water softened water make up to steam boiler

horseshoe

Hi installing a water softener. I wanted to take the hardness out of the whole water including water going to boiler make up. was going to install it were the water comes in so eveything has soft water. does anyone know of any problems in doing that? I am a little concerned about more salt in the water, pipe rusting out faster. been watch allot of Dans videos.

gerry gill

This is really a tough one to answer..I was taught not to put softened water in a steam boiler..but if you go to the commercial end of steam they purposely soften the water to the boilers..my personal belief says it has more to do with the question’ Is anyone monitoring the quality of the water on an ongoing basis.?’...If not I would be inclined to use city water of a known quality..

mattmia2

There are conditioning cartridges you can put in line that are designed mainly for hot water systems as well. Not sure if those result in the right chemistry for steam or not.

Jamie Hall

Don't do it. Fully softened water is fiercely corrosive. Not only is the increased chloride content a problem, but all the normal buffering minerals (mostly calcium carbonate, some magnesium carbonate) have been removed, making pH control problematic at best.

If you use fully softened water, you must add buffering and pH control compounds to the boiler water, and monitor the water chemistry.

Provided that the steam use is not consumptive -- that is, you aren't adding more than a gallon or so a week to the system -- the amount of scale forming minerals which are present (unless the water is outrageously hard) is not a problem.

Note that his does not apply to power boilers, or boilers used for consumptive usage. In both cases, there are benefits to using either reverse osmosis or distilled water, or to frequent blowdowns (particularly consumptive use), or to very careful -- daily, in the case of large power boilers -- water chemistry monitoring and the addition of an interesting (and sometimes very toxic) chemicals to control pH and corrosivity and oxygen content. You don't want to go there.

PerryHolzman

gerry gill said:

This is really a tough one to answer..I was taught not to put softened water in a steam boiler..but if you go to the commercial end of steam they purposely soften the water to the boilers..my personal belief says it has more to do with the question’ Is anyone monitoring the quality of the water on an ongoing basis.?’...If not I would be inclined to use city water of a known quality..

You are partially correct in that commercial boilers do use purified water. However, they do not use salt based ion exchange water softeners typical of home usage.

Commercial installations typically either use reverse osmosis (2 stages) to remove virtually all non water ions; or they use a hard acid and hard based demineralizer ion exchange system (Sulfuric Acid and Sodium Hydroxide are most common). Sometimes they use a reverse osmosis (1 stage) to feed a demineralizer.

The above systems dramatically remove almost all non-water ions from the system - leaving very pure water (which is highly corrosive and requires chemical buffering to protect the boiler (in line with Jamie Halls post); which commercial boilers have an onsite chemistry lab, technicians, and installed equipment to do so.

You may correctly lable the pure water produced to feed a commercial boiler as "softened"; but it is vastly different than what "soft water" from a home "softer" produces.

A Sodium Chloride salt based ion exchange system typical of a home "water softener" does not lower the total amount of non-water ions in the system. It just substitutes sodium ions for most of the other substances that are naturally in ground or lake water.

This water is not safe for most boilers. Sodium likes to preferentially attack a whole series of metals when they are warm or hot - and at typical boiler temperatures.

Please feed hard water to the boiler.

As a homeowner with a mid 1950's home I also added a water softner at my wife's request. I left hard water to the outdoor faucets, 2 toilets, drinking and cooking water (the water supply to the filter system for those), and to the boiler.

That did require me to build a new cold "soft water" main and split the system. But, it was the right thing to do.

I wish you well with your project,

Perry

hot_rod

A common "water softener" is an ion exchange device, it basically removes only the common scaling + ions. calcium and magnesium. It does this by exchange with the - sodium ion, the exchange.

Purified waters done by RO, DI or distilling. The difference is water from one of these has all the ions removed both the + and -.
It will be "hungary" aggressive water after one of those methods, ph in the 6 range. You would want to add some conditioners to buffer the ph up.

How hard is the fill water? That may nhelp determine the best approach, up to 8 gpg is probably acceptable, above that it may be time to look at a treatment plan.

Steam boilers like the water a bit on the alkaline side, this helps protects the cast iron surfaces. Many of the steam treatment chemicals are boosting ph.

Many opinions on hard or soft water for boilers, steam or hot water. I think it comes down to how hard, and how much water is added. Closed loop hydronics typically only get filled once. Steam systems do use additional water, so it is a good idea to "fix" the water before it goes in
These illustrations show how the various duos are removed by either softening or purifying. the terms do get mixed a lot.

Jamie Hall

By outrageously hard above I meant over 180 mg/L You can check this map: https://www.usgs.gov/media/images/map-water-hardness-united-states to get some idea whether your water may be a problem.

Robert_25

PerryHolzman said:

This is really a tough one to answer..I was taught not to put softened water in a steam boiler..but if you go to the commercial end of steam they purposely soften the water to the boilers..my personal belief says it has more to do with the question’ Is anyone monitoring the quality of the water on an ongoing basis.?’...If not I would be inclined to use city water of a known quality..

