First, a brief description of my dilemma. In an effort to reduce heating/electric bills (going green!), I am in the process of replacing two mechanical line voltage fan coil thermostats in my condo with digital programmable thermostats. The building was built in the 70’s so the heating/cooling is hydronic (I think, after doing research) with a 2-pipe system. In April, the hot water starts flowing through the pipes and causes the switch connected to the pipe to switch the thermostat to “COOL” mode and vice versa. Many hours of research produced the major obstacle of finding a programmable, line voltage (120 vac) thermostat that wouldn’t break the bank. I have found (obvious to you, I am sure) that Home Depot, Menards, Sears, etc do not stock these. So I turned to the Internet and contractor supply channels. After finding one that fits all criteria and ordering, it is on back order and won’t be shipping for over a month. In addition, they weren’t cheap :-/. Ugh.

So, instead of trying to find a digital, programmable thermostat that can handle an input of 120vac, I instead want to place a 120vac to 24 vac step down transformer (where a “normal” HVAC system takes care of this) in between the house line voltage and a 24 vac thermostat. My thinking is this would afford me a much wider array of consumer programmable thermostats that I could purchase from the aforementioned retailers. I would expect these transformers would be inexpensive and found something on Radioshack.com that does this.

Question: Am I on the right track and if so, what kind of product would I be looking for and where would I find it?

Thanks a ton and I look forward to your response.

JP
Chicago, IL

There is some missing info like: How many wires, what are the terminals called, what model whatchamacallits it connects too and the anticipated current at 120 it has to switch.

Is this an auto-changeover type application? Is a fan involved? How is it controlled? Is it part of a zone controller?

You are on the right track, it's a very common way of solving line voltage switching... BUT as KISS said, you need to supply much more information before any of us can help you. WE're waiting.

I think you are going to have to have a relay that is operated by the 120 volts to send line voltage to a transformer that will then send 24 volts to the thermostat, so that as it makes or breaks it will send the 24 back to the really to then switch the 120 volts telling it to open or to close the water valve.

There is some missing info like: How many wires, what are the terminals called, what model whatchamacallits it connects too and the anticipated current at 120 it has to switch.

Is this an auto-changeover type application? Is a fan involved? How is it controlled? Is it part of a zone controller?

Thermostat(7): International Environmental TC126

7 wires total. 3 from fan (blower)Red(HI),Blue(MED),Black(LO). 3 from sensor attached
to water pipe Yellow(? ),Light Blue(COOL), Red(HEAT). 1 from hot house

line(14GA),Brown(COM).

Fan Coil(4): International Environemntal 4PMOD3-2 (3 speed)

4 wires. Blue(MED), Red(HI), White(Neutral bus house line 14GA), Black(LO)

Wires from House line(2):

1 Black (HOT) to thermostat. 1 W (neutral) to fan White

Now, in terms of the terminals, there is no wording at all, this is an old mechanical thermostat with just soddered connections. I made the table below to orient the connections.

9pin connector (house side-->thermostat)
Color Function Connects to:
---------------------------------------------------------------------------
Black 120 V AC Thermost Brown(COM)
Red (pipe sensor) ?? Switches heat/cool Thermostat Yellow
Black Fan Hi Thermostat Blue
Blue Fan Med Thermostat Black
Red Fan Low Thermostat Red
Black (pipe sensor) Heat Thermostat Red
Blue (pipe sensor) Cool Thermostat Light Blue
N/C
N/C

The house White (Neutral) connects to the fan White directly bypassing
The above mess.

It is auto changeover in the respective seasons. When the bldg maintence staff switches from boiler to chiller (vice versa) the sensor on the water pipe communicates to the thermostat switching to HEAT or COOL. (at least this is how I see it happening)

The water pipes feed into a series of "fins" that cools/heats the return air. I can't see well enough to determine the mechanism of how air is returned but there is a filter we replace that sits in front of the "fins".


Hope this helps. Thanks for your expert opinions.

Is there any way you can confirm what the 3 wire sensor is.

Based on 3 wires, it's probably an RTD
2 wires will read zero
And between any one of these and the other; guess around 100 ohms.

What is the typical loop temp for heating and cooling?

Your thinking that the fan speed is the stage and the sensor determines heat or cool based on loop temperature?

So, I'd like to know the loop temp in heat and cooling modes?

