DLS 24V Interfaces and CVP

In earlier days of mini splits, there was a strong push away from native controls because they were not user friendly in numerous ways. Also, a high demand for “smart” TSTATs with Wi-Fi capability necessitated the need for 24V interfaces to integrate DLS inverter driven technology matched with standard controls and equipment. The 1^st generation of these interfaces did not last long before being revamped to 2^nd generation.



Enter the KSAIC0301230, lovingly nicknamed “The Bomb Shelter” by one of my favorite trainers. With it, we could drive a DLS 1 to 1 system using a 24V thermostat. In multi-zone systems, it was required to have one for each IDU, if desired. It was also used as the original crossover, where we could match a standard Carrier/Bryant fan coil with a DLS outdoor unit.

The inventory of the KSAIC0301230 has been depleted, but there is still a supply of the KSAIC0401230 at RC (same interface but originally sold for ICP equipment). This is the correct replacement while supplies last. However, many systems are currently drawing from Carrier and show that it is superseded by the 3^rd generation KSAIC0601230 mini and KSAIC0501230 interfaces.

However, the 601 is only backwards compatible with 410A cassettes and pancake (slim duct) units and cannot be used to combine a standard fan coil or furnace with a DLS outdoor unit. The 501 is backwards compatible but was never approved for combining a a standard fan coil or furnace with a DLS outdoor unit. Using one for this application is not in the manual and not recommended.

KSAIC0601230 <<3rd Generation Interfaces>> KSAIC0501230

To further convolute things, we have new government compliance as of 7/7/2026. Now, neither 601 nor 501 pass compliance standards of CVP***, and both are being replaced by the KSAIC0801230.

KSAIC0801230 <<3^rd Gen CVP Interfaces>> Crossover KSAIC0701230

The Crossover 37MU* built-in 24V interface also does not pass compliance standards and has been relegated to emergency use only. When matching a 37MU* with a 45MU* you must use S1-S2 communication. When matching a standard fan coil or furnace with a 37MU* you must use a KSAIC0701230 interface that will communicate with the ODU on S1-S2. Because of this, Carrier is allowing standard TSTAT to be used if certain conditions are met. See below. Historically, only shielded, stranded wire was permitted.

***NOTE (As of 7/7/2026): 24v communication between the indoor and outdoor units is prohibited from use as a standard method of communication due to compliance issues. It can be used for purposes of emergency operation, service procedures, and troubleshooting only. Scenario 1 and 2 wiring methods are approved methods of communication that allow for proper operation, regulatory compliance, and meet published performance ratings. See CVP Governing Standard: Standard 210/240-2024 and is published under 10 CFR Part 429 and Part 430 (Docket No. EERE–2022–BT–TP–0028, RIN 1904–AF49).

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