How Long Does a Boiler Service Take? Typical Duration, Steps, and Time-Savers

TL;DR

• Most standard domestic boiler services take 45-90 minutes if there are no faults.
• Combi boilers are usually fastest; older conventional systems and back boilers take longer.
• Add 20-40 minutes for dirty filters, sludge, or if the tech has to repressurise the expansion vessel.
• Repairs discovered during service can extend the visit by 30-120+ minutes, or be booked for another day.
• Clear access, hot water switched off beforehand, and the manual/service record ready can shave 10-20 minutes off the appointment.

If you’re trying to wedge a boiler service between the school run and a Zoom call, the big question is time. Will the plumber be in and out, or are we talking a half-day saga? Here’s the plain answer: a clean, modern boiler with easy access takes under an hour. A tired, neglected unit or a system with issues can push two hours or more. I live in Wellington and plan my boiler check the same way I plan around my son Thaddeus’s pickup-buffer a little time for surprises, and you’re fine.

Realistic boiler service times (by job and boiler type)

The most direct answer: a typical domestic boiler service is 45-90 minutes. That covers the safety checks, cleaning, flue test, and paperwork. Commercial plant, back boilers, or systems with tricky access take longer.

Quick decision guide:

• Annual service, boiler under 10 years old, no error codes lately: expect 45-75 minutes.
• It’s been 2-3 years since last service or there’s visible sludge in the filter: plan for 60-90 minutes.
• Old system, hard-to-reach cupboard, or flue that needs attention: 90-120 minutes.
• They find a fault that needs parts: either +30-120 minutes now or a follow-up visit if parts aren’t on the van.

In New Zealand, gas work must be done by a licensed gasfitter (per the Plumbers, Gasfitters and Drainlayers Board). Many plumbers are also licensed gasfitters, but not all. If yours is doing combustion tests, touching the gas valve, or opening the combustion chamber, they must be licensed. That’s not just red tape-licensed techs do the correct safety checks, which affects both time and peace of mind.

If you stumbled here searching how long boiler service because you’re juggling work and kids, here’s my rule of thumb: book a 2-hour window around the appointment. Most of the time, you’ll finish early and get your day back.

What the plumber actually does and what adds time

Knowing the steps makes the timing make sense. A thorough service is more than a quick vacuum and go. Here’s the typical flow for a standard residential gas boiler:

1. Arrival and briefing (3-5 min)
   You explain any symptoms-noises, pressure drops, intermittency. Good techs listen; this short chat often saves time later.
2. Safety and isolation (2-5 min)
   Power off, check gas tightness if indicated, and lay down protective sheets. In a tight cupboard, even moving stuff aside adds minutes.
3. Visual inspection (5-10 min)
   Look for leaks, rust, scorch marks, and signs of flue problems. Check ventilation if the boiler is in a cupboard.
4. Case off and internal checks (10-20 min)
   Inspect burner, heat exchanger, seals, electrodes, condensate trap. On older units, screws seize or panels stick-cue extra minutes and gentle persuasion.
5. Cleaning (10-20 min)
   Brush/vacuum the burner and heat exchanger, clear the condensate trap. Heavy sooting or scale means more time.
6. System-side checks (10-20 min)
   Expansion vessel pressure, PRV operation, pumps, valves, magnetic filter clean, inhibitor level. Recharging an expansion vessel adds time; so does sludge in the filter.
7. Controls and safeties (5-10 min)
   Thermostat, programmer, interlocks. If your home has multiple zones, testing each adds a few minutes.
8. Combustion test (10-15 min)
   Using a calibrated flue gas analyser to confirm CO/CO₂ ratios and combustion efficiency. If readings are off, adjustments and retesting follow.
9. Reassembly and leak check (5-10 min)
   New seals if required, torque checks, and a quick visual once everything is back together.
10. Run test and documentation (5-10 min)
    Boiler fired, radiators warming, hot water checked (for combi). You should get a service sheet with readings and notes.

Things that speed it up:

• Clear access to the boiler, airing cupboard, and flue termination.
• Heating and hot water switched off 30-60 minutes before arrival so the boiler is cool to handle.
• Service record and manual ready; Wi‑Fi available if the tech uses cloud forms.
• Pets secured, parking sorted, and a working outdoor tap if they need to rinse a filter.

Things that slow it down:

• Hidden boiler behind stacked storage, a locked cupboard, or a ceiling hatch without a safe ladder.
• Sludge-heavy systems, a neglected magnetic filter, or evidence of past leaks.
• Expired or perished case seals-the tech won’t run the boiler until these are safe.
• Out-of-range combustion readings; adjusting and confirming takes extra cycles.
• Finding faults that cross from “service” into “repair,” like a failing fan or sensor.

What’s included vs. extra, time-wise:

• Included in a standard service: safety inspection, cleaning accessible components, condensate trap, pressure/expansion checks, flue test, and paperwork.
• Often extra: full system balance, bleeding every radiator, chemical top-ups, replacing TRVs, fixing leaks, powerflushing, or swapping parts beyond small consumables (like gaskets).

Safety and compliance notes (NZ context):

• Gasfitting work must be by or under the supervision of a licensed gasfitter (PGDB).
• Combustion testing and flue checks align with NZS 5601 gas installation standards and manufacturer instructions.
• WorkSafe NZ expects adherence to safe isolation and verification; that adds a few minutes, and it’s time well spent.

Manufacturers like Bosch, Vaillant, and Baxi specify annual servicing for warranty and performance. Skipping years doesn’t “save time”-it stores up longer visits later.

