gusherb
Well-known member
Two of my electromechanical programmable thermostats shown here, and a few of my oldest ones as well. The Carrier was the one that controlled my grandmas 1960 Carrier furnace, I imagine it came in the box with the furnace.
Honeywell thermostat
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GusHerb, the unit in pic 6 far left looks like the one on my Aunts HVAC unit. Can you help me understand how it controlled both function with no other controls?
gusherb
Well-known member
The thermostat would've had three wires and been a heat/cool model. The mode selection would've been controlled elsewhere. These were uncommon but did exist, the most recent example is a Honeywell zone system from the 80s-90s called TrolATemp where a "master" thermostat controlled the system mode and the others were called "slave" thermostats. The slaves had three wires run to them and could do heat or cool.
The thermostat in the top right is another like the type you describe, except it is heat only, just like the one before that you pointed out.
The other Honeywells are T86's, the low temp one is an early T87. Two of the T86's were the original smaller dial design, one is for electric heat only, and the other has a positive off switch. Those are the only two smaller dial ones I have.
The thermostat in the top right is another like the type you describe, except it is heat only, just like the one before that you pointed out.
The other Honeywells are T86's, the low temp one is an early T87. Two of the T86's were the original smaller dial design, one is for electric heat only, and the other has a positive off switch. Those are the only two smaller dial ones I have.
diesirae7
Well-known member
nice
collection you have! I've saved a few, there is a heating supply store here that still has new ones in stock, if you are looking for a certain one I can see if they have it. They also have lots of vintage NOS plumbing, like sinks and toilets still new in the box from the 1970s.
collection you have! I've saved a few, there is a heating supply store here that still has new ones in stock, if you are looking for a certain one I can see if they have it. They also have lots of vintage NOS plumbing, like sinks and toilets still new in the box from the 1970s.
gusherb
Well-known member
Wow! Sounds like I need to make a trip!
This thread came at an opportune time as I just got three used round, mechanical, heat only Honeywell thermostats that I installed and have a few questions I hope someone here might answer.
The one Im having most trouble with is a T87F2873. It has provision for three wire hookup. Base plate states Red to R, White to Y and Blue to W. The system is hot water radiator and uses only two wires. Only way thermostat works is hooking wires to R and Y but it operates backwards. If I turn the set temp lower than the room temp it turns circulator on. If I turn the set temp higher than the room temp it turns circulator off. I knew it wouldn’t make a difference but I reversed the wires and it operated the same.
The other two I installed are not the exact same model as above (I don’t have the model number of them while I write this) and seem to be working okay but there are a couple things Ive noticed with them. Number one will allow the room temp to drop at least three degrees below the set temp and not call for heat. Just how much its allowing the room temp to drop before turning the circulator on Im not sure. How many degrees is acceptable? Should it be calling for heat when the room temp drops exactly to the set temp?
Number two consistently shows a room temp 6-8 degrees above the set temp. I realize that after being satisfied and turning the circulator off the room temp will continue to rise some but this is not the case. Im finding the higher room temps with the baseboard cold to the touch. So it seems the thermostat is keeping the room temp higher than what its set for.
What is the adjustment made with the copper colored pointer at the 5 o’clock position? The scale below the pointer has numbers 1.2, .8, .6, .5, .4, .3, .2, .15, .12, .10. At the right end of the scale is the word LONGER with an arrow pointing towards the left. For some reason the pointer on the T87F2873 will not move the full range of the scale like it does on the other two.
Thanks for any info anyone here might be able to give me.
The one Im having most trouble with is a T87F2873. It has provision for three wire hookup. Base plate states Red to R, White to Y and Blue to W. The system is hot water radiator and uses only two wires. Only way thermostat works is hooking wires to R and Y but it operates backwards. If I turn the set temp lower than the room temp it turns circulator on. If I turn the set temp higher than the room temp it turns circulator off. I knew it wouldn’t make a difference but I reversed the wires and it operated the same.
The other two I installed are not the exact same model as above (I don’t have the model number of them while I write this) and seem to be working okay but there are a couple things Ive noticed with them. Number one will allow the room temp to drop at least three degrees below the set temp and not call for heat. Just how much its allowing the room temp to drop before turning the circulator on Im not sure. How many degrees is acceptable? Should it be calling for heat when the room temp drops exactly to the set temp?
