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Date: 19 Oct 2006 05:04:02
From: Robert Harmon
Subject: I'm confused about PID for HX
I'm seriously considering putting a PID on the Bunn ES-1A I'm restoring. As
I see it the TC placement would work best if it were centered in the boiler.
I was thinking of silver soldering a 1/4" thick flange on the boiler,
drilling a hole through it, solder a length of copper tubing sufficient to
place the tip dead center, and inserting the TC in this. It sounds like more
work than it is & none of it's close tolerance.

I understand the value of a PID for pulling shots, but what impact would it
have on steam production? I was hoping the use of a PID would do away with
the pstat altogether. Is that not possible or would I need to wire a second
PID & a switch for when I want steam? It's late & I'm getting confused.
--
Robert (duck & cover) Harmon
http://tinyurl.com/pou2y
http://tinyurl.com/psfob
http://tinyurl.com/fkd6r






 
Date: 19 Oct 2006 16:32:45
From: RoughJaw
Subject: Re: I'm confused about PID for HX
Wow.

RoughJaw 100,327

--
Posted via a free Usenet account from http://www.teranews.com



 
Date: 19 Oct 2006 04:53:45
From: daveb
Subject: Re: I'm confused about PID for HX
Very well put, ken and jim.

dave 129



  
Date: 20 Oct 2006 17:04:03
From: Espressopithecus (Java Man)
Subject: Re: I'm confused about PID for HX
In article <1161258825.449632.94330@f16g2000cwb.googlegroups.com >,
davebobblane@gmail.com says...
> Very well put, ken and jim.
>
Good for you, dave.

Rick


 
Date: 19 Oct 2006 01:11:17
From: Ken Fox
Subject: Re: I'm confused about PID for HX
jim schulman wrote:
>
> That being said, a PID controller doesn't do much for HX machines,
> unless like Ken's, the HX itself has a large charge of water and you
> drastically reduce the temperature (to around 110C) to convert it into
> a sort of "no flush required" single boiler. This will work if the
> Bunn has a large boiler (2.5 liters or more) and you only steam 4
> ounces at a time for cappas, since the hit you'll take on steam power
> doing this won't matter for such small milk amounts.

Jim,


I'm not sure I agree with your last paragraph, for a couple of reasons.
One is that although the HX in my Juniors is larger than the HX in
(say) your typical E-61, it still only holds 4-6 ounces in actual use.
Other machines may have HXs intermediate in size between mine and that
found in an E-61. I'm not even sure that the size of the HX is
determinative for shot temperature stability, being as a smaller HX is
going to respond more quickly to boiler temperature and it is, in fact,
the boiler temperature that is going to be controlled in most any HX
PID installation. Many series of shot temperature curves I have
generated show the shot temperature declining initially and recovering
mid shot, which I attribute to the effect of the element kicking on in
response to the PID controller.

At least one other person has posted generally similar results, using
another machine altogether. I forget the details or which venue the
posts were on, but they are out there.

In any event, I think the most useful benefit of the PID is not the
temperature control, which can be obtained in other ways such as Dan
Kehn's "water dance" and other variable flushing methods. What I like
the best about the PID is the ability to change boiler temperature at
whim; I actually use this at least once each day. When I'm going to
make a cappa, I bump the boiler temp up a couple of degrees F, which
still gives me a nice tasting shot but at the same time takes the
frothing capacity from "good" to "very good" or better. Also, if you
like to use a variety of blends or beans, this ability to easily change
boiler temps is nice.

Pstats, among their other problems, are such a PITA to adjust, and are
often located in inconvenient places internally, with the result being
that they are generally set and forgotten.

ken



 
Date: 19 Oct 2006 02:08:32
From: jim schulman
Subject: Re: I'm confused about PID for HX
On Thu, 19 Oct 2006 05:04:02 GMT, "Robert Harmon"
<r_h_harmon@Zhotmail.com > wrote:

>I understand the value of a PID for pulling shots, but what impact would it
>have on steam production? I was hoping the use of a PID would do away with
>the pstat altogether. Is that not possible or would I need to wire a second
>PID & a switch for when I want steam? It's late & I'm getting confused.

On an HX, the steam boiler remains at a constant temperature, roughly
120C to 125C, so a sngle PID is fine.

That being said, a PID controller doesn't do much for HX machines,
unless like Ken's, the HX itself has a large charge of water and you
drastically reduce the temperature (to around 110C) to convert it into
a sort of "no flush required" single boiler. This will work if the
Bunn has a large boiler (2.5 liters or more) and you only steam 4
ounces at a time for cappas, since the hit you'll take on steam power
doing this won't matter for such small milk amounts.


 
Date: 19 Oct 2006 00:20:13
From: Paul Sack
Subject: Re: I'm confused about PID for HX
"Robert Harmon" <r_h_harmon@Zhotmail.com > writes:

> I'm seriously considering putting a PID on the Bunn ES-1A I'm restoring. As
> I see it the TC placement would work best if it were centered in the boiler.
> I was thinking of silver soldering a 1/4" thick flange on the boiler,
> drilling a hole through it, solder a length of copper tubing sufficient to
> place the tip dead center, and inserting the TC in this. It sounds like more
> work than it is & none of it's close tolerance.

I got a cap for the p-stat boss, drilled it out, put a ferrule through
the cap, sealed it in with JB weld, and put a sheathed TC through that. (I
had intended to solder the ferrule, but I ordered the wrong kind.)
More expensive and less work than what you're proposing. I think the
parts came to around $50.

> I understand the value of a PID for pulling shots, but what impact would it
> have on steam production? I was hoping the use of a PID would do away with
> the pstat altogether. Is that not possible or would I need to wire a second
> PID & a switch for when I want steam? It's late & I'm getting confused.

It can do away with the p-stat, unless you want to leave it in as a
safety measure. I left mine out, since it'd mean several more
expensive BSPP fittings. The impact on steam is negligible. There will
be a very small delay for the element to turn on when you open the
steam valve, versus a far smaller delay with the p-stat. But we are
talking about maybe 20 ms. Of course that may depend on the PID device
you use.

Isn't the Bunn an HX machine? Why would you want a second PID or a
switch for steam?

Anyways, you should dig up Ken Fox's old posts on the subject of
PIDding an HX machine.