Low NOx Replacement Water Heaters from Lochinvar

Direct gas-fired water heaters have been providing hot water for many commercial and industrial buildings in the UK and Ireland for more than 40 years. Lochinvar Knight and Charger ranges were amongst the first of their type.

When it comes to replacing these products, Lochinvar would normally recommend that customers upgrade to condensing type water heaters, but this may not always be a practical option. The flue installation is often a major obstacle, as installing a condensing model to replace an atmospheric water heater will almost certainly mean that the existing flue installation will require replacement. This can add considerable cost and disruption, even when such replacements are part of an planned plant room refurbishment.

In many cases, the requirement to replace has a high level of urgency, and the main goal for building owners and managers is to restore their hot water supply as quickly as possible, and in the most cost-effective way.

As an established manufacturer of water heaters and boilers, the development department at Lochinvar has developed products over the years and improvements in efficiency and reduction in emissions has been a major priority.

Knight Low NOx water heaters

Launched in 2018, the Knight Low NOx range is particularly suitable for replacing existing water heaters. Four models are available with storage capacities ranging from 110 to 365 litres and hot water recovery rates from 140 to 290 litres per hour.

Charger Low NOx water heaters

The new Charger Low NOx range now provides models with higher storage capacities and have the ability to provide larger volumes of hot water over short periods. This is an important factor for many commercial buildings, which are subject to peak demand for hot water. The three-model range provide storage capacities from 294 to 351 litres and hot water recovery rates from 850 to 1600 litres per hour.

In all cases, hot water recovery rates published are based upon a temperature rise of 50ºC.

High output

The largest model has a nominal output of 89.9Kw; in terms of this type of water heater, we believe this to be the highest output currently available in the UK.

The replacement of existing water heaters often provides practical installation challenges; and especially when replacing products which may have been in situ for up to 20 years. To provide further flexibility we have three types of draught diverter available. The standard type has a vertical outlet to connect the flue, and there are two further options; a 45º outlet or a 90º degree. Either of these low level draught diverter options provide a good solution, particularly where there are headroom restrictions.

These draught diverter options also mean that Charger Low NOx water heaters are often suitable to replace water heaters from other brands.


Both Knight and Charger Low NOx water heaters comply with the most recent ErP legislation on NOx emissions; in fact, both ranges are comfortably within the maximum limit of 56mg/kWh.


All models are held in stock at our Banbury-based UK facility and standard delivery to most areas of the UK is 2 to 3 working days. We can often provide next-day delivery for particularly urgent requests, although an additional charge may be applied for this service

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