Number two consistently shows a room temp 6-8 degrees above the set temp. I realize that after being satisfied and turning the circulator off the room temp will continue to rise some but this is not the case. Im finding the higher room temps with the baseboard cold to the touch. So it seems the thermostat is keeping the room temp higher than what its set for.
What is the adjustment made with the copper colored pointer at the 5 o’clock position? The scale below the pointer has numbers 1.2, .8, .6, .5, .4, .3, .2, .15, .12, .10. At the right end of the scale is the word LONGER with an arrow pointing towards the left. For some reason the pointer on the T87F2873 will not move the full range of the scale like it does on the other two.
Thanks for any info anyone here might be able to give me.
Okay. Did some checking online and looks like thermostat should be hooked to R and W for heat only. Im sure I tried that but will try again and see what I get. As far as adjustment scale at 5 o'clock position I see that is to be set on the number that corresponds to the current rating of the primary control of the system. Something must be jammed or broken in thermostat that's not allowing the pointer to be moved full length of the scale.
philr
Well-known member
Ken, if your baseplate has no switch for heat/cool, you want the wires to be connected to the two lower left terminals of the baseplate, the upper right terminal is for cooling. If for some reason, the thermostat doesn't work with these terminals connected, there must be a problem with it.
As for the anticipator, from what range can you adjust it? This model should be adjustable from 0.1 to 1.2 according to this:
https://customer.honeywell.com/en-US/pages/product.aspx?cat=HonECC+Catalog&pid=T87F2873/U
As for your thermostats keeping the room too cool or too hot, first, verify that the red pointer shows the actual room temperature accurately (with at least another thermometer as a reference next to it). If it does, then the angle of the baseplate might have to be adjusted a bit so the mercury switch trips at the correct temperature (that might cause the thermostat not to be perfectly level but if it's more accurate like that, that's better!). And you have to make sure that the anticipator works and that it's set correctly so the system cycles on and off the appropriate time to maintain the room temperature. On my system, they should be set at 0.4 but I set them at slightly shorter settings around 0.35. The temperature is constant and follows the pointer setting on my old thermostats, at 0.4, the cycles are a bit too long and they'll still call for heat for a long time and the room temp would rise a bit above the set temperature.
On most of my old thermostats, I had to adjust the thermometers so the pointer shows the correct room temperature and I didn't install them perfectly level to compensate for wear(?) or incorrect adjustment of the bi-metal. I had a few with anticipators that either didn't set low enough or didn't seem to work at all but most worked just fine.
As for the anticipator, from what range can you adjust it? This model should be adjustable from 0.1 to 1.2 according to this:
https://customer.honeywell.com/en-US/pages/product.aspx?cat=HonECC+Catalog&pid=T87F2873/U
As for your thermostats keeping the room too cool or too hot, first, verify that the red pointer shows the actual room temperature accurately (with at least another thermometer as a reference next to it). If it does, then the angle of the baseplate might have to be adjusted a bit so the mercury switch trips at the correct temperature (that might cause the thermostat not to be perfectly level but if it's more accurate like that, that's better!). And you have to make sure that the anticipator works and that it's set correctly so the system cycles on and off the appropriate time to maintain the room temperature. On my system, they should be set at 0.4 but I set them at slightly shorter settings around 0.35. The temperature is constant and follows the pointer setting on my old thermostats, at 0.4, the cycles are a bit too long and they'll still call for heat for a long time and the room temp would rise a bit above the set temperature.
On most of my old thermostats, I had to adjust the thermometers so the pointer shows the correct room temperature and I didn't install them perfectly level to compensate for wear(?) or incorrect adjustment of the bi-metal. I had a few with anticipators that either didn't set low enough or didn't seem to work at all but most worked just fine.
Phil
Thanks for the info. The two left terminals are R and W. I will try them and see what I get. The pointer on the anticipator has very little travel. Only from .275 (the line right of .3) to half way between .2 and .15.
I know the anticipator isn't set correctly on the other two. I will do that and then see how they act.
Thanks for the info. The two left terminals are R and W. I will try them and see what I get. The pointer on the anticipator has very little travel. Only from .275 (the line right of .3) to half way between .2 and .15.
