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Posted by Frank Stearns on March 3, 2008, 2:55 pm
I've got some wild temp swings between an office, machine
room, and production room (and the bathroom is almost
always too cold 9 months out of 12). This part of the
building has its own separate 1.5 ton heatpump for these
areas, but it's on one thermostat in the office.
Active zoning should take care of those temp issues, and
the air-handler/heat exchanger is down below in a nice,
easy-access crawl space. All the ducting is simple to get
to as well.
The folks who do the retrofit bladder system for zoning
want a MINIMUM of $7K. It appears I can get a computer good
for four zones, four stats, and the various dampers for
probably around $700-800.
Seems simple enough, but I always approach such things with
caution.
Has anyone done this? Any overlooked "gotchas"? Any
suppliers/brands better than others?
Given that the tiny machine room will probably call for
cooling when nobody else does, there might be too much back
pressure on the fan, as the duct in that room probably
represents less than 5% of total system airflow capacity.
(I might put in a larger duct and vent.)
I still might also need a bypass damper. Are those
"passive" (too much pressure opens a spring- or weight-
loaded damper); or are there active ones controlled by the
computer?
I thought perhaps a variable speed blower might be the way
to go, but that means a new fan, and still a likely chance
for a coil freeze or overheat, unless the computer has the
added smarts to run the blower longer and the compressor
less.
It'd be nice if the system was smart enough to use
(recirculate) the waste heat from the machine room first,
before calling for heat from the heatpump.
A central computer where I could add functions or modify
standard heating/cooling "events" would good. For example,
I'd like to start the blower for a while first to
redistribute the air before switching on a compressor, or
perhaps periodically run the blower for all zones just to
recirculate the air. (I do that now manually. This alone
helps quite a bit.)
And, a central computer with a heatpump "anti-slump"
timeout would be good too.
If anyone's done their own zoning on a forced-air system,
I'd be interested in hearing your experiences, suggestions,
and recommended DIY-friendly HVAC suppliers.
Thanks in advance,
Frank
--
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Posted by Bubba on March 3, 2008, 4:39 pm
On Mon, 03 Mar 2008 19:55:16 -0000, Frank Stearns
>I've got some wild temp swings between an office, machine
>room, and production room (and the bathroom is almost
>always too cold 9 months out of 12). This part of the
>building has its own separate 1.5 ton heatpump for these
>areas, but it's on one thermostat in the office.
>
>Active zoning should take care of those temp issues, and
>the air-handler/heat exchanger is down below in a nice,
>easy-access crawl space. All the ducting is simple to get
>to as well.
>
>The folks who do the retrofit bladder system for zoning
>want a MINIMUM of $7K. It appears I can get a computer good
>for four zones, four stats, and the various dampers for
>probably around $700-800.
>
>Seems simple enough, but I always approach such things with
>caution.
>
>Has anyone done this? Any overlooked "gotchas"? Any
>suppliers/brands better than others?
>
>Given that the tiny machine room will probably call for
>cooling when nobody else does, there might be too much back
>pressure on the fan, as the duct in that room probably
>represents less than 5% of total system airflow capacity.
>(I might put in a larger duct and vent.)
>
>I still might also need a bypass damper. Are those
>"passive" (too much pressure opens a spring- or weight-
>loaded damper); or are there active ones controlled by the
>computer?
>
>I thought perhaps a variable speed blower might be the way
>to go, but that means a new fan, and still a likely chance
>for a coil freeze or overheat, unless the computer has the
>added smarts to run the blower longer and the compressor
>less.
>
>It'd be nice if the system was smart enough to use
>(recirculate) the waste heat from the machine room first,
>before calling for heat from the heatpump.
>
>A central computer where I could add functions or modify
>standard heating/cooling "events" would good. For example,
>I'd like to start the blower for a while first to
>redistribute the air before switching on a compressor, or
>perhaps periodically run the blower for all zones just to
>recirculate the air. (I do that now manually. This alone
>helps quite a bit.)
>
>And, a central computer with a heatpump "anti-slump"
>timeout would be good too.
>
>If anyone's done their own zoning on a forced-air system,
>I'd be interested in hearing your experiences, suggestions,
>and recommended DIY-friendly HVAC suppliers.
