Questions about boiler water

Zman

A client of mine had a large cast iron boiler fail prematurely (22 years) so we tested the water before installing a new boiler. I am having trouble getting my head around the results. The hardness number does not make any sense to me (it seems way low and is likely expressing grains rather than ppm) given that the system in general has not been very well maintained. I spoke with Rhomar and they confirmed the results and felt that the water was likely deionized.

I have attached the Rhomar report as well as the new boiler requirement and local water report.

The system is ~3,000 gallons so dumping and replacing is not preferable.

@hot_rod, @Derheatmeister, @kcopp @Jamie Hall

TIA,

Carl

hot_rod

How low? Lochinvar suggests hardness below 7 gpg.  How’s the ph?  Right out of a DI or RO the ph will be low, maybe into the 4-5 range

You can buffer it up, usually it will buffer itself to neutral within a week by pulling ions from the metals. 

Has it been taking in fill water regularly?

Jamie Hall

I honestly don't see much wrong with that water quality. The biggest problems usually are the two corrosives -- and those are excellent. I suspect, though, from the 0 chlorides and low hardness that the initial fill, at least, must have been deionized or distilled water -- deionized more likely -- which is what I would use if it needed topping off.

leonz

Adding the cryotek non toxic antifreeze would help you a lot too.

JakeCK

leonz said:

Adding the cryotek non toxic antifreeze would help you a lot too.

Please explain how adding glycol to a system that I can only assume doesn't need freeze protection going to help him out with his water parameters?

Glycol is not cheap, requires more maintenance, has a lower heat capacity, and requires more pumping power. 

WMno57

It already is 25 percent glycol.

I do have a question for the water experts. Is the conductivity number shown in the report OK?

And question for Zman. Any more details on the type of failure, rust, dissimilar metals, unknown?

Zman

I am having trouble getting my head around the high conductivity and the very low hardness. Particularly given that the system has not been maintained very well. There is no chance that the fluid was deionized.

We will add glycol to bring the level 30%

I am thinking about retesting the fluid.

WMno57

"Total Hardness, ppm CaCO3"

Sounds like their Total Hardness number is just PPM of calcium. Does that mean they don't even attempt to measure magnesium? Given the hard rock mining history of your location, I'll bet there are all kinds of metals and minerals in the water which are contributing to the conductivity number.

Jamie Hall

The total conductivity isn't really that odd. There are two major anions present in the water (one's not a big deal -- total alkalinity. The other is there as part of the chemical treatment -- phosphate.) The total alkalinity may also reflect the water treatment, as it may be (likely is) part of a buffer system to control the pH (possibly, at a guess, a sodium carbonate/sodium bicarbonate type buffer). The total hardness is expressed as Calcium Carbonate, but the tests used usually also measure magnesium (and anything else in that column of the periodic table, such as Strontium or Beryllium or Barium -- or Radium -- but those are usually minor or very minor constituents). In water which does not have buffer or corrosion treatment -- like out of the tap -- it is much more common for the total hardness and the total alkalinity to be comparable, but as soon as any treatment is added this is no longer true. It is a little confusing for them to be both reported as Calcium Carbonate, but this is just a chemist's way of saying that if you wanted to achieve the same concentration of anions (the total alkalinity) or cations (the total hardness), this is the amount of Calcium (a cation) Carbonate (an anion) you'd have to use -- and has nothing to do in general with what ionic species are actually in the water.

Zman

WMno57 said:

It already is 25 percent glycol.

I do have a question for the water experts. Is the conductivity number shown in the report OK?

And question for Zman. Any more details on the type of failure, rust, dissimilar metals, unknown?

The original boiler was a WM Weil Mclain cast iron sectional boiler. It leaked and pitted between the sections and could not be resealed. The boiler room is welded steel pipe. The distribution piping is steel groove pipe and soldered copper.

Water quality may not have been responsible for the failure.

SeanBeans

It's that weird Colorado water man

Zman

SeanBeans said:

It's that weird Colorado water man

It can be very counterintuitive. The Molybdenum number is pretty low when you consider that one of the biggest Molybdenum mines in the country is directly upstream.

JakeCK

WMno57 said:

It already is 25 percent glycol. I do have a question for the water experts. Is the conductivity number shown in the report OK? And question for Zman. Any more details on the type of failure, rust, dissimilar metals, unknown?

That's what I get for assuming. I was unable to read the report. When I opened the pdf it was corrupted. I still don't think glycol is going to correct the water chemistry, that's not really it's purpose? Yes it has a corrosion inhibitor but that is because the glycol it's self is corrosive isn't it?