Re: zoned or not zoned?? thermostatic control of multiple spaces

["Lighthouse" <gruntledlark@xxxxxxxxx>]

Marc, i honestly am not sure now. many homes and buildings in this area
were originally heated w/ steam. in this building, i noted that the
living spaces all have the newer baseboard type radiators that i think
are called "slant-fin". i honestly don't know if they are making use of
hotwater or steam. one unit in the building has an old fashioned iron
radiator--the kind i associate w/ steam. it is small and only heats an
office space. when i was in the units they seemed to be warm and
comfortable and i didn't hear any water hammer when the inspector i
hired turned the thermostat up to observe the operation. at the time i
didn't think to ask many questions about the system other than to be
sure it worked adequately.

Marc_F_Hult wrote:
> Lighthouse,
>
> You need to find out what you are buying. Single-pipe steam systems (steams
> moves out a single pipe, condenses to water in the radiator, and flows back to
> the boiler via the same pipe) are a whole lot different that hot water
> systems. Do the radiators have a vent that allows air to escape when the heat
> goes on? If so, is most likely steam (and I commiserate).
>
>
> ...Marc
> Marc_F_Hult
> www.ECOntrol.org
>
> On 8 Dec 2006 07:28:15 -0800, "Lighthouse" <gruntledlark@xxxxxxxxx> wrote in
> message  <1165591695.608049.295350@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>:
>
> >i should clarify my situation a bit. i should note that this building
> >isn't technically mine yet. it's scheduled to close in January. i'm
> >trying to be proactive and doing a little homework. the boilers are
> >relatively new--only about 6 years old. the radiators i *think* are on
> >a single pipe system (the building is over 100 years old and probably
> >had big-ass cast iron radiators originally). i really want to make the
> >place much more comfortable as i plan to move my own father into one of
> >the units. believe me, i don't plan to torment anyone. hahaha. there
> >are 6 units altogether w/ 2 boilers. one boiler heats 3 units on one
> >side of the building. the other boiler heats 3 units on the back side
> >of the building. 3 floors--2 units per floor. uninsulated brick
> >construction.
> >
> >the current tenants are relatively comfortable right now. the problem
> >is that since ONE tenant controls the therm for 3 units, if he goes
> >away for the weekend or something and the temp changes drastically...
> >i'm sure you get the idea. obviously, the best solution would be to
> >refit the system so that each unit can control its temp independently
> >of the others. i will probably do that in about 2 years. i am in the
> >process of buying this building right now. it is my first commercial
> >building and i am putting ALL my cash on the line for the d/p'mt. i
> >really can't afford to bring in a heating expert this year to install
> >shunts, bypasses and thermostatically controlled valves. i'm looking
> >for a low cost, low tech temp solution that works. I hope that makes
> >the puzzle more clear. i appreciate all the views you guys are posting.
> >
> >
> >
> >
> >
> >Marc_F_Hult wrote:
> >> To answer your last question first:
> >>
> >> One could/can use simple inexpensive, traditional Honeywell thermostats
> that
> >> have a bimetallic spring as the temperature sensor and a mercury (ugh :-(
> tilt
> >> switch as the switching mechanism. But these have a manual COOL-OFF-HEAT
> >> setting in part because you can only set the dial to one temperature, not
> two.
> >> If there are inexpensive thermostats available that let you set two
> >> temperatures (I dunno), that is, separate COOL ON and HEAT ON settings,
> they
> >> might be adapted to your use. Okay so far?
> >>
> >> Assuming that you have a thermostat arrangement (whether one or two
> physical
> >> units)  that complete two circuits with a Single-Pole, Single-Throw (SPST)
> >> switches when the temperature is TOO COLD or TOO HOT (that is, "call for"
> heat
> >> or cool), you use this information to override the signal from your
> >> conventionally installed 4th/7th thermostat which is the Tstat that
> controls
> >> the boiler most of the time.
> >>
> >> Assuming for the moment that your boiler control consists in a 24VAC
> circuit
> >> that needs to be completed with a SPST switch, and you have a conventional
> >> thermostat with effectively a SPST switch like the Honeywell I describe in
> the
> >> first paragraph above,
> >>
> >> TstatTerm1 -- NC_TooHot_1 -+- NC_TooHot_2 -+- NC_TooHot_3 -+--- Boiler
> >>                            |               |               |
> >>                                                     NO_TooCold_1
> >>                                                            |
> >>                                                     NO_TooCold_2
> >>                                                            |