You are partially correct in that commercial boilers do use purified water. However, they do not use salt based ion exchange water softeners typical of home usage. Commercial installations typically either use reverse osmosis (2 stages) to remove virtually all non water ions; or they use a hard acid and hard based demineralizer ion exchange system (Sulfuric Acid and Sodium Hydroxide are most common). Sometimes they use a reverse osmosis (1 stage) to feed a demineralizer. The above systems dramatically remove almost all non-water ions from the system - leaving very pure water (which is highly corrosive and requires chemical buffering to protect the boiler (in line with Jamie Halls post); which commercial boilers have an onsite chemistry lab, technicians, and installed equipment to do so. You may correctly lable the pure water produced to feed a commercial boiler as "softened"; but it is vastly different than what "soft water" from a home "softer" produces. A Sodium Chloride salt based ion exchange system typical of a home "water softener" does not lower the total amount of non-water ions in the system. It just substitutes sodium ions for most of the other substances that are naturally in ground or lake water. This water is not safe for most boilers. Sodium likes to preferentially attack a whole series of metals when they are warm or hot - and at typical boiler temperatures. Please feed hard water to the boiler. As a homeowner with a mid 1950's home I also added a water softner at my wife's request. I left hard water to the outdoor faucets, 2 toilets, drinking and cooking water (the water supply to the filter system for those), and to the boiler. That did require me to build a new cold "soft water" main and split the system. But, it was the right thing to do. I wish you well with your project, Perry

Perry - I am in the middle of a boiler swap at home and was pretty surprised at the corrosion inside the cast iron circulators that I installed 10 years ago.  It is a hot water system and has seen minimal make up water, so I was not expecting this.  The system was filled with softened water, so now I am wondering if that is the reason.  I will change the fill valve piping so it is upstream of the softener, and probably add some boiler conditioner once the system is up and running.  

Thanks for the info.

hot_rod

Corrosion in the form of red rust or black magnetite is usually from O2 getting into the system. It is hard to stop oxygen ingress completely. Making sure air vents are properly placed, proper expansion tank and circulator relationship, valve packings tight, barrier type pex if any was used, etc.

I feel adding a good hydronic conditioner is worth the time and money, it protects the health of the fluid.
Start with a cleaned system, use a hydronic cleaner first. Then use low TDS water, add a pint or so of conditioner as the manufacturer requires.

Then check that fluid every couple years, boost the conditioner level if required.

gerry gill

PerryHolzman said:

gerry gill said:

This is really a tough one to answer..I was taught not to put softened water in a steam boiler..but if you go to the commercial end of steam they purposely soften the water to the boilers..my personal belief says it has more to do with the question’ Is anyone monitoring the quality of the water on an ongoing basis.?’...If not I would be inclined to use city water of a known quality..

You are partially correct in that commercial boilers do use purified water. However, they do not use salt based ion exchange water softeners typical of home usage.

Commercial installations typically either use reverse osmosis (2 stages) to remove virtually all non water ions; or they use a hard acid and hard based demineralizer ion exchange system (Sulfuric Acid and Sodium Hydroxide are most common). Sometimes they use a reverse osmosis (1 stage) to feed a demineralizer.

The above systems dramatically remove almost all non-water ions from the system - leaving very pure water (which is highly corrosive and requires chemical buffering to protect the boiler (in line with Jamie Halls post); which commercial boilers have an onsite chemistry lab, technicians, and installed equipment to do so.

You may correctly lable the pure water produced to feed a commercial boiler as "softened"; but it is vastly different than what "soft water" from a home "softer" produces.

A Sodium Chloride salt based ion exchange system typical of a home "water softener" does not lower the total amount of non-water ions in the system. It just substitutes sodium ions for most of the other substances that are naturally in ground or lake water.

This water is not safe for most boilers. Sodium likes to preferentially attack a whole series of metals when they are warm or hot - and at typical boiler temperatures.

Please feed hard water to the boiler.

As a homeowner with a mid 1950's home I also added a water softner at my wife's request. I left hard water to the outdoor faucets, 2 toilets, drinking and cooking water (the water supply to the filter system for those), and to the boiler.

That did require me to build a new cold "soft water" main and split the system. But, it was the right thing to do.

I wish you well with your project,

Perry

Hi Perry, that is just an absolutely OUTSTANDING explanation!
I don’t know if the original poster appreciates it but I sure did. I’m going to figure out how to print that as it is truly informative and of tremendous value. Thanks

hot_rod

The Brits have a different take on boilers and softened fill water. Apparently the German VDI 2035 does also?
Perhaps the lesser of two evils if you have extremely hard water?

https://www.hydroworks.co.uk/knowledge-hub/can-you-put-soft-water-into-boilers

PMJ

I have run a standard salt based water softener on my 2MM BTU/HR triple pass fire tube boiler providing low pressure process steam for over 25 years. I am in a higher hardness area on city water. This setup was recommended by the boiler chemical company right from the start and they monitor the boiler water monthly. It is process steam and probably consumes on average 20-30 gallons a shift. The boiler is from 1974 and previously heated a building we are not using. I moved it in 1996 so it already had 22 years of operation on it before the 25 I have put on.

I have never replaced an upper tube and as far as I know they are original. In those 25 years there were 3 leaking tube events which resulted in replacement of a total of 6 lower tubes. Just this year I elected to replace all the lowers instead of just the one leaker to get them all on the same page.

I do not have a water softener at my house. In a home heating system I think water consumption is the whole game. If there isn't any consumption then the water can't be the source of corrosion.

The switch to intermittent fire from coal dramatically increased the introduction of fresh air into these systems and thereby the amount of water lost to evaporation. This is rarely discussed. While some may like the humidifying effect of this, it clearly only subtracts from boiler life. How much can be debated. That it is a negative can not. It is just one more reason why vacuum operation is superior to open vented, beyond its performance enhancing features. The water loss in a system that will hold vacuum beyond blow down water is negligible.

Jamie Hall

As you note, @PMJ , process steam is a whole different ballgame from domestic heating.

PMJ

Jamie Hall said:

As you note, @PMJ , process steam is a whole different ballgame from domestic heating.

Yep. And feeding lots of water into a residential boiler is always a bad idea, softened or not. As I said, if you are hardly putting any in it can't be the source of a problem.