Transitional electric blues

2

Comments

  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues
    run the gennie and pump for 1/2 a day to fill the tank(s)

    Are you saying that it will take half a day to fill one 35 gal pressure tank with water using an AC 1/2 hp pump? I thought it would only take a few minutes.

    Crap.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues
    Hairfarm wrote: »
    Are you saying that it will take half a day to fill one 35 gal pressure tank with water using an AC 1/2 hp pump? I thought it would only take a few minutes.

    Crap.

    My 1/3 HP pump fills that 35 gallon PT in about 6 minutes. That tank is roughly equivalent to an 80 gallon "standard" tank. 1/2 Hp pump around 10 gpm = approx. 8 minutes from empty.

    I don't know where Tony got his 1/2 day figure from - maybe he's thinking about the way we 'schedule' water times: so you'd be doing all your 'heavy' water use (dishes, showers, laundry) while the generator is running. Then just let it fill the PT and shut everything down - gives you 'reserve capacity' for general water use all day.
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Transitional electric blues

    Where I get my 1/2 day figure is not proofing my text. It should read "~1/2 HOUR per day! My bad. Typical deep well pump should pump in the order of 5 gpm, so thirty minutes would be ~150 gallons.

    Sorry!

    T.

    PS I have been up on a neighbours roof all day in the hot sun, stripping and reshingling! I'm getting to old for that,, but so is he! I think my brain was out in the sun too long. That's my story and I am sticking to it.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues

    I'm glad I'm not the only one with that sort of problem! :p

    Anyway, it's even easier than that 'cause there's no well involved here: 2500 gallon on-ground tank. Shouldn't have any trouble with 10 gpm from 1/2 HP pump - maybe more (random pump rating says 12.7 gpm @ "5 feet" depth). Three of the 35's would fill in about 20 minutes tops. But those big tanks are nearly $300 each.
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Transitional electric blues

    Buy them at a wholesale house, if you are buying three, they should sell to you off the road.

    T.
  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues
    Three of the 35's would fill in about 20 minutes tops. But those big tanks are nearly $300 each.

    Instead of buying two or three Pt's, why not buy a bigger PT like the one in here:

    http://store.solar-electric.com/chalpc85galw.html

    That's double the capacity of a 35gal PT for roughly $400. Are the problems with using a PT that's over 35 gals?
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Transitional electric blues

    One big Ptank, multiple little ones, doesn't make any real difference. Cost/availability/space available etc.

    Tony
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues
    Hairfarm wrote: »
    Instead of buying two or three Pt's, why not buy a bigger PT like the one in here:

    http://store.solar-electric.com/chalpc85galw.html

    That's double the capacity of a 35gal PT for roughly $400. Are the problems with using a PT that's over 35 gals?

    I think you'll find that's actually the same as the diamond tank I mentioned, which is an 82 gallon "equivalent" in a "standard" (i.e. non-pressurized) tank. Read the specs on that one from NAWS. It says "26.4 gallon draw down".

    To really go bigger you'd need this one:
    http://store.solar-electric.com/wwt-120.html
  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues

    It just occurred to me that I'll need a pump capable of pumping a higher pressure than the pressure tank otherwise I won't be able to pump water into the pressure tank.

    In other words, if the pressure tank is set to 40lbs and I have a water pump that pumps, say 30lbs, then I wouldn't be able to get water into the pressure tank (?) Is this correct? Or can I still pump water into a pressure tank even though the pump is weaker than the pressure tank's 40lbs. Probably overthinking...

    The pump I have in mind is a 1/2 hp shallow well pump.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues
    Hairfarm wrote: »
    It just occurred to me that I'll need a pump capable of pumping a higher pressure than the pressure tank otherwise I won't be able to pump water into the pressure tank.

    In other words, if the pressure tank is set to 40lbs and I have a water pump that pumps, say 30lbs, then I wouldn't be able to get water into the pressure tank (?) Is this correct? Or can I still pump water into a pressure tank even though the pump is weaker than the pressure tank's 40lbs. Probably overthinking...

    The pump I have in mind is a 1/2 hp shallow well pump.

    Nope. The PT's bladder pressure is adjustable. It's set at 2 psi. below the pump's 'turn on' pressure. With a working pressure range of 30-50 psi the air bladder is set at 28 psi. (It's a standard 'tire fitting' for filling.)

    In your case a good deal of the pressure is going to come from having '0' lift requirement on that pump!
  • BB.BB. Super Moderators, Administrators Posts: 28,633 admin
    Re: Transitional electric blues

    You are correct... If the tank is pressurized to 40 PSI--a 30 PSI pump will not fill the tank.

