Thanks so much for the comprehensive reply, all of which is absolutely spot on (I was an NHER surveyor in a previous life, so know where you are coming from!)
CP, NE England
Solarcrest design, supply, install & commission MVHR systems by Airflow, Zehnder, Brink and Vent Axia
The Big Picture

MVHR Design Service

Why free designs are not worth the money..

Lots of people advertise free MVHR designs, from budget wholesalers to the manufacturers. Just about anyone with a red and blue pen and a basic understanding of domestic ventilation seems happy to have a go. So if you can get it for free, why consider paying for it?

When MVHR ducting is installed in the building fabric, it becomes part of the building fabric. Potentially hundreds of metres of hidden pipes penetrating dozens of walls to connect every room to a central ventilation unit. Potentially more than one unit in a large property. It has to work correctly for the life of the building, because rectifying acoustic or condensation issues later, which only materialise