>
>Thanks in advance,
>
>Frank
Not to get all over you but it works this way:
If it sounds to good to be true ($700-$800).....
it probably is ($7k)
After you replace a few compressors, fan motors and blower wheels,
along with a multitude of other problems with the system never working
right, refrigerant leaks and ridiculous energy bills, you might begin
to understand that "Zoning" aint for the average joe.
Good luck,
Bubba
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Posted by Frank Stearns on March 3, 2008, 5:19 pm
self-snips
>>If anyone's done their own zoning on a forced-air system,
>>I'd be interested in hearing your experiences, suggestions,
>>and recommended DIY-friendly HVAC suppliers.
>>
>>Thanks in advance,
>>
>>Frank
>Not to get all over you but it works this way:
>If it sounds to good to be true ($700-$800).....
>it probably is ($7k)
Maybe you missed a few items...
- That's PARTS ONLY that I obtain (CPU, stats, dampers), I do the 2-3 days labor
and
dialing in... (And oh yes, I know the building well -- I designed it, had it
built,
but did all the electrical and was on site everyday. Short-sighted at the time,
I
declined a 6 zone system and settled for two, one of which handles the rooms in
questions. Live and learn.<g>)
- I don't have a massive regional radio ad and marketing campaign to pay for in
that
parts budget, nor is there a home office and staff to fund. I don't at all
begrudge
their asking $7K, it's just that I'm willing to investigate this further on my
own,
given that I have some appitude for this stuff.
>After you replace a few compressors, fan motors and blower wheels,
>along with a multitude of other problems with the system never working
>right, refrigerant leaks and ridiculous energy bills, you might begin
>to understand that "Zoning" aint for the average joe.
Well, not exactlty an average joe... extensive background with several kinds of
engineering, and a lot of practical DIY experience across many areas (including
being a multi-unit landlord for many years) -- enough overall experience to know
that each trade has its interesting twists and that it's good to get as many
data
points as possible.
So why a compressor failure? Blower & fan failures? Would that be due to no anti
slump? Coil freeze? Too much back pressure?
I hope I addressed those concerns by getting a smart enough CPU that will either
"baby" the compressor or could have "events" added to its program so that the
system
would be treated gently.
Not sure why the energy bill would be higher... Can you give me more background
on
that one?
Thanks for your reply, and any added advice you might have.
Frank
--
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Posted by Bubba on March 3, 2008, 5:38 pm
On Mon, 03 Mar 2008 22:19:43 -0000, Frank Stearns
>
>self-snips
>
>>>If anyone's done their own zoning on a forced-air system,
>>>I'd be interested in hearing your experiences, suggestions,
>>>and recommended DIY-friendly HVAC suppliers.
>>>
>>>Thanks in advance,
>>>
>>>Frank
>
>>Not to get all over you but it works this way:
>>If it sounds to good to be true ($700-$800).....
>>it probably is ($7k)
>
>Maybe you missed a few items...
>
>- That's PARTS ONLY that I obtain (CPU, stats, dampers), I do the 2-3 days
labor and
>dialing in... (And oh yes, I know the building well -- I designed it, had it
built,
>but did all the electrical and was on site everyday. Short-sighted at the time,
I
>declined a 6 zone system and settled for two, one of which handles the rooms in
>questions. Live and learn.<g>)
>
>- I don't have a massive regional radio ad and marketing campaign to pay for in
that
>parts budget, nor is there a home office and staff to fund. I don't at all
begrudge
>their asking $7K, it's just that I'm willing to investigate this further on my
own,
>given that I have some appitude for this stuff.
>
>
>>After you replace a few compressors, fan motors and blower wheels,
>>along with a multitude of other problems with the system never working
>>right, refrigerant leaks and ridiculous energy bills, you might begin
>>to understand that "Zoning" aint for the average joe.
>
>Well, not exactlty an average joe... extensive background with several kinds of
>engineering, and a lot of practical DIY experience across many areas (including
>being a multi-unit landlord for many years) -- enough overall experience to
know
>that each trade has its interesting twists and that it's good to get as many
data
>points as possible.
>
>So why a compressor failure? Blower & fan failures? Would that be due to no
anti
>slump? Coil freeze? Too much back pressure?