Some systems are Heat pump based and the loop temp isn't that much different. Your thinking that it's just a fan coil with the loop temp determining heat or cool mode?

I will have to track down a maint staffer to answer the loop temp. I'll get back asap. Would a pic of the archaic system help? Being able to visualize always helps me. Not sure if I can attach low-res pics on this site since I am a newbie.

Their website is IEC International Environmental > Home (http://www.iec-okc.com) but it looks like they are not too helpful. In their stat literature they do mention a changeover sensor, which matches what you suggested. It may measure temperature or could be an SPDT switch.

3 heat/3cool stats might be difficult to find although you can only use 2 cool.

You can wire a stat like you would for a damper, so it does auto changeover (Y and W are combined), so heat and cool activate the same fan speed. Then you will have to do something with G.

Which means you won't have choice of fan speed using "FAN".

Or you can buy their programmable stat?

Pics can be attached in the "go advanced" section. The limits are specified. IrfanView - Official Homepage - one of the most popular viewers worldwide (http://www.irfanview.com) resizes images.

Any thought about going communicating stats? I'm not sure what's available.

Loop temps are 42-48 and 120-140 respectively. The maint staff called it the Water FLow Sensor, which indeed does measure temp but HOW it works is beyond the scope of my objective, what it does is paramount.

I assumed I would lose the fan speed option but who cares. Now, back to the question... can I use a transformer in my scenario so I can open up the range of programmable stats I can purchase? (i.e. install a 110-120v receptacle and plug-in a 24vac transformer and connect it's leads to the C terminal?

If by two-way communcation between the stats is what you mean then, originally, communicating stats were considered but budget and simplicity overrode that option. If you meant something completely different than please fill me in.

It's probably out of budget: Aprilaire Communicating Thermostats &#124 HVAC Home Automation System Thermostats (http://www.aprilaire.com/index.php?znfAction=ProductDetails&category=23&sub=comm&item=8870)

You are on the right track, it's a very common way of solving line voltage switching.....BUT as KISS said, you need to supply much more information before any of us can help you. WE're waiting.

MB or KISS,

Do you have enough information to render further assistance? You state it is a very common way of solving the line voltage issue but I am still seeking a feasible, practical solution to my obstacle. Thanks in advance for your help.

JP

Is this heating system just for your (personal) condo? Is the system actually 30 years old? In order to keep the original line voltage controls, you will need a relay to independently switch each line voltage circuit. These relays would need to be a low voltage type (typ 24ac) and they would need their own power supply and control transformer. Then a low voltage thermostat would in actuality control the relays which in return would control the line voltage load. What you have is two systems (correct me if I am wrong) that are currently controlled by one thermostat for each zone. There isn't a simple way to fix this... other than replacing the HVAC equipment. But it can be done, probably not simply or economically. You need to design a low voltage control panel to switch the line loads. You won't find one at Menards. (where are you that there is a Menards available?) You just me better off pursuing a live voltage programmable thermostat.

Assuming it switches a low current 120 V, these relays would be fine: https://www.ecomfrontier.com/asi/member/product.asp?pf_id=x766842&sn=yes&logon=Y&cid=11981

They are about $10 ea. You'll need a piece of T35 DIN rail cut in two and 4 end stops. The WEB data says 24 VDC coils, but the PDF says AC/DC coils. This is about as cheap as your going to get. 3 relays, one for each speed.

I guess the option of fan only for circulation makes no sense? Help me here.

It's going to cost you about $40-50 just to convert the signals from 24 VAC to relays assuming two places.
You can use two transformers or one. 1 location or two. Use DIN terminals to engineer a solution. You can put it in a box or not. All will drive up cost, but increase reliability in the long run. You can get 24 VAC DIN rail mountable power supplies.

This diagram might clear things up a bit: http://www.white-rodgers.com/wrdhom/pdfs/instruction_sheets/0037-6808.pdf

You could supply power to Rc or Rh depending on the season to avoid blasts of the wrong air. You could also measure the temp of the line and switch to cool or heat mode by applying power to Rc or Rh, but that may not be the only way.

You'll need at least a 3 heat/2 cool stat.

See: Thermostat signals and wiring - Transwiki (http://wiki.xtronics.com/index.php/Thermostat_signals_and_wiring)

1st stageheating, will connect to low fan speed
1st stage cooling to med fan speed 24 VAC relay coil
2nd stage heating to med fan speed 24 vac relay coil
2nd stage cooling to hi fan speed coil
3 rd stage heating to hi fan speed

It doesn't really matter if the tstat is set to electric or conventional because your not able to control the fan separately and you won't use the G terminal.