    I am not a pumped water person.. But at the very most, I would guess, the tank should be set to the pump's turn-on pressure (when the tank is empty of water--no water pressure present).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues
    Nope. The PT's bladder pressure is adjustable. It's set at 2 psi. below the pump's 'turn on' pressure. With a working pressure range of 30-50 psi the air bladder is set at 28 psi. (It's a standard 'tire fitting' for filling.)

    Do I have to set this bladder pressure manually or does the bladder automatically adjust to the incoming pressure from the pump.

    thanks,
  • BB.BB. Super Moderators, Administrators Posts: 28,633 admin
    Re: Transitional electric blues

    Not an expert here...

    As far as I know, there are too major types of tanks...

    A "wet tank" (air over water). Which has to be refilled fairly often with compressed air because the water dissolves the air into solution.

    And a bladder type, which has a plastic "balloon/bladder" which separates the air from the water.

    Both have an air fitting (like that on your car tires) where you can add or remove air.

    Here is a very nice DIY web page on replacing an old tank. Should answer pretty much all of your questions:

    www.hammerzone.com/archives/plumbing/well/pressure_tank/replace.htm

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues
    Hairfarm wrote: »
    Do I have to set this bladder pressure manually or does the bladder automatically adjust to the incoming pressure from the pump.

    thanks,

    You pre-set the bladder pressure to 2 psi below the pump's "on" pressure. As the pump fills the tank, it works against the bladder - pressure in both go up. After the initial setting there's really nothing to do except check it once in a while (yearly at least).
  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues
    Here is a very nice DIY web page on replacing an old tank. Should answer pretty much all of your questions:

    http://www.hammerzone.com/archives/p...nk/replace.htm


    I noticed that there are electrical wires coming off of the pressure switch. I will not have any electricity. I need a pressure tank system that doesn't require plugging anything into an outlet.

    This is why I'm looking for a tankless water heater that runs only on LP, although I'm having a heck of a time finding on that has good reviews.

    thanks though. :)
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues
    Hairfarm wrote: »
    I noticed that there are electrical wires coming off of the pressure switch. I will not have any electricity. I need a pressure tank system that doesn't require plugging anything into an outlet.

    This is why I'm looking for a tankless water heater that runs only on LP, although I'm having a heck of a time finding on that has good reviews.

    thanks though. :)

    If you don't have electricity, how are you going to run the pump?

    The wiring for the pump goes through the pressure switch, which turns the pump on & off as needed. Even with running from a generator you need this. After the tank is filled (pressurized) electricity becomes irrelevant until the next time it needs filling; the water will flow from the pressure in the tank.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Transitional electric blues

    The wires aren't coming off the tank. They are coming off the pressure switch which turns the pump on and off.
  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues
    If you don't have electricity, how are you going to run the pump?


    Actually I was going to use the power of positive thinking to run my pump ;)

    Ok, there's definitely a learning curve with this stuff, my bad. I thought the pressure switch in the diagram posted by Bill was a separate component. But yes, I will have a 5k watt, gas generator to use until I go full solar. This is why I'll be using an ac water pump at first (so I can plug it into my AC gen) then switch to a dc water pump later when I get the solar hardware installed.

    BTW, will a solar powered Direct Current water pump be compatible with a pressure tank? Are the Dc powered pumps strong enough to fill a pressure tank? I'm thinking this depends on the power of my solar array, right?

    What do some of you use for DC water pumping into a PT.

    thanks again!
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Transitional electric blues
    Hairfarm wrote: »
    Actually I was going to use the power of positive thinking to run my pump ;)

    Ok, there's definitely a learning curve with this stuff, my bad. I thought the pressure switch in the diagram posted by Bill was a separate component. But yes, I will have a 5k watt, gas generator to use until I go full solar. This is why I'll be using an ac water pump at first (so I can plug it into my AC gen) then switch to a dc water pump later when I get the solar hardware installed.

    BTW, will a solar powered Direct Current water pump be compatible with a pressure tank? Are the Dc powered pumps strong enough to fill a pressure tank? I'm thinking this depends on the power of my solar array, right?

    What do some of you use for DC water pumping into a PT.

    thanks again!

    Yes, a DC pump (Shurflow is what I have) will fill the pressure tank, it just takes longer. My DC pump is in parallel with the jet pump for purposes of backup. If the jet pump or pressure switch fails, or the inverter dedicated to the jet pump fails, we still will have water pressure.

    Having spent many years on submarines, I ALWAYS have a backup system, and PREFER to have a backup system for a backup system, if THAT makes any sense.

    Phil
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues

    Will a DC pump work with a pressure tank? Depends on the pump. Nothing to do with AC or DC.

    Some pumps are designed for volume, some for lift, some for pressure. Actually, they all accomplish all three but in different ratios. Some of the "solar pumps" are variable speed - pump whatever they can with whatever power is coming directly from solar panels.

