What water for model copper boiler? (Stuart 504)

[jamespetts]

I have a distinct recollection of reading a thread on this forum some time ago about what sort of water should be used in model steam boilers, but, having searched this evening, cannot for the life of me find it.

As I am now getting near the stage of having an operational steam plant with my Stuart Score/504 boiler (provided that I don't make a terrible mess of silver soldering the pipes this week-end), I need to know what sort of water that I should use. I strongly suspect that water straight out of the tap would be a bad idea (I live in a hard water area), but am not sure what would be a good idea.

The (rather ancient) instructions that come with the 504 suggest "boiled or rain" water, "boiled" presumably referring to home-distilled water, rather than just to water that's been brought to boiling point for a few seconds in the kettle. Both of those possibilities seem distinctly impractical. Would any of the following suffice:

(1) tap water where a domestic water softener is installed;
(2) bottled spring water (Evian, etc.);
(3) "deionised" and/or "demineralised" bottled water for car batteries/steam irons;
(4) any of the above having been passed through a domestic water filter (a "Brita filter")?

If none of the above would suffice, can anybody suggest an alternative more practical than buying a rainwater butt and waiting a considerable amount of time for heavy rain (bearing in mind that the South-East of England, where I live, receives less annual rainfall than the Sahara desert), or setting up a water distillery? Any replies would be much appreciated, and apologies if this topic has already been covered, but, as indicated above, all attempts by me to find it have ended in failure.

[houstonceng]

If you have a de-humidifier, use the water from that. Most of the gauge 1 fans in our club do that.

Next choice is rain-water. Our club in SE England gathers enough from the club and station roof to run all our 5" locos (always 5 on the track) at public running for 3 hours every other Sunday between April and October.

Wouldn't use Bottled water as it has minerals in it that can fur up yer boiler.

Brita type filters may only remove some impurities. I know that for my mains connected tri-tap system by Franke, you can get different filters to remove specifics like heavy metals.

Soft water from domestic softeners wasn't recommended for use in a dish-washer - so may not be the best thing for boilers either. Perhaps it disolves the metal the same as the soft water in some cities (eg Glasgow) did to the lead pipes.

De-inonised is OK but expensive. If you boil tap water for a reasonable time the temporary hardness (the salts that deposit as fur) will precipitate out and the remaining water should be ok. Don't know how long you'd have to boil it for.

What about asking The Viffer in a PM - he's usually good for anything to do with chemicals.

[baggo]

I'm sure I've read somewhere not to use deionised water in silver soldered boilers as the water removes the silver ions from the solder which may lead to eventual failure of the joints. Think it was in connection with the Hornby live steam locos.

John

[jamespetts]

If I was to boil tap water, should I boil the original hard water, or the softened water? And does anyone have a more definitive answer re: deionised water?

Thank you both very much for your replies, though :-)

[Shawki Shlemon]

I have been in the club I am in now for over 25 years , i have not seen anyone including myself using anything but the good !!! water that come out of the tab .just a remark .

[simonwass]

Water was discussed late last year-
modeleng.proboards20.com/index.cgi?action=display&board=general&thread=1188207376&page=1
Our boiler water (500MW steam turbine, 3500000kg/hr) is so pure that it scavenges ions from metal.
Its River Trent water which has gone through a huge reverse osmosis plant, which then feeds 3 streams of resin ion exchange towers. Its usually 0.3 micro seimens conductivity at the water treatment plant outlet to the boilers.
Rain water is quite good now the atmospheric sulphur load is reduced and soft tap water is usually fine for boilers. If your kettle stays clean use your tap water.
I did try dehumidified water in my Clayton but it primed horribly and when blown down was very gungy, I have no idea what went wrong there as it should be good water?

[jamespetts]

Thank you very much for finding that thread - I looked for that for ages before I posted this one! Very interesting, although I suspect that reverse osmosis would be going rather too far for one little boiler. Perhaps a combination of water passed through a "Brita" filter and adding a small amount of mild acid (vinegar) to the boiler now and again to defeat alkaline scaling would be the most practical solution? Or can anyone see any difficulties with that?

(As to the kettle, we use the hard water not passed through the domestic softener, but passed through a Brita filter. There is a buildup of scale, but less than I remember there being years ago before we used the Brita filter).

[chris vine]

Hi James,

It is simple, just use rain water. Even hard tap water will take a long time to fur up because you will probably not use it often enough. Rain water is ideal though.

Dehumidifier water. Simon, it is a good idea and one I had myself but apparently the water collected is not as pure as one might imagine and your experience bears this out. I once was talking to the manager of a large sports/gym complex. He told me that the water collected in the dehumidifier tanks was foul and full of fatty sweat.

