A vapor recovery unit that sat idle for weeks needs more than a start button. Fluids settle, seals take a set, and small issues that developed during idle show up in the first minutes of a restart. A staged approach catches them cheaply. This article lays out the checks before power-on, what to listen for at first start, and how to run the first week so the rest of the season stays quiet.
Before Power On
Check vacuum pump oil level and condition, look for condensate that accumulated in the unit during idle, and verify that isolation valves are in their correct positions. A visual pass through the vapor path, from intake to discharge, takes minutes and prevents most restart surprises.
Add a slow rotation check where the layout allows it: brief the power-off inspection with a look at coupling condition and belt tension (or drive alignment on direct-coupled units). Idle periods relax belts and let sets form in elastomers, and finding that before the motor spins costs nothing. The checklist for this stage stays short on purpose — it has to be done every time to work.
First Start Behavior
Run the unit briefly and listen. Bearing noise that appears only at restart often fades as lubricant redistributes; a noise that persists means a closer look before continuing. Watch vacuum build-up against the normal pattern recorded in the unit’s log.
Give the first start a defined end point: a short run, then a deliberate shutdown and a feel of the bearing housings, then the real start. Temperature found by hand right after a short run tells you more than a week of hoping. If the unit has a soft-start or minimum-load mode, this is the moment to use it.
Condensate Handling
Idle periods let condensate collect in low points. Drain lines and the condensate management section deserve a check before sustained running, since slug carryover on restart is one of the more common first-week issues.
The restart sequence for condensate-prone units follows a simple order:
| Step | Action | What it prevents |
|---|---|---|
| 1 | Drain all low points and pots | Slug carryover into the pump |
| 2 | Verify trap and separator levels | Liquid entering vapor lines |
| 3 | Short run, listen, feel, shut down | Running a fault into a failure |
| 4 | Log readings against last season’s close-out | Missing the drift that started over idle |
The First Week
Treat the first week of operation as a watch period: daily glance at pressures, temperatures, and recovered volumes against seasonal expectations. Units that pass their first week cleanly tend to run their whole season without drama.
Close the week with a written entry — readings, observations, anything adjusted. Next season’s restart begins with this note instead of a blank page, and each year the baseline gets sharper. The habit costs minutes; skipping it costs the only record of how this unit actually behaves.
Frequently Asked Questions
How long should the first run last?
Long enough to reach stable temperature and short enough that any developing fault stays cheap — typically minutes, not hours. The purpose is observation, not production. If everything reads normal, release the unit to normal service; if anything lags the old baseline, that gap is exactly what the first week is for.
Should oil be changed before or after restart?
Before, if the idle was long or the oil shows condensate haze; otherwise a verified level and condition is enough. Restarting on suspect oil puts water straight into bearing surfaces during the highest-load minutes the unit will see all season. When in doubt, change it — oil is cheap relative to a pump.
Do these checks apply to units that only idle for weeks, not months?
The same list, lighter application. Short idles still settle fluids and relax seals, just less. Keep the pre-power checks and the first-run listen; the week-long watch can shorten to a few days. What never changes is writing down what you saw — VOHON supplies vapor recovery units with commissioning and restart guidance, and our team supports seasonal startup planning. Contact us for start-of-season support.