MB:
A line stat doesn't come close either.

The speed of the fan is the stage.

I did point out that the manufacturer has programmable fan coil stats, but lacks useful online information.

Here is a fan coil stat:

http://cgproducts.johnsoncontrols.com/met_pdf/2497150.pdf

It controls the line voltage directly for the fan speeds.

Just means the price went up:

SC-E03-24VAC Products (http://web1.automationdirect.com/adc/Shopping/Catalog/Motor_Controls/Fuji_Contactors_-z-_Overloads/9_to_25_Amp/SC-E03-24VAC)

Might work?

Don't know if you can mechanically interlock 3 relays for each fan speed. You can probably do it electrically with the aux contacts. Mechanically is safer.

The cool and heat wires could be used to switch the mode of the stat. Basically pick one. Make heat the failsafe position.
Use the existing stat (you can move it out of sight) and it's sensor to determine heat or cool mode.

I'm still assuming that there is no FAN only mode.

If you take a look here: Honeywell VisionPro Thermostats - iaqsource.com (http://www.iaqsource.com/category.php/?category=1624)

There are a number of stats. What's interesting is that Honeywell offers a gizmo that will provide and interlock the 120 control relays and, I think, provide the 24 VAC to their FAN coil stat.

This fan coil stat does offer an speed control.

If you take a look here: Honeywell VisionPro Thermostats - iaqsource.com (http://www.iaqsource.com/category.php/?category=1624)

There are a number of stats. What's interesting is that Honeywell offers a gizmo that will provide and interlock the 120 control relays and, I think, provide the 24 VAC to their FAN coil stat.

This fan coil stat does offer an speed control.

KISS,

Would this model work in my application? It uses 120V AC input but I am not sure if it would work in my application. It is made by CAS.

Model No. System Fan Function
T202-G5B63 Heat/Off/Cool Auto/on 3 speed

Here is the wiring diagram. I just am not sure where the pipe sesnsor connections would go.
Wiring

1 stage Heat / 1 stage Cool
-------------------------------
1- Input (L1)
2 -Common
3 - Heat
4 - Cool
5 - Lo fan
6 - Med fan
7 - Hi fan
8 - Rev. Valve heat
9 - Rev. Valve cool

1 Heat / 1 Cool
Heat Pump
------------
Compressor, add Jumper to 3,4

1 - Input (L1)
2 - Common (Neutral)
3 - Heat 1 stage
4 - Cool 1 stage
5 - Lo fan
6 - Med fan
7 - Hi fan
8 - Rev. Valve heat (damper)
9 - Rev. Valve cool (damper)

Is this stat even applicable to 2-pipe heat/cool system? I am going to attach pics for you to enjoy of my lovely system. I have also attched a PDF of the CASD stat I was looking at.

To answer MB's question, there are two independent systems in each corner of the condo. The 2-piping water source (see pic) is common piping to all units so if bldg "boiler" or "chiller" goes down then all units in bldg suffer. But thermostatic controls are per unit. A guy in a nother unit replcaed his mechanical (original IEC) t-stat with the non-programmable honeywell T6575 but I was looking for a programmable option.

Thx.

Actually, take peek at this http://www.ntsupply.com/files/products/62-0278.pdf

I would have places to put all my wires incl. the sensor wries. Which wiring scenario would be most applicable and can I rig the T202 with this wiring in mind?
I know... I'm all over the road but bear with me I really appreciate your time.

I am still unclear on how to attach pics/files. Infraview seems to be just a freeware image viewer. Is there a site I can attach images to and just post the links in this forum?

Page 2 is very similar to your stat. In fact the lower link is identical.

http://l.b5z.net/i/u/6065183/i/T202_Rev_A_6-29-05.pdf

I may have an idea. Let me think a little bit.

Is Heat/Cool used on the original stat? Somehow I don't think so.
So, I think all we may have to do is prevent Heating or Cooling based on the pipe temperature. Does this seem reasonable? Now what bothers me is the contact ratings. Is it possible to read any info off the fan motor? Like HP or FLA and LRA?

Here: http://www.ntsupply.com/files/products/62-0278.pdf

Page #5 is interesting.

