[KISS]

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?

[KISS]

Marketing at its best?

Untitled Document

[KISS]

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.

[KISS]

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

Note how simple it really is.

[hvac1000]

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

[Missouri Bound]

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]

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.

[KISS]

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

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

[KISS]

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

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.

[KISS]

Here is the other part (transformer/relays):

http://customer.honeywell.com/techli.../95C-10811.pdf

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

[KISS]

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

[KISS]

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.

[Etaz]

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.

[Etaz]

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?

[KISS]

Link to model procured.

Do you own a multimeter?

[Etaz]

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.

[Etaz]

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...

[Etaz]

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.

[KISS]

How is $53 for quantity #1

Patriot Supply - CONTROLLED AIR SYSTEMS INC Products

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/p...mable_fan_coil

[hvac1000]

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