Resideo (Honeywell) TMVX-00108 Thermostatic Expansion Valve – R404A/R507A, External Equalizer, ±0…−50 °C, Interchangeable Orifice

Resideo (Honeywell) TMVX-00108 is an externally equalized (external equalizer) thermostatic expansion valve body for R404A / R507A (and R402A, R407B, R502). Evaporating range ±0 … −50 °C — the operating band of cold rooms, blast freezers and freezer display cases. The orifice is changed as a cartridge: depending on the cartridge selected, the same body serves from 0.36 kW to 15.8 kW (R404A).

Externally Equalized Body: Mandatory for Evaporators with Distributors and Multiple Circuits

An internally equalized valve "sees" the pressure at the evaporator inlet, an externally equalized valve the pressure at the outlet. If the evaporator has a liquid distributor, or the circuit is long and multi-pass, there is a significant pressure drop between inlet and outlet. Because an internally equalized valve cannot see this drop, it reads the superheat too high and starves the evaporator. The 7/16" UNF equalizer line of the TMVX is connected to the evaporator outlet; the valve opens according to the actual suction pressure and the capacity is fully used. Honeywell makes external equalization mandatory in systems with distributors.

Adsorption (combination) thermostatic charge. Even if the capillary tube and valve head warm up, the charge responds only to the temperature of the sensing bulb; therefore it operates stably in systems with hot gas defrost and in icy environments, without hunting. The same thermostatic charge covers all five refrigerants in the R404A group — when the refrigerant changes, the valve does not.

Technical Specifications (Official Honeywell Product Data EN0H-1900GE23)

• Model: Resideo (Honeywell) TMVX-00108 — valve body + sensing bulb clamp; orifice cartridge not included
• Type: thermostatic expansion valve, externally equalized, interchangeable orifice, no MOP
• Refrigerants: R404A · R507A · R402A · R407B · R502 (single thermostatic charge)
• Evaporating range: ±0 … −50 °C
• Max. pressure: PS 36 bar(a) · test pressure PF 39.6 bar(a)
• Connections: inlet 5/8" UNF · outlet 3/4" UNF (flare nut / flare) · equalizer line 7/16" UNF
• Capillary tube: 1.5 m · sensing bulb Ø12 mm · max. bulb temperature 140 °C
• Static superheat setting: ≈3 K (adjusted with the spindle; 1 turn ≈ 0.55 bar)
• Material: brass body · stainless steel thermostatic head and diaphragm (welded under shielding gas)
• Weight: ≈0.36 kg — official dimensional drawing in the 2nd image

Orifice Cartridge Selection — R404A Capacities

The capacity is determined by the cartridge, not the body. Official table conditions: t0 = +4 °C, tc = +38 °C, 1 K subcooled liquid. In low-temperature applications (−30 °C and below) the actual capacity falls below these values — choose the next larger cartridge.

• 🚨 A valve without an orifice does not pass refrigerant. Order the TMVD cartridge that matches your capacity together with the body; the cartridges are listed as separate products in our catalog.
• 🔧 Equalizer line: taken with 6 mm / 1/4" tube from the top of the suction line, after the sensing bulb. Leave a loop (overbow) so that oil does not escape into the line. A TMVX whose equalizer line is not connected or is clogged will not work properly at all.
• 🔧 Sensing bulb: on the upper half of the horizontal suction pipe, before, not after, the liquid trap; do not crush the bulb when tightening the clamp, and insulate it.
• 🔧 When tightening the flare nuts hold the body by its wrench flats; if a solder adapter is used, the body must not exceed 100 °C.
• If MOP is required (pressure limiting to protect the compressor at start-up), the MOP counterpart of this body is TMVX-00110 (MOP −10 °C). This model has no MOP; it is the version preferred in most cold room and freezer applications.
• Internally equalized counterpart: TMV-00012 for small single-pass evaporators without a distributor (same refrigerant group, same range).