HVAC Inventory Management: Parts, Truck Stock, and Reorder Points
The short answer: Good HVAC inventory management splits stock into two locations, the warehouse and each truck, sets a reorder point for every part so you restock before you run out, and costs parts at their average cost so job margins are accurate. The reorder point formula is Reorder point = (average daily usage × lead time in days) + safety stock. CRMb tracks stock per truck and per warehouse, alerts you when a part drops below its reorder point, and applies each part's average cost to the job it goes on, so a capacitor pulled from the van shows up in that job's margin.
Nothing kills an HVAC day like driving back to the shop for a part, or worse, discovering the truck is out of a common capacitor on a no-cool call in July. Inventory management is not paperwork; it is whether your tech fixes the system on the first visit. This guide covers the two-location model, how to set reorder points that actually hold, and how to keep parts costed correctly on every job.
Why HVAC inventory is harder than a stockroom count
HVAC inventory is difficult for three reasons that a simple shelf count ignores.
First, your stock moves. Most of it lives on trucks that are scattered across the service area, not on a shelf you can walk past and eyeball. Second, demand is seasonal and spiky, run capacitors and contactors fly off the trucks in a heat wave and sit quietly in spring. Third, a single missing part has an outsized cost: a $12 capacitor you do not have turns a one-hour call into a two-visit job with a second trip charge you often eat.
The fix is a system that knows what is on each truck, tells you when to reorder before the shortage, and ties every part to the job it was used on.
The two-location model: warehouse and truck stock
Stop thinking of inventory as one pile. HVAC stock lives in at least two kinds of place, and they play different roles.
- The warehouse is your bulk reserve and the source for restocking trucks. It holds depth: cases of common parts, seasonal build-ups, and the slower-moving items you do not want on every van.
- Each truck is a working set sized for the jobs that truck runs. It should carry enough of the high-frequency parts to complete most calls without a shop trip, and little of the rare stuff.
When a tech uses a part off the truck, the truck's count drops. When the truck restocks from the warehouse, that is a transfer, stock moves from one location to another without changing what you own. Tracking transfers is what keeps both counts honest. CRMb's inventory is multi-location by design: warehouse and each truck are separate stock locations, and moving parts between them is a recorded transfer, so you always know what is on which van. For a deeper look at organizing the van, see truck stock inventory for field techs.
Set a reorder point for every part
A reorder point is the stock level that triggers a restock. Hit it, and you reorder before you run out, accounting for how long the supplier takes to deliver. The formula:
Reorder point = (average daily usage × lead time in days) + safety stock
Work an example on a common run capacitor:
- Average daily usage: you go through about 2 per day across the fleet in season.
- Lead time: your supplier delivers in 5 days.
- Safety stock: you keep a 5-unit buffer for a bad week.
Reorder point = (2 × 5) + 5 = 15. When your capacitor count hits 15, you reorder. That 15 covers the five days of delivery lead time (10 units) plus a cushion (5 units) so a busy stretch does not leave you empty.
Set reorder points seasonally. The summer usage rate for capacitors is not the spring rate, and a reorder point built on annual averages will leave you short in July and overstocked in October. For the full method, see reorder points and low-stock alerts.
Standardize truck stock with par levels
A par level is the target quantity of a part a truck should carry. Set pars once, restock each truck back to par on a schedule, and every van becomes predictable. A starting point for a residential service truck:
| Part | Warehouse par | Truck par |
|---|---|---|
| Run capacitors (common sizes) | 40 | 8 |
| Dual-run capacitors | 30 | 6 |
| Contactors | 25 | 5 |
| Hard-start kits | 15 | 3 |
| Float switches / safety switches | 20 | 4 |
| Common thermostats | 12 | 2 |
| Refrigerant (by the pound) | bulk | job-based |
These are illustrative, your pars come from your own usage. The discipline is what matters: restock trucks to par on a set day each week, and the guesswork disappears. A tech who knows the van always leaves the shop at par stops hoarding parts "just in case," which is what makes fleet counts drift in the first place.
