Gas Multipoint Water Heaters

Gas multipoint water heater – What are they, and what are the benefits? A gas multipoint water heater is a gas fired water heater that heats domestic hot water instantaneously to multiple points around your home or building – thus the term “multipoint”. These energy efficient multipoint water heaters allow you to connect the water heater to a number of hot water outlets throughout your property or home or even a commercial building.

This type of hot water system, provides a simple and proven solution for providing instantaneous domestic hot water on demand, without the need of a cylinder and a gas boiler. These gas fired water heaters, which are available in either natural gas or propane (LPG) are simple, reliable and a lot more effective than instantaneous electric water heaters, which can’t transfer the heat to the water, like a gas fired unit can.

Some people may refer to these units as an instant on gas water heater, instant gas water heaters,gas hot water heaters or a gas instantaneous water heater. These terms all apply to our multipoint gas-fired water heaters.

Instant gas water heaters or continuous water heaters are also an energy saving solution to more traditional hot water storage systems, as they only heat the water when its required, saving not only energy itself, but also wasted energy costs as well. These facts have made multipoint water heaters not only the users gas instantaneous water heater of choice, with great user comfort, but also the plumbers / heating installers choice as well.

What are the benefits of Gas Fired Multipoint Water Heaters?

High performance mains water pressure to all hot water outlets with our on-demand water heaters

 

ErP Class “A” energy efficiency for your domestic hot water requirements with our gas instantaneous water heater range

 

Tankless -no hot water cylinder required -Tankless water heater systems are far more energy efficient than storage

 

Low NOx gas fired water heaters – less polluting and better for the environment

 

High hot water flow rates of up to 29 litres per minute with a water temperature rise of 33 Degrees C

 

Natural Gas & LPG product versions of these instant hot water heaters are available

 

Internal and Externally mounted gas hot water heater versions are available – External gas water heaters are detailed on their own dedicated webpage here – External gas water heater range

 

These gas fired multipoint water heaters are suitable for domestic and commercial applications such as domestic properties, cafes, pubs, restaurants ,offices or shops

 

Modular – Flexibility of usage – multiple water heaters can be used to supply greater hot water demands, in cascade.

 

The gas heaters are simple to install and maintain in any small or limited space location.

 

Condensing or non condensing gas fired water heaters ?

For a gas water heater to condense, the water coming into the contact with the heat exchanger, must be under the dew point of 54°C or lower for natural gas – as you can see from the chart below on this webpage – the maximum incoming cold water temperature , even in the height of summer is 20 Degrees C  for the UK ,meaning you’re going to have the water heater operating in the condensing mode all year round ! . This means energy savings 12 months a year.

Thus, this gas fired condensing water heater process will deliver up to 105% net thermal hot water efficiency – making them the most energy efficient gas water heater on the market, resulting in significant energy savings when compared to conventional non-condensing gas fired water heaters.

Should you wish to operate the multipoint water heaters in a secondary hot water return system, which normally flows at 60 Degrees C, then there is still a good chance that the return water temperature will come back into the water heater lower than 54 Degrees C, and condense.

Ultimately, condensing multipoint water heaters just make perfect sense. They are slightly more expensive than non-condensing water heaters, but that price is warranted with lower running cost, and lower impact on the environment.

We do however, produce one gas hot water heater, which is a non-condensing water heater for the cost conscious, our “SF Low NOx Evolution” model, which is available with an output of 24 kW. This has been a very popular model for the domestic / caravan water heater market, although most consumers can now see the benefit of the condensing hot water heaters, with the market moving towards this type.

Factors to consider when selecting / sizing your gas multipoint water heater

There are three important factors to consider when selecting the correct gas fired multipoint water heater for your requirements. These are –

Flow rate 

This is the amount of warm water the heater will produce and directly related with the temperature rise that the water heater is required to achieve (more on this in point 2). You basically need to cover the flow rates of your hot water appliances – for example –

A standard shower head has a hot water demand of 7 or 8 litres a minute, although European Water Label (which is an organisation designed to aid governments in their quest to reduce water consumption, save energy and save money) “green band” shower heads have a demand of 6 litres a minute. Think of this standard as an “ErP” rating for hot water bathroom products, taps etc for domestic properties.

