BS: Thermostats

Subject: RE: BS: Thermostats
From: dianavan
Date: 03 Oct 05 - 08:24 PM

Jon - There are many, many models of Honeywell thermostats. Mine doesn't look anything like the one in your link.

When I finally found a picture of the old one, it was the same voltage as the new one which was 30V max.

It has now been callibrated and it seems to be working. I also checked to make sure it was level. It was.

Diana

Subject: RE: BS: Thermostats
From: GUEST,Jon
Date: 03 Oct 05 - 08:32 PM

Yes Diana (and please believe me that I'm really glad you are safe). Can you not see that I could not have found you the stat I gave you in the link I supplied and maybe (in all innocence) have hurt you?

That it did not happen seems somewhat less relaavant to me.

Subject: RE: BS: Thermostats
From: Jeri
Date: 03 Oct 05 - 08:48 PM

Jon, I don't know if information on this model is relevant and I know it's not dianavan's, but the directionf for this one (Adobe Acrobat) say to check calibration, the first thing you do is remove the cover. You can then fiddle with the dial and the ring to your hearts content. There is no imminent danger of zapping.

Subject: RE: BS: Thermostats
From: GUEST,Jon
Date: 03 Oct 05 - 09:05 PM

Jeri, i think the heart might not be content with the Honeyqell I fond. Maybe as RB suggest, a weaaaker one is neded, but I'm sure people can get hurt.

RG is right by the way over millimps killing.. The voltage is the force that may push those tiny figures through the resistance of the body.

Subject: RE: BS: Thermostats
From: JohnInKansas
Date: 04 Oct 05 - 08:33 AM

dianovan -

The T87F 3855 that you replaced is the "classic standard" round dial thermostat (and coincidentally the same one Kendall's HVAC installer used). The T87F is essentially the same thermostat - for your purposes - as your replacement, the CT50A4775.

Since it is an attempt to retain the original Honeywell Thermostat "look" the T87F is not really adaptable to modern (cheap) manufacture, and usually sells for more than functionally equivalent thermostats of more modern design, but people still like the look. It doesn't do anything that your new one can't do for you.

T87F and CT50 are "base model numbers," and the "digits that follow" may describe additional features. You apparently need a simple ON/OFF thermostat for heating only, so the cheapest thing you can find that does this (and fits your room decor) is the appropriate one for you. You have the CT50 so it's obviously cheapest now to keep what you've got, and there's no real reason to look for something else - unless you have something you haven't mentioned like a humidifier or air conditioner to deal with.

The only remaining quibble is with the "adjustment of the two(?) screws" that Kendall refered to. As Kendall indicated (correctly) if these are set too far wrong they can prevent the thermostat from turning on the heat. Some thermostats do have separate adjustments for heating and for cooling. The basic CT50A/CT51A thermostat has only one, but "variants" of the basic model may have both.

The additional detail you should check, now that you're up and working, is that the "anticipator" should NOT be set all the way to one end as a general rule.

The anticipator is essentially a rheostat. Moving the pointer changes the length of a small resistive wire to change the amount of heat it generates. If you move the pointer all the way to the low resistance end, you have a very short wire carrying a lot of current, and it will (sometimes) eventually burn itself up and/or degrade the (usually plastic) board that it's mounted on - and then you'll need a new thermostat. If you move it all the way to the other (high resistance) end, it will not generate the heat needed to provide the function for which it's intended.

If you still have your old thermostat and it hasn't been "readjusted" you can look at it to see where its anticipator was set. You should try setting your new one to the same number.

If you don't still have the old one, or if you've played with it and changed the setting, the number that should be set is the "current rating of the primary control device" that the thermostat connects to (in the basement). This device will probably be a valve of some sort on your system, and probably is the thing that actually turns the water flow on and off. (This is not the transformer.) For a typical gas heating system, the gas valve would probably be at about 0.2 (0.2 amps or 200 ma on the valve nameplate) but for a water valve it may be more like 0.8. (I'm assuming that heating of the water is controlled separately, and your room temperature controller just turns the water flow on/off.)

Since thermostats of this kind are most commonly used on gas burner control systems, the "factory setting" for the anticipator was probably at 0.2. If your water control valve needed an 0.8 setting the current (0.8 amps) when the switch closes would heat the anticipator so fast that the thermostat shut itself off before you could tell it came on. This is probably what was happening before you "turned the screws."

If the anticipator is set too high, the thermostat won't turn off until room temperature actually gets high enough flip the mercury switch. Heat stored in the radiators will continue to dump into the room, and you'll get an unnecessarily large temperature cycle. When you have more than about 2 degrees F (1 degree C or so) variation in room temperature, most people respond by feeling "cold" when the temp is at the low side of the swing, so they push the thermostat up. Waste of fuel.

