feedwater for domestic steam boiler

stevenknaub

My home has a 13 year old Burnham Independence IN-4 steam boiler. Our domestic water supply is very hard and treated with chlorine and fluorine and has been used in the boiler for all but the last year. I have had to add approximately 2 pints of water every two weeks during the heating season here in Pennsylvania for as long as I can remember, and have not been able to find any leaks anywhere, including after removing the top of the housing and looking inside the flueway. I have only one condensate return and I replaced about 1/2 of it with new black pipe, so I know it is clear. All piping is above the floor. I replaced the near boiler piping with a drop header and also opened up the second steam tapping, piping that into the drop header, like shown on the installation manual, and in the Lost Art of Steam Heating.(thank you!). The PH is between 10 and 11, and I am attempting to monitor and reduce the PH to between 9 and 10.
Also important to know is that during my leak checking, I over-filled the boiler to a point above the top of the housing and no leaks occurred that were visible.
a couple of questions: 1) is a pint a week excessive? 2) because I wish to limit additional buildup of scale, and possibly reduce the amount of scale in the boiler, while reducing the PH, would it hurt the boiler cast iron by adding baking soda to distilled water or to reverse osmosis water, for all additional feed water. I figured plain distilled water may harm the cast iron, OR, possibly not harm it because surely there must be a lot of scale buildup.
My system holds only about 8 gallons of water, including what is in the return. So, if I do add baking soda, any idea how much to lower the PH to 9-10 from current 10-11?
Thanks always for any guidance you can provide, I appreciate it.
You cannot provide too much information. Steve

mikeg2015

So this is a 2 pipe system correct? What pressures are you running? Most likely you are getting some tiny leaks around radiator valve stems. Lower pressure will reduce or almost eliminate leaks the system. 2 pints is small enough I’d be surprised if it’s a condensate leaks. Those normally use gallons.

Baking soda raises ph. However, your 10-11 isn’t bad. Corrosion is inhibited with those higher PHs... which is why your city likely keeps it that high.

Above 11 the water can foam. But if you aren’t having surging or foam, don’t worry about it. The high PH is otherwise good. Corrosion is almost impossible.

Jamie Hall

Adding baking soda would raise the pH, not lower it, and that you do not want to do if you are already at 10 or so. As @Fred said, 2 pints a week is not excessive in terms of water use.

It appears from your comment about your water being chlorinated and fluoridated that you are on municipal water. That being the case, it is also likely that the water is treated and balanced for corrosion protection and that the hardness is controlled. I doubt that using that water -- certainly in that quantity -- in your boiler will harm it or build much more scale. That said, you could use distilled water or RO water for further makeup, but be sure to add correct quantities of some additive -- such as SteamMaster -- to provide some buffering against corrosion and pH instability. It would take very little additive, however at that feed rate, and overdosing is much more harmful than underdosing

stevenknaub

It's a one-pipe system, with vapostat set at 6 ounce cut out. City water is very hard, around 15 - 25 on the strips I use to test. I have a softener installed which treats all but our drinking water and outside spigot, and while I have a domestic feed to the boiler, I have not been using the feed at all for about a year or so. I add water directly through a standpipe that comes off the Hartford Loop and is valved. Sometimes I add the water through an upstairs radiator, by removing a vent. I have a bluetooth camera focused on the site glass, very handy for monitoring water level, and I've noticed some minor "bouncing", perhaps a 1/2" or so during the heating cycles. I think that is an indication that I have foaming, is that correct? My system is nearly noise free, and other than water collecting in perhaps 2 or 3 of my airvents (I think they are Jacobus/Maid O Mist) and the need to add water every 2 weeks, everything is the best it's been in 35 years since moving in. So is bouncing a sign of foaming? If so, I need to bring the PH down a point or two until eliminated. If it is foaming, my steam is too wet as well, perhaps that is why 2-3 vents are getting waterlogged very often?

Fred

A half inch bounce is pretty typical and does not indicate foaming.
If you don't soften the drinking water, why not just tap off of that line into your boiler?
Your Vaporstat may be set correctly but when is the last time you cleaned out the pigtail? It may be clogged and the pressure may be running higher than you think, which may be a reason for the water logged vents. Are the radiators pitched properly? Another reason for water to collect in the vents.
Some water will evaporate during the heating season and is likely part of your water loss. Spitting vents may be the rest.

ethicalpaul

How much water collects in your vents? Some drops are no big deal, steam must condense in order to heat the vents of course but more water might be an indicator that they are leaking steam, perhaps slowly.

I wouldn't add softened water to the boiler, I can't tell from your description if that's what you're doing.

There is a demineralization filter you can add to your boiler's water feed: https://www.supplyhouse.com/Caleffi-NA573100-1-2-FNPT-Demineralizing-Filter-Housing-and-Color-Changing-Cartridge?utm_source=HeatingHelp.com

The bouncing doesn't sound bad to me. Are you able to skim your system just in case there is some scum floating on your water? You can lower your ph a bit to see if it helps, like to 9.