I suppose the place smells of fatty sweat so it must be in the air. It is then blown over the coils and it must end up in the tank. I too would have thought it a good supply of distilled (condensed) water.....

C

[jamespetts]

I have put a large bucket for collecting rainwater on my shopping list. Should I just leave the bucket in the back garden and wait for it to rain?

However, if it doesn't rain (or doesn't rain much) between now and the time that I want to steam the engine, is Brita filtered water acceptable, or should I use the demineralised water for irons and/or car batteries (or is that too pure; and, if so, should that be mixed with other water)?

[jgb7573]

James, If you're going to run the boiler a lot (a couple of hours or more a day, every day) then it's worth looking at using treated water. If you're not going to use the boiler a lot, then tap water's fine, before or after Brita treatment, even in hard water areas like the Chilterns if you don't have access to rain water. You may have to descale the boiler more often, but it should still not be a big issue.

John

[Nexuas]

I use Rainwater in my model, but you can get RO water from most fish shops for about £4 for 25 litres, this is as pure as water can get so should give no scale build up at all? Our fish seam to like it...

[steam4ian]

G'day all,

I can claim to know a very little about water for steel boilers having been involved with cathodic protection.

The main thing is to keep the total dissolved solids low hence rain water or deionised water. But straight deionised water needs buffering, that is adding some ions which will not attach the metal. The usual addition is sodium hydroxide or washing soda (Sodium Carbonate). Be careful with choride ions because copper chloride is soluble, the ions will attach the copper and the solubility means the copper chloride can wash away. Sulphate ions will have the same effect but are less common. Water from the water softened will have chloride ions.

Summary, unless somebody knows something better use rain water (but not in highly polluted areas) or dionised water and add some washing soda th raise the pH.

Our 12"/1ft railway uses rain water for the boilers and still adds soda and tannin.

Regards
Ian

[ChrisCrosskey]

I'm about to list an Admiralty moisture meter on ebay, if you're having problems working out whetehr the water you've got is wet enough you ought to think about bidding on it..... ;D

Always wondered why the admiralty needed moisture meters...

"I say Number One, does that sea look properly wet to you?"
"Wouldn't want to say Skipper"
"Able Seaman Jones!"
"Sir!"
"Break out the Moisture meter and get a reading on that sea"
"Sir"
[splash]
"I'd say that's quite conclusive wouldn't you Number One?"
"Right you are Skipper"

chrisc

[alanstepney]

Going a bit smaller than the Stuart 504, I have a Mamod that has run, on and off, for around 60 years. In the early days it had lots of use!

Going up in size, I built a boiler for a Maisie some 40+ years ago.

Both are still in good condition, although I am now replacing the Maisie boiler as I dont like the workmanship or method of construction.
However, it did run and do a lot of hard work for 40 years, and hasnt failed a test.

Both of these boilers, plus many others have survived on a diet of tap water.
Having lived in different parts of the country, that has varied from hard to soft.

The one thing all of them have had is a good annual clean out.

[jamespetts]

Thank you very much for all your replies, contradictory though they sometimes are ;-) It seems that the most practical solution for someone who will not be running the boiler anywhere near every day (no more than twice a week, and probably usually far less than that, with months on end of not running it at all) is to go for the filtered tapwater (slower scale buildup, no ion problems), and clean the boiler whenever it needs cleaning with, presumably, weak acid such as dilute citric acid or dilute vinegar. Is that a fair summary?

[steam4ian]

G'day James

IMHO unless you tap water is particularly hard or overly chlorinated your proposed regime should be OK.

Watch out for chlorine (used to disinfect the water) it attacks copper. If your water filter includes a carbon filter then you will be OK.

Regards,
Ian

[jamespetts]

Hmm - how would I find out whether the filter includes a carbon filter? Will letting the water stand for a while suffice? When chlorinated water is left to stand in the open, the chlorine evaporates slowly.

[steam4ian]

G'day James

Boiling the water will drive off the free chlorine. It will also cause some of the hardness to settle out as the bicarbonates break down. I am not sure how much boiling for calcium carbonate but I know that sodium bicarbonate breaks down at boiling temperature, it even make cake dough rise. So there is no need for prolonged boiling, in fact too long increases the salt concentrations. Bring to boil and let stand.

Regards,
Ian

[mmaidnz]

I'm sure I've seen an additive advertised,to be used in steel boilers.Would this not serve your purp[ose?

[jamespetts]

mmaidnz said:

I'm sure I've seen an additive advertised,to be used in steel boilers.Would this not serve your purp[ose?

Would it? My boiler is copper.

As to boiling, the original instruction manual suggested "boiled" water - perhaps it did mean water that's just been brought to the boil in the kettle and let to cool again rather than home distilled water after all. I'll try that. Thank you all for your help :-)