Honeywell T87K1007 Heat Only Thermostat
Introduction
This is a real replacement component. The following item’s model number and name are: Honeywell T87K1007 Heat Only Thermostat.
PRE-INSTALLATION CHECKLIST
CHECK PACKAGE CONTENTS:
- Thermostat
- Wall anchors & screws (2 each)
CAUTION: ELECTRICAL HAZARD
Can cause electrical shock or equipment damage. Disconnect power before beginning installation.
MERCURY NOTICE
If this product is replacing a control that contains mercury in a sealed tube, do not place the old control in the trash. Contact your local waste management authority for instructions regarding recycling and proper disposal.
PRODUCT APPLICATION
This thermostat provides electronic control of:
- 24 VAC heating systems (T87K)
SYSTEM TYPES
- Gas or oil heat (T87K)
- Heat only, 2-wire, and 3-wire hot-water valve (power open and close valves)
SPECIFICATIONS
- TEMPERATURE RANGE 40° to 90°F (4.5° to 32°C)
- SHIPPING TEMPERATURE -20° to 120°F (-28.9° to 48.9°C)
- OPERATING RELATIVE HUMIDITY 5% to 90% (non-condensing)
ELECTRICAL RATINGS
- VOLTAGE: 20–30 VAC
- RUNNING CURRENT:02–1.0A
INSTALLATION TIPS
Install the thermostat about 5 feet (1.5 m) above the floor in an area with good air circulation at average temperature.
Do not install in locations where the thermostat can be affected by:
- Drafts or dead spots behind doors and in corners
- Hot or cold air from ducts
- Sunlight or radiant heat from appliances
- Concealed pipes or chimneys
- Unheated/uncooled areas such as an outside wall behind the thermostat
WALLPLATE INSTALLATION
- Pull wires through wire hole. Position wallplate on wall, level, and mark hole positions.
- Drill holes (3/16” for drywall, 7/32” for plaster) and tap in supplied wall anchors.
- Pull wire through wallplate, position over anchors, then insert and tighten mounting screws. Check level if desired.
WIRING
- Loosen screw terminals, insert wires into terminal block, then re-tighten screws.
- Push excess wire back into the wall opening.
- Plug the wall opening with nonflammable insulation to prevent drafts from affecting thermostat operation.
TERMINAL DESIGNATIONS
- W: Heat relay.
- R: Power. Connect to secondary side of heating system transformer.
- Y: This terminal can be used for some 3- wire hot-water valve systems (power open and close valves).
CYCLE RATE SETTINGS
Move the cycle rate switches to the proper setting for your system (see table below).
| Heating System | Switch 1 | Switch 2 |
| Steam or gravity (1 CPH) | On | On |
| High efficiency warm air
(90%+), hot water, or heat pump (3 CPH) | Off | On |
| Gas or oil warm air
(factory setting) (5 CPH) | Off | Off |
| Electric warm air (9 CPH) | On | Off |
THERMOSTAT MOUNTING
Align the slots on the base with tabs on the thermostat, then push gently until the thermostat snaps into place.
FAQs
The CT87 also has a lithium battery. No difference there at all. I’m told by Honeywell that this one is discontinued. Hence, it’s labeled as an OEM replacement part.
As I measured–less than 2in. from wall extended out–from base of thermo across less than 4in.–working well for the last 2 winters–has a click when going on- off.
As I remember, this thermostat has a simple mercury bulb. If the two wires from your gas fireplace have a 24V AC signal (or some similar voltage) the mercury bulb should handle the current with no problems. But if your two wires are carrying 110 VAC you will burn out the thermostat.
I installed this a while ago so I can’t remember the wire colors, I bought this to replace the same style and brand. I never replaced a thermostat before but it was pretty easy, and is still working perfect to this day!
That is within the margin tested by the manufacturer. A professional contractor told me that +/- 3 degrees is the norm on this model.
The instructions show that it is compatible with a heat only system (2-wire).
I’m sorry to say I do not have the answer for that question, but it certainly should be less than 5-7°. A temperature differential of only 2° is enough to create discomfort.
It is my understanding that all Round Honeywell Thermostats have the same Lithium battery (CR2450) and the way to replace it is best demonstrated on the following link: https://www.youtube.com/watch?v=6VKowLXfERo
It should. We have a huge 2000 s1q.ft. farmhouse I am putting on two zones. Later, I plan to install another zone.
Mine only had three wires, I hooked up the red to red, black to black, yellow? to yellow? or whatever. I taped the extra wire. (I think it’s for air conditioning) It works great.
Yes with instructions showing where the screws should go in the wall. This is a wired thermostat so you will also need a cable to go from thermostat to the heating system.
You might consider buying a blank single gang wall plate to which you’d mount the thermostat. It a single isn’t large enough; a double gang would be. This would require a few holes to be drilled in the plate, to mount the thermostat and allow the wires to pass through the plate. A couple inserts and screws would be used to mount to plate to your wall.
If this thermostat has a black wire & white wire, the white would be your ground and the black the hot. If it happens to have green wire, that would be the ground.
two wires for heat only.
Sorry not an expert on millivolt units. However, this uses a contact closure. You can hear the relay click on and off.
