Put boiler flush water back in reservoir?

[coolguy121]

Hi all! First of all very glad to have this community of very knowledgeable group, looking forward to learning more each day and hopefully share some inputs on other questions.

Anyways, I tend to flush the steam boiler through hot water spout for the purpose of regulating boiler temp when pulling darker roasts. Also fanned out the E61 group to reduce the Eric's probe to read closer to 180F (will go to 186F once pump is turned on).

It yields a really good and not bitter espresso!

Getting a bit wasteful though.

I use exclusively RPavlis water with 50GH Alkalinity, so even with 2x concentration it'll be 100GH, which is well within acceptable range based on RPavlis.

Thinking if dumping the "Flush" water back in to reservoir to reduce waste. Does it seem logical to think that this does no harm to the boiler?

Thanks!

[Nate42]

What kind of espresso machine do you have? 186F is awfully low for a grouphead temp, not sure what the benefit of that would be.

Anyway, to your original question, I wouldn't reuse steam boiler water. It is likely not particularly fresh and will have an unknown mineral content.

[coolguy121 (original poster)]

Appreciate the feedback! You're right, perhaps it's not a great idea to reuse the boiler water.
Although I believe that with RPavlis water and 2-3x concentration without any regular boiler flushing, it means water is sitting at 100-150GH?
Unless some boiler material leech to the water?

It's an Appartamento, and it regularly reached 213F on the grouphead, which is scorching hot. But at the same time steaming power is amazing! Noticed that it's steaming 6 oz of milk in less than 9 sec from 35F to 140F, with great vortex!

I attempted 205, 200, 195, 190, 185, and only at 185F it stopped bringing bitter/sour flavor at the same time (harsh). Surprised that I can easily enjoy those "burnt" beans with 185F temp and 1:0.9 ristreto @ 35 sec.

Keep in mind I use "generic" La Colombe decaf bean @$25/2.5 lbs bag at bulk pricing (friend runs cafe), which is ultra dark. Trying to save for a machine upgrade

On lighter roast anaerobic ethiopian, I aim for 205F for pleasant fruitiness.

[Nate42]

If you like those lower temps I suppose that's fine. Unusually low temperatures can work well for very dark roasts I just don't use thise very often. Keep in mind Eric's thermometer shows the group temp when idle and the temp of water in hx when pump is on, and actual shot temp is somewhere in between. Most people allow the group to be hotter than their desired shot temp and flush the hx to lower hx temperature (flush and go method) rather than trying to lower boiler temperature. But what works for you works for you.

The reason I said mineral content is unknown is because every time you steam you are releasing distilled water and concentration of minerals in boiler increases. I suppose if you are flushing the boiler routinely that maybe isn't a problem.

[Randy G.]

I might be missing the point, but it sounds like you are wasting water and electricity to save time when steaming milk. How about lowering the steam boiler temp? Or use the water for the garden or house plants?

[coolguy121 (original poster)]

Unfortunately that is the case
Was about to lower boiler temp back but pressurestat screw is stripped. Would need a new pressurestat or find a "hack" to fix the screw.

So for now I decided to turn on the machine "on demand". That way it's not too hard to manage temp.
When the machine is on for just 10 min, grouphead temp is at roughly 160F. With puck prep and pouring milk, it usually sits at 175F, which when pulled and combined with boiler water will go to 185F.

I complicated my own life for now but hoping to get a new pressurestat to lower it back down.

[LittleCoffee]

It sounds like you have a HX machine - is that right? In that case I think you can safely ignore the "unknown mineral content" comment about what comes out of the steam tap. In an HX machine seeing normal usage the volume of water exiting through the steam wand is likely orders of magnitude smaller than the volume of water entering the system from the reservoir, and therefore the mineral content of the hot water tap water is almost certainly v. close to the mineral content of the reservoir.

I personally have a dual boiler I feed with store bought (soft) mineral water. The steam boiler in a dual boiler needs regular flushing in order to avoid mineral build-up, but because I'm using store bought water that also feels very wasteful. I have been feeding the flush water back in the reservoir with no problems to report. I do cool it down before pouring it back in to make sure it doesn't react with the plastic reservoir tank in some unpleasant way. I also make sure I wash the cup I use for this well - otherwise there's a risk of dishwasher residues. Finally, for the avoidance of doubt, I would not do this with flush water from the group head as that will have coffee stuff in it which you definitely don't want re-entering the system.

Out of curiosity I've been monitoring the TDS of what comes out of the hot water tap and the TDS of the reservoir water. This isn't that straightforward because cheap TDS meters don't adjust for temperature and the reading is highly temperature sensitive. But after some crude correction for that, I am able to keep my boiler mineral TDS within 20% of the reservoir TDS which for me is acceptable.

[BaristaBoy E61]

We have a DB machine. I always preheat cups with steam boiler water not only to preheat the cups but to flush the bottom of the steam boiler and to keep it from becoming stagnant and scale laden. The water from the preheated cups are poured into a Mason jar that is then used by my wife in her Braun filter coffee machine to prevent that from scaling up.
This way we make full use of the rather expensive filtered water rather than pouring it down the drain. Our plants would probably do better by watering them with the full mineral content of our city tap water.