I know the anticipator isn't set correctly on the other two. I will do that and then see how they act.
diesirae7
Well-known member
Heat anticipator
That is actually a mini heater in the thermostat, once a call for heat it slowly warms to shut the thermostat off before the room reaches temperature, the furnace will continue to blow out heat after its off and reach the temperature the thermostat is set at. Those numbers on the slide are milliamps, it must be set to the milliamp draw of the gas valve, which would require a milliamp meter installed at the thermostat to see what the amp draw of your gas valve is, sometimes the gas valve will have it printed on the body, one thing you can look for if you don't have a milliamp meter. Even new digital thermostats have this option, in a series of numbers called differential or something like that. Also its very important to level the sub-base of the mercury thermostats for them to work properly.
This post made me check my old thermostat drawer in the shop, looks like I have about 4 Honeywell Rounds, I've always saved them after replacing thermostats for people. I have a really neat Lennox brushed aluminum rectangle thermostat from the 50s in a box somewhere, I'll have to try and find it.
That is actually a mini heater in the thermostat, once a call for heat it slowly warms to shut the thermostat off before the room reaches temperature, the furnace will continue to blow out heat after its off and reach the temperature the thermostat is set at. Those numbers on the slide are milliamps, it must be set to the milliamp draw of the gas valve, which would require a milliamp meter installed at the thermostat to see what the amp draw of your gas valve is, sometimes the gas valve will have it printed on the body, one thing you can look for if you don't have a milliamp meter. Even new digital thermostats have this option, in a series of numbers called differential or something like that. Also its very important to level the sub-base of the mercury thermostats for them to work properly.
This post made me check my old thermostat drawer in the shop, looks like I have about 4 Honeywell Rounds, I've always saved them after replacing thermostats for people. I have a really neat Lennox brushed aluminum rectangle thermostat from the 50s in a box somewhere, I'll have to try and find it.
philr
Well-known member
I assume the thermostats have to be set to the current draw of the gas valve (in amps) on single zone systems that don’t use switching relays? My system uses 3 RA832A switching relays and they apparently require the thermostats to be set at 0.4 amps. At least, that’s what I understand from the first picture below.
I also took a few pics showing different thermostats in a 1965 Honeywell Tradeline catalog and a picture of a few more thermostats I have.
I also took a few pics showing different thermostats in a 1965 Honeywell Tradeline catalog and a picture of a few more thermostats I have.
diesirae7
Well-known member
yes
correct, in using the switching relays, one would need to set it at what the manufacturer recommends. What make are your zone valves? I've had to replace two of them in a three zone system I service in a large two story home built in 1904, they are Taco brand, they complained of no heat in certain areas of the home, found two bad power heads, they failed in the closed position. This is a hot water system as well, I do service two residential steam boilers, rare these days but very neat to work on, and very HOT heat indeed!
correct, in using the switching relays, one would need to set it at what the manufacturer recommends. What make are your zone valves? I've had to replace two of them in a three zone system I service in a large two story home built in 1904, they are Taco brand, they complained of no heat in certain areas of the home, found two bad power heads, they failed in the closed position. This is a hot water system as well, I do service two residential steam boilers, rare these days but very neat to work on, and very HOT heat indeed!
gusherb
Well-known member
Phil, I'm gonna be studying those catalog pages for awhile, that looks awesome!
To go a bit deeper on heat anticipation, here is an article about it: http://www.carolfey.com/articles/anticipation.html
To match the heat anticipator to the amp draw will give about 6 CPH which is good for older lower efficiency forced air systems. I personally like to go about 3 CPH for forced air, and for hot water anywhere from 1-3 CPH. So to get 3 CPH on a heat anticipator you multiply the measured amp draw by 1.2. To achieve 1 CPH you set the anticipator to its max setting of 1.2 amps.
I would use an amp meter to check amp draw vs going off of the zone valve/gas valve as the real draw can differ from the nameplate. I would also wait til the system has been functioning for a few minutes. For example, on my Trane's, I don't achieve full amp draw until the gas valve opens. They also both draw .7 amps which differs from their recommendation of setting to .4 amps. To get the 3 CPH I want I would need to set the anticipator to .84 in that case.
