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Hot Water Systems

The Problem - the need for instant hot water
Modern living dictates that buildings shall have hot water available whenever and wherever needed - and preferably instantaneously.

Hot water is normally provided by a boiler in a centralised or localised heating system.

After draw off of hot water at a supply point, the pipe feeding that supply point remains full of hot water which, under static conditions, cools to ambient conditions.

When demand resumes, there is a delay period whilst the now cold water is replaced by water heated from the boiler. The delay is both frustrating and costly, as the volume of the static head of water must effectively be heated each time a tap or valve is opened.

Traditional re-circulating System

Virtual instant hot water at taps was provided by a twin flow and return re-circulation system. The length of dead-legs was minimised so that hot water flowed soon after opening the tap, and so wastage was reduced.

This system has numerous shortcomings:

  • The flow/return re-circulating pipework and thermal insulation has twice the capital and insulation costs compared with a single pipe system.
  • Heat losses from the flow/return re-circulation system are twice those of a single pipe system.
  • Maintenance costs are incurred with the introduction of pumps and other items having moving parts.
  • Dual pipe systems require twice the space.
    The system must be balanced.

The Solution - The HotWat System

The HOTWAT single pipe temperature maintenance system overcomes ALL of the shortcomings of the re-circulation system.

The HOTWAT self-regulating heating cable is fitted to a single hot water supply pipe to maintain the hot water temperature by compensating for heat losses under no-flow conditions. Compared with a re-circulating system, this results in:

HotWat (HW)

Reduced Capital Costs

The HotWat system requires:

  • Half the amount of pipework
  • Half the amount of thermal insulation

The cost of the heat tracing system will always be less than this saving

Reduced Operating Costs

  • Half the pipework equals half the heat losses.
  • Maintenance free (no moving parts).
  • Half the space.
  • No balancing required.

HotWat Regular (HWR)

The Economics
The need for instant hot water
Capital Costs

The average 80% savings in the installation time and costs of a single pipe HOTWAT system will normally result in an overall capital investment saving of 10-25% compared with a re-circulation system.


Re-circulation System

HotWat System

Operating Costs

Half the pipework operating at reduced maintenance temperatures reduces energy consumption by an average 60%. Even allowing for higher fuel costs, total operating costs of a single pipe HOTWAT system will be 20-30% less than an equivalent re-circulation system.


Re-circulation System

HotWat System

Hotwat Regular is basically an uncontrolled system where the heat output from the heating cable is in thermal balance with heat losses from the pipework.

This occurs at a maintain temperature of 55 Deg C, and 50 Deg C for the standard and reduced specifications respectively.

The only control devices required for an Hotwat Regular system are over current protection circuit breakers and optionally earth leakage protection devices

HotWat Plus (HWP)

POWERTRIMMING Variable Temperature Settings

Greater system flexibility is provided by the addition of variable system temperature settings. Where required, different parts of the building can be programmed to maintain different temperatures. Control is provided by a technique known as Powertrimming.

D-BUG Thermal Pasteurisation

The HOTWAT system can be provided with D-BUG, a pasteurisation process whereby the static pipework system is periodically raised in temperature to disinfect the system.

Disinfection can be carried out automatically, or manually.

CRUSADER Circuit Temperature Scanning

The system control panel can include a CRUSADER circuit digital temperature scanning system to ensure optimum energy efficiency and and power trim settings.

BMS Integration

HOTWAT can be tied into a Building Management System for programmed temperature changes or thermal pasteurisation.

LEGIONELLA - Hotwat Reduces Risks
Guidance to minimising the risk of Legionnaires disease is provided in Codes of Practice issued by the HSE (Document HS(G)70), CIBSE (TM3) and NHS Estates TM.2040.

The subject of heat tracing to reduce risks is addressed and in particular pasteurisation of the system by heat raising above the temperature at which bacteria is instantly killed is recommended by the HSE Code.

The HOTWAT PLUS heating system with Heat Trace's D-BUG timed thermal pasteurisation provide such a facility.

Product and Application Datasheets
HotWat Datasheet
Hotwat Application Guide (June 19)

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