>
>I hope I addressed those concerns by getting a smart enough CPU that will
either
>"baby" the compressor or could have "events" added to its program so that the
system
>would be treated gently.
>
>Not sure why the energy bill would be higher... Can you give me more background
on
>that one?
>
>Thanks for your reply, and any added advice you might have.
>
>Frank
Nope, actually I didnt miss any items.
There is no "dialing in" on the system. It has many settings. They get
set properly. No guessing. It doesnt matter how well you know the
building or that you "built it" etc. That has nothing to do with
installing a zoned system properly. Your EE'ing counts for nothing
either....sorry.
The fact that you have no idea why an improperly installed zone system
will fail a compressor, blower or blower wheel tells me you need to
leave it to someone that does.
Improper static pressure in ductwork can make a blower wheel look like
someone has bashed it with a sledghammer. Ive seen it many times.
Improper air flow through a coil will also destroy a compressor. Ive
seen that many times over too.
There is NO cpu that will "baby" your compressor. Try telling your cpu
manufacturer that you want a free new compressor because their cpu
didnt take care of your compressor. There also are not "events" you
can put in to "treat your system gently".
Its called Proper Technique, Proper Installation and a whole lot of
knowledge. Ive seen companies that do this regularly that can screw
them up. Ive seen companies that only do a few of them that screw them
up even worse.
If you have the "money to burn" then have a stab at it and watch the
sparks fly.
Have Fun,
Bubba
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Posted by Frank Stearns on March 4, 2008, 3:55 am
>On Mon, 03 Mar 2008 22:19:43 -0000, Frank Stearns
>>
>>self-snips
>>
more snips
>>Maybe you missed a few items...
>>
>>- That's PARTS ONLY that I obtain (CPU, stats, dampers), I do the 2-3 days
labor and
>>dialing in... (And oh yes, I know the building well -- I designed it, had it
built,
>>but did all the electrical and was on site everyday. Short-sighted at the
time, I
>>declined a 6 zone system and settled for two, one of which handles the rooms
in
>>questions. Live and learn.<g>)
>>
>>- I don't have a massive regional radio ad and marketing campaign to pay for
in that
>>parts budget, nor is there a home office and staff to fund. I don't at all
begrudge
>>their asking $7K, it's just that I'm willing to investigate this further on my
own,
>>given that I have some appitude for this stuff.
>>
>>
>>>After you replace a few compressors, fan motors and blower wheels,
>>>along with a multitude of other problems with the system never working
>>>right, refrigerant leaks and ridiculous energy bills, you might begin
>>>to understand that "Zoning" aint for the average joe.
>>
>>Well, not exactlty an average joe... extensive background with several kinds
of
>>engineering, and a lot of practical DIY experience across many areas
(including
>>being a multi-unit landlord for many years) -- enough overall experience to
know
>>that each trade has its interesting twists and that it's good to get as many
data
>>points as possible.
>>
>>So why a compressor failure? Blower & fan failures? Would that be due to no
anti
>>slump? Coil freeze? Too much back pressure?
>>
>>I hope I addressed those concerns by getting a smart enough CPU that will
either
>>"baby" the compressor or could have "events" added to its program so that the
system
>>would be treated gently.
>>
>>Not sure why the energy bill would be higher... Can you give me more
background on
>>that one?
>>
>>Thanks for your reply, and any added advice you might have.
>>
>>Frank
>Nope, actually I didnt miss any items.
>There is no "dialing in" on the system. It has many settings. They get
Sure there is. In the various kinds of engineering I do, we routinely test;
generally at very conservative settings until we know something is going to
work.
And I do appreciate the dangers of modifying a system to do a job is was not
designed to do.
What I'd probably do, especially if I'm adding programming to the CPU (or
perhaps
getting my own 6x6 industrial controller and programming the whole thing
myself), is
run the zoning controls (dampers, stats, CPU) NOT CONNECTED to the ductwork, but
out
in the shop. Emulate conditions; see how the added programming is working. Next
move
the stats into the spaces, dampers still not connected, and see if everything
still
looks good.