To go a bit deeper on heat anticipation, here is an article about it: http://www.carolfey.com/articles/anticipation.html
To match the heat anticipator to the amp draw will give about 6 CPH which is good for older lower efficiency forced air systems. I personally like to go about 3 CPH for forced air, and for hot water anywhere from 1-3 CPH. So to get 3 CPH on a heat anticipator you multiply the measured amp draw by 1.2. To achieve 1 CPH you set the anticipator to its max setting of 1.2 amps.
I would use an amp meter to check amp draw vs going off of the zone valve/gas valve as the real draw can differ from the nameplate. I would also wait til the system has been functioning for a few minutes. For example, on my Trane's, I don't achieve full amp draw until the gas valve opens. They also both draw .7 amps which differs from their recommendation of setting to .4 amps. To get the 3 CPH I want I would need to set the anticipator to .84 in that case.
philr
Well-known member
There are no zone valves in my heating system, I have two old Taco Perfecta 152 circulators (the one for the garage is a newer and smaller 007).
The 152 circulators are early wet rotor circulators from the late 1950s or early 1960s, they still have a removable back cover and there's also a bleeding screw on this cover. The model 195 that followed still had a bleeding screw but no cover at the back.
https://www.taco-hvac.com/archives/150-152.pdf
The 152 circulators are early wet rotor circulators from the late 1950s or early 1960s, they still have a removable back cover and there's also a bleeding screw on this cover. The model 195 that followed still had a bleeding screw but no cover at the back.
https://www.taco-hvac.com/archives/150-152.pdf
diesirae7
Well-known member
Very nice!
Always nice to see a clean boiler room! There should be a Taco air scoop in a horizontal run out of the boiler to catch air and a self venting brass valve on it. Also a good idea to open the bleeders on the radiators once a season to make sure there is no air in the system.
Always nice to see a clean boiler room! There should be a Taco air scoop in a horizontal run out of the boiler to catch air and a self venting brass valve on it. Also a good idea to open the bleeders on the radiators once a season to make sure there is no air in the system.
philr
Well-known member
Jonathan, I have some Honeywell T-832A round thermostats that have weird anticipators, away from the bi-metal coil. I don't quite understand how they work!
I partially dismantle one to fix the setback timer mechanism and I took pictures of it while parts were removed...
The pictures show two different thermostat, both were new in box. The first one (T832A 1000 in the 3 first pictures) doesn't have a on/off switch and it's anticipator can't be set lower than 0.4 amps. I tried it briefly and my heating system would stop much too late with the anticipator set at 0.4 amps so I replaced it with a regular thermostat and I didn't bother trying the other one once I fixed it's mechanical timer. That one (T832A-1083 in pictures 4-5) has an anticipator that can be set to 0.1 amps. They both have wires that run from the anticipator to the bi-metal coil.
I partially dismantle one to fix the setback timer mechanism and I took pictures of it while parts were removed...
The pictures show two different thermostat, both were new in box. The first one (T832A 1000 in the 3 first pictures) doesn't have a on/off switch and it's anticipator can't be set lower than 0.4 amps. I tried it briefly and my heating system would stop much too late with the anticipator set at 0.4 amps so I replaced it with a regular thermostat and I didn't bother trying the other one once I fixed it's mechanical timer. That one (T832A-1083 in pictures 4-5) has an anticipator that can be set to 0.1 amps. They both have wires that run from the anticipator to the bi-metal coil.
philr
Well-known member
Troy,
I just replaced the 4 Vent-O-Mist valves this week as some were corroded and occasionally leaking and I didn't trust leaving them open, I added a 9AS automatic shortstop to each.
Pictures 1 to 6 show how it was before and 7 to 11 show the new valves. I don't have a Taco air scoop but there's an American air purger that I guess is similar on the picture 11.
I just replaced the 4 Vent-O-Mist valves this week as some were corroded and occasionally leaking and I didn't trust leaving them open, I added a 9AS automatic shortstop to each.
Pictures 1 to 6 show how it was before and 7 to 11 show the new valves. I don't have a Taco air scoop but there's an American air purger that I guess is similar on the picture 11.
gusherb
Well-known member
Phil
Those T832A's are fascinating thermostats, looking through those catalog pages I see so many redundant items it would make a bean counter these days cringe. Yet these companies back then seemed to have no issue making a bunch of redundant or semi redundant products. Looking at old Kohler and American Standard catalogs I'd see the same.
