How long will an EcoFlow DELTA Pro Ultra run a gas combi boiler?
About 2.4 days — 2 days 11 h typically, from 2 days 7 h in the worst case to 2 days 14 h at best. That assumes a gas combi boiler pulling 85 W for 60% of the time (average 51 W), plus the station's 25 W AC mains socket overhead — 76 W in total out of 4,465 usable watt-hours.
Note how much of that draw is the station rather than the appliance: 33% of the energy goes on keeping the inverter awake. On a load this small, the idle draw matters more than the capacity does.
Before you rely on it
The battery is the easy part. Most boilers are wired into a fused spur with no plug, and some will not light on a station's floating output because they sense the flame through earth. The boiler guide explains both problems and who can fix them.
The numbers
| Setup | Average draw | Cautious | Typical | Best case |
|---|---|---|---|---|
| 1 × gas combi boiler, UK 230 V | 76 W | 2 days 7 h | 2 days 11 h | 2 days 14 h |
| 2 × gas combi boiler, UK 230 V | 127 W | 33 h 5 min | 35 h 10 min | 37 h 14 min |
| 1 × gas combi boiler, US 120 V | 76 W | 2 days 7 h | 2 days 11 h | 2 days 14 h |
- 7.3 nights of eight hours, or 2.45 days of continuous running.
- Usable energy: 4,465 Wh of the 6,144 Wh on the box, after chemistry, inverter losses and the reserve.
- To keep it going for a full 24 hours you would need about 2,510 Wh of rated capacity — which this station has.
- Start-up: the gas combi boiler asks for 85 W at switch-on against this station's 11,200 W (230 V) / 14,400 W (120 V) peak — comfortable.
Buy the EcoFlow DELTA Pro Ultra
Where to buy
Amazon and approved-programme links are affiliate links; the site may earn a commission at no extra cost to you. Links marked “official site” are untracked. Prices and stock change constantly — check before you buy.
If this is for a power cut
Heating is what a battery does worst. In a power cut, warming people rather than rooms goes much further, and none of this needs a socket.
Without a power station: a 20,000 mAh power bank runs a USB heated throw for about 7 h 24 min. See the power bank numbers.
Hot water bottle and a vacuum flask. Boil water while you still can, keep it hot in a flask, and refill the bottle through the night.
Look for: A bottle made to BS 1970 in the UK, and a flask of a litre or more.
Hand warmers. Air-activated packs give hours of heat with no power at all, and a pocketful helps children and older relatives.
Look for: Long-duration packs, and the expiry date on bulk boxes.
Amazon links are affiliate searches for a type of product, not endorsements of a model; the site may earn a commission at no extra cost to you.
More: How to keep warm in a power cut, and the power cut essentials list (US edition).
What changes the answer
| If instead… | Typical runtime | Change |
|---|---|---|
| The pack is two years old | 2 days 6 h | -8% |
| The pack is five years old | 47 h | -20% |
| It is −10 °C outside | 2 days 2 h | -15% |
| You run it flat, no reserve | 2 days 17 h | +11% |
| You keep 20% back | 2 days 4 h | -11% |
The gas makes the heat, so a battery only has to run the fan, pump and controls. Most boilers are wired into a fused spur rather than a plug, and some will not light on a station’s ungrounded output — read the boiler guide before relying on it.
If you need it to run longer
Nothing in this catalogue runs a gas combi boiler for twice as long as the EcoFlow DELTA Pro Ultra. Either it is already near the top of the range, or this appliance is beyond what portable batteries do well — see the gas combi boiler page for the full ranking.
Smaller options that still work
| Station | Wh | Typical | Weight | Indicative price |
|---|---|---|---|---|
| Jackery Explorer 5000 Plus | 5,040 | 2 days 5 h | 61 kg | — / $3,499 |
| Zendure SuperBase V4600 | 4,608 | 47 h 10 min | 53 kg | £2,999 / $4,999 |
| Goal Zero Yeti PRO 4000 | 3,993 | 42 h 4 min | 52.5 kg | — / $4,000 |
| EcoFlow DELTA Pro 3 | 4,096 | 41 h 56 min | 51.5 kg | £2,799 / $3,199 |
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