What does this expansion tank annual checklist cover?

13 items across 4 sections, covering pre-charge, bladder integrity, shell, connection and air vent, return to service. Each item spells out what the person walking the job is actually looking for, not just a box to tick.

Who should run this inspection?

The plumbing service tech on the annual service, with the tank isolated and the water side relieved so the pre-charge can be read cold.

When in the schedule should this walk happen?

Once a year, the only pass where the tank is actually isolated and gauged rather than judged by tapping, and re-charged to match the current system pressure.

Why do these items ask for a photo?

6 of the 13 items call for photo evidence, 7 photos in all. A checklist answer without the photo is a claim; the photo is what makes the record worth something in a dispute and lets a reviewer approve work without re-walking the job.

What most often fails an expansion tank annual inspection?

Pre-charge read with system pressure still on the tank, giving a meaningless number and leaving the tank set wrong for another year. Tank re-charged to a generic figure instead of the actual system fill pressure at that tank's height, so it still can't take up expansion properly.

Can I use this checklist in RTI?

Yes. Start a free RTI workspace, build this list as a checklist, and the Photo Gate holds the submit button until every mandatory item is answered and its photos are attached. Approved inspections roll into a branded turnover package with a tamper evident audit trail.

Free checklist

Expansion tank annual maintenance checklist

The annual expansion tank service is the deep pass: the measurements, cleanings and tests a quarterly round doesn't reach. This checklist keeps the full service on record with the photos that make it defensible later. Work is commonly verified against manufacturer's published instructions. Confirm the edition your authority having jurisdiction has adopted.

Start free with this checklist Download as PDF

The checklist

Every item, and the photo evidence it needs

The photo count on each row is what RTI would require before the item can be submitted. Work the list here and watch the gate hold, or load it into RTI and let it enforce the real thing.

Pre-charge

Tank isolated and water side relieved before gauging
Tank valved off from the system and its water pressure bled down so the air pre-charge is read with no system pressure fighting the gauge.
No photo
Isolation valve tag hung while the tank is off line
Tag hung on the closed tank valve, the heat source held off or the loop held at steady temperature while the tank is out, and anyone near the relief discharge warned.
Air-side gauge checked against a reference before charging
The air-side gauge compared with a second or calibrated gauge before the charge is adjusted, since a gauge that reads off sets every tank it touches wrong.
No photo
Pre-charge set to the system fill pressure
Air pre-charge measured and adjusted to match the system's cold fill pressure at that location per the published instructions, then re-checked after adjustment.
No photo
Plain steel tank drained and air cushion restored
On a plain steel tank, the tank drained through its drain fitting to let air back in, then refilled until the gauge glass shows its normal marked level.
No photo

Bladder integrity

Bladder proven intact under charge
Air valve holds the set pre-charge and blows clean air with no water, confirming the bladder is separating air from water rather than passing it.
No photo
Drained water checked for sediment and rust
Water drained from the tank side looked at for rust, scale or sediment, which points to corrosion inside the shell or debris loading the bladder.

Shell, connection and air vent

Shell, tapping and any air vent serviced
Shell and seam free of corrosion under a close look, connection re-sealed and supported, and any automatic air vent on the tank tapping proven to seat and not leak.
Nameplate rating checked against the system relief setting
Rated working pressure and temperature on the tank nameplate confirmed above the system relief valve setting and the loop's operating temperature.
Air control piping checked on a plain steel tank
On a plain steel tank, the air control fitting and piping from the air separator slope up to the tank and are clear, so separated air reaches the cushion.
No photo

Return to service

Tank reopened to the system and tag removed
Isolation valve fully reopened by the person who tagged it and the tag removed, with the system gauge back at fill pressure and the tank on line.
System pressure checked at operating temperature after service
Gauge near the tank read once the loop is back at operating temperature; the rise from fill pressure sits within the design range and the system relief stays dry.
Annual tank record filed with the owner
As-found and as-left precharge, nameplate data, sediment findings and any replacement recommendation filed with the owner on the tank record.
No photo

What usually sends this back

The failures are almost always the evidence, not the work

Pre-charge read with system pressure still on the tank, giving a meaningless number and leaving the tank set wrong for another year.
Tank re-charged to a generic figure instead of the actual system fill pressure at that tank's height, so it still can't take up expansion properly.

Common questions

6 answers

What does this expansion tank annual checklist cover?: 13 items across 4 sections, covering pre-charge, bladder integrity, shell, connection and air vent, return to service. Each item spells out what the person walking the job is actually looking for, not just a box to tick.
Who should run this inspection?: The plumbing service tech on the annual service, with the tank isolated and the water side relieved so the pre-charge can be read cold.
When in the schedule should this walk happen?: Once a year, the only pass where the tank is actually isolated and gauged rather than judged by tapping, and re-charged to match the current system pressure.
Why do these items ask for a photo?: 6 of the 13 items call for photo evidence, 7 photos in all. A checklist answer without the photo is a claim; the photo is what makes the record worth something in a dispute and lets a reviewer approve work without re-walking the job.
What most often fails an expansion tank annual inspection?: Pre-charge read with system pressure still on the tank, giving a meaningless number and leaving the tank set wrong for another year. Tank re-charged to a generic figure instead of the actual system fill pressure at that tank's height, so it still can't take up expansion properly.
Can I use this checklist in RTI?: Yes. Start a free RTI workspace, build this list as a checklist, and the Photo Gate holds the submit button until every mandatory item is answered and its photos are attached. Approved inspections roll into a branded turnover package with a tamper evident audit trail.

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Run it with the Photo Gate

A checklist nobody can submit half-finished

Load this list into RTI, stick a QR tag on the area it covers, and the submit button stays locked until every mandatory item is answered and the 7 required photos exist. Approved walks roll into a branded turnover package with a tamper evident record behind every line.