Hap_Hazzard

Bouncing indicates a rough boil, which can be caused by an accumulation of oilly residues on the surface of the water, which are best removed by skimming the boiler, or sediments coating the insides of the sections, which are best removed by flushing and "wanding" the boiler. Oil on the surface prevents small bubbles from breaking through until they coalesce. Sediments block the nucleation sites on the surface of the cast iron, making it more difficult for small vapor bubbles to form, so they form more explosively.

hot_rod

The water treatment chemical causing the most problem, in addition to excessively high chloride is orthophosphates.

These are increasingly added to coat pipes to prevent lead and copper leaching, think Flint Michigan. It basically coats the metal surfaces, which for protecting potable water piping may be a good thing.

The concern is the precipitation of this treatment in boiler systems running above 140F. We know minerals precipitate in relation to temperature, look no further than your tea kettle.

A wood boiler manufacturer I know called a year or so ago for ideas on why they are seeing more failures in their steel tanks. A thick layer of sludge was forming in systems filled with public water. When analyzed it was determined running 180F plus temperature was causing those ingredients to come out of solution and created a sludge, the steel corroded below that layer.

Ortho and polyphosphates are common fertilizers also, so any surface water or even wells may see elevated levels. Same applies, as the soil temperature increases the phosphate conversion speeds up and the fertilizers are absorbed into the soil.tr

First determine the levels of chemicals in the feed water, ph and TDS. Within TDS determine the levels of chlorides and phosphates. If they are on the high side and you have a system filled with or occasionally topped off with that water, you may consider treating it.

IF you did strip water ion free with DI or RO, you get aggressive low ph water, that you would want to buffer up with conditioners specifically designed for steam or hydronic systems. You basically remove the harmful ions and replace with beneficial ones. You get a thin film provider to coat and protect the cast iron, but not excessive "bad" minerals that sludge or put excessive layering on heat exchange surfaces.

Have the water tested, report back, find and seal any leaks, of course.

Jamie Hall

A minor pint, perhaps... while you are looking at the analysis of your water, do not confuse chlorides with chlorine or chloramine. Chloride is ionic, and in any significant quantity quite corrosive (think road salt). Chlorine and chloramines are not ionic and are not corrosive; indeed they are quite harmless particularly in boiler water.

I know it's only one letter different. Chemistry is funny that way.

SteamingatMohawk

Go read this and look at the green and blue table.

https://pediaa.com/difference-between-chlorine-and-chloride/

Jamie Hall

Good enough -- as far as it goes. Which isn't very far... Chlorine and some chlorine compounds (particularly chloramines) are very powerful disinfectants, since -- as the article points out -- the chlorine atoms are not happy with their electrons, and want one more -- which they will happily grab from many other things (technically, an oxidation reaction). If the other things are atoms or molecules making up bacteria or virus, that will kill or deactivate, as the case may be, the bacterium or virus. Chloride ions already have enough electrons, and don't disinfect anything -- but they do make very good electrolytes, which makes water or moisture containing chlorides remarkably aggressive (think road salt and your Toyota).

The safest way to add chlorine to water (or wastewater!) is sodium hypochlorite, although the powder/pellet form has to be handled with care since it is a very powerful oxidizer (it doesn't burn itself, but it accelerates combustion radically when it's heated). Chlorine gas is also used, but is harder to handle. Often small amounts of ammonia (or urea) are added at the same time, to form chloramines, which are much more stable and thus last longer in the water supply, thus maintaining the disinfectant action.

SteamingatMohawk

@Jamie Hall My eyes popped when I read the comment about adding ammonia to a form of chlorine. In the cleaning arena, it can be deadly to mix chlorine bleach and ammonia, because it forms ammonium chloride which is toxic. One of my aunts inadvertently mixed them while cleaning and almost "bit the dust". Anyone reading this should take serious notice.

Now, here's an interesting point. My wife picked up some name brand disinfecting wipes that say "bleach free" on the label, but the contents include two forms of an ammonium chloride in very small amounts (each is 0.184%), just to give you an idea of how strong it is.

Jamie Hall

Trust me, @SteamingatMohawk , you don't just go out there and mix the stuff casually. It's manufactured for the purpose -- not on site. The pure stuff is rather nasty (and is shipped through your community in semitrucks...). The manufacturing reaction is in two stages -- first, you take ammonia and make it into a secondary amine. Not hard to do. Then you react that with chlorine -- or more often, sodium hypochlorite. Also not hard to do.

But mixing the two at home? Ah... no. Please don't.

dopey27177

Two pints of water every two weeks is a small amount of water loss.

To see if your radiator vents are passing steam take a cold glass and place it over the vent valve when the system starts up.

If the vent valve is passing steam it will condense on the glass.

Does this mean the vent is defective?

That depends on the type of vent valve you are using. Some times water is retained in the vent valve and when steam reaches the vent valve some water may be dribbled out of the vent valve.


Jake