Pictures:

Use "Go advanced" and then "Manage Attachments"

Irfanview is an image resizer if it does fit the size requirements.

Any possibility you can get a wiring diagram of the FAN coil and get it scanned?

Ah. Ideas coming to life.

http://controlsdepot.ca/siebe/pdfs/REDPDF/TC2931.PDF

Available at:

South Side Control Supply Co Invensys Barber Colman TC2931 Strap On Changeover Stat 75F TC-2931 (http://www.southsidecontrol.com/acatalog/Products_Invensys_Barber_Colman_TC2931_Strap_On_Ch angeover_Stat_75F_TC_2931_2415.html)

Now we are getting somewhere.

Yep, that's it. But that works! I don't need another one of those. Ohhhhhh... I see you were thinking out load ;-). Is all my psycho-blabber starting to "connect"?

Yep. Thinking outloud.

I need a question answered:

Am I correct that the fan is not allowed to run to just circulate air, because if it did it would blow hot or warm air, correct?

I think I can make it work "correctly" with one contactor and 1 additional relay + the Changeover switch above.

I need to sleep on it.

You are correct. Fan has to blow whatever the temp of water is running through the pipes.
"chat" later...

The "pipe sensor" is probably like the TC2931 switch and not a temperature sensor at all.

I think by adding the following logic, the t-stat will work.

If (water hot) and (call for heat) Motor is allowed to run.

If (water cold) and (call for cool) Motor is allowed to run.

(allowed to run) means t-stat controls the speed of the motor from off to high.

A few comments at this point:

To those reading, some pics were too big and sent privately.

The possible stat CAN be made to work with some effort. I'm waiting for the mfr to reply concerning what Auto means. It can be Auto-changeover because of the pipe temp or auto-changeover because of a heat and cool setpoint.

There may be other stats available. I didn't have a chance to look at another promising one. Now that I know what I'm looking for, it should be a bit easier.

The changeover sensor is probably an SPDT switch and it would have to be used.

The energy savings may not be as steep as you would think because you may only be paying for electricity to run maybe a 1/3 HP motor. Maybe 300 W when running.

The changes required, which I would like to avoid, in words would be:

A junction box or enclosure would have to be put in the FAN COIL enclosure to protect the suggested additional controls.

HEAT and COOL wires would have to be used in the tstat box. You probably can use 2 of the 3 wires from the changeover sensor that are running to the current stat.

A contactor would have to be placed on the Neutral side of the motor. (Motor allowed to run). [Need nameplate data to size]

A DPDT relay (120 V coil) would also be used. It would be designed such that when OFF, heat is the default mode. The Changeover sensor (2 of the 3 wires) will be used to provide the switch to energize this coil when the loop water is hot.

What this relay will do is select the HEAT or COOL output of the stat and power the coil of the added contactor. If chatter occurs a small time delay relay can be added.

Standard DIN rail construction techniques can be used. Bushings would have to be used for the penetrating wires.
I'm not real happy about the wire nutted motor connections not in a junction box.

So, in theory, it's possible.

This was a Carrier stat I found http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/33cs-56si.pdf

But there is one major gotcha. The fan has to run on Low all the time unless off.

It's a low voltage stat and a relay interface board is required.

The necessity of the fan running all the time makes this one impossible to use

All this EE talk of throwing new relays and contactors into the witch's brew is making my headspin. Let's step back and scale back.

What if I lose the ability to auto-changeover<grimace>, make it a manual step from the stat. Cap off the sensor wires. Now what do we have? Given the T202 stat that I would like to work in the existing framework, what would have to happen. Refer back to the wiring diagram earlier. Having 3 speeds on fan is overkill, so only have LO or MED speed available when energized? My head is still spinning. :-|

Actually a 3 speed manual selector switch for 8.00 bucks on Ebay does the trick. Got one on my unit a camp. When playing cards with the guys I just dial it down to the next lower speed. Nice and quiet. I just bolted it to the furnace in a 4x4 handy box.

Addendum. Let me reflect on my original obective: Replace archaic manual stat with programmable digital stat for energy savings and more presice temp control.

