Fun with a Water TDS Meter and Brewtus

[iiifrank]

Hi there. I've recently posted about problems with my Expobar Brewtus in another thread. In a nutshell, since initial ownership was taken, the machine was dispensing foul-tasting water with black flecks in it. WLL graciously received the machine and replaced the mysteriously blackened boilers (among other things) and my problem seems to have improved. The water is not as foul and there are fewer flecks.

However, being a curious niggling anal sort of person, I want to know why the problem happened in the first place. In addition, I wonder why the water still doesn't taste as good as water from my electronic tea kettle. Having read the Water FAQ and every CG water thread I could find in preparation for receiving the machine last year (I've owned the Brewtus for almost 13 months now) I've always used a blend of Crystal Geyser Alpine Spring Water and distilled water. Thinking that it might not be as pure as I hoped, I recently ordered a HANNA TDS1 Digital TDS Meter, as mentioned by HB in a water thread on this site. I took before and after samples of water in the reservoir and after it had been pulled from the side hot water dispenser (and cooled down). Here are the results:

Initial Water Mixture: 31 ppm
Post Brewtus: 115 ppm

Huh?! Can anyone explain this? Not understanding water or the process of heating water very well, I decided to take a similar test using the electronic tea kettle to see if this increase was the norm:

Initial Water Mixture: 40 ppm
Post Tea Kettle: 45 ppm

That's what I would have expected...almost no change. There was a small remainder of Ice Mountain Spring Water (~160 ppm) in the bottom of the kettle before I added my 40 ppm mixture which might have increased the final number.

Any thoughts on what I'm seeing here? Why is water coming out of Brewtus harder than it entered? And should I not expect to have very clean tasting water from the dispenser? As always, I hope this doesn't affect espresso. So far, I'm very pleased with the results in the cup, but fear the boilers are going to somehow end up in the same blackened state as before.

Thanks!!

[cannonfodder]

Did you let your post Brewtus sample cool? The meter shows its accuracy rating at 68F not the 200+F you get on the outbound side of the machine.


Accuracy (@20°C/68°F): ±2 % F.S.

[Dogshot]

The hot water tap connects to the steam boiler. I expect that the steam boiler would show a higher mineral content if it has been used at all to steam. The steam will leave the minerals behind, which will gradually increase the hardness of the steam boiler water. This is why many people drain the steam boiler (using the tap bleed from a hot but powered-down machine) every few weeks.

Have you tried doing the same trick from the brew boiler? The problem there will be that any coffee-related impurities in the brew path will throw your measures off.

I suspect that tds readings from the output of either side of the machine will not be very informative. How does the water taste? I found that the biggest factor that contributed to differences in taste between cooled brew water and tap water was the reservoir. I rinse and replace my reservoir water daily, and that takes care of any taste issues in my BII. Just topping it up is not a good idea.

Mark

[iiifrank]

Added info...I let each heated sample (from Brewtus and kettle) cool for 2 hours. Thanks again.

[iiifrank]

The hot water tap connects to the steam boiler. I expect that the steam boiler would show a higher mineral content if it has been used at all to steam. The steam will leave the minerals behind, which will gradually increase the hardness of the steam boiler water. This is why many people drain the steam boiler (using the tap bleed from a hot but powered-down machine) every few weeks.

Interesting. I steam every day so that makes sense. I do drain the tap a cup or so every week, but while powered on. I will add the powered-down tap bleed to my routine.

Have you tried doing the same trick from the brew boiler? The problem there will be that any coffee-related impurities in the brew path will throw your measures off.

That's exactly why I haven't...I figured all the coffee would throw it out of whack. I'll try tonight for grins.

I suspect that tds readings from the output of either side of the machine will not be very informative. How does the water taste? I found that the biggest factor that contributed to differences in taste between cooled brew water and tap water was the reservoir. I rinse and replace my reservoir water daily, and that takes care of any taste issues in my BII. Just topping it up is not a good idea.

Well, from both the tap and the grouphead the water doesn't taste as good as the water straight from the tea kettle. This was the case even after receiving the repaired machine back from WLL with both boilers replaced. It's not horrible like it was when I first got the machine new, but it's certainly not good enough to where I'd prefer to drink it straight up or in, for example, tea.

THANKS!

[cannonfodder]

You could try running some backflush detergent through the system to thoroughly clean it. I ran some JoeGlo through my Faema when I got some milk contamination in the boiler. Fill it up, let it soak for a couple of hours, then flush it out. When you think it is completely flushed, flush it a little more.

If the dispensed water does not taste good, than the espresso it produces will not be good.