I would imagine they're relying on the conductivity of the metal in that thermostat to transfer heat to the bimetal coil. Like the way a cooling anticipator in the T87 works, which is just a resistor in the subbase with a contact that contacts the shaft of the bimetal coil in turn heating it up when the system is in cool mode but not calling for cooling. That leads me to something I noticed when I was trying to use a T87 for cooling, if the room was within a couple degrees of setpoint and I turned the thermostat to cool for the first time in awhile I'd have to wait for that resistor to warm up in order to get the A/C to come on by itself. While the T87, when leveled and anticipator adjusted correctly did a great job with heating, I found it lousy with cooling. It was very slow to react to load changes as the day carried on and sun beat down on the house, it would just let the room temperature climb while not really cycling any longer than at night when it would overcool by a degree or two.
Those T832A's are fascinating thermostats, looking through those catalog pages I see so many redundant items it would make a bean counter these days cringe. Yet these companies back then seemed to have no issue making a bunch of redundant or semi redundant products. Looking at old Kohler and American Standard catalogs I'd see the same.
I would imagine they're relying on the conductivity of the metal in that thermostat to transfer heat to the bimetal coil. Like the way a cooling anticipator in the T87 works, which is just a resistor in the subbase with a contact that contacts the shaft of the bimetal coil in turn heating it up when the system is in cool mode but not calling for cooling. That leads me to something I noticed when I was trying to use a T87 for cooling, if the room was within a couple degrees of setpoint and I turned the thermostat to cool for the first time in awhile I'd have to wait for that resistor to warm up in order to get the A/C to come on by itself. While the T87, when leveled and anticipator adjusted correctly did a great job with heating, I found it lousy with cooling. It was very slow to react to load changes as the day carried on and sun beat down on the house, it would just let the room temperature climb while not really cycling any longer than at night when it would overcool by a degree or two.
philr
Well-known member
I meant Maid-O-Mist in my previous post!
As for the heat anticipator, I'm wondering how it works in this T-832A thermostat (which is heat-only) but it certainly didn't work too well in the one I tried! The anticipator not only is located far away at the top of the thermostat, it's insulated from the timer mechanism (in the metal housing) which doesn't even extend below the bi-metal coil. I guess the amount of heat from this that gets to the coil is very small! And since it's wired to the coil, I'm wondering if there's some resistive material that might generate heat on the bi-metal coil itself?
I should try the other one I got with the anticipator that can be set at a lower (shorter) setting but that means changing the mounting plate again as those thermostats are much larger than the regular T86/T87 and they use a different mounting plate. [this post was last edited: 12/19/2017-11:22]
As for the heat anticipator, I'm wondering how it works in this T-832A thermostat (which is heat-only) but it certainly didn't work too well in the one I tried! The anticipator not only is located far away at the top of the thermostat, it's insulated from the timer mechanism (in the metal housing) which doesn't even extend below the bi-metal coil. I guess the amount of heat from this that gets to the coil is very small! And since it's wired to the coil, I'm wondering if there's some resistive material that might generate heat on the bi-metal coil itself?
I should try the other one I got with the anticipator that can be set at a lower (shorter) setting but that means changing the mounting plate again as those thermostats are much larger than the regular T86/T87 and they use a different mounting plate. [this post was last edited: 12/19/2017-11:22]
Oh, I MISS
the heat only Roundie at my previous apartment !!!!! Do not miss the landlord, or the unreliable furnace, but at least the thermostat and I were on good terms!
This place has an electronic programmable by a company I have never encountered before, "PRO." The office manager made a copy of the instructions, but I still do not understand the blasted thing!! I have read the instructions more than once.....
Lawrence/Maytagbear
the heat only Roundie at my previous apartment !!!!! Do not miss the landlord, or the unreliable furnace, but at least the thermostat and I were on good terms!
This place has an electronic programmable by a company I have never encountered before, "PRO." The office manager made a copy of the instructions, but I still do not understand the blasted thing!! I have read the instructions more than once.....
Lawrence/Maytagbear
