You have decided to control heat with a thermostat rather than switching mats on by hand. The next question is what one controller actually does when you are planning several heat mats, and whether the feedback it acts on belongs to each tray group or to all of them at once.
A controller can have more than one outlet and still have only one probe. That is the short answer, and it is easy to get wrong. More outlets, more independent programs and more sensor inputs are three different counts, and one does not imply another. This article sets out the distinctions, then shows how to record what a given setup can and cannot establish.
Three counts that are not interchangeable
Before comparing any controller, separate the numbers that get folded together in product descriptions.
| Term | What it counts | What it does not tell you |
|---|---|---|
| Outlet or output | Documented power sockets or controlled outputs | How many devices may be connected, or how many independent measurements exist |
| Independent program | Separately configurable rules or operating modes | Whether each output has its own measured feedback |
| Sensor input | Documented sensor connections and measurement sources | Which output uses each reading, or whether separate feedback control is supported |
These are separate specifications. For example, the AC Infinity CONTROLLER 75 PRO, model CTR75P, is documented with two independently programmed outlets and one probe. Its documented temperature-triggered operation uses the probe reading. A time-based schedule, however, does not by itself establish measured feedback. Separate programming does not demonstrate measurement at two different places.
Air and growing-medium measurements are not interchangeable
Air temperature and temperature inside a growing medium describe different conditions. The permitted sensing location must be checked for the exact probe; a probe described for climate monitoring should not automatically be treated as suitable for insertion into growing medium.
The Hydrofarm Jump Start Heat Mat Thermostat instructions, marked MTPRTC / 55MTPRTC, describe a probe in the rooting area and a separate option for measuring air outside that area. This is a model-specific example, not permission to use every probe in both locations. When comparing controllers, record the intended sensing medium and probe position as well as the temperature requirement.
What the documents actually support
Two specific manufacturer examples help show why the document and model reference belong in the comparison.
The Hydrofarm MTPRTC / 55MTPRTC instructions describe a heat-mat connection, one temperature probe and a temperature set point. They do not establish separate measurements for several tray groups.
For AC Infinity, the current product specification table identifies CONTROLLER 75 PRO as CTR75P. The SOT2312X1 manual covers that model and CONTROLLER 79 PRO (CTR79P). It lists one supplied probe per model, two numbered outlets and separate outlet programming. It also describes low-temperature triggering and a buffer that separates trigger-on and trigger-off conditions. The temperature and humidity displays refer to the documented probe; these pages do not establish a separate measured root-zone input for each outlet.
The limited inference is that independent programming alone does not demonstrate two independently measured root zones. This is an interpretation of these documents, not a verdict on all controllers. Additional sensor inputs would still need documented routing to the intended outputs and confirmation of the required feedback-control mode.
Requested requirement against confirmed capability
It helps to keep what you want and what a model is documented to do in two separate columns, so an unmet requirement does not get read as a satisfied one.
| Requested requirement or check | Hydrofarm MTPRTC / 55MTPRTC instructions | AC Infinity CTR75P documentation |
|---|---|---|
| Documented outlet arrangement | One heat-mat connection described; verify the supplied unit | Two outlets documented |
| Separate program per output | Not established by the reviewed instructions | Separate outlet programming documented |
| Documented probe arrangement | One temperature probe described | One supplied temperature/humidity probe documented |
| Independent measured feedback per tray group | Not established | Not established by the two-outlet / one-probe description |
| Intended sensing medium | Rooting-area and air uses described for this probe | Climate measurements described; growing-medium insertion permission not established |
| Temperature-based operation | Temperature set-point control described | Temperature-triggered operation described |
| Compatibility with a specific supplied kit | Unknown | Unknown |
| Meets the buyer's output-group and feedback requirement | Unknown | Unknown |
The unknowns remain open until the exact supplied model and version are checked against the buyer's requirement. The current CTR75P product page advertises VPD-related functions, but this does not make VPD a separate directly measured probe input or establish root-zone sensing. Do not transfer a current product-page feature into a different manual version without confirming the applicable documentation.
Recording a four-mat, two-group setup
Consider a hypothetical planning record: group A contains mats 1 and 2, and group B contains mats 3 and 4. These labels assign equipment to tray groups for discussion; they do not specify electrical connections or confirm that either example controller can power this arrangement. The records below separate the requested temperature-feedback arrangement from capabilities still awaiting confirmation.
| Field | Entry |
|---|---|
| Exact controller / version | Unknown |
| Requested operating mode | Temperature-triggered control; supplied unit's mode unconfirmed |
| Requested group labels | A: mats 1 and 2; B: mats 3 and 4 |
| Actual output and device assignment | Unknown; requires model-specific confirmation |
| Measurement source and position | Shared P1 requested at a recorded rooting-area position in group A; probe model, permitted use and actual position unconfirmed |
| Group A feedback basis | P1 requested to govern group A's assigned output program; actual routing unconfirmed |
| Group B feedback basis | The same P1 requested for group B's assigned output program; no reading in group B provided by this proposal |
| Group B's separately measured condition | Not provided by the proposed P1-only record; the actual condition is unknown |
| Evidence needed | Documentation showing which assigned outputs and temperature-control rules use P1 |
| Buyer decision | If separately measured group-B feedback is required, this shared-reading proposal does not document that requirement as met |
If a supplied controller is documented to apply separate temperature-triggered programs to the same input, the programs may differ while still using shared measurement. That shared reading does not establish a separately measured condition for both groups. A reading at one position also does not establish uniform temperature across every tray in that group. Time-based schedules should be recorded as time-based operation, not as proof of measured temperature feedback.
Record two: independent measured feedback per group
| Field | Entry |
|---|---|
| Exact controller / version | Unknown |
| Requested operating mode | Separate temperature-feedback control for groups A and B |
| Requested group labels | A: mats 1 and 2; B: mats 3 and 4 |
| Group A measurement | Dedicated P_A requested at a recorded rooting-area position in group A; suitable probe and actual position unconfirmed |
| Group B measurement | Dedicated P_B requested at a recorded rooting-area position in group B; suitable probe and actual position unconfirmed |
| Input-to-output mapping | Requested: group A's assigned output program uses P_A; group B's uses P_B. Actual model routing is unconfirmed |
| Independent control capability | Unknown; confirm that the required rules can operate separately using the respective readings |
| Buyer decision | Requirement unconfirmed until the proposed model documents both group-specific measurements, their mapping and separate temperature-feedback operation |
| Evidence needed | Applicable model/version documentation and a supplier-confirmed input/output/control mapping |
A probe count alone cannot complete this record. A controller might display several readings without using each one to control the corresponding output. The reviewed one-probe descriptions do not demonstrate the requested two-group feedback arrangement; another proposed model must supply its own evidence.
What to settle before ordering
First define the tray groups, the condition to be measured in each and whether the requirement is a schedule or temperature-based feedback control. Then check the exact controller and probe versions, output arrangement, input-to-output mapping and supported operating modes together.
Send the intended mat models and quantities, tray-group labels, requested sensing medium and feedback requirement for each group. Scarecrow Garden Supplier Co., Ltd. can discuss the sourcing request; the exact controller version, connection arrangement and control capability remain subject to confirmation against applicable documentation.
For the earlier decision about adding temperature control, see our propagation heat mat thermostat guide. For a specific request, use the contact form.