# Should I use a hot water generator instead of a steam boiler for low-temperature heat?

Canonical: https://senseible.earth/answers/hot-water-generator-vs-steam-boiler-fuel

If your process needs water below about 90 °C, making steam and then cooling it back to hot water wastes fuel through flash, condensate and blowdown losses. A hot water generator heats water directly. Check your process temperatures first, then compare fuel per kilolitre heated.

## Where steam loses heat

- Flash steam and condensate not returned.
- Blowdown to control dissolved solids.
- Trap and line losses at higher temperature.

## When to keep steam

- Processes above water's boiling point, sterilisation or direct steam injection.
- Sites where one boiler already serves high-temperature users.

## How to compare

Fuel per kilolitre of water heated, before and after, from invoices or a meter. A heat pump may beat both for low temperatures; see the linked page.

## What Senseible does here

Senseible reads fuel invoices and electricity bills and applies IPCC 2006 factors and the CEA grid factor (0.710 kg CO2 per kWh), so you can compare Scope 1 and 2 before and after a change from the documents themselves.

- [CO2 per tonne of steam](https://senseible.earth/answers/co2-per-tonne-of-steam)
- [Hot water saved per kL](https://senseible.earth/answers/hot-water-saved-co2-per-kl)
- [Heat pump for process heat](https://senseible.earth/answers/heat-pump-for-process-heat-india)

Sources: [2006 IPCC Guidelines, Volume 2 Energy](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html), [Bureau of Energy Efficiency](https://beeindia.gov.in), [GHG Protocol Corporate Standard](https://ghgprotocol.org/corporate-standard)

Last reviewed 2026-10-22.