Once you're close to a good setting, you can make SMALL adjustments to get even temperatures, but you should let the room temperature stabilize for at least 5 to 10 hours before making another adjustment. Instructions for your thermostat suggest that if the temperature cycles over too wide a temperature range (furnace stays on too long) you should move the anticipator lever clockwise. If the furnace cycles on and off too frequently, move it counterclockwise. Make SMALL adjustments, and wait for it to settle before making another one. This can take days (or weeks) to get really right if you're too fussy. Don't worry too much about it if the heat comes on and you're comfortable.

Your new thermostat should have included a brief "Installation Instructions" sheet that probably (no guarantee) includes instructions on all this. Honeywell makes good products, but does a really shitty job of providing tech information on their websites. In the event the instruction sheet wasn't there you might look at:

CT50A Installation Instructions (610 KB .pdf) in English, but really ratty.

CT50 Installation Instructions (2.72 MB .pdf) the same stuff, in Enlish, much larger download, a little clearer pictures but still poor.

With either of these, unless you have a great imagination, you'll probably want to print them and patch the pieces together before you try to make sense of them.

For clear pictures (the same ones) you can also download the Spanish version I linked at 02 Oct 05 - 04:39 AM. All three of these appear to be the "same instructions" but only the Spanish one is really legible.

John

Subject: RE: BS: Thermostats
From: kendall
Date: 04 Oct 05 - 08:39 AM

Talk about A tempest in a teapot.

Subject: RE: BS: Thermostats
From: GUEST,Jon
Date: 04 Oct 05 - 09:31 AM

I thought we were out of it Kendall? Seems to me you can not even obey your very own:

Ok, time to put it to rest.

Subject: RE: BS: Thermostats
From: kendall
Date: 04 Oct 05 - 04:47 PM

You never did answer my question.

Subject: RE: BS: Thermostats
From: GUEST,Jon
Date: 04 Oct 05 - 05:36 PM

Well I thought I tried Kendall with the thickness of a wire (the conductor) one.

Please don't get me wrong BTW. I do not think you are "dangerous" in the sense you would wilfully harm anyone (I "know" you as a nice guy who once sent me a small "pc mic" out of nothing but kindess - If I gave the impression I believe you are "evil" or something like that, I'm sorry - and will spell it out that I believe no such thing of you and believe you to be kind hearted). Whether I'd turn to you for tech advice is another matter - not sure I'd really even turn to myself for that!

Subject: RE: BS: Thermostats
From: kendall
Date: 04 Oct 05 - 06:35 PM

Ok,, Jon, Good enough. Few people come to me for the truth anyway.

Subject: RE: BS: Thermostats
From: dianavan
Date: 04 Oct 05 - 10:24 PM

John in Kansas -

I'm more confused than ever! My heating system is a gas fired boiler that gravity feeds hot water (not steam) to the radiators. It appears that the CT50A is for gas or oil only - according to the manual.

I am also quite unsure about the anticipator. As I mentioned before, I had read it should be at 8 for a gravity fed hot-water system. You seemed to confirm in a previous post that this was correct. I have only a single metal arm called the anticipator.   

I think I'm going crazy and the Honeywell manuals that you linked are useless. Just when I get to the information I need, part of the page is missing! When I go to the boiler, the thermostat is hooked to a little metal box on top of the boiler and it is absolutely plain with no markings except the Honeywell name.

I know this is not straightforward for many reasons. The man who owned the house before me was from Germany and worked in a shipyard. You would not believe this system (or the house for that matter). Its 100 years old, straight grain, first growth fir, re-inforced with concrete and steel. The heating system is really old and obviously home-made but it does work beautifully if I can just get a grip on this thermostat. The boiler (one of two remaining in Vancouver) is actually a feature of the house (men are in awe) but I have been told that you need to be a member of the boiler makers union to run this system. :>)

I am now like a dog with a bone and I won't give up. At this point, I am tempted to buy a new (old style) round thermostat exactly like the one I replaced. At least I know that it is made for a hot water system and I can read the temperature in degrees.

Now I know why the old owner said, "If it isn't broken, don't fix it"! I should have known better.

Thanks for all your help.

Subject: RE: BS: Thermostats
From: JohnInKansas
Date: 05 Oct 05 - 07:05 PM

dianovan -

DON'T BUY ANOTHER THERMOSTAT.

The new Honeywell CT50 thermostat you just installed IS EXACTLY THE SAME as the "round" Honeywell T87F that you removed, except:

1. The CT50 isn't "round."
2. The T87F probably costs more.



ONE STEP AT A TIME:

I'm more confused than ever!

Welcome to mudcat.



My heating system is a gas fired boiler that gravity feeds hot water (not steam) to the radiators

We thought we had that figured out. I'm glad you've confirmed it.




It appears that the CT50A is for gas or oil only - according to the manual.

The usual use for the CT50A is for turning a gas or oil burner on/off. That just means that most people who buy one will use it that way. The installation instruction sheet that comes with the "round one" you removed SAYS EXACTLY THE SAME THING.

The ONLY thing that distinguishes a "gas or oil" thermostat from a "convection hot water" thermostat in most cases is where they set the anticipator before they put it in the box.