Now I have walked into a realm where I should just boil water over a flame and watch the hamster on the wheel chase the Cheezit to run the gernerator to power my girlfriend's hair dryer.
Your screenname says it all, KeepItSimpleStupid. Let's hover over this acronym and apply it here. Or because of the archaic system, in order to achieve long term energy savings do I HAVE to throw money at the solution up front? Re-engineering cost savings is also paramount due to budgetary constraints.
Fire when ready... :-/

Etaz... would you consider moving? Seems like a lot less of a headache. And somehow the phrase "keep it simple stupid" doesn't apply to this anymore. Hmm... Well thanks for opening up the doors Etaz, once in a while it's nice to have our interest peaked. As I said early on you are on the right track. But it would behoove you to have someone you personally know and trust look at the system and advise you rather than make any changes based on comments made on this informative but alas long distance information forum.

Keep the faith.

Don't blame you a bit, MB. Thanks for your input. It has been enlightening and I will pursue the suggestions rendered in this forum. Cheers.
Nowwww where did I put my analog TV antenna...

Don't blame ya a bit, MB. Thanks for your input. It has been enlightening and I will pursue the suggestions rendered in this forum. Cheers.
Nowwww where did I put my analog TV antenna...


Here is part of your system. It was built for a prison but something like this will work for you. Now all you have to do is figure it all out.

Hey, I'm getting an education too. In some respects it's fun. I like "thinking out loud" because it hopefully opens up possibilities and closes others. Finding something simple is sometimes hard. This seemed to be a mini fun research project as well. I'm used to getting things initially ridiculed, but as I'm telling it helps to home in on a solution.

There is cheap. There is easily serviceable. There is comfort. There is manual. There is automatic. There are combinations. You don't want things to be too complex that after you sell the condo, you have to provide a 100 page manual just to operate the HVAC system <G>.

A few things are now apparent:
1. There are no standards
3. There are low voltage and high voltage solutions.
4. Contact ratings were not addressed yet.
5. Most solutions are designed for hospitality industry.
6. The fan running all the time for some solutions makes no sense to me at all.

The most sensible system would vary the fan speed depending on how far the setpoint is from measured value. This results in the quietest system and the most energy efficient.

This is why I was trying to make a conventional thermostat stage select a particular fan speed. This gets off on the wrong track because stage 3 (fossel fuel) is way different than a heat pump. If the manufacturers of the tstat made the characteristics of the stages independently selectable rather than a system type, life would be easier.

The most sensible system would not allow one to get a blast of the wrong temperature air and would make it more marketable to a new buyer of the condo.

Having the fan run all the time defeats your purpose and won't work. Most stats being hospitality oriented with occupancy sensors and door open sensors doesn't help the selection. Your fan coil is super simple, thus you may have found out about the way your HVAC system operated AFTER you bought the condo. The guys building the condo put in the cheapest toaster (HVAC system) that they could find and your paying for it in terms of reduced comfort (high noise levels, no reduced temp for sleeping) and higher electric bills.

My proposed design is elegant providing assuming a stat with the following characteristics are found:

1. Programmable FAN coil stat
2. Multiple fan speeds that change automatically
3. A fan that won't run unless there is a call for heat or cooling.
4. The contact ratings for the fan is adequate in the stat.
5. A change-over sensor isn't required for the proposed stat.

#3 is a MUST.

There is still versions of HVAC1000's suggestions:

Place fan speed control at fan coil where it should not be moved when fan is running. Switch must be properly rated.

Place a seasonal switch in the fan coil area. e.g. Only allows heat or cool.

Variations of adding a contactor and low voltage AC supply to turn the fan on. The thermostat just uses simple on/off control.

And now we are almost right back where we started from adding complexity to make something else work or an elegant solution providing a better tstat choice can be found.

I may try to sketch a simple control ckt. The current tstat choice doesn't change the speeds automatically and it seems that the fan doesn't run all the time.

What are the markings on the blower motor label?

Marketing at its best?

Untitled Document (http://www.rdcontrolsystems.com/rd_new.html)

At 1/20 HP means it's about 40 W or about 1 KWH per day if running all the time. At $0.15/Kwh that means about 15 cents per day if the fan ran continuously, so energy savings isn't going to be the motivation. Contact ratings are nearly irrelevant.

It would have to be comfort and repeatability of setting the temperature.

Here is a quick and dirty sketch of a proposed interface.

Note how simple it really is.

At 1/20 HP means it's about 40 W or about 1 KWH per day if running all the time. At $0.15/Kwh that means about 15 cents per day if the fan ran continuously, so energy savings isn't going to be the motivation. Contact ratings are nearly irrelevant.

It would have to be comfort and repeatability of setting the temperature.


