Minimum use for rotary pumps

[sheygetz]

Hi all,

several times now I've come across the statement that rotary pumps need a certain "turnover" to continue to work properly, else they'd get "stuck". Advice has included not going on a holiday for more than a week in a row , running at least 1L of water thru the group every day plus assorted vodoo stuff.

Hoping to tap into any real life experience among HBF members: What is the technical lowdown for this phenomenon (if it is a phenomenon)? Would this be a serious detriment to having a rotary in a 6-8 drinks/ day environment? Any easy work-arounds, including one to allow for 3week holidays (dump and leave the pump head in distilled water, maybe)?

sheygetz

[HB]

No real life experience, but I've heard the same comments, i.e., rotary pumps will wear out more quickly if used infrequently. I perused the Procon website and found the usual manufacturer platitudes ("PROCON vane pumps do not have to be lubricated and are virtually maintenance free throughout their entire life."), which doesn't jive with claims that they demand special attention. Based on this exploded view, it looks to be a pretty simple beast, should repairs be necessary.

[bobroseman]

I would guess that water hardness and perhaps PH might have a causal effect concerning pump failures.

Here in Atlanta, I have been running a rotary for a year now at low usage rates of 2 to 5 doubles a day with frequent 2 week dead periods while traveling, with no apparent pump problems. Atlanta water has very little mineral content.

Bob.

[AndyS]

several times now I've come across the statement that rotary pumps need a certain "turnover" to continue to work properly, else they'd get "stuck". Advice has included not going on a holiday for more than a week in a row , running at least 1L of water thru the group every day plus assorted vodoo stuff.

Hoping to tap into any real life experience among HBF members: What is the technical lowdown for this phenomenon (if it is a phenomenon)? Would this be a serious detriment to having a rotary in a 6-8 drinks/ day environment?

Remember, vibe pumps fail, too, and probably at a much higher rate than do rotaries.

If you want to make the jump to rotary pump, I would not let these kind of stories hold you back. My home rotary has been happily sucking out of a bottle, a few shots a day, with occasional vacations, for 4 years.

[JonR10]

My home rotary has been happily sucking out of a bottle, a few shots a day, with occasional vacations, for 4 years.

This is very comforting, especially considering my plans to make the switch to a bottle-fed rotary pump in the very near future...

[AndyS]

This is very comforting, especially considering my plans to make the switch to a bottle-fed rotary pump in the very near future...

Yes, there's something comforting about sucking out of a bottle. Reminds me of...mom.

[sheygetz]

If you want to make the jump to rotary pump, I would not let these kind of stories hold you back.

This is very comforting, especially considering my plans to make the switch to a bottle-fed rotary pump in the very near future...

@Andy, Jon,
would you care to enlighten me on the benefits that you saw in/ expect from a rotary in a non-plumbed, bottle-feed environment, please.

The advantage of not having your reservoir heated by the boiler comes courtesy of the external tank, even w/ a vibe. The higher noise level of the vibe could be dampened by rubber mountings or similar to uncouple (term?) it from the casing or having it external (afaik Dan did that). (Anyway, from all I read there seem to be noisy and less noisy vibe as well as rotary pumps.) Add to that a current thread Flojet and rotary pump questions that seems to suggest - albeit no hard facts as yet - that a rotary's pressure will vary with line pressure. Plus, while

vibe pumps fail, too, and probably at a much higher rate than do rotaries.

they do come a lot cheaper, too.

one puzzled sheygetz

[AndyS]

@Andy, Jon,
would you care to enlighten me on the benefits that you saw in/ expect from a rotary in a non-plumbed, bottle-feed environment, please.

The advantage of not having your reservoir heated by the boiler comes courtesy of the external tank, even w/ a vibe. The higher noise level of the vibe could be dampened by rubber mountings or similar to uncouple (term?) it from the casing or having it external (afaik Dan did that). (Anyway, from all I read there seem to be noisy and less noisy vibe as well as rotary pumps.) Add to that a current thread http://www.home-barista.com/forums/flojet-and-rotary-pump-questions-t322.html that seems to suggest - albeit no hard facts as yet - that a rota's pressure will vary with line pressure. Plus, while

vibe pumps fail, too, and probably at a much higher rate than do rotaries.

they do come a lot cheaper, too.

one puzzled sheygetz

When I switched my machine from (unregulated) vibe pump to rotary, I felt I saw a significant improvement in shot "smoothness." This was before Greg Scace and others popularized pressure regulation for vibe pumps. So it may be (or it may not be) that vibes can pull just as good a shot as rotaries when they're regulated properly.

One reason why I'd be loath to return to a vibe pump machine is an aesthetic one. When you've used a rotary for a while, it's tough to go back to the loud buzzy vibe pump. Sure you could do it, but why?

[JonR10]

@Andy, Jon,
would you care to enlighten me on the benefits that you saw in/ expect from a rotary in a non-plumbed, bottle-feed environment, please.

Here are my own reasons for wanting to change:

* Chris Tracy seems convinced that the rotary pump has an advantage in terms of the shot quality by virtue of its operating characteristic. I'm guessing that's due to smoother delivery (presumably).

* I have plenty of experience with vibe pumps, and I'm ready to try a rotary pump setup for myself.

* I like the idea of not having to fill the reservoir and empty the drip tray every day (sometimes 2 or 3 times in a day).

* I like that it will be quiet.

* I can

[another_jim]

When I switched my machine from (unregulated) vibe pump to rotary, I felt I saw a significant improvement in shot "smoothness." This was before Greg Scace and others popularized pressure regulation for vibe pumps. So it may be (or it may not be) that vibes can pull just as good a shot as rotaries when they're regulated properly.

Now I think it remains an open question. Here's my data:

* after regulating the vibe on Ken Fox's vibe Junior, neither he nor I could tell the difference between it and his rotary junior. We used the same espresso blend for all the comparisons.

* On my regulated vibe Tea, the shots sometimes do not equal the taste from my little spring lever la Peppina; sometimes they do. It seems to depend on the blend used.

* I exploited the opportunity to test some blend versions at Intelligentsia to take my Peppina there and try it out against their test machines. The taste clarity handily beat the stock Silvia they had there (properly used, I hope, by me, in terms of pressure and temp). It also beat that of a rotary 2 group La Spaziale, which produced shots virtually identical to the Silvia. The LM produced shots with the same taste clarity as the Peppina, but with much more body and crema. We ended up using it and the Peppina to test blend variations, since differences showed up most clearly on those machines.

These facts leave me baffled. They indicate that pump vibration does make a difference (Tea versus Peppina), but that it also interacts with the blend being used and other design factors of the machine (La Spaziale versus LM, and the two Juniors). What those design factors could be, I don't know.

[Abe Carmeli]

Jim,

How did you regulate your vibe pump?

[HB]

Jim apparently missed your question; he used a Variac and documented his results in More pressure games and Pressure Games - Final Post (?). The topic comes up regularly, for example in Pressure profiling.