External gas water heater range in LPG Propane or Natural gas

 

Our external gas water heater range consists of gas fired tankless water heaters that are instantaneous water heaters or continuous flow water heaters that have been designed to withstand the rigours of being externally mounted.

Also referred to as an outdoor gas hot water heater, outdoor on demand water heater, or an external water heater, our external gas hot water systems are available in either LPG (propane) or natural gas fired options.

This water heater range consists of continuous flow water heaters that can produce high volumes of domestic hot water at intermittent times that can be fitted on an external wall and are an alternative solution to installing a gas water heater in an internal space or location, which may have flue runs that are complex or impossible to achieve, have gas lines issues or internal space is not available.

They have lower operational costs because they are condensing gas water heaters being highly energy efficient.

With an exterior mounted tankless water heater, there is no risk of CO₂ poisoning happening from the gas water heater, as they are in the external free air environment being externally mounted.

Exterior tankless hot water heater

Our exterior tankless hot water heaters are available in both natural gas and LPG (propane)-powered options. They are condensing continuous flow water heaters with excellent flow rates and are far more efficient than older non-condensing water heater technology.

The condensing process ensures a low exhaust temperature range, as the latent heat is recovered and used to heat the water.

This means that they are around 16% more efficient than non- condensing units, reducing energy costs and operational costs whilst lowering your domestic hot water impact on the climate, with low NOx emissions.

Tankless water heaters for exterior installation

An outdoor gas hot water heater, which are tankless water heaters are traditional multipoint water heaters but with added features such as a IPX5D weatherproof rating casing, a frost protection system to prevent freezing of the water heater etc.

These factors as well as not having a tank means that tankless systems take up less room and there is less chance of water damage should the tankless unit every fail.

Tankless systems generally have a longer lifespan than traditional tank storage hot water systems. They are the preferred method to heat water now since they are significantly more efficient than storage systems as well as achieving space savings.

Hot water on demand outdoor water heaters

Being a gas fired outdoor on demand water heater, unlike a tank style water heater, they only produce hot water when there is a demand, heating water when required. This has the added advantage of reducing your hot water heating energy requirements and fuel bills.

Gas outdoor water heater range

We offer gas fired instantaneous condensing water heaters with powers of 28 kW, 34 kW, 50 kW and 100 kW in single units and up to 300 kW in cascade. Our stainless steel heat exchanger, which, by recovering the latent heat otherwise lost to the flue gases, achieves efficiencies of over 105% when producing domestic hot water.Heating water like traditional multipoint water heaters but with the added advantage that the unit is mounted on an external wall.

The water temperature settings range from 35°C to 60°C as standard for this gas outdoor water heater range,producing instant hot water at mains pressure.

Flow rates

Water flow rates for typical hot water fixtures –

Standard showers—7 or 8 litres per minute.

Be careful of drench-type showers—these can range from 15 litres to 35 litres or more.

Bath taps – 12 litres per minute

Kitchen sink taps—4 to 6 litres per minute.

Sink taps: 4 litres per minute—standard type.

Spray sink taps: 2 litres per minute.

You can determine how much hot water you need by adding up all your possible hot water outlets and then taking into account the fact that not all fixtures / hot water outlets will be utilised at the same time, i.e., a diversity factor.

Water temperature rise

You want DHW the most in the winter period.

Heating water generally to up to 40°C for bathing although for dishwashing you may require 50°C to remove grease from plates and cooking utensils etc.

In the winter months, generally the mains cold water temperature is the lowest at 10°C for the majority of the UK, but for Scotland this is 5°C. You shower or bathe at 38°C to 40°C. Thus, the temperature rise the unit must produce is known as T° variation or delta T, which when abbreviated looks like this: “ΔT”.

Therefore, we define a temperature rise as 30°C for the majority of the UK during the winter and 35°C for Scotland.

So, either “ΔT30” or “ΔT35,” depending on where the gas outdoor water heater is located.

In the summer months, cold water temperatures can get as high as 20°C for all of the UK, thus the temperature rise in this period required is only 20°C, i.e., ΔT20.

Both water heating periods are shown on our performance data below: Yellow: summer; red: winter.