 

Please be aware drench showers – can have some huge flow rates from 15 litres to pretty much any flow rate – 30 litres per minute is not uncommon.

Kitchen sink taps – 4 to 6 litres per minute

Sink taps – 4 litres per minute – standard type.

Basin / cloakroom “spray taps” – 2 litres per minute – these water saving spray taps, are very popular now, as they save water and energy requirements.

Bath mixer taps – modern bath taps have an approximate demand rate of 12 Litres per minute.

So by adding all your potential hot water outlets and then applying a diversity factor (a factor that not all the hot water outlets will be used at the same time), you can calculate your hot water demand.

Water Heating – Temperature rise 

The temperature rise that the gas multipoint water heater has to achieve. This is also known as T ° variation or delta T which when abbreviated looks like this “ΔT”. Quite simply the amount of hot water produced by any multipoint hot water heater, is directly affected by the temperature rise of the hot water required. An example of this is –

If you set the hot water temperature to 35 ° C and the cold water entering the multipoint water heater is 15 ° C, then you have a variation of temperature or delta T  of 20 ° C (35 ° Degrees C minus 15 ° Degrees C),then you may have a maximum hot water flow rate of 20.66 litres per minute from one of these gas fired multipoint water heaters. Alternatively, if the appliance was set to a desired hot water temperature of 40 ° C, then the temperature rise or delta T would be 25 ° C (40 °- 15°) then the maximum flow would decrease to 16.53 litres per minute. 

In essence, it’s just a simple matter of the law of physics – the larger / more powerful the multipoint water heater, the greater the flow rate of hot water. This is especially true , when in the winter months , as the cold water entering temperatures drops, and this is an important to consider in an northern European climate.

Mains cold water temperature for the UK

The incoming mains cold water temperature for the UK, for various regions is as follows –

We have two sources of information here –

Please use whatever data your comfortable with, but we are more inclined to use the first data chart below.

 

 

Below on the following chart , in the blue line , you can see the average cold water temperature for the UK , over the period of one year.

 

The above chart shows the coldest water temperature in January at around 5 Degrees C – Source TUV

Gas Capacity

You need to ensure you have the gas supply to power the instant hot water heater – for example a standard U6 gas meter, fitted to typical household has the ability to  supply up to 65 kW of appliances. The distance from the gas appliances to the meter may have a bearing on whether you need a larger meter, because the gas pressure drops over the distance travelled.

Even our largest gas multipoint water heater, has an kW input rating of 50 kW, so generally this natural gas hot water heater can be used with a U6 gas meter, subject to the conditions mentioned above.  

Multipoint water heater range

We do both a domestic multipoint gas water heater and a commercial multipoint gas water heater range, both of which have great temperature control

 

Unlike a lot of our competitors, which tend to quote the flow rates of their multipoint water heaters at a 25 Degrees C temperature rise (i.e. summer working conditions) , we are more than proud to publish our performance data at many different temperature increases , as there may be applications – such as commercial kitchens or other applications which require the water to be produced at higher temperatures, such as industrial hot water systems.

First our Low NOx non condensing instant hot water heater – For domestic properties only – designated the SF14 model 

• Wet chamber copper exchanger that prevents thermal inertia; With large 16mm diameter water ways – so it benefits from very low pressure drops, guarantees lower risks of clogging, greater thermal efficiency, and greater ease of cleaning for this multi point gas water heater.
• Self-diagnostic electronic board.
• Hot water temperature setting range from 35°C to 60°C
• Ease of access and maintenance.
• Possibility of integration with other renewable energy source (e.g., solar panels)
• Possibility of remote shutdown.
• Reduction of initial overtemperatures with low withdrawals:
• Degree of electrical protection: IPX4D;
• Very low NOx emissions, maximum 50 mg / kWh.

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60	Flow rate
SF14 Low NOx water heater	15.82	12.65	10.54	9.04	7.91	6.33	5.27	Litres/min
	949.2	759	632.4	542.4	474.6	379.8	316.2	Litres/hour

 

Download the SF14 Low NOx gas fired water heater manual Flexiheat UK

for any locations or buildings prone to freezing temperatures such as a barn, outhouse, shepherd hut etc- then we highly recommend our electrical heating kit for our SF14 water heater, which will protect the water heater from freezing down to a temperature of minus 10C.

