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JEM Mechanical and Electrical Building Services Ltd

Home / Domestic / Ventilation


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What’s the difference?

Whilst everyone recognises the humble extract fan, there are now many different types of mechanical ventilation that can be matched to the need and the home type. Types are:

  • Intermittent Extract Ventilation
  • Passive Stack
  • MEV
  • MVHR
  • Alternative approach

Intermittent Extract Ventilation

This type of extract ventilation is typically used for single rooms e.g. bathroom, utility, kitchen.

Intermittent Extract Ventilation
Intermittent Extract Ventilation Unit

Multiple Extract Ventilation (MEV)

This type of extract ventilation can be a Centralised MEV which extracts from more than one room through ceiling mounted points, or a Decentralised MEV – units which run continuously at a low rate, until a higher rate is called for by either automatic intervention for reducing humidity or manual pull cord to clear odours.

vent-mev vent-dmev
Centralised MEV Decentralised MEV

Mechanical Ventilation with Heat Recovery (MVHR)

Heat recovery ventilation is available in both whole house and single room types but is best suited to “Air tight” homes. Fresh supply air is provided to “dry rooms” and stale air is removed from “wet rooms” – the airflows both go through the central unit and heat that would otherwise have been wasted is recovered resulting in huge fuel savings that can easily pay for the cost of the unit.

vent-mvhr vent-singleroom
MVHR central unit A single room heat recovery ventilation unit

Positive Input Ventilation

Positive Input Ventilation takes air from the outside (usually via the loft) and provides filtered air to the whole house. The air in your loft is warmer than outside so heat is redistributed through your home.

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How Positive Input Ventilation works PIV central unit
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Why ventilate?

We used to live in draughty houses with open fires that created a draught and sucked air up chimneys – this ventilated the home but was draughty. We had badly fitting single glazed windows and doors – again draughty.

In today's homes we have reduced draughts (ventilation) by taking out and sealing up fireplaces, installing double glazing, etc. The cost of heating our homes leads to people not opening windows to ventilate and the odours, chemicals, and moisture laden air can’t escape creating an unhealthy atmosphere. Some refer to this as a “toxic soup”

The moisture in the air is measured as % Relative Humidity (RH) with 100% being saturated and 0% being no moisture present. Cooking, bathing, breathing etc all add to the RH.

The increased cost of heating our homes leads to a reduction in heating, this in turn means the moisture in the air is released onto cold surfaces as condensation and if not dealt with can lead to mould. The increase in humidity can also create ideal living conditions for dust mites, the dust mites leave “things” behind that humans breathe in and can lead to Asthma.

Without correct ventilation condensation can lead to dampness and mould.

One recent customer in Huddersfield talked of JEM curing the condensation in a property that she rents out. Not only did we install ventilation we provided written advice on how to heat the property, position furniture to avoid cold spots and aid air movement and much more. Happy tenants and a happy customer!

Ventilation is important - why else would it be a legal requirement in new houses? Not only is it a legal requirement it is so important that recent changes mean it must be installed by a BPEC trained installer, (preferably JEM!)

The reasons it has become a legal requirement is the realisation that in the past products have been fitted, wired up and assumed to be working – just because the blades are turning does not mean the ventilation is working!

Most installers are not trained – rest assured Brian is! JEM can provide you with a guaranteed, energy efficient, sustainable solution to your ventilation needs.

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JEM not only install we maintain too, if your ventilation has stopped working or you feel its performance is not what it used to be contact us.

A visit to determine the best solution is £35 we may be able to fix it at no further cost or it may need a chargeable part.

maint-1 maint-2
Routine maintenance of a Single Room Heat Recovery Ventilation Unit Checking ventilation rate
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Joined Up Thinking

We try to carry solutions with us or prepare in advance of a visit so reducing your costs.

Work with us - send us a photo and it may mean we can save a visit and save you more.

Download the pdf file: JEM Brief Guide to Preventing Condensation
JEM Brief Guide to preventing condensation

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What others had to say

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Take the next step

For advice or to discuss a solution to fit your needs and budget, contact Brian Moughtin at JEM Mechanical and Electrical. Use the contact form on this page, call 01484 664301 or 07979 397834 or , and we will be in touch as soon as possible.

Contact Us


If you're a tradesperson willing to work in partnership with me, please use the contact form above or call/text me on 07979 397834.


JEM Mechanical and Electrical Building Services Ltd
Registered in England Company No. 07592614
Office 4, Quarry Close, Holmfirth HD9 7AY

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