Needing advice on how to take water to house off grid. « Alternative Technology Assn Forums

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Needing advice on how to take water to house off grid.

(20 posts) (8 voices)

Started 5 years ago by Eagle10
Latest reply from Halcyon

Tags:

Off grid house

Eagle10
Member

Hi all, First off what a great source of information!!

I live in New Zealand and I have 2 acres out in the country. My house is on the low side of the road on a hill and is on the highest point of land. From front to back, the floor of the house at front or top is 600mm off ground to the back which is 2.3m. I harvest rainwater from my roof (I have increased the harvest area by 400%). I have a 3m stud height inside.

I have 2 water storage tanks (around 25000 litres each). One (concrete) tank that is below floor level and acts as a deck ( at back of house), the other (plastic) tank would only have the top metre of it above floor level and is midway down slope about 6m from the house. All plumbing is midway to back of house.

I have a wetback system which is rated at 4.4kw in my "Metro Wee Rad" fireplace. I am able to boil my hot water cylinder in 3 hours from dead cold (I know that's dumb but i didn't realise how efficient it was) so in winter I turn off the HWC.

My house is within 300m of a small substation and the power from it is "lumpy". by that i mean the lights regularly go bright then dim then bright then dim and I often get blown light bulbs, and some small appliances get smoked (I have used rcds to combat).

My Ambitious Aim: To generate my power eventually.

The point of this "novel":
I would like to remove my electrical water pump and replace it with some sort of gravity fed or at least a non-powered system. I realise I could use a solar system to run the pump and still may but if I can, I'd like to remove that from the power equation.

I have read in these forums and seen many calcs on head, height, friction and pressure but none (i think) fits my scenario and that I really understand and there is conflicting info out in cyberworld. Would love to hear from someone who could help me.

My thought was some sort of tower with a 2500 litre tank on it, I'd put a small pump run by a small solar panel to fill it and just leave it running, My real concern is creating enough pressure (30-50 psi?) for the shower, dish washer and Washing machine.

Forgive me if this has already been tackled and i missed it

Thanks in advance

Posted Monday 10 Oct 2016 @ 9:57:30 am from IP #
Diver
Member

One metre head = 1.42 psi.

Posted Monday 10 Oct 2016 @ 10:15:00 am from IP #
Eagle10
Member

Diver,
Thanks for the speedy reply!
Oh my Goodness, does that mean I need to build a tower around the 35m high mark (assuming i was right on what psi i would need to meet)?

Cheers

Posted Monday 10 Oct 2016 @ 10:26:47 am from IP #
Diver
Member

Yes...and an additional allowance for friction loss.

30-50 psi is 21 to 35 metres.

However and of interest...

Mains water supply to the most disadvantaged fixture only needs to be 50 kPa (7.25 psi) to be compliant and it must also be remembered that the old roof cavity gravity fed hot water tanks usually only supplied about 3 metres of head to most fixtures in most situations.

The problem now would be the higher pressure washing machine solenoids used in the modern machines but there might be some obliging models with lower pressure solenoids available but I don't know if there are. Most other fixtures can use low delivery pressure.

Your house pipes will also be plumbed (hydraulically calculated) for mains water pressure.

People get confused about water pressure and think for example that if you have 500 kPa pressure and you suddenly find yourself with 250 kPa, you will only get half the usual flow rate but this isn't the case. To double the flow rate requires four times the pressure and so to double the flow rate when you have 250 kPa pressure would require 1,000 kPa.

You would be surprised at how efficiently water can flow at low pressure but pipes are also sized to aid efficiency. As another example, doubling a pipe's diameter increases the internal volume exactly X4 but the flow rate will increase by approximately X6 due to less friction loss.

I hope this helps.

Posted Monday 10 Oct 2016 @ 1:56:12 pm from IP #
Audrey
Member

Does the dishwasher need a certain flow of water? If so, and also if you want to lessen your electricity consumption, get rid of the dishwasher. Washing up can be quite a social thing as well! And then you can think about a manual tumbler washing machine....... Just thinking outside the square.

