Heat Pump Controls for United States Makers: Heat Pump Shipments Rose 16 Percent in February 2026, and a 10 Kilohm Thermistor Divider Has 34 Walsin 0603 Resistors at 1 Percent, Only 1 on the Shelf and Only 3 at 50 ppm

Heat pump controls for United States makers rest on small resistors. AHRI reported heat pump shipments up 16 percent in February 2026. We counted Walsin’s 0603 10 kilohm resistors: 34 are rated 1 percent, 3 of those reach 50 ppm per degree, and only 1 is on our Hong Kong shelf.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the Walsin Technology (Walsin) chip resistor export of 234,815 rows, 234,401 of them distinct part numbers. This post is for a design engineer or buyer at a United States maker of heat pumps, air handlers or HVAC controllers who wants to know what a Hong Kong source can offer on the sensing side of a control board. Every part number below is real and every count is ours. It gives no refrigerant, safety or efficiency advice. Where it states a market fact, it names the source, its date and the day we read it.

What do the 2026 heat pump numbers say about control boards?

They say demand for heat pump control boards is moving while air conditioner demand is not. AHRI’s February 2026 tracker, reported by ServiceMag on 24 April 2026, put heat pump shipments up 16 percent year on year and standalone air conditioner shipments down 4.2 percent, to 328,145 units from 342,542. Combined volume was 638,841 units, up 0.4 percent. We read the article on 22 October 2026.

Our subtraction, not AHRI’s: 638,841 combined less 328,145 air conditioners leaves 310,696 heat pumps in the month. The refrigerant side is moving too. ACHR News (27 March 2026) reported that 91 percent of HVAC distributor sales involved A2L equipment by the end of the 2025 cooling season, and that higher charge limits for some A2L systems may call for leak detection or circulation fans. It added that the EPA had proposed revising the 2023 Technology Transitions rule, drew nearly 2,300 comments, and was expected to finalise that summer. We have not confirmed whether it has.

Why does a 10 kilohm resistor matter on a heat pump controller?

Because it often sits in the divider that turns a thermistor into a voltage, and its drift moves the reading. Over a 60 kelvin swing from 25 to 85 degrees Celsius, a fixed resistor held to 100 ppm per degree can move by 0.6 percent of its value, one held to 50 ppm by 0.3 percent, and one held to 25 ppm by 0.15 percent.

That is arithmetic, not a Walsin claim. The TCR column states a bound (“within plus or minus 100”), so the figures are the worst case, and the swing is our illustration. Your board may use another reference temperature, another divider arrangement, or a different sensor. We assume a 10 kilohm negative temperature coefficient thermistor with a 10 kilohm fixed resistor, because that value is common on coil, suction and ambient sensing. That is our description, not a source. Whether 0.6 percent matters depends on your error budget, which only you hold.

Fixed resistor TCR bound	Drift over 60 K (our arithmetic)
100 ppm per degree	up to 0.6 percent
50 ppm per degree	up to 0.3 percent
25 ppm per degree	up to 0.15 percent

How many Walsin 0603 10 kilohm resistors exist at 1 percent, and at what TCR?

There are 34, and the tight-TCR end is thin. We parsed all 234,815 chip resistor rows: 515 hold 10 kilohm, 95 of those are 0603, and 34 of the 95 are rated 1 percent. Of the 34, 24 are within 100 ppm, 7 within 200 ppm and only 3 within 50 ppm.

The 3 parts at 50 ppm are WK06K1002FTL, WF06K1002FTL and WF06K1002FTLJ, all from Walsin’s high precision thick film TC50 family. A 25 ppm part at 1 percent does not exist at 0603 in the export. The 25 ppm rungs start at 0.5 percent, with WF06J1002DTL, and at 0.1 percent, with WF06J1002BTL. We have not seen this counted anywhere: for a 10 kilohm 0603 divider at 1 percent, the choice is 24 parts at 100 ppm and 3 at 50 ppm, and halving the drift moves you into a different family.

The 34 also include power, surge, high voltage and anti-sulfuration series, and a convex array, WA06X1002FTL, which holds four resistors and is not a one-for-one swap. Our post on thick film against thin film chip resistors covers the step beyond 25 ppm, where the export, not the datasheet, is the limit.

Which Walsin parts cross a 10 kilohm 1 percent 0603 divider resistor?

One general purpose part matches on value, tolerance and case, and the tighter parts differ in family. Say your board has a 10 kilohm, 1 percent, 0603 resistor and you want to know what Walsin offers. These are the real parts nearest to it.

