanuki]

Roughly, 2' = 1 psi. 30' depth equals 1 atmosphere.
So 3 meters would be just about 3 psi.

That drag would also affect your circulator.

Pressurize with captive air tank?

Yeah no plans to pressurize tank.

plan was for 2" pipe from tank to the circulating pumps they each have a 3/4" input, I guess I will have to play with it and see. worse case I replace pump with a positive displacement pump, but they use a lot more power to operate I would bet.
@Hedges thanks for the input. Thanks to all actually, helped clear up some questions I had.

 

[G00SE]

To piggyback on this thread.
If one converts a WH from 240v to 120v, it may reduce the power draw but daily usage would end up similar no? I too don’t fully grasp this concept but if recovery time doubles, it will simply run that much longer right?
Is the allure, the lack of instant power required?

 

[ricardocello]

if recovery time doubles, it will simply run that much longer right?

Recovery time will quadruple.
Energy usage over the day will be the same if the thermostat isn‘t changed.
Instantaneous power will be greatly reduced.

 

[OzSolar]

Pressurize with captive air tank?

I don't think so, at least not in the way I understand how they work. I believe they only work in a pressurized system to give your well pump some relief in-between drawdowns before it cycles again.

 

[green mountain boys]

wonder what the pressure is from a 2 meter elevation change? my property is on a a slope and this thing is going to the back of the house on the slope so it will be at least 2 meters higher than the circulators... wonder if that will be enough, or if I will have to spring for something more robust.

29 years ago I installed an outside wood boiler (Central Boiler). This was at a time when few people had ever heard of one and there was even fewer experienced people to ask for advice. I installed it myself, after the 2 biggest plumbing outfits in the area said my design would never work. Partly, because the boiler operated without any pressure and I had no pump or pressure in my design. One of 3 buildings I heat with the boiler, has 4 circulators (3 zones) with a head of no more than 2 meters. 1 zone is a second story, so it is about 3 meters above the boiler. I have never had any problem with the circulators. No problems with air. Not even in the zone serving the second floor. I have 6 Taco circulators and 1 Grundfos. They have all worked well.
In the years since I installed my boiler, I have heard complaints from others, who have had problems with their circulators in similar installations as mine. I am not sure what the difference is. All I know is mine has been flawless.

 

[Daddy Tanuki]

29 years ago I installed an outside wood boiler (Central Boiler). This was at a time when few people had ever heard of one and there was even fewer experienced people to ask for advice. I installed it myself, after the 2 biggest plumbing outfits in the area said my design would never work. Partly, because the boiler operated without any pressure and I had no pump or pressure in my design. One of 3 buildings I heat with the boiler, has 4 circulators (3 zones) with a head of no more than 2 meters. 1 zone is a second story, so it is about 3 meters above the boiler. I have never had any problem with the circulators. No problems with air. Not even in the zone serving the second floor. I have 6 Taco circulators and 1 Grundfos. They have all worked well.
In the years since I installed my boiler, I have heard complaints from others, who have had problems with their circulators in similar installations as mine. I am not sure what the difference is. All I know is mine has been flawless.

maybe large feed pipes to the circulation pumps? going up I honestly do not see as a problem. it should thermo-syphon to a great degree if the pipes are straight. Nuke reactors on US subs use passive circulation to a degree to quieten them down... if it works for them...

 

[green mountain boys]

maybe large feed pipes to the circulation pumps? going up I honestly do not see as a problem. it should thermo-syphon to a great degree if the pipes are straight. Nuke reactors on US subs use passive circulation to a degree to quieten them down... if it works for them...

At the time, the recommendation was 1" pipe to supply a building. Today that is changed to at least 1.25". The pipe supplied to me by Central Boiler was only about 7/8". Once inside the building the plumbing is all 3/4" copper pipe. If I did it over again, I would use 1.25" supply lines but mine is acceptable until the temperature goes below -25F. Then I wish for a little more volume.

 

[Hedges]

Pond or fountain pump? They operate with 1' of water or less.

I don't think so, at least not in the way I understand how they work. I believe they only work in a pressurized system to give your well pump some relief in-between drawdowns before it cycles again.

captive air tanks are used there for a bit of water supply, and in hot water loops to allow expansion.

When your (circulator?) pump moved water, you didn't want a vacuum drawn without pressure to move water in from behind.

This wouldn't work for an un-pressurized open system. But with a closed system not fed by municipal or off-grid pressurized system, you should be able to attach one of these tanks, fill with water/purge air. Then pressurize the tank. That would maintain a moderate pressure as you circulated, and as temperature changed.

 

[JRH]

When I had an electric heater a brand new one just filled with cold water was hot enough for a shower in 30 minutes.

Seemed fast enough for me.

Your a guy…very few fluff issues bothers guys..we generally just go with the flow …
with that said, try to figure out why that may not work well in many peoples life.