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Raw or Soft Water?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by George Webster, Dec 30, 2012.

  1. George Webster

    George Webster New Member

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    My boiler is currently plumbed to my house soft water supply. I have access to the raw water, which is quite hard - calcium hardness of 150ppm or so as I recall. I've heard conflicting opinions about which is better for the boiler. I am about to break into the manifolds again, so this would be a good time to replumb the supply if raw water is better for the system. I have the same question about storage, since I will soon be filling my tank with 800 gallons and again, I can use either raw or softened water.

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  2. BoilerMan

    BoilerMan Minister of Fire

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    I did a bit of reading on this and it seems to be the consnesus that you are choosing a lesser of two evils. That being said you should get oxygen scavengers and hardness buffer chemicals for your system anyway. Personally, I'd fill it with straight water and run it up to temp (i know alot of wood to heat all that cold water up). Then drain it down to rid it of acidic soldering flux rust etc. Pour in chems for total system volume and re-fill with cold water. Done, the minerals INHO are less harmful than salted water and steel. The water will be basically dead in short order anyway, as with any closed system, leaks no matter how small are the worst enimy.

    For what it's worth, your softner will not do much on the way of keeping the hardness down when an 800+ gallon draw anyway, removing the hardness and replacing it with sodium chloride.

    TS
  3. Sorghum

    Sorghum Member

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    Would either Distilled water or Deionized water be preferable to hard or softened water? An industrial process water company could supply DI water. Cost??
  4. farmerblue

    farmerblue New Member

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    I have a 150 gpd 6 stage RODI system I use for filling my boilers.

    I get about 4 gallons of waste water for 1 gallon of RODI water, so unless you have a use for the waste water. We hold the waist water in tank and use it.

    Some pool and spa places sell and delver filter water. I'm not sue of the price, but my dad gets his spa water that way.

    If you Google “Spa & Pool Water Fill Filter” you will find filters that you put on your garden hose. They help reduce the amount of minerals, cheap, and disposable.
  5. Bob Rohr

    Bob Rohr Minister of Fire

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    That's about 8.7 grains, not really all that hard. I'd use a softener if you have one, backwash it first then fill the system. Even a small 24,000 grain softener will supply plenty of water. If the water was 24 grains hard, a 24K softener would give you 1000 gallons before it had to backwash. So with 8- 9 grains hardness a small softener would be adequate. Most residential softeners are 18- 32,000 grain capacity.

    DI water is also a good choice, you can rent a DI unit to connect to your water supply, fill the system, keep a 55 gallon plastic barrel with some spare water and return it. Around my area Culligan rents DI units.

    I like to run a hydronic cleaner through the system first, even a TSP mix will clean out flux, pipe oils, etc. Then fill it with the treated water.
  6. George Webster

    George Webster New Member

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    So, it would appear the debate goes on, but your take is softened is preferred to raw. My softener is rated at 30K and I just rechecked my test results and the hardness is 12.9GPG, so I still have way more capacity than I need to fill the tank. There shouldn't be a lot of gunk to get rid of on the tank side, since I was able to flush out the soldering deposits prior to installation and the balance is either NPT or pex crimp. I have the ability to flush through both the supply and return side, so I may flush with hot softened water, then drain the tank prior to the fill.
  7. dogwood

    dogwood Minister of Fire

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    Say farmerblue, does your dad purchase his filtered spa water in the Roanoke area? If so, I'd be curious where, since we live nearby and would like to check out how much they might charge for 1000 gallons. 1000 gallons is a lot of water for our well to churn out to be de-ionized. It would run dry for a bit. If we rent a Culligan de-ionizer by the day that might be something we have to consider. Maybe delivery of water would be not so costly. We're in Botetourt by the way.

    Thanks
  8. nate379

    nate379 Guest

    I use soft water in my natural gas boiler, though hardness here is around 30gpg.

    Several folks said I could expect 7-10 years at most out of my boiler and maybe 5 years on the pumps.

    I had to pull apart the water fill valve and the floor manifolds after less than a year running hard water. Everything was jammed up with minerals!
    Had to the do the same to my neighbor's system as well (almost the same as mine).

    The hard water also clogged up my dishwasher, washer and several times the kitchen and bathroom faucets!

    Put in a water softener after that first year and haven't messed with anything since.
  9. farmerblue

    farmerblue New Member

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    My dad is out near Fincastle. I'm not sure what company he uses or what type of filter they use. I think he gets about 1,200 gallons at a time. Next time I talk to him I will see if I can get more info off him.
  10. dogwood

    dogwood Minister of Fire

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    Small world. My wife and I live a mile and a half outside of Fincastle. I'd appreciate any info you could provide from your Dad on his supplier. I had no idea you could purchase quantities of water like that around here. Thanks farmerblue.


    Mike
  11. Bob Rohr

    Bob Rohr Minister of Fire

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    Here is a 4" HW main from a building in Minnesota. Hard water continue to precipitate out, and the higher the water temperature, the more the minerals come out. You spend a lot of $$ on these hydronic boilers and components, good quality fill water is a cheap investment to assure the best HX performance.

    Also a shot of a HX from a small condensing boiler that had started to lime up, and caused the stainless HX tubed to over heat.

    Attached Files:

  12. Fred61

    Fred61 Minister of Fire

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    Be careful about using RO water in boiler systems. It is a necessity in some applications like making fresh water on your yacht but when used in boiler systems and other systems that contain any metals it will be corrosive. With all the minerals and metals removed, the water, by it's nature, wants them back and will grab them from the surrounding surfaces.
  13. dogwood

    dogwood Minister of Fire

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    Fred does your warning apply to DI water as well?
  14. Bob Rohr

    Bob Rohr Minister of Fire

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    Good advice! RO water can run 5-7ph, much too aggressive for boilers. Only if you add chemicals to boost the ph should it be used. Boiler water should have a higher alkalinity, 9 or higher ph. This provides an oxide film to protect the metal surfaces from corrosion.
  15. Fred61

    Fred61 Minister of Fire

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    Not that I'm aware. I used thousands of gallons od DI in an electroless plating operation and saw no ill effects.
  16. farmerblue

    farmerblue New Member

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    RODI water should have a "true" pH very close to 7. I do add some tap water to the boiler to try to get a hardness between 50 and 60 mg/l. My tap water has a hardness around 150 mg/l and I have never let it gas off to get a true pH test.

    PH testing is some what useless. C02 forms carbonic acid that lowers pH readings. Well water and spring water can have high c02 levels. Centralized water systems can also have a high pH depending on the water source and how it is treated. We use water hardness tests on the farm for record keeping.


    Dogwood I'm about to send you a pm.
  17. dogwood

    dogwood Minister of Fire

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    Thanks farmerblue.

    Mike

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