Place fan speed control at fan coil where it should not be moved when fan is running. Switch must be properly rated.

The switch I used can be moved while the equipment is in operation. All it does is break the hot leg from contact and activate the other contact for the speed change. Switch rated at 10 amps. I use Baldor (yep the real expensive ones) for all my personal blowers on all my equipment. Last time I checked a 1/2 hp mptor was around 273.00 retail and 196.00 cost. In 50 years of using Baldor products I have never replaced one. The only problem is they are real heavy since they are loaded with real copper and the magnet structure has to be seen to be believed. Plus being such a good quality motor they can be tuned with the proper selection of capacitors. IE I can put a probe on it and tune the motor for maximum efficiency. Just love Baldor.

BTW FanHandler or Opto. I usually hang one of these on one switch leg just in case I want to go automatic. Or at the main house I let the computer select. I do not mind fliping switches at camp but not in my own home. LOL

Etaz... I just realized that if you posted your question in the heating and cooling forum it would have probably been answered in one or two posts... Have you tried putting it there? http:hvac-talk.com

Etaz...I just realized that if you posted your question in the heating and cooling forum it would have probably been answered in one or two posts....Have you tried putting it there? http:hvac-talk.com

Actually I went there first. But after getting a user ID and signing in, THEN I read their site rules... NO DIY.
So, yeah, I could've dragged 'em through it pretending to be a HVAC contractor or maint tech but I thought better of it and decided to wear my true green colors and just out right admit I am DIY and seeking compassionate experts. ;-)
Besides, you guys seem to be having fun with my "puzzle" and obviously are passionate about your trade.
I like to think I made the right choice.

That was one twentieth (1/20) of a horsepower. Not 1/2 HP from a pic of the nameplate.

This was interesting:
Index of /download/thermostat (http://www.enernetcorp.com/download/thermostat/)

Can't get their website to work. Interesting, but leaves MANY unanswered questions.

It looks like this stat will do what you really want to do except it's 24 VAC: Buy Honeywell TB7100A1000 MultiPro Commercial Thermostat | Honeywell TB7100A1000 (http://www.iaqsource.com/product.php?p=honeywell_tb7100a1000&product=172898)

It can be configured as two pipe with sensor and does the variable fan thing and is programmable. So, I think it satisfies the control creiteria.

Now all we have to do is find the gizmo that does the conversion from 24 V control to 120 V control. I think the transformer and three relays (probably 4) is available pre-packaged. Just have to find it.

Here is the other part (transformer/relays):

http://customer.honeywell.com/techlit/pdf/95c-00000s/95C-10811.pdf

May or may not come with the Snaptrak. Snaptrak can mount on DIN rail.

At this point:
1. Need to double-check that it will work
2. Need to see if Honeywell as a 120 V version of the stat
3. It may not be DIY
4. Have to find where to purchase the 95C-10811

1. Didn't double check yet
2. No 120 V version
3. Your call - is it DIY?
4. It's going to be an HVAC supply house only item. Some aren't friendly to DIY's. Honeywell sells this product to consumers through contractors.

So, Etaz. You have 3 possible solutions:
1. The use any stat that looks ugly with no info.
2. The stat with the 3 speeds that looks like it will work. I'd ask whether the fan has to run all the time before committing.
3. The Honeywell approach. Seems to have all of the correct bells and whistles. Needs a second glance.

KISS,
I'm online now, gimme a few minutes or so to put some dinner down and will get to your answer. Thanks for yhour continued interest.

Ok, I procured a comparable model to the one I mentioned earlier but it is not auto-changeover.I got a great deal ($65 for either model) I can get the auto-changeover by 12/22 (backordered) .
So let's work w/ that one and I would LOVE to get the auto-changeover to work for the end product. So, let's start w/ what I have. Whaddya think?

Link to model procured.

Do you own a multimeter?

No but I can get one from home depot or menards. Always wanted one anyway.
I am sending you the PDF for the model via email addy.

One thing I noticed about this model vs. auto, The housing actaully prevents you from manually switching to AUTO. So, with housing off, I can switch to AUTO, are all the hardwaire pieces there and active for AUTO to work? Or does the mfr actually disable the AUTO feature at the firmware level or some other way? Just curious...

Just to let you know... I know my way around the electrical. I have put in hardwired undermount lighting and added 120v receptacles and switched outlets here and there so I am not completely green. I am comfortable with the fuse box and have mapped out the ckts... am doing a kitchen remodel in the coming weeks so had to sketch all out.