    Considering that you have a 2500 gallon tank on the ground, there is essentially no lift. It will i fact produce pressure from the weight of the water without any pump. This is a very easy pump application!

    As I mentioned before, why buy the big pump to begin with when you don't really need it? A 120 VAC Shurflo would fit the specs, run with a PT, and not be a big drain on batteries when you switch to "full solar". No sense buying two pumps when you only need to buy one. This would probably meet your needs: http://store.solar-electric.com/2088-594-154.html

    Unless you're planning on not having an inverter at all, of course.

    In case you are wondering, I have a 1/3 HP AC pump which I've been using since the time when generator power was all there was. I'm planning on switching to the Shurflo when the existing pump needs replacing because it uses less power and I don't have much need for lift either (about 10'). I will probably use two, because I like to have lots of water flow and fill the bath quickly! :p
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Transitional electric blues
    As I mentioned before, why buy the big pump to begin with when you don't really need it? A 120 VAC Shurflo would fit the specs, run with a PT, and not be a big drain on batteries when you switch to "full solar". No sense buying two pumps when you only need to buy one. This would probably meet your needs: http://store.solar-electric.com/2088-594-154.html :p

    Marc,

    I have one of those pumps too and it works great. This is different than the 12VDC Shurflo that is the backup for our water pressure. I use the 120VAC Shurflo to supply our icemaker from a 5gal water bottle (delivered monthly, a small indulgence). We are on a well and I dislike the 'residue' left in my glass after using 'well-water ice'.

    Phil
  • VolcanoSolarVolcanoSolar Solar Expert Posts: 56
    Re: Transitional electric blues

    Holy Endless Thread, Batman!

    Okay I think I finally found the end :D

    One question: will you be using a tankless-type water heater? Because if so, they have minimum pressure requirements. We swapped in a 40-60psi pump controller for the stock 30-50 psi unit, because they really need that 40psi minimum. And even at that, if our shower head clogs at all (minor grit in the system) the pressure drops and it goes cold :grr

    If using such a heater, then of course using gravity feed from a ground-level water tank won't work. We have just such an interim arrangement right now. I just plumbed the house I'm building to have the option of gravity-feed for the washing machine, which just means a long slow filling time (not a problem); toilets too are fine this way, unless you need that second flush in a hurry (ahem), but the Bosch Aquastar (etc) tankless heaters all need that higher pressure.

    Also, I once had three large bladder tanks all hooked up to a single jetflo-type water pump, but was surprised because even at that, the pump turned on twice a day. So for me the bang-for-the-buck wasn't there, with extra tanks. Of course, I was only doing it to save on inverter-load time, not running a generator.

    Lastly there are water pumps around that are twice as efficient as jetflo pumps; they use pistons, are far more expensive, and can be rigged either with an AC or a DC motor (I have one set up for 48 volts DC, not yet put into service however). Just as one more option to confuse you with. :D:D

    - Ted
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues

    I don't know what you've got for a hot water heater, but the Bosch I have specs at min. pressure of 2 psi @ 0.5 US gpm. There's no reason why you should need a minimum pressure of 40 psi - there's something wrong there. Mine still fires even when I let the tank go down to empty (when the water stops, so does it) and it's 'turbine' ignition too.

    Instant hot water heaters do require a 5 micron filter to keep them from clogging with sediment, but that won't do anything for you if you've got hard water and it's building up 'scale' inside. There are 'descalers', but I have no reliable data on whether or not they work.

    If you have three large tanks hooked up properly, the pump will run 1/3 as much as it would with just one. If you see no difference, something is not hooked up right.
  • VolcanoSolarVolcanoSolar Solar Expert Posts: 56
    Re: Transitional electric blues

    I just pulled out the manual; my Aquastar 125B lists min. 18 psi at 4 GPM. Can't explain why it cuts out below 40 psi, maybe it's the GPM? But it does so regularly, as did our previous Paloma, whether newly installed or sitting a long time. Water is not hard; it's rainwater catchment, slightly acidic if anything, that's been roughly filtered (fine screen inline). What model is your Bosch?

    Yes, I had longer times between pump cycling; I guess my thinking was that it would go a day or more between cycles, but did not, and so to me was not worth the expense and bother of multiple pressure tanks.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues
    I just pulled out the manual; my Aquastar 125B lists min. 18 psi at 4 GPM. Can't explain why it cuts out below 40 psi, maybe it's the GPM? But it does so regularly, as did our previous Paloma, whether newly installed or sitting a long time. Water is not hard; it's rainwater catchment, slightly acidic if anything, that's been roughly filtered (fine screen inline). What model is your Bosch?