Since most people who buy either a CT50 or an T87F will use it to turn a gas or oil burner valve on/off, the anticipator will be set to ".2," "0.2," (or for some other brands to "200,") because most burner valves will require about two tenths of an ampere, (or 200 milliamperes) at 20 or 30 volts, to be turned on/off.

If you go seek out a "different thermostat" for a convection circuit water heating system, you are quite likely to get THE SAME THERMOSTAT with the anticipator pre-set to about ".8," "0.8," or "800" because common low-volt water shutoff solenoids (valves) usually require about eight tenths of an ampere to turn on/off. It will likely have a slightly different "detail model number," and will cost you a bit more or a bit less depending on the mood of the guy who wrote the latest "how much can we screw them for this" list.



I am also quite unsure about the anticipator. As I mentioned before, I had read it should be at 8 for a gravity fed hot-water system. You seemed to confirm in a previous post that this was correct. I have only a single metal arm called the anticipator.

A typical setting for a gravity fed (convection) hot-water system would be ".8" or "0.8". The ONLY THING that matters is how much current is required to pass through the switch in the thermostat, to turn on the valve that lets the water flow when you need to warm the room.

Please note: IT DOESN'T MATTER VERY MUCH in most cases.

1. Any setting that results in the room getting warmer when it should get warmer, and doesn't result in the room getting warmer when it should not get warmer, is okay.

2. Setting the anticipator more precisely may make you more comfortable, and potentially can save a bit of fuel, but it's extremely tedious and time consuming to "adjust" one, so most people use a default setting.

3. Setting the anticipator ALL THE WAY to one end, IF the valve actually requires a fair amount of current, may result in burnout of the anticipator or in reduced life of the thermostat. All the way to the other end won't hurt the thermostat, but it's hard to tell that end from 'tother end, so just "don't go all the way 'less it's for a good reason." Your mother told you that years ago.

WHAT SHOULD YOU DO ABOUT YOUR ANTICIPATOR

1. If your heat comes on and eventually goes off (and eventually comes back on again) you don't really have to do anything.

2. If your old thermostat hasn't been changed, you can look at it and set the anticipator on your new one to the same number it used.

3. If you can find the valve that actually turns on the water to provide heat, you can look at its nameplate to see how much current it needs, and set the anticipator to a matching number.

4. You can make a guess, and hope, and it will probably be okay. With your system about 0.8 or so should be a good guess unless you find that you need to use a different value to make things work. Since it's an old, and apparently "homemade" system, the original cobbleruper might have used an unusual valve that needs something a bit different, although it's unlikely.

Eventually, when you decide whether you're comfy or need to actually be concerned:

1. If the heat doesn't stay "turned on" long enough, it will cycle on and off frequently but may "never quite get there" in terms of making you feel warm enough. Move the anticipator to a slightly higher number and give it a day to see if it helped.

2. If the heat stays "turned on" too long, the room may overshoot to a "too warm" condition every time the thermostat flips, but then may get "too cool" before it flips again. Move the anticipator to a slightly lower number and give it a day to see if it helped.

Adjusting to anything other than default settings usually is so time consuming (calendar time) that something breaks before you finish and you have to start over. That's why they sell "gas/oil burner" control thermostats with the anticipator preset to 0.2, and "convection water valve" control thermostates, with a different part number and different price and with the preset at 0.8. If you can turn the screw (or slide the lever) they're the EXACT SAME PART - except for the package, the name, the price, the color, the shape, the adverts, etc. ad nauseum.

And they (nearly) all have illegible installation instructions.

John

Subject: RE: BS: Thermostats
From: dianavan
Date: 06 Oct 05 - 01:16 AM

Thank-you, J in K -

I'm warm and cozy now. Sure have learned alot. Thanks for teaching me so much! I'm feeling quite brave now and wonder if I should tackle the hissing toilet next. :>)

d

Subject: RE: BS: Thermostats
From: open mike
Date: 06 Oct 05 - 01:26 AM

unfortunte that you supported the honeywell company..
because they make triggers for nuclear weapons..
and often it is their products and componenets
that are transported by the white (nuke) trains

oh well, hard to seperate yourself from the military
industrial complex because it is, well, complex.

Subject: RE: BS: Thermostats
From: JennyO
Date: 06 Oct 05 - 04:05 AM

wonder if I should tackle the hissing toilet next. :>)

Dianavan - so you are being bothered by the "flush of a distant toilet"? Seems to be a lot of that round here :-)

Anyway, I'm glad the thermostat's been turned down on this thread. Things were getting a bit hot for a while....

Subject: RE: BS: Thermostats
From: dianavan
Date: 06 Oct 05 - 07:41 PM

open mike - I didn't have musch choice. Who said monopolies were illegal?

Subject: low voltage (15 to 30) CT87A,BJ, ROUND
From:
Date: 14 Oct 05 - 10:33 AM

question there are 3 poles R,W,Y WJAT KINDA WIRE DO I NEED 2 PAIR? what guage wire do i need its 45 feet from t-stat and connectiona at each end please