Walsin part	Family	Case	Tolerance	TCR bound	Rated power	In stock 23 September 2026	Your incumbent	Match / mismatch (10 kilohm, 1 percent, 0603)
WR06X1002FTL	General purpose	0603	1 percent	100 ppm	1/10 W	Yes	___	Match on value, tolerance and case; confirm TCR against yours
WF06K1002FTL	High precision TC50	0603	1 percent	50 ppm	1/10 W	No	___	Match on value, tolerance and case; mismatch on TCR (tighter), not stocked
WK06K1002FTL	High precision TC50	0603	1 percent	50 ppm	1/10 W	No	___	Match; mismatch on family prefix, not stocked
WF06J1002DTL	High precision TC25	0603	0.5 percent	25 ppm	1/10 W	No	___	Mismatch on tolerance (tighter) and TCR
WA06X1002FTL	Resistor array, 4 in 0603	array	1 percent	100 ppm	1/10 W	No	___	Mismatch: four resistors in one package
WR08X1002FTL	General purpose	0805	1 percent	100 ppm	1/8 W	Yes	___	Mismatch on case; same value and tolerance

Leave the incumbent column for your own part. The stocked rows come from our snapshot and the other rows are factory orders. Confirm TCR, power and the full tolerance statement against the Walsin datasheet. For the general purpose WR family we hold the sheet ASC_WR_V24, dated September 2016, which is ten years old. Our post on chip resistor power rating by case size covers the rated-power side.

What do we hold in stock, and what do we not hold for HVAC?

Three 10 kilohm lines and no HVAC documents. We counted our stock list as at 23 September 2026, 1,125 part numbers: 3 of the chip resistor lines hold 10 kilohm, all general purpose WR parts at 1 percent, in 0201, 0603 and 0805, and none of the 28 Walsin datasheets we hold, 451 pages, contains the words heat pump, HVAC, thermostat or refrigerant.

A part on this list is not an HVAC-qualified part, and we make no appliance-safety or temperature-sensor claim for any of them. The 0201 line, WR02X1002FAL, is rated within 200 ppm, looser than the 0603 and 0805 lines. The stock list is a dated snapshot and moves. The ready stock page shows what is held in Hong Kong now, and we quote part-number counts, never piece counts.

How can Venatech help a United States heat pump maker?

By crossing the resistor you have already chosen, stating the differences, and telling you what is missing. Venatech Limited is an authorised Walsin distributor in Hong Kong. Walsin is our only authorised line, and the other lines we supply are Stackpole and Viking.

• Cross-reference. Paste your incumbent number into the free cross-reference tool, which decodes 18 manufacturers’ part numbers across 800,000+ crossable parts, and read each Walsin candidate with match and mismatch stated field by field.
• BOM check. Upload a control-board bill of materials to /bom/ and have each line checked against the same engine.
• Ready stock. The ready stock list is a Hong Kong snapshot dated 23 September 2026, never live-synced.
• Service. Hong Kong-based, small lots, cross-referencing help, and a quote requested through the site. Our address is Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong, telephone (852) 2628 4777.

A worked example from our own export: a 10 kilohm, 1 percent, 0603 divider resistor maps to WR06X1002FTL if 100 ppm is enough, and to WF06K1002FTL or WK06K1002FTL at 50 ppm, which are factory orders. Our chip resistor range lists the families. Confirm against both datasheets and qualify in your own circuit.

The short version

AHRI’s February 2026 tracker had heat pump shipments up 16 percent. A 10 kilohm 0603 divider resistor has 34 Walsin parts at 1 percent, 24 at 100 ppm and 3 at 50 ppm, and only the 100 ppm WR06X1002FTL is on the shelf. None of the 28 datasheets we hold names a heat pump.

Send us the thermistor divider from one control board and we will return the Walsin parts with the differences stated. If your error budget cannot spend 0.6 percent on a resistor, which family are you really buying?

Sources

Fetched 22 October 2026. The market statements above are taken from these pages; the part data comes from our own Walsin export and stock list.

• ServiceMag, “Heat Pump Shipments Climbed 16% in February as A/C Volumes Slid Again” (AHRI data), 24 April 2026: https://www.servicemag.org/news/heat-pump-shipments-february-2026-ahri
• ACHR News, “A2Ls Advance Despite Regulatory Uncertainty”, 27 March 2026: https://www.achrnews.com/articles/166001-a2ls-advance-despite-regulatory-uncertainty

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Frequently asked questions

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