Please see below for an overview of FlexEJ’s burgeoning domestic hot water solutions or just call us direct on 01384 881188 to talk to an DHW expert…
24hr Shipping
On all stock items ordered.
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Design & Manufacturing
Full in-house design & manufacture to EN / ASME / PED.
ISO14001 Accreditation
FlexEJ has an accredited Environmental Management System.
Domestic Hot Water
DHW Systems
We supply a range of products to help you build efficient and reliable Domestic Hot Water (DHW) Systems, for use with ASHPs, Hybrid systems, and typical boiler systems. Whether you’re installing a new system or upgrading an existing one, our high-quality products are designed to deliver optimal efficiency, safety, and durability from day one.
FlexEJ's DHW Solutions Overview
PhexPak
- Highly customisable
- Up to 1200kW
- Gasketed PHE
- PID Controller with BACnet
- Manufactured in the UK by FlexEJ
- Instantaneous & semi-instantaneous hot water
- Gasketed plate heat exchanger with control components
PhexPak Lite
- Highly customisable
- Up to 150kW
- Brazed PHE
- PID Controller with BACnet
- Manufactured in the UK by FlexEJ
- Instantaneous & semi-instantaneous hot water
- Brazed plate heat exchanger with control components
PhexStore
Skid mounted and pre-assembled hot water generation package, comprising of a PhexPak, Buffer Vessel, and all required unvented components.
- Highly customisable
- PHE combined with storage
- PID Controller with BACnet
- Unvented components included
- Manufactured in the UK by FlexEJ
- Semi-instantaneous hot water
- Plate heat exchanger with control components and storage
Buffer Vessels
High quality stainless steel DHW buffer vessels to add capacity to a hot water system to meet high peak demands.
- Range of standard sizes available
- High quality
- Sparge pipes included
- Bespoke sizes available
- Manufactured in the UK by FlexEJ
- Semi-instantaneous hot water
- 316 stainless steel
DHW Calculator
The FlexEJ Domestic Hot Water Calculator allows you to find the power required for instantaneous DHW or power plus storage volume required for semi-instantaneous DHW. The calculator provides packaged plate heat exchanger and buffer vessel selections, see here.
FlexEJ's DHW Solutions Comparison Table
- Power / Capacity
Power kW
The highest normally available power from your system’s heat source. - Instantaneous DHW flow Instantaneous DHW flow
The instantaneous DHW flow rate is based on the available power. If the instantaneous flow is insufficient either a higher power heat source is required, or storage must be added. - Rated Pressure
- Insulation Jacket
- Control valve Control valves
A 2-port valve is the most cost-effective solution and allows for a simple pipe layout. A 3-port valve provides better flow and temperature control by mixing recirculated water. A 4-port valve is best suited for applications requiring a low pressure drop. - Primary Pump Primary Pump
The primary pump in the heat exchanger package is optional. If the head required by the primary side of the packaged plate heat exchanger can provided by your system then a primary pump is not required. Otherwise, a primary pump in the heat exchanger package is required. - Secondary Pump Secondary Pump
The secondary pump in the heat exchanger package is optional. If the system is instantaneous you will require a recirculation pump and this can be included in the heat exchanger package if not provided elsewhere. If the system is calculated as semi-instantaneous (available power is less than power required for instantaneous) a transfer pump is required and will be included in the package. - Digital Functionality
DHW Model Finder
Search for PhexPak, PhexPak Lite and PhexStore models by required power (heat load duty), DHW flow and primary/secondary pumps as needed. DHW flow data based on assumed 80°C primary flow temperature:
Can't see what you want? Need help?
Call us. Or use Live Chat.
For instant advice. We can custom-design and engineer almost any expansion joint you need for delivery in the UK or worldwide. Call our expert team on +44 (0) 1384 881188 Or email us sales@flexej.co.uk
Frequently Asked Questions
A. A plate heat exchanger is a series of corrugated plates (usually stainless) placed in sequence to form a series of primary and secondary circuit channels that alternate throughout the plate pack.