Posted Monday 10 Oct 2016 @ 10:02:20 pm from IP #
Eagle10
Member

Hi Audrey, I could remove the dishwasher but my wife says its a marriage breaker and as the dishwasher left she would go with it. (I secretly agree with her). As for the washing machine, it might be good exercise but i think we can afford another avenue :P.

Appreciate your input though

Posted Tuesday 11 Oct 2016 @ 4:59:50 am from IP #
Eagle10
Member

Audrey,
When I re-read what I typed I may have sounded dismissive and i apologize for that. My wife and I are around 60 years old and we are looking for some creature comforts. We want to spend our retirement years (coming up) in the garden and raising calves and looking after the chickens, outside stuff. We both are not great fans of washing dishes and would like to spend more social time around a good glass of wine or a bourbon :P. I'm doing this to get ready for when we retire.

Thanks

Posted Tuesday 11 Oct 2016 @ 5:32:06 am from IP #
axess
Member

Eagle10,

Re the dodgy substation output:

What about setting up an inverter to run the entire house from a battery bank that is charged by the dodgy substation input? you could then switch to either PV or some kind of independent power system backed up by a generator if you preferred not to stay connected to the grid. The inverter, supplied from the battery/ies, would smooth the power supply helping your appliances etc, and its charging function would deal with the variations from the substation.
You could also trial run pump, dishwasher and other loads to work out the changes you require in usage.

Posted Tuesday 11 Oct 2016 @ 6:45:18 am from IP #
Eagle10
Member

Hi Diver,
thanks for the great explanations. Now I'm wondering what to do or other options... I think a solar powered water pump will be up for consideration. There were 2 thoughts i had tho, one was just a header tank on a 6m high tower coupled with, for the shower - washing machine - dishwasher "circuit", I have seen those inline pumps that boost an unequal pressure systems hot water line.

The second was .. in a normal hot water cylinder (not mains) you have an ajax valve and that pipe going through the roof and the longer the pipe the more water you get out of nozzle and can get those fittings on the end of pipe... why can't i have a "cold" hot water cylinder system and along side the "Hot" hot water cylinder?

I know that if i have a 7.6m pipe out of top of HW cylinder is approx 76kpa which is on the max the cylinder can take and that equates roughly to 11psi

Cheers

Posted Tuesday 11 Oct 2016 @ 7:08:13 am from IP #
Eagle10
Member

Hi Axess,
Great thought... I'll need to look into costs and how many batteries etc for the power consumption to cost ratios as we intend adding a swimming pool and a spa pool to get off grid as they a power hogs. That will be our next project as well as grey water management (which I see is a topic here).

First off the rank though is to work out a way to get our water delivery system not only off grid but "power-less" and still useful

I'm sure it can be done but I think its more that I'm not asking the right questions.

I'm trying to eat my elephant one bite at a time!!

Thanks for your thoughts!

Posted Tuesday 11 Oct 2016 @ 7:29:54 am from IP #
Johnnojack
Member

You can have a cold tank as well as a hot tank. That is what I built 34 years ago and it still works well. Gravity feed HWS in ceiling and cold tank in ceiling to showers only. Variable pressure from a rainwater pressure pump had no effect on the shower at all.

Posted Tuesday 11 Oct 2016 @ 10:31:49 am from IP #
Eagle10
Member

Hi Johnnojack, that sounds really interesting.. can I ask what your set up is? mine is as above .. so do you what pressure do you have and is the cold tank in ceiling space the highest point of your water storage? I havent got a 60 metre hill above mine to give me the pressure i need to do away with my water pump and I'd really like to have my water supply as close to having no source of electricity to run it. I'm happy to use a solar panel onto a little slush pump to get the water from my 2 x 25000 litre tanks to a smaller holding tank in ceiling or somewhere but would like when i turn a tap on to have no power assistance (if that makes sense).

thanks

Posted Thursday 13 Oct 2016 @ 11:49:44 am from IP #
Johnnojack
Member

Constant pressure solar HWS tank in ceiling on a small stand, larger pipes with constant fall to taps. A small plastic tank on stand in ceiling which supplied the cold water to the showers only with 20mm piping. Plenty of flow at showers with ordinary arm type shower not a high pressure water saving thing. Water fluctuations from pressure pump completely isolated from showers. Water supplied to both HWS and cold tank through float valves in tanks. Hope this describes it for you. The hot water to the matching machine was a bit slow but I believe you can get low pressure solenoid valves to help this. Having ceiling tanks for all taps in the house would not work to well though. Pressure pumps are the way to go. Can't see how you can do away with one unless you go back to what we had when I was a kid, tank on 20 foot stand and water pumped up daily with a hand pump. (My job).