How is $53 for quantity #1

Patriot Supply - CONTROLLED AIR SYSTEMS INC Products (http://www.patriot-supply.com/products/manufacturer_detail.cfm?manu_id=287&startRow=41)

What was the exact model purchased?

Do you have a real instruction manual yet?

The mfr didn't answer my email.

I really need to know how the fan operates.

The manufacturer is here: http://www.controlledairsystem.com/programmable_fan_coil

Nelson Bender designed the first Accustat. He is the president of Controlled Air.

I'm not happy with the website.

Etaz:
Do you want to pursue a 24 VAC solution or keep things at 120 V. This product seems similar to the Honeywell product. Relay Boards (http://www.wistat.com/relay_boards)

Honeywell uses snaptrack and I LOVE snaptrak.

I just HATE when mfs forget to list essential s*it like size and type and size of terminations. You get into a project and find it need 0.110 fastons instead of 0.250 or #10 lugs rather than #6 lugs. Baaah Humbug.

Do you think I can find a job that lets me look at stuff for the first time and point out missing ESSENTIAL information?

WHOA! You da man. Ok, we'll just consider this our lil' sandbox here with this one.
Yea, I have the instr manual. WIll send you the page for the wiring.
What else can I do about the fan? Were you able to read the lable from the pic? Unfortunately, I don't have any other data for the outdated POS (better not let it hear me say that because it just might decode to stop working). Monday I can track down a mainttech and ask if they have any diags for the unit models.

KISS,
Of course. 24V AC was always the intent because of options. Keep in mind though budget. I don't mind adding relays and such, just have to keep bottom line in check.

Wiring and "How the fan operates". If it's on continuously, then it's a no go.

Monday try to track down a Honeywell W6380B Fan Relay Center so we can leave Sparky where Sparky belongs.

Not sure what you mean by "on continuously".
It shuts off when it reachs it's setpoint temp. Lil confused here.

Whatchu talking about? Sparky? The fan or the stat? Guess I should go drinkin' instead of horsin' around with Sparky.

How does this sound:

Get about 5 LED's and five 2.2K 1/2 watt resistors, 5 1n400x diodes (x=1 to whatever) and the cheapest 24 VAC transformer you can find.

Connect the diode and led and resistor in series. Put it across the 24 VAC. If it doesn't light, turn the diode around. Now wire up the stat so that low, med, hi, heat and cool are now lights on the "bench" and "see" what happens.

If it appears it won't work, then you can send it back.

You could use a breadboard or solder the LED string together and use heat shrink.

FAN: A lot of the stats I looked at reverted to a continuous fan when the temperature was satisfied. With hot and cold valves, this is possible to ventilate the stuffy motel room. If the stat does that, IT Won't WORK!

IDEALY it should change fan speeds based on the difference of desired temperature and temperature. The Honeywell does.

SPARKY: A name given to electricians, particularly ones who mess up. Keeping Sparky where Sparky belongs basically means make the tstat wires low voltage which minimizes possible damage. Cost increases. Safety increases.

MAGIC SMOKE Not covered yet.. But Magic Smoke makes electronics work. To prove it, once a piece of electronics smokes it eases to work. Therefor Magic Smoke is the secret.

PROPOSAL #1 would be re-worked slightly to use 24 VAC control wiring. Thus safer. It also opens up the possibility that the Honeywell stat can be used. It's up to you. I'd add an LED light to indicate the cool state of the changeover switch.

J-Box We need to find a relatively shallow box, guess 4-6" tall that will fit nicely in the FAN COIL that will house the new stuff. We need to know heights and size of the stuff. It will also need a few bushings.
Professional and not sloppy.

In order to assemble this mess, I was thinking of a small enclosure and grommets to pass the wires through. We don't know the sizes, so don't order it.

9x6x5h
http://www.newark.com/bud-industries/au-1040/au-series-utility-cabinet/dp/

Snaptrak is here: Catalog 126 | Newark.com (http://www.newark.com/jsp/content/printCatalog.jsp?cat=c126&page=1032&display=single)

and you need the clips on the next page to mount the Honeywell thing if it doesn't come with it.

