Heat Interface Unit (HIU)

Heat Interface Unit

BSI ISO 9001 & 14001 CERTIFIED




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    Heat Interface Unit (HIU) Commissioning Services

    Heat Interface Unit (HIU) Commissioning Services

    Comfort Services Group is a leading independent commissioning and water treatment company and one part of our works is commissioning and testing HIUs.

    Our hands on balancing and commissioning team have vast experience testing heating/hot water flow rates to achieve optimum design flow control, adjusting/monitoring flow and return temperature for operating efficiency better occupant temperature control resulting in energy saving and lower running costs and low maintenance overall.

    What needs to be done before commissioning can take place

    Prior to commissioning, the primary centralised heating circuit and HIU secondary heating circuits need to be hydraulically flushed cleaned and chemically treated to the clients specification to ensure good water quality is maintained as poor water quality will have a negative effect on the centralised plants , heat district network and if the secondary side of each HIU this will have an effect on the space heating circuit. The water treatment should be a one-off task generally carried out by a water treatment specialist employed by the installer. Our water treatment team are specifically trained and qualified to carry out a full BSRIA or non-BSRIA types of flushing and constantly updated with any changes in regulations to negate any queries that could potentially arise. Once water treatment works are complete it’s handed over ready for the next stage of works.

    “The team at Comfort Services Group were awesome when they carried out the Legionella Control works at our offices, they were very accommodating, Tom and the guys on site were a pleasure to work with. I would recommend the services of Comfort Services Group without reservation. Excellent First impressions with the Office Team, which was mirrored by the guys who did the work. Thanks guys.”


    Where are Heat Interface Units (HIUs) used?

    Heat interface units (HIUs) are most commonly installed in new buildings with multi dwellings whether rented accommodation, private or social housing and refurbished apartment blocks to provide an all in one localised heating and domestic hot water service. There are now available a wide range of HIUs from quality hiu manufacturers in the UK that are KIWA approved so there are a lot of good choice of product on the market to choose from.

    How does a HIU work

    HIU’s operate from an internal plate heat exchanger supplied from a heat source generally from a centralised boiler primary heating plant within the building or from a main district heating system acting as the primary circuit feeding multiple apartment blocks from one external boiler plant room / energy centre(renewable energy such as biomass are commonly seen to work along side these installations).

    The primary distribution pipework installation whether fed from a gas boiler installed within each buildingor a district heating scheme provides a network of pipes to each individual HIU giving instantaneous indirect heating and hot water to each apartment rather than each property relying on a central heating system / hot water system or a communal heating system where any adjust made in one property could potentially effect another, also eliminates any need for individual gas in dwellings for obvious safety concerns for the tenant so there are many benefits.

    With the HIU thermal integration with smart meters can help developers as a selling point to high efficiency and stabilisation of energy bills especially in the current climate.

    The mechanical installation needs to be of high standard carried out by BESA qualified installers using WRAS approved valves and fittings that are easy to install. Due to the primary energy source being centralised the HIUs are electronic controlled with no gas supply so no individual installation of a flue is required.

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      Frequently Asked Questions

      Heat interface units are generally located within an individual dwelling, inside an airing or storage cupboard and transfer the incoming primary heating source through heating exchangers to serve domestic hot water and secondary heating systems, there are normally individual heat exchangers so can work on-demand, hot water generation is instantaneous to save on space and storage requirements ie: no hot water calorifiers. Heating demand is controlled by either one central or local room thermostats, generally there are radiators (low surface temperature in assisted spaces) or underfloor manifolds with sub-loops.

      There is no direct gas supply, flame or combustion process within the Heat Interface Unit, only heat transfer from the primary water source via pipework from the heat network. Although gas along with biomass maybe used within the central boiler room as these are some of the most energy efficient ways of producing large volumes of hot water, this would be under the landlord or building owners demise and maintenance, servicing and operation would be their responsibility.

      Heat Interface Units are the bridging gap between the incoming hot & cold domestic services and heating requirements from the central source network boiler rooms to many new build and modern complex housing buildings, these units are self contained, self controlling and stand alone once connected and commissioned with associated pipework and controllers.

      Not quiet although they do look very similar, the output is the same which is to provide hot water services to either or both domestic and heating systems but the input to the heat interface unit is different, there is no gas burner or electric element but two heat exchangers served from primary heat source pipework within a heating district network. The HIU simply transfers the required amount of heat from one system to another, this is very advantageous in terms of flexibility, easy of install, use and being cost effective.

      Like most things there is no specific answer to this question but Heat Interface Units should be serviced and maintained annually and it’s life span will be dictated by demand and usage on component parts such as control valves, sensors and secondary pumps. Water quality is also paramount in keeping internal surfaces operating efficiently, chemical water treatment should be present to alleviate calcium deposits and hard scale buildup, incoming mains water under the control of others will be pre-conditioned prior to entering the heat interface unit. That being said we have experienced units operating satisfactorily for 10 – 15 years with no problems.



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