28kW SFK Water heating performance data

Flow rates at various water temperature rise

Full technical details are in the following manual

Download the SFK28 Rain external gas condensing water heater technical manual

34kW SFK Water heating performance data

Flow rates at various water temperature rise

Full technical details are in the following manual

Download the SFK34 Rain external gas condensing water heater technical manual

50kW SFK Water heating performance data

Flow rates at various water temperature rise

Full technical details are in the following manual

Download the SFK50 Rain external gas condensing water heater technical manual

Internal pump

The internal pump allows various modes of operation, from continuous flow or draw mode to a DHW recirculation system. In cold weather conditions, the pump automatically switches on in either mode to protect the gas water heater from freezing. The unit automatically starts when the internal water temperature in the heat exchanger gets down to 5°C and lifts the water temperature up to 20°C in the exchanger. At this point, the pump operates for an additional 20 seconds in post-circulation mode.

Larger exterior tankless water heater range

We have 50kW or 100kW external or outdoor gas water heaters that are commercial gas water heaters; these tankless water heaters or instantaneous water heaters come pre-packaged and can be used in a cascade installation of up to 300kW of output. These are external water heaters, as they come complete with an ABS cover for outdoor installation and are weatherproof outdoor gas water heaters.

 

These gas water heaters, designated the “Modulo” range are floor standing external fas fired water heaters have either one 50kW or two “SKF50” water heater modules for the 100kW model withing the casing (see above water heating performance for the SFK50 heat exchanger), thus the 100kW external or outdoor gas hot water heater can produce a large flow rate of 49.2 Litres per minute with a 30C water temperature rise.  

These outdoor gas water heaters can be coupled up to a DHW storage tank (normally located internally within a building, although we can provide an external domestic hot water storage tank if so required) should you require a stored hot water volume, or they can be used in a continuous flow on demand mode.

Download the technical manual for the 100kW Modulo external / outdoor gas water heater unit here –

Modulo “SFK100” technical and installation manual – 100kW external floor standing gas fired water heater – Natural gas or LPG Propane fired

Product features

Our gas external water heaters all have the following features and benefits:

Large stainless steel heat exchanger – 28mm diameter

With a large diameter of 28mm, the stainless heat exchanger, which all models benefit from, offers the benefit of very low pressure drops, ensuring lower risks of clogging, greater thermal efficiency, and greater ease of cleaning.

Water temperature range

Adjustable domestic hot water temperature range is from 35°C to 60°C. At special request we can supply units with a higher temperature range of up to 85°C.

Low flue exhaust temperature range

Being a condensing gas water heater range the flue exhaust temperature range is low – between 35°C at minimal output and 50°C at maximum output, as the units are always in the condensing mode as cold mains water will always be below the 55°C required for condensation process to occur and maximize efficiency. This ensures that operational costs are permanently lower all year round.

Frost protection

As standard with our SFK outdoor gas tankless water heater range, when the temperature sensor detects a temperature below 5°C within the heat exchanger, the pump runs, and the burner lifts the temperature to 20°C. Upon reaching this temperature, the burner switches off, and the pump continues to run for 20 seconds as a post-circulation measure. This automatic system prevents freezing and any damage to the gas water heater as long as you have gas available down to minus 10°C external or outside air temperature.

If you require frost protection for areas that may see temperatures lower than minus 10°C, then we can supply an electrical frost protection kit, which requires a 1-phase, 240-volt electricity supply to operate, for these LPG (propane) or natural gas exterior tankless water heaters.

Enclosure or cover made for the rigours of outside mounting and weather conditions

The IPX5D-rated water heater corrosion resistant cover or enclosure, along with the internal insulation of the casing, provides better thermal and acoustic insulation, helping mitigate the effects of the weather conditions and providing a quiet tankless unit. This ensures greater flexibility at the design stage in selecting the location for externally mounting these water heaters, be it a house, flat, or even installing them for a shower block at a camping site or sports facility.

External LPG water heater

The most popular sellers in this range of outdoor water heaters are our external LPG water heaters. We have supplied these to glamp pods, shepherd huts, and shower blocks located in remote locations that have no natural gas mains supply available. Depending on the output of the outdoor gas hot water heater, it will dictate the size and quantity of LPG cylinders or LPG gas storage tank required.

Outside continuous flow water heaters for sale

If you’re looking for an outdoor gas hot water heater that can be used in a variety of settings, from a flat or house to a shower block, for domestic or commercial water heating applications, our external gas water heater /outdoor gas water heaters are the perfect choice.

Please contact us at 01202 822221 or use the website contact email form to get more information, prices or costs, check stock status and delivery or advice.