2021-08-12T15:44:26Z

BD:

It is common for HIU's to include a thermostatic bypass to maintain heat across the domestic hot water plate heat exchanger at all times, this helps minimise delays in hot water supply when a tap is opened.

The DATA, DIGI, SPLIT and SLIM HIU's all perform a similar function with the Economy or Comfort mode, by momentarily opening the domestic hot water stepper motor to allow small quantities of primary water to creep into the unit at regular intervals. The primary pipework leading to and from the HIU usually loses heat faster than the HIU itself, hence the unit will typically settle trickling in heat fast enough to keep the primary return at or just below domestic hot water temperature. The DATA, DIGI, SPLIT and SLIM HIU's are the only HIU's capable of this level of control with electronics to ensure that primary return temperatures remain below the domestic hot water setpoint at all times.

Note that the units perform a Legionella protection cycle every 24 hours overnight, for 60 minutes over 57°C, enabling the safe use of lower keep warm temperatures.

Each HIU has two domestic hot water keep hot modes, Economy or Comfort. These can only be selected during commissioning or by a trained engineer.

The default setting is Eco mode, and this can be specified to run for 0 minutes (which turns the feature off all together), 15, 30, 60 or 120 minutes after the last hot water draw off. In Eco mode the heat exchanger is kept to a specified temperature (between 25 and 60 Deg C) for the selected period of time and after this period of inactivity has elapsed the stepper motor closes completely and the temperature in the domestic hot water circuit is allowed to drop through natural dissipation to minimize energy consumption. If a hot water draw off is made any time throughout the Eco mode function the unit will deliver hot water as usual and the Eco mode function will begin counting down for the selected time once again.

In Comfort mode the heat exchanger is continuously supplied with a trickle of primary water for quicker hot water delivery, however energy consumption will be slightly higher than if the unit was set in Eco mode.

====Commissioning Options====

The DATA, DIGI, SPLIT and SLIM HIUs all offer a choice between two modes of keep warm function:

* Comfort Mode maintains heat up to the HIU at all times
* Eco Mode maintains heat up to the unit for a set period of time following hot water use, then goes cold for up to 23 hours. The period of time is selectable.
*Keep Warm Temperature determines the temperature maintained in the HIU.

====Comfort Mode====

In Comfort Mode, the HIU maintains temperature into the HIU by pulsing in a calculated volume of primary flow water every few minutes. The amount of water let in is very small, and not enough to pass through the plate heat exchanger. The heat then dissipates throughout the plate.

{{IMG|kw1.png|600}}

====Reduced Comfort Temperature====

The latest firmware provides for a separate temperature setpoint for the keep warm mode, that can be set lower than the hot water temperature setpoint. This is to allow the system to be setup to maintain heat in main distribution pipework, but let branch pipework drop significantly in temperature.

The Comfort temperature setting must be high enough to maintain enough overall flow to maintain heat in the primary flow pipe.

{{IMG|kw2.png|600}}

The following shows how the use of reduced comfort mode at 26°C settles to a state where heat is maintained in the main pipework in readiness for a draw-off, however the branches see considerably lower temperatures and lower heat losses. Return temperatures are just above room temperature at all times (outside of heating season and Legionella cycles).

{{IMG|Riser_20_26C_keep_warm.png|link=http://heatweb.co.uk/w/images/d/db/Riser_20_26C_keep_warm.png|600}}

====Economy Mode====

Economy mode allows HIUs to turn off during periods of inactivity, only coming up to heat once per day as part of the sterilisation cycle.

The following diagram shows how the network can go completely cold, however there is significant risk that one system may call for hot water overnight, and experience a significant delay before heat can arrive from the plant, as the entire volume of cold primary flow pipework will need to be expelled.

{{IMG|kw4.png|600}}

To overcome this, a thermal bypass can be fitted on the end of the primary pipework. Given the main primary branches are well insulated, the heat losses in maintaining them at temperature this way is far lower than if HIUs are kept warm also. The primary return will reflect the setting of the thermal bypass.

{{IMG|kw3.png|600}}

2021-08-12T15:19:52Z

BD:

== Introduction ==

The Split Security Case, is an attractive, sleek, steel case painted white for a more appealing display.

[[File:HIU_Split_case.jpg|link=http://heatweb.co.uk/w/images/f/f1/HIU_Split_case.jpg|300px]]
[[File:Cropped Back Pipework.jpg|link=http://heatweb.co.uk/w/images/6/6c/Cropped_Back_Pipework.jpg|255px]]

The Split Security Case has been put in place so that when it is installed their is limited access to the general public. This is to ensure that no tampering can be done to the system, such as the metering in place. As well as, an inexperienced party can't be harmed if they wanted to try and access the HIU itself. A prime example of this is, being installed in a student accommodation block.

A typical HIU has a EPP housing for insulation which is then fitted in a cupboard out of the way, but with the boisterous nature of students this type of casing can get damaged quite easily. A prevention measure has to be put in place which is where the Split security case is perfect. It's robust enough to protect the HIU and it looks much nicer and cleaner than a black EPP housing.

= Mounting =
The mounting of the Split security case allows for the pipe work to be plumbed up behind the HIU. Which allows for further tamper resistance, as well as, a compact tidy design with minimal amount of copper pipe on display. Another feature of the Split Security case is that the brass fittings are incorporated into the case which improves rigidity, and means the only access to these fittings is from within the case.

[[File:split case fittings2.jpg|link=http://heatweb.co.uk/w/images/b/b2/Split_case_fittings2.jpg|250px]]

SPLIT security case

2021-08-12T15:12:22Z

BD:

SPLIT security case

2021-08-12T15:11:05Z

BD:

SPLIT security case

2021-08-12T15:09:30Z

BD:

File:Slow Green Flash.gif

2021-08-12T15:09:12Z

BD: File uploaded with MsUpload

File uploaded with MsUpload

SPLIT security case

2021-08-12T15:07:40Z

BD:

SPLIT security case

2021-08-12T15:05:35Z

BD:

File:Fast Green Flash.gif

2021-08-12T15:05:13Z

BD: File uploaded with MsUpload

File uploaded with MsUpload

SPLIT security case

2021-08-12T14:55:14Z

BD: