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I've recently found out I have a HIU (heat interface unit) in my new build flat. I've been searching the web for info on how they work, but none of them answer my main question - does HIU work by providing heated water direct from a central plant into my flat, or is the heat generated by it used to heat the mains water into my flat?

I don't really understand what the mechanism is.
 

Brambles

Advent Win
It is interface between your flat and the centralised heating / hot water system in the building. It provides the heat / hotwater and the recent more sophisticated ones, record the amount heat imported into your flat. Presumably your lease clearly defines who supplies and pays for what.
 

chris watkins

Esteemed
Plumber
As above, but there are a couple of different types, do you have a hot water cylinder (Megaflo) or is the hot water that comes out of your taps heated from the HIU directly?
Heating water is supplied from a central plant & is pumped to the HIU's where the heat is exchanged (using a plate heat exchanger) to the heating water circulating around your flat so the two waters done mix.
You are likely to be responsible for your side as far as servicing & repairs are concerned.
 
As above, but there are a couple of different types, do you have a hot water cylinder (Megaflo) or is the hot water that comes out of your taps heated from the HIU directly?
Heating water is supplied from a central plant & is pumped to the HIU's where the heat is exchanged (using a plate heat exchanger) to the heating water circulating around your flat so the two waters done mix.
You are likely to be responsible for your side as far as servicing & repairs are concerned.
This is the one I have (shown on this page):
SAV Systems’ Indirect FlatStation Heat Interface Units

Since found out it is indirect, meaning the HIU heats the heating and hot water in my property using 2 heating plates (one for each) from the central part heating source.
 

chris watkins

Esteemed
Plumber
Strictly speaking the domestic hot water is heated directly (Just like a combination boiler does) but they call the HIU direct & indirect if they don't or do heat the domestic HW, it can be very confusing.
 

centralheatking

Esteemed
Plumber
I've recently found out I have a HIU (heat interface unit) in my new build flat. I've been searching the web for info on how they work, but none of them answer my main question - does HIU work by providing heated water direct from a central plant into my flat, or is the heat generated by it used to heat the mains water into my flat?

I don't really understand what the mechanism is.
HIU are my specialist area ...it’s really quite simple, a plant room generates hot water on a district system which circulated around the building...always large...1000 plus dwellings. each dwelling has an HIU which takes heat via a hex and thus goes 2 ways ..1.. Domestic hot water. 2. Wet radiator heating under pressure. The units are smart and accrue the energy consumed and then put up a charge remotely directly to the consumer . Centralheatking
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Strictly speaking the domestic hot water is heated directly (Just like a combination boiler does) but they call the HIU direct & indirect if they don't or do heat the domestic HW, it can be very confusing.
No gas or outside power just hot water ...they do resemble combi units but use hot water it’s a relatively safe system for large dwelling blocks ..no gas to go BANG ..remember Rownan Point it came down like a pack of cards chking
 
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HIU are my specialist area ...it’s really quite simple, a plant room generates hot water on a district system which circulated around the building...always large...1000 plus dwellings. each dwelling has an HIU which takes heat via a hex and thus goes 2 ways ..1.. Domestic hot water. 2. Wet radiator heating under pressure. The units are smart and accrue the energy consumed and then put up a charge remotely directly to the consumer . Centralheatking
Hi CHK.
So out of curiosity take one plant room feeding say your 1000 HIU what KW size heat source is a typical example for systems you install/maintain?
Domestic heating is all my knowledge, despite the desire to learn I have no experience in large scale systems.
 

centralheatking

Esteemed
Plumber
Hi CHK.
So out of curiosity take one plant room feeding say your 1000 HIU what KW size heat source is a typical example for systems you install/maintain?
Domestic heating is all my knowledge, despite the desire to learn I have no experience in large scale systems.
yes its quite wacky, each dwelling is rated around 10kw ..total take..but this is a lot to do with the thermal mass of the building so 1500 flats at 7-10 kw ..plus circulation loss u do the maths. These plant rooms are huge ..they often have 2 or 3 heat sources to get the grants. so Biomass, Gas and maybe a back up...one could build 2 or 3 houses in these plant rooms ...its mostly automated and remotely monitored etc. the area heating circuit can be 3 or 4 inch galv always at least 3 pumps in parallel everywhere in case of breakdown chking
 

centralheatking

Esteemed
Plumber
Hi CHK.
So out of curiosity take one plant room feeding say your 1000 HIU what KW size heat source is a typical example for systems you install/maintain?
Domestic heating is all my knowledge, despite the desire to learn I have no experience in large scale systems.
I only have input into the design of the HIU units and the pressure needed for the domestic sub systems via Top Up Mate produced by Flowflex one of my patented heating products. We have passed the 10,000 sales mark with Top Up Mate in 2 years via this route and combi boilers ..centralheatking
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Wow, that's one big plant room lol. I dread to think how large a heat source is to supply all that power
If you are still curious the I will ask my partners just what the heat input is for a particular multi block
...its in the mega watts area ...as I say only deal in the units kw needs and of course ..pressure..water dynamics is to moi fascinating
Chking
 
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I only have input into the design of the HIU units and the pressure needed for the domestic sub systems via Top Up Mate produced by Flowflex one of my patented heating products. We have passed the 10,000 sales mark with Top Up Mate in 2 years via this route and combi boilers ..centralheatking
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If you are still curious the I will ask my partners just what the heat input is for a particular multi block
...its in the mega watts area ...as I say only deal in the units kw needs and of course ..pressure..water dynamics is to moi fascinating
Chking
I'm just curious really. I did do a quick calculation based on 1500 apartments with the same heat loss and DHW requirements, plus a rough loss through pipework and it was like you say megawatts. I did have a quick Google on size of pipes required to carry this power but wasnt very successful. Like I said my experience is only on domestic properties, I would love to experience larger systems and definitely want to gain experience with commercial and industrial oil fired appliances. I'm not gas trained, oil is all we ever did.
 

centralheatking

Esteemed
Plumber
I'm just curious really. I did do a quick calculation based on 1500 apartments with the same heat loss and DHW requirements, plus a rough loss through pipework and it was like you say megawatts. I did have a quick Google on size of pipes required to carry this power but wasnt very successful. Like I said my experience is only on domestic properties, I would love to experience larger systems and definitely want to gain experience with commercial and industrial oil fired appliances. I'm not gas trained, oil is all we ever did.
I do not know how to advise you, the fellas I encounter are are well qualified and experienced ...and really well paid. The nearest person I know is a senior contracts manager they supply a Jaguar and he gets z£100,000 per year but the pressure to deliver at all levels ..inc me ..is not for the faint hearted
I love it ...centralheatking
 

chris watkins

Esteemed
Plumber
The pipes to the HeatX under the block I was looking at this week on Kidbrook Village were 6" but lord knows what they are from the energy centre. HIU in each flat but also an exchange to each block maybe to help with the circulation around the site as a whole but seems a bit wasteful as with every exchange there is a loss of temperature.
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
I'm just curious really. I did do a quick calculation based on 1500 apartments with the same heat loss and DHW requirements, plus a rough loss through pipework and it was like you say megawatts. I did have a quick Google on size of pipes required to carry this power but wasnt very successful. Like I said my experience is only on domestic properties, I would love to experience larger systems and definitely want to gain experience with commercial and industrial oil fired appliances. I'm not gas trained, oil is all we ever did.
havent got any decent pics now but this is the best i can find



230 homes (two tower blocks and one disabled/ old peoples home / assisted living ) all on hius (district heating system)

around 1.5mw 3 gas boiler ideal i max with slave units
 

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