How to prep, costs in NZ, FAQs, and what to do if it’s taking too long

If you want the visit to run fast and smooth, a little prep goes a long way. I book morning slots, get the house quiet after school drop-off, and pull the manuals. It’s boring, but it pays off.

Fast-prep checklist (10-15 minutes):

• Turn off the heating and hot water 30-60 minutes before the appointment so the boiler is cool.
• Clear 1-1.5 metres of space in front of and under the boiler; empty that utility-cupboard floor.
• Open access to the hot water cylinder, pump, and magnetic filter if you have them.
• Find the service record and manual; note any fault codes or odd noises you’ve seen.
• Make sure there’s parking and safe ladder access if the flue terminates in a loft or on a balcony.
• Keep kids and pets in another room. The fewer interruptions, the quicker it goes.

Typical NZ timing and cost context (2025):

• Standard domestic service: 45-90 minutes of on-site time.
• Travel + admin: many firms book a 1.5-2-hour slot to allow for traffic and paperwork.
• Costs: you’ll usually see a fixed service fee or 1-2 hours of labour at local rates, with small extras for gaskets or seals. Parts and bigger repairs are additional.
• Seasonality: April-June is busy ahead of winter. Lead times stretch, but service duration on-site stays about the same.

How to tell if a service is thorough (without dragging on):

• You see a flue gas analyser appear, and the tech records numbers (CO/CO₂, O₂, or efficiency).
• They remove and clean the condensate trap on condensing models.
• They check system pressure and expansion vessel pre-charge, not just the boiler casing.
• You receive a completed service sheet with readings, notes, and any advisories.

Red flags if it feels too quick:

• No combustion test on a gas boiler.
• They never removed the case to access required service points.
• No mention of seals, condensate, or flue integrity.
• No written record. If it isn’t documented, assume it isn’t done.

Mini-FAQ

• Do I need to be home the whole time?
  Yes. The tech will need access to radiators, controls, and possibly the cylinder cupboard. Plan for up to 90 minutes, plus a buffer if repairs pop up.
• Can they service the cylinder too?
  If you have an unvented cylinder, safety valve and expansion checks add 10-20 minutes. Some cylinders require a specialist-ask when booking.
• How often should I service a boiler?
  Annually. Manufacturers expect it, and it’s good practice for safety and efficiency.
• Will bleeding radiators be included?
  A quick bleed might be, but full balancing is usually extra and can take an hour or two depending on the system.
• What if they find a fault?
  If the part is on the van and you approve costs, add 30-120 minutes. Otherwise you’ll get a quote and a return visit.
• Is a powerflush part of servicing?
  No. It’s a separate, all-day job if your system is sludge-clogged or radiators are cold at the bottom.
• Is it safe to use the boiler right after?
  Yes-once the tech finishes testing and signs it off, you’re good to heat the house and run hot water.
• Why did my neighbour’s service take 30 minutes?
  Either their system was spotless and very new, or some steps got skipped. Under an hour is possible but uncommon if the full checklist is done.
• Gas vs. electric: does it change the time?
  Electric boilers skip combustion testing, so they’re often faster. Heat pump systems are a different ballgame altogether.

If it’s taking longer than expected

• Ask what they’ve found. A quick explanation should map to extra time-sludge, bad readings, perished seals.
• Request a time estimate for the added work and whether it’s today or another visit.
• If you’ve got commitments (school run!), ask them to make the boiler safe and return later for non-critical tasks.

How the season and scheduling play into time on site

• Busy season means less flexible appointment times, but the on-site job shouldn’t be rushed. If it feels rushed, ask them to run through their checklist.
• Early-day slots tend to be more punctual. Traffic and earlier overruns stack later in the day.
• If your system is noisy or pressure drops overnight, mention it when booking-some tests need cold-start conditions and can save a repeat visit.

Common time traps and how to avoid them

• Tight cupboards: measure the opening. If the case can’t come off, the tech can’t do a proper service.
• Forgotten keys: boiler locked behind a door or garage-have keys ready.
• Radiators without access: furniture against TRVs or lockshield valves slows bleeding/balancing.
• Noisy toddler meeting a toolbox: I get it-I’m a dad. Have a quiet corner prepared; it keeps the work flowing.

What a good service report includes (so you know the time was well used)

• Boiler details (make, model, serial) and the date/time.
• Gas tightness/combustion readings recorded with actual numbers, not just “OK”.
• Visual findings and advisories (e.g., seals aging, filter starting to clog, inhibitor low).
• Work done: cleaned heat exchanger, condensate trap, filter; checked expansion vessel; tested safeties.
• Any parts replaced and next due date for service.

If your system has extras, expect these time tweaks:

• Weather compensation or smart controls: +5-10 minutes to test and document.
• Multiple heating zones: +10-20 minutes to check valves and operation.
• Loft flue/access: +10-15 minutes to set up safe access.
• External boiler house: +5-10 minutes walking and securing.

Pro tips from the field:

• Book before winter: February-April usually has better availability, less rush.
• Tell the office your boiler’s make/model: techs can bring likely gaskets and seals, saving a second trip.
• Note error codes: a photo of the display or any flashing LED pattern helps the tech prep.
• Ask for readings: you don’t need to be an engineer; just keep the sheet. Trends over years tell a story.

Bottom line on time: plan for an hour, allow for two. If the job is done in 50 minutes with all checks documented, great. If it stretches because something’s off, that extra time is solving a problem you’d otherwise find on a cold night.