Water Ph

erussell58

Do any of the great minds here on this forum have any idea what might be causing such a high Ph in my boiler water? The green Ph of 7ish is my boiler feed water. The blue Ph of 13-14ish is water collected from my boiler at blowdown. Any ideas why there is such a broad range? 

ethicalpaul

did anyone add any boiler treatment in the past?

erussell58

Ethicalpaul. Not to my knowledge. I have been here now for two years. We just replaced an old Peerless with a new WM 688. It has been in operation now for approximately 6 months.

ethicalpaul

So is the boiler more than two years old, or is it the new WM688 that you just replaced?? It doesn't really matter but I'm confused If someone just installed it, it is very common for an installer to put some kind of high-ph treatment in there.

Anyway are you worried about the PH? I wouldn't really be. That higher PH is going to reduce corrosion in your boiler.

If you'd like it to be a bit lower or if you suspect you're experiencing surging just drain the water and refill it and manage the ph with something like Rectorseal 8-way (but put it in a little at a time until the ph is what you want). Aim for 11 or so.

Canucker

What was the temperature of the solution at both readings @erussell58 ? Keep in mind that those are referred to as "guess" strips by anyone that has to accurately measure pH of solutions. It's probably good enough for measuring boiler water but it should have a temperature correction listed somewhere. If your feed water is relatively free of any buffers, it wouldn't take much of anything to get the pH swinging in any direction

Hap_Hazzard

Concentrated sodium hydroxide (aka lye) has a pH of 13.0–13.6. If your boiler water doesn't burn your skin, the pH indicated by the test strip can't be correct. If you can safely touch it, does it feel slippery, like chlorine bleach? If not, it's less basic than bleach (pH 12.5). Either the test strips don't work correctly with high pH solutions or they are reacting with iron or other solutes to give a false indication. Try measuring the pH of household ammonia to see if the strips are accurate. It should be somewhere between 10 and 11.

You might have better luck measuring the pH of the boiler water with a liquid indicator, but metal ions might have a similar effect, or you could pick up an electronic pH meter. They give good results from 2.5–10.5 pH. If the pH is really higher than 10.5, you can dilute the sample and extrapolate the result.