Freeze protection kit for SF14 Water heaters to minus 10C -Part number  50-00106

Condensing gas multipoint water heater range

We do five models – that are condensing water heaters, which must be fitted in commercial applications due to recent building regulation changes – see this webpage for more details – condensing water heaters legislation for the UK 2022

All these gas instantaneous water heaters are available in either a natural gas hot water heater or an LPG gas hot water heater configuration.

The 28kW and 34 kW units come as two options , these being

“SFC” models have no internal pump – so are used for direct on demand water heating systems – with no DHW recirculation.

or

“SKF” models which have an internal pump for DHW return systems – that are often required in larger water heating applications, as per the diagram below

 

SFC /SFK28 Gas Fired Multipoint Water Heater – Condensing -Tankless

Hot water temperature setting range from 35°C to 60°C

 

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60		Flow rate
SFC / SFK 28	20.66	16.53	13.78	11.81	10.33	8.27	6.89		Litres/min
	1239.89	991.91	826.59	708.51	619.94	495.96	413.30		Litres/hour

 

Download the SFC28 Gas water heater manual with no pump – Internal version

 

Download the SFK28 Gas water heater manual with pump – Internal version

 

SFC /SFK 34 Gas Fired Multipoint Water Heater- Condensing -Tankless

Hot water temperature setting range from 35°C to 60°C

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60		Flow rate
SFC / SFK34	25.09	20.07	16.73	14.34	12.55	10.04	8.36		Litres/min
	1505.40	1204.46	1003.72	860.33	752.79	602.23	501.60		Litres/hour

Download the SFC34 Gas water heater manual with no pump – Internal version

Download the SFK34 Gas water heater manual with pump – Internal version

 

SFK50 Gas Fired Multipoint Water Heater- Condensing – Tankless

NB: This unit is only available with a pump, which can be switched on or off depending on your system requirements, i.e., straight through on demand water heating or DHW recirculation system.

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60	Δt 75	Flow rate
SFK50	36.90	29.52	24.60	21.09	18.45	14.76	12.30	9.84	Litres/min
	2,214	1,771	1,476	1,265	1,107	886	738	590	Litres/hour

Please note the standard maximum water control temperature is 60 Degrees C, however we can also produce a higher temperature unit (at request), that can go up to 85C maximum – these units are often used in dairy or farming industry applications for the pasteurisation process, or used in other applications which require high temperature water for process applications or high temperature wash downs etc. 

Download the SFK50 Gas water heater manual with pump – Internal version

Controller options for these water heaters 

You can set the water temperature on the control panel of the water heater (which could be located in another room or area). However, should you wish the facility to change the water temperature without having to go to the water heater and manually adjust this, then we have a remote controller that you can site in your kitchen for example to boost the water temperature to 50 °C for dishwashing, which is the recommended water temperature for removing grease from cooking utensils and dishes.

The manual for this wired controller is here – 

Easy remote control manual for water heaters or boilers – wired type

LPG multipoint water heaters

Our range of multi point water heaters, are available in either natural gas or LPG Gas. LPG (Liquefied Petroleum Gas) is a gas that exists in a liquefied form, and is a very popular fuel for heating homes, and also in commercial applications such as caravan parks, leisure parks and any other locations where mains gas is not available.

Whilst LPG gas is the smaller proportion of our sales numbers for our gas multipoint water heaters, when compared to mains gas, it is still a significant number.

The most common LPG gas used for water heaters is propane, as this gas is ideal for outdoor use, as it is not affected by cold weather conditions that we can have in the U.K.

This gas has a classification of “G31 Propane”, and can either be stored in larger tanks or mobile cylinders.

Should you wish to run your gas fired multipoint water heater on (LPG) propane gas , we would recommend a bulk gas tank, however you can run these units of gas cylinders for example – a 47kg propane cylinder maximum continuous off take rate is per hour 32.94 KW, for water haters rated above this input, your LPG hot water heating system will require more than one and thus automatic changeovers valves sets are used.