Bushings
I was also looking for these the nylon bushings on the right top. http://www.keyelco.com/pdfs/M55p120.pdf

Then a small piece of DIN rail: http://onlinecatalog.digikey.com/WebProject.asp?BookCode=dus08flx&SectionIndex=0&PageIndex=338#

and you have the basis of the project, or at least the idea so things don't get messy.

In the ideal case, you bring the cables in to their own terminal and branch from there.

So, you have motor (5), Sensor (3), Stat (7 or so) and power.

That and a couple of relays.

That's why the project is mechanical as well as electrical. You can easily change things around and the parts are reuseable.

Ah, Magic Smoke... installed at the assembly factory, and once it escapes, it can't be put back in...

That is why it is always good to have a box of magic smoke control handy. The box contains the same parts that you were working with but the smoke is still inside the parts waiting to be released on the second try.

Advances in technology are leading to the availability of smoke color options. Exciting!

Kind of like the smoke I used to put down on the landing zones to tell of possible evil enemy in the area so they would know if we were hot or not..

I always insist on genuine "Magic Smoke"... some of the cheap imitations do not perform nearly as well...

How do you determine if the Magic smoke is authentic? The destructive "smoke test"?

I will never forget the time Sparky was wiring the thermostats on a union job (I had no choice but to let them do it). When all was done I gave them the privilege of turning on the main power to activate the unit. I told the sparky that did the low volt wiring to go stand near the thermostat just in case we need to shut it down. When the power was hit the fun began. Each Honeywell 2 stage heat and cool got just a tiny glow and a nice little puff of smoke. Those were the heat anticipators going out. It cost the company doing the electric wiring 4 of those thermostats. BTW they let us wire them in the next go round. That is one of the storys I always tell the class.

You guys are too much. Glad to see this my forum is a vehicle for reminiscencing Sparky memories and conversations on where good "magic smoke" is harvested.

Kiss, I have come to the inevitable decision to take my mess and all this forum's experts' suggestions to a local reference. I have indeed learned a lot and acquired uselful resources that you have supplied. Carry on and thanks! I'll let you know how I get everything ends up... sans magic smoke (hopefully).
Cheers.

Sometimes we need a diversion. You shouls see some of the threads that we end up talking to ourselves.

If you can, can you scan the entire manual for the T202 stat. I'm very curious as to how it's supposed to behave.

I'm not sure what a "local reference" is. Can you elaborate.

Looking at how the cover is designed, you may just be able to insert the required relay etc. on a DIN rail on the side. A few stategicly placed cable clamps should work fine.

Just connecting the N, L1, L, M and Hi connections, the stat should work EXCEPT there is a possibility that it can blow the wrong desired air.

Two relays and some re-wiring will fix that. A relay with a coil LED would aid in troubleshooting. e.g. tells you when the loop temp changed. You would just move the sensor wires going to the stat and make them heat and cool going to the fan coil.

A 24 VAC solution for safety is possible. Adds cost. Would be useful if you were thinking about changing the stat.

Finally the Honeywell stat is EXPENSIVE and is 24 VAC, but adds the following desired features:
1. Thermostat indicates if cool or heat locked out
2. Automatically varying the speeds makes it function somewhat like a VAV ( Variable Air Volume) control system.
Once you have experienced a system that controls the fan speed automatically ambient noise is reduced considerably and your not awakened in the night with a high blower speed.
3. You get arm chair programmability as a value added option (big whoop)

Fan Coil systems are either hospitality based or institutionally based. From a marketing point of view programmability has little value. It would appeal only to codo owners like you. The hotel industry has different requirements (occupancy detection, window open, Leave for a while) etc. Any other application requires a building automation system so that the owner of the heat/cool plant saves money.

There is no incentive for the condo association to undertake a large upgrade because they just pass the costs onto the condo owner. The condo owner's get the short end of the stick.

You have a budget to contend with. You have options now where their didn't appear to be any. You'll get lower temperature for sleeping and repeatability for setting the stat. Bet you have a small mark where the dial goes.

I enjoyed this. Controls are a specialty of mine.

I'm working on one myself which is messy. But I'm in no hurry to complete it. There are options and I haven't ruled any of them out. I need to force a damper open at a about 1:00PM for about 10 minutes when Carrier does it's daily filter test and control that damper with a stat otherwise. The ease of getting into override for about 8 hrs is what I need. Precise control, I do not. Damper closed at all other times except when controlling or in test.
Just not there yet. Collected most parts. Tstat register damper and control box, transformer and one relay.