A. A packaged plate heat exchanger starts life as a basic plate heat exchanger, it is then combined with control components such as a primary pump, control valve, temp sensor and various other optional extras. Do see FlexEJ’s range of fully-customisable PhexPak packaged plate heat exchangers with a wide range of power and flexibility options.
A. A gasketed plate heat exchanger uses soft gaskets to seal between the plates in the stack. The plates are compressed together between the end plates by long tie bolts. This arrangement is very flexible and allows the heat exchanger to be very closely optimised for the application. The stack can be dissembled for cleaning and may be reconfigured if conditions change. Do see FlexEJ’s range of fully-customisable PhexPak packaged gasketed plate heat exchangers with a wide range of power and flexibility options.
A. Plate heat exchangers work by forcing a medium through the small channels between the plates, causing the heat to be extracted from one circuit and transferred to the other.
A. Packaged plate heat exchangers manage and optimize the transfer of flow and heat by monitoring and reacting to a temperature sensor, usually placed on the secondary flow.
A. Phexpak is a fully modular and customizable product. It can be specified and designed to meet your exact requirements.
A. Hot water requirements for commercial projects are typically calculated using CIBSE guidance to meet the required standards. We utilise BS EN806 and BS 8558 to help our customers understand their requirements and can provide suitable product options to meet those requirements.
A. In a word, yes. A packaged plate heat exchanger is a great replacement for a calorifier for the vast majority of applications.
A. Not entirely, but it will significantly reduce the risk if installed to supply DHW instantaneously due to the vastly reduced volume of water in the system when the storage element is removed.
A. In a word, yes! Like our other products, the PhexPak is available to order directly from us. Just get in touch with our sales team to start the process.
A. Plate heat exchangers are one of the most efficient ways to transfer heat in the HVAC industry, in fact they are 99% efficient with only a 1% heat loss in most scenarios. Couple this with the most efficient pumps and control components available in today’s market and you have an unbeatable solution.
A. Packaged plate heat exchangers are typically installed freestanding in a plant room, and are connected via the 4 following connection points: Primary flow, Primary return, Secondary flow, and secondary return. Power is then supplied to the control panel and the unit is ready for commissioning and setup.
A. Packaged plate heat exchangers tend to cost more than standalone plate heat exchangers, but offer a wide range of benefits that a standalone plate heat exchanger simply can’t offer. They are also supplied with all the required pumps, valves and control components fitted to ensure optimum performance of the heat exchanger.
A. A calorifier is a storage buffer vessel that holds a body of water (most commonly DHW), and has an internal coil or similar heating element which circulates a primary heating circuit, designed to indirectly heat the body of water in the vessel.
Yes, the PhexPak is a great direct alternative to the Stokvis Econoplate packaged plate heat exchanger, which is no longer available. Please get in touch for help with your requirements or to request more info on the PhexPak.
A. Yes, please contact us with your product and project requirements and we will quote the PhexPak packaged plate heat exchanger.
A. Yes, please contact us with your product and project requirements and we will quote the PhexStore. PhexStore is a direct alternative to the Econostore, which is no longer available.
A. Yes, FlexEJ can quote and supply DHW buffer vessels from our standard range up to 1000l or bespoke design and manufacture anything larger.
A. Yes, FlexEJ can offer help and support either remotely or on site if required, utilising BSEN806 and BS8558 to determine DHW requirements.
A. Yes, FlexEJ can quote and supply a huge range of heat exchangers for DHW and LTHW applications.
A. FlexEJ can quote and supply a whole host of plantroom accessories, from product specific insulation jackets to full unvented system component kits. Please get in touch with your requirements.
A. Yes, in April 2024. Please contact FlexEJ for quotes and technical assistance on packaged plate heat exchangers, buffer vessels and hybrid buffers.
Yes, in April 2024. Please contact FlexEJ for quotes and technical assistance for all your packaged plate heat exchanger, buffer vessel and hybrid buffer requirements.