We go into more depth on our LPG instantaneous water heater range here – LPG water heaters 

For the above reasons, our LPG gas multipoint water heaters are very popular in camping and caravan sites, for shower blocks or restaurants and with sports / leisure facilities, such as football and rugby clubs, again for showering facilities, as these water heaters can by used in multiples or in a cascade configuration to give its official name.

Instantaneous gas water heaters in cascade 

You can also bank up or cascade (to give it the official term) these instantaneous gas water heaters.

We specifically designed these “SKFG” high-efficiency condensing water heaters for larger hot water heating systems to produce instantaneous domestic hot water, either independently or in conjunction with a domestic hot water storage tank.

These instantaneous gas water heaters are a fully packed single piece unit, with either three 50kW water heaters in the 150kW water hater or four 50kW water heaters in the 200kW water heater, vertical floor standing configuration.

In this configuration we can supply up to 400 kW of instant hot water heating power with two 200kW units in cascade (we are working on a controller that can cascade up to 8 of these gas fired water heaters, either in natural gas (mains gas) or LPG for heating water for your properties demand.

 

Performance of these large instantaneous gas fired water heaters, with some incredibly high volumes of hot water flow rates is as follows  –

150kW Instant hot water gas fired water heaters

 

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60	Δt 75	Flow rate
SFKG 150	110.19	88.15	73.46	62.96	55.09	44.08	36.73	29.38	Litres/min
	6,611	5,289	4,408	3,778	3,306	2,645	2,204	1,763	Litres/hour

200kW Instant hot water gas fired water heaters

 

Water Temperature Rise	Δt 20	Δt 25	Δt 30	Δt 35	Δt 40	Δt 50	Δt 60	Δt 75	Flow rate
SFKG 200	146.92	117.53	97.94	83.95	73.46	58.77	48.97	39.18	Litres/min
	8,815	7,052	5,877	5,037	4,408	3,526	2,938	2,351	Litres/hour

We go into more depth on this range on the following dedicated webpage – commercial instantaneous water heater 

Hot water recirculation system

If you have lots of pipework runs from the water heater to various taps or showers, then a hot water recirculation system may be a system you would want to install.

You can install these gas fired water heaters in a hot water recirculation system, which provides the hot water to the fixtures i.e. the taps or showers in instant, without waiting for the water to get hot at the point of use, which can also be annoying.

Many studies have shown that –

• They conserve water – reduce the amount of water that goes down the drain while the user or homeowner waits for the desired temperature to be achieved.
• They save time – Recirculating water systems deliver hot water to taps quickly, adding convenience for the user.
• They reduce civil energy waste – The water companies use a lot of energy pumping and treating the water prior to it arriving at your property or building, which is wasted as the user waits for the tap or shower water to get to the desired temperature.

As a norm, the water in this type of system should be at 60 degrees C, and then blended down with temperature mixing valves at the point of use – normally 43 Degrees C maximum, for bathing use. This is to ensure that the water won’t scald the user.

Although there are some interesting systems, for potentially running the system at a lower temperature such as 43 Degrees C, using copper and silver water treatment or UV light to prevent Legionella. These systems can produce energy savings of 33% and carbon reduction of 24%. We can put you in touch with experts in this field.

Flue pipe options

You can use various flue configurations on these appliances, but the most common flueing option is the co-axial 80/125mm flue pipe configuration, which takes the combustion air for the unit from the external air of the building, and allows the products of combustion to be discharge to the outside environment.

The most common flue kit we supply is the horizontal version, depending on what model, you can flue the appliance up to 10 metres with a co-axial system or up to 60 metres if you use a split flue system i.e. one for combustion air and one for combustion gases in 80mm diameter.

 

The other option is the vertical co-axial flue kit, flue distances are the same.

 

Hopefully this web page gives enough information for you our customers, but for more information on our energy efficient tankless water heater systems products , which are manufactured in accordance with ISO 9001 and ISO 14001 as you would expect from any gas product manufacturer, or delivery times, to place an order ,get a price or to check stock then email us at the following email address : sales@flexiheatuk.com or give our sales team a call on 01202 822221.