Re: Water issues
Posted by:
Mike Clark (IP Logged)
Date: October 27, 2003 08:37PM
<HTML>The July Issue of “The Steam Car” had an article by Monty Goding, a professional in the design and operation of industrial boilers, which covered this issue of water quality.
Monty feels that the accumulation of dissolved solids in boiler water is as serious a problem as hard water scaling. Dissolved solids are salts which, when concentrated by distillation in the boiler, make the water surface unstable so that frothing and priming occurs and sight gauge readings become unreliable. Driving a non condensing car for a day’s tour of, say 120 miles, without blowing down could easily cause a ten or twelve fold concentration of dissolved solids, bringing them up to danger levels. In modern static boilers it is usual to have a continuous blowndown of up to 25% of the water going through the boiler simply to get rid of these dissolved solids; obviously this is acceptable on a static system with efficient heat exchangers but hardly practical for us. It would seem to be a good idea to blow down almost to empty at the end of the day but inconvenient to do any worthwhile amount of blowing down during the run. We should be aware of the increasing chance of misleadingly high sight gauge readings as the day goes on. It is actually possible to taste these salts in the blowdown water after a day’s run and have you noticed how much the sight gauge level drops as soon as you park and shut down the burner?
Monty also commented that it is better to use stream and pond water since this is not too far from rain, and much less likely to contain salts and scale forming compounds than mains water which is often taken from deep boreholes having spent thousands of years absorbing minerals from the rocks. If you are concerned about picking up grit with the siphon a small carburettor air filter (mine is from K&N) can easily be adapted to the suction hose. Monty also made the very useful suggestion that a water softener unit from a scrap dishwasher could be used to treat water being put into the tank and then regenerated with salt at home. It will take the full rate of flow from hose or by siphon.
Finally we have discussed previously the best way of storing the boiler over winter, full, empty, dry or whatever. I put some central heating corrosion inhibitor into the boiler which was then filled to overflowing. I did the same last year and in Spring it drained out absolutely clear with no rust in the water. Auto antifreeze would no doubt do the job but my workshop never freezes.</HTML>