>set properly. No guessing. It doesnt matter how well you know the
Seems that many of the systems done by "professionals" relies on a lot of
guessing
-- I've observed much HVAC nonsense, both in residential and commercial
settings:
noise (wrong duct and/or blower size or bad layout or wrong diffusers), hot/cold
spots, short or long cycles because the thing wasn't sized correctly. and so on.
>building or that you "built it" etc. That has nothing to do with
Maybe, maybe not; I do have the advantage of having been in this space for 15
years.
I know its thermal (and other) quirks; I know that at one time the coil froze
way
too often (didn't blow the comp, though, knock on wood; but it did trip the
overpressure limit a few times). I mitigated that -- all on my own. Two HVAC
pros
couldn't figure out what was going on (only that I should replace nearly new
hardware for no good reason... well, $$$ for them).
I finally figured out the problems by looking (the pros wouldn't even go down in
the
crawl space and look!). Freezing is now a far more rare occurrence.
>installing a zoned system properly. Your EE'ing counts for nothing
>either....sorry.
Only that I'm generally conversant in new areas and understand much of the
common
design logic. But you don't know me, so that's a fair statement -- and I know
what
you mean. I've rolled my eyes at amateurs in my fields as well.
>The fact that you have no idea why an improperly installed zone system
>will fail a compressor, blower or blower wheel tells me you need to
>leave it to someone that does.
Gee, I thought I covered that: back pressure, insuffient air flow over the coil
such
that it freezes (or return air that's "overly conditioned" due to poor return
locations), etc, etc.
If you'd like, provide a high-level overview of the more esoteric aspects that I
missed.
>Improper static pressure in ductwork can make a blower wheel look like
>someone has bashed it with a sledghammer. Ive seen it many times.
>Improper air flow through a coil will also destroy a compressor. Ive
>seen that many times over too.
Certainly makes sense.
>There is NO cpu that will "baby" your compressor. Try telling your cpu
>manufacturer that you want a free new compressor because their cpu
Agreed. Not their responsibility.
>didnt take care of your compressor. There also are not "events" you
>can put in to "treat your system gently".
Specifically, I was considering a longer fan runtime after the set temps had
been
reached, and also a longer antislump interval, given that such a system will
tend
to short-cycle because through zoning we're changing the entire design load "on
the
fly". And that's hard on everything. I was also considering a longer
minimum run interval, and dumping the "extra" conditioning into the other spaces.
I do know, for example, that the production room will tend to heat nearly as
much as
the machine room. So "extra" time on the machine room could go into the
production
room.
Also, programmatically, it'd seem that increasing the fuzziness of some of the
zones
would be useful. A +/- 5 or even 10 degrees in the machine room would be fine.
Doesn't need to be +/- 1 degree. Production room could be +/- 3; the office
would
nice a little tigher, but it doesn't matter all that much either, if it's better
for the system.
Programmatically, I'd also be looking at a logical weighting of using the blower
before calling for conditioning. (In fact, programming the blower on/off in an
of
itself might get me 80% of what I'm looking for -- I do that manually now, but
it's
a pain to remember to do it right.)
I've noticed in a lot of "modern" HVAC design thinking wants to hold things very
tight, perhaps too tight, unless the system is sized *exactly right* and takes
into
account thermal loads from windows and other sources. Hell, around here, those
calcs are routinely blown out of the water given the number of southern windows
coupled with the wide variance of sun and cloudy days.
>Its called Proper Technique, Proper Installation and a whole lot of
>knowledge. Ive seen companies that do this regularly that can screw
>them up. Ive seen companies that only do a few of them that screw them
>up even worse.
Could not agree more. I've seen the same. The difference is that because I own
the
joint I realllly want to be careful with this.
Even if I were willing to spend the $7K, I'm not entirely sure I'd find pros
that
would care as much as I do, and would be willing to follow through as carefully.
>If you have the "money to burn" then have a stab at it and watch the
>sparks fly.
>Have Fun,
Let me guess... you're an HVAC guy and hate it when consumers do their own
stuff.
That's fine. Do what I do in my fields and (a) offer to eval for a consult fee
(but
you'll need to provide your credentials and a reference list); (b) smile and
clean
up their mess afterwards -- on an open-ended cost-plus basis.
In the meantime, as long as your responding to the posts, perhaps you could take
a
stab at the original questions, if so inclined?
Thanks in advance,
Frank
--
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