> >>                                                     NO_TooCold_3
> >>                                                            |
> >> TstatTerm2 ----------------+---------------+---------------+--- Boiler
> >>
> >> where NC_TooHot_x are the Normally Closed (NC) contacts of a relay and
> >>       NO_TooCold_x are the Normally Open (NO) contacts of a relay.
> >>
> >> So any closure of any NC_TooHot switch will turn off (override) the boiler
> >> unless any of the NO_TooCold-x switches are closed. One can modify the
> >> override logic by (eg) moving the location of the NO_TooCold_x switches to
> the
> >> locations shown with the + .
> >>
> >> Note that the circuit diagram above shows the control signal to the boiler,
> >> not the signal from each SPST switch in each thermostat to each relay coil,
> >> Right?
> >>
> >> The relays themselves are powered by whatever voltage the relay coils that
> you
> >> choose should happen to need (12vdc, 24VAC etc). One wrinkle is that the
> >> anticipator circuit in the conventional thermostats described are designed
> for
> >> 24VAC so you might avoid complications by using 24VAC throughout -- but
> maybe
> >> not, Depends on the thermostat chosen.
> >>
> >> HTH ... Marc
> >> Marc_F_Hult
> >> www.ECOntrol.org
> >>
> >> On 6 Dec 2006 20:14:47 -0800, "Lighthouse" <gruntledlark@xxxxxxxxx> wrote
> in
> >> message  <1165464887.275804.321050@xxxxxxxxxxxxxxxxxxxxxxxxxxx>:
> >>
> >> >Marc, this sounds pretty close to what i want to do. not the Aprilaire
> >> >thing (way outta my budget), but the other. hope you don't mind helping
> >> >me out w/ a few of the details. ok, conventional therms, cat5, serial
> >> >wiring, parallel wiring. i'm down w/ all that. i'm not sure about the
> >> >24V xformer and the relays. i'm assuming that both of those get
> >> >installed in the boiler room along w/ my 7th therm. what kind of
> >> >relays?  is the 24v xformr the kind used in doorbell circuits? how do
> >> >those fit into the wiring scheme? is it possible for you to sketch this
> >> >out for me?
> >> >
> >> >what would be the difference w/ using an AUTO therm instead? as for
> >> >discouraging tampering w/ the settings i could possibly camo the therms
> >> >inside the casing of a smoke alarm unit.
> >> >
> >> >thanks for the ideas!
> >> >
> >> >Marc_F_Hult wrote:
> >> >>
> >> >> I would do this with three (or four) communicating Aprilaire 8870
> >> >> thermostats and Homeseer software running 24x7 on a low power dedicated
> PC.
> >> >>
> >> >> But here's a solution that doesn't use a PC, is extremely reliable,
> >> >> presumably inexpensive compared to your energy bill, could be installed
> >> >> and(or) serviced by any competent HVAC serviceman, does not look out of
> the
> >> >> ordinary to the occupants, could be incorporated as part of a future
> zoned
> >> >> system, and requires no custom programming, PICs, soldering etc:
> >> >>
> >> >> 1) Install two inexpensive, conventional thermostats in each apartment
> in
> >> >> no-tamper (fat chance! ;-) enclosures. Thermostat wire is OK but I
> suggest
> >> >> using CAT-5.
> >> >>
> >> >> 2) You'll need 24VAC transformers and relays as well as the thermostats.
> >> You
> >> >> might also find a low-cost  thermostat with an AUTO setting (not manual
> >> >> Cool-Off-Heat as is conventional) that could replace each pair of
> >> >> thermostats.
> >> >>
> >> >> 3) In each apartment, set one thermostat to COOL with the maximum
> tolerable
> >> >> high temperature (say 76 F), and one to HEAT at the maximum tolerable
> low
> >> >> temperature (say 66 F).
> >> >>
> >> >> 4) Install a seventh (!) thermostat in a centrally located ('average')
> >> >> location that you can access.
> >> >>
> >> >> 5) Use each of the COOL outputs to energize a relay the controlled
> contacts
> >> >> of which are wired in parallel fashion with the other two. This creates
> a
> >> >> logical OR to force a TOO COLD OVERRIDE.
> >> >>
> >> >> 6) Use each of the three HEAT outputs to energize a relay the controlled
> >> >> contacts of which are wired in parallel fashion with the other two. This
> >> >> creates a logical OR to force a TOO HOT OVERRIDE.
> >> >>
> >> >> 7) Control the boiler with centrally located thermostat's output in
> series
> >> >> with the TOO HOT OVERRIDE (TOO HOT opens circuit) and in parallel with
> the
> >> >> TOO COLD OVERRIDE (TOO COLD completes circuit).
> >> >>
> >> >> This creates a system in which the building w/should not exceed any of
> the
> >> >> six independently set table TOO COLD OVERRIDE and TOO HOT ORERRIDE
> limits
> >> >> and between those limits is controlled conventionally by the centrally
> >> >> located thermostat.
> >> >>
> >> >> As implied earlier, the fly in the ointment is the concept of a
> >> >> "tamper-proof" thermostat enclosure.
> >> >>
> >> >> ... Marc
> >> >> Marc_F_Hult
> >> >> www.ECOntrol.org