Cost parts at average cost, or job margins lie
When you buy the same part at different prices over time, which price do you use when it goes on a job? The answer for most HVAC shops is average cost, the running weighted average of what you have paid.
Say you bought 20 contactors at $9 and later 30 at $11. Your average cost is ((20 × 9) + (30 × 11)) ÷ 50 = $9.80 each. When a tech pulls one for a job, it is costed at $9.80, your true blended cost, not the oldest or newest price. CRMb tracks average cost per part automatically and applies it when the part is added to a job, so the reports view shows real material cost and therefore real margin. Cost parts at retail or at a stale price and every job's profit is wrong.
Keep counts honest with barcode scanning
Manual counts drift the moment a tech grabs a part and forgets to write it down. Barcode or QR scanning closes that gap: scan a part as it comes off the truck onto a job, or as it is received into the warehouse, and the count updates without anyone typing. CRMb supports barcode and QR scanning, so receiving a delivery or logging a part to a job is a scan, not a spreadsheet entry. Fewer keystrokes means counts you can trust, which is the whole point of tracking inventory at all.
Close the loop: from low-stock alert to purchase order
The payoff of reorder points is that restocking becomes automatic instead of reactive. When a part drops below its reorder point, you get a low-stock alert. From there, the right workflow is: alert, purchase order to the supplier, receive the delivery back into warehouse stock.
CRMb's purchasing side turns a low-stock list into a purchase order you email to the supplier, then receives the delivered parts back into stock at their real cost, which updates the average cost automatically. That is the full circle: usage drives the reorder point, the reorder point triggers a PO, the PO restocks the warehouse, and the warehouse restocks the trucks. No part of it depends on someone remembering.
Frequently Asked Questions
How do I calculate a reorder point for HVAC parts?
Multiply the part's average daily usage by the supplier's lead time in days, then add a safety-stock buffer. For a capacitor used twice a day with a five-day lead time and a five-unit buffer, the reorder point is 15. Recalculate seasonally, because HVAC usage swings hard between peak cooling season and the shoulder months.
What should I keep as truck stock on an HVAC van?
Carry enough of your highest-frequency parts, capacitors, contactors, hard-start kits, float switches, common thermostats, to finish most calls without returning to the shop, and little of the rare items. Set a par level for each part and restock each truck back to par on a set schedule. The exact quantities come from your own usage data, not a generic list.
How should HVAC parts be costed for job costing?
Use average cost, the weighted average of what you have paid across purchases, so a part that was bought at several different prices is costed at your true blended cost when it goes on a job. Costing at retail or at a single stale price makes every job's material cost wrong. Software that tracks average cost applies it automatically as parts are used.
What is the difference between warehouse and truck inventory?
The warehouse is your bulk reserve and the source for restocking trucks; each truck is a working set sized for the jobs it runs. Moving parts from the warehouse to a truck is a transfer, it relocates stock without changing what you own in total. Tracking transfers is what keeps both the warehouse and each truck count accurate.
Do I need inventory software for a small HVAC business?
Once you are running more than one truck, spreadsheets stop keeping up, counts drift, seasonal reorder points are hard to maintain, and parts go uncosted. Software that tracks stock per location, alerts you at reorder points, and applies average cost to jobs removes the manual work and keeps margins honest. For a single tech with one van, a careful spreadsheet can still work.
Getting started
Start with one truck: list the parts it carries, set a par level and a seasonal reorder point for each, and decide your safety stock. Do that for your busiest van and you will already stop the most expensive shortages.
CRMb tracks HVAC stock across your warehouse and every truck, alerts you before a part runs out, and costs each part at average cost on the job it goes on, so your margins reflect the real cost of parts. It runs on Mac, iPad, and the web. Start free and get your truck stock under control.