Posted Thursday 13 Oct 2016 @ 10:54:10 pm from IP #
Halcyon
Member

You can do a similar thing to Johnno by having the hot water header tank in the ceiling or higher (fed from pressure system) and take the cold water feed for the shower from the same header tank.
Result is constant temp. in shower.

Posted Thursday 13 Oct 2016 @ 11:03:24 pm from IP #
ilmessaggio
Member

I think he means constant pressure

Posted Friday 14 Oct 2016 @ 2:46:15 am from IP #
Greg
Member

I think we will run into economics here. How much does it cost to do all this stuff vs electricity saving. As an example, you could spend some capital on a large bladder tank, use a solar pump to pressurise it and and have water at pressure all day. That way you could keep your existing plumbing and not worry about low pressure solenoids or toilet cistern valves etc. Is it cost effective - too hard for me to work out but its an option. :-).

Posted Friday 14 Oct 2016 @ 3:40:39 am from IP #
Johnnojack
Member

I agree Greg. Not worth it trying to eliminate a pump, with solar power being so cheap.

Posted Friday 14 Oct 2016 @ 9:48:29 am from IP #
Eagle10
Member

Hi Greg
thanks for that, I'm now looking for that bladder and how to pressurise it .. got the bladder but no info on the pressurising of it part .. my hot water is always very poor too but thats another story.

Johnnojack

I'm tending to agree with you .. maybe change the type of pump to a solar one as eventually i want to add to it the control of power to a swimming pool.. apparently the best thing for a clean and nice pool is water movement (12hours a day they recommend) I'd like that off my power bill as its a 1kw motor.

Halcyon
Thanks for your comments, I cant quite get my head around what your saying (I'm slow on understanding some things), I know you're saying something clever but I've missed it somehow
Could you please fill in some detail if you have time.

I'm looking for anything even out of the box

And should I be targeting 50 psi as good overall general pressure?

Food for thought is what I'm getting ..

Hey thanks everyone

Posted Friday 14 Oct 2016 @ 10:05:21 am from IP #
Johnnojack
Member

20 psi is quite adequate. This is the usual minimum for pressure pumps which don't operate at constant pressure. Most of the newer ones give constant pressure by varying their speed, but that means they start every time you turn on a tap. Not what you've said you are looking for. A pressure tank could be a 100 litre tank so the pump may not need to start for hours, maybe even overnight.

Posted Friday 14 Oct 2016 @ 11:27:24 am from IP #
Halcyon
Member

Hello again Eagle,
The general idea is to have the hot water header tank (this is a tank,usually copper, with a ball valve in it that feeds to the hot water unit) as high as possible so as to give yourself acceptable pressure. The hot water unit can be anywhere, but you would want to have it as close to the main water uses as possible ie. kitchen and bathroom. Some people have the hot water unit in the ceiling space, but I don't like this idea - the obvious reason being the danger of leaks. Because the header tank provides the pressure, you can place the HWS at ground level and outside.
The usual places for the header tank are the ceiling space or clamped to the chimney(if you have one). If you take the cold water feed for the shower from the bottom of header tank then it will have the same pressure as the hot water and hence a constant temp. A cold water feed from a pressure system will have a changing pressure and hence changing temp.
If the header tank is in the ceiling space you will need a drip tray and overflow pipe to the outside and you need to inspect it occasionally to be sure that wasps or birds haven't blocked it.

Posted Saturday 15 Oct 2016 @ 7:03:54 am from IP #

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