    It could be that with your particular pump set-up you aren't getting the minimum flow @ pressure. Pumps can put their HP into lift, flow, or pressure in any combination. The more lift, the less flow and/or pressure et cetera. Usually installs favour lift, because the important thing is to get the water out of the well of course! If you're using a rainwater catchment, there should be no lift issue. I don't know: there's a lot to a water system and I'd have to see every little detail to figure out what's going on.

    My Bosch is an older one: W 400-7.k..
    Yes, I had longer times between pump cycling; I guess my thinking was that it would go a day or more between cycles, but did not, and so to me was not worth the expense and bother of multiple pressure tanks.

    Yes, in order to get up to that "once a day" pump cycling you have to figure on 50-100 gallons of water per person per day. That's a lot of tank!
  • BB.BB. Super Moderators, Administrators Posts: 28,633 admin
    Re: Transitional electric blues

    I would be careful of running a tankless (or even tanked) water heater at very low pressure.

    Basically, water boils at 100C/212F at sea level (~14.69 PSI). At 40 PSI relative pressure water boils at ~141.5c/287F.

    In a heater, the surface of the tubes/tanks/elements are much hotter than the water in order to get good heat transfer... At low pressures, the surface of the element/heating surface will generate steam bubbles... These create small areas of insulation (limit heat transfer, cause surface temperatures to rise even more, causing surfaces to fail, minerals to precipitate, etc.) plus the steam bubbles collapse--creating local pressure changes that can damage/erode the surfaces of the heater...

    If you hear the boiling (sounds a bit like rocks breaking or a "pinging" gasoline engine)--you probably have some problems (low water pressure, calcium/lime build up, etc.).

    You may end up limiting the useful life of your hot water tank with low pressure in your piping and one reason why they are rated with a minimum operating pressure. (another being is that tankless water heaters have a fairly high pressure drop from inlet to outlet too).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Transitional electric blues

    A couple of notes,

    To Volcanosolar, I agree with Marc that you probably have an obstruction in the water inlet. Most demand water heaters have a finger strainer or filter on the inlet side. On my gravity tanks, I have to clean the filter every month or so because of the stuff that gets in the tank.

    As for Bill's point about low pressure. While I agree in principle that water boils at a higher temperature with increased pressure, the reality is that many (but not all) demand water heaters will run just fine and indeed are spec'ed to run at very low pressures. The reason I have used Palomas over the years is that they have a minimum water pressure of ~5 psi if I remember correctly. I know that I have run one for years on ~12 psi. As you suggest, the critical thing to safe operation is to make sure that all the air is purged from the water circuit before firing, and that you have a T&P relief valve installed. I know that in theory the fire should quit when the water flow stops, but I have had mine continue to fire due to an obstruction in the diaphragm or an air lock. In that case you certainly can have a dangerous situation, if you are pouring ~50,000 btu/hr into a stalled water circuit.

    Tony
  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues
    I don't know what you've got for a hot water heater, but the Bosch I have specs at min. pressure of 2 psi @ 0.5 US gpm. There's no reason why you should need a minimum pressure of 40 psi - there's something wrong there. Mine still fires even when I let the tank go down to empty (when the water stops, so does it) and it's 'turbine' ignition too.


    The pdf for the tank I'm interested in states:

    Technical Specifications:

    Water pressure:
    Minimum: 30 PSI
    Maximum: 150 PSI


    Minimum flow to activate:
    0.5 gallons per minute (gpm)


    Here is a link to the pdf specs.

    http://www.cpotanklesswaterheaters.com/static/info/www.cpotanklesswaterheaters.com-1600h-ng.pdf


    Should I be worried about the minimum 30 psi minimum with a pressure tank. I'm a bit confused now.

    thanks,
  • HairfarmHairfarm Solar Expert Posts: 225 ✭✭✭
    Re: Transitional electric blues

    I think I'm leaning toward this model:

    I found a guy with 15 in stock even though they are discontinued:

    http://www.tanklesswaterheaters.com/palomaph24m.html


    One question though. The minimum working water pressure in the PDF manual is listed as:

    Minimum - 2.4psi
    Full - 12.9

    What do they mean by the FULL 12.9 spec? I hope they don't mean maximum 12.4 psi.

    The above info can be found here:

    http://lib.store.yahoo.net/lib/lowenergysystems/paloma.pdf


    thanks,
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Transitional electric blues

    Reading through the pdf (specifically page 6) it appears it is talking about the different minimum water pressure necessary for operating the heater at full capacity vs. reduce capacity (i.e. fewer gpm). It also talks about head loss and drop in pressure through hot water lines, and says the PH-6 model should have a minimum working system pressure of 40 psi. This may be a clue to VolcanoSolar's problem: the Aquastar may have a similar requirement (in order to maintain proper flow past the heater).

    I don't see anything in the documentation that would indicate a problem with running the PH-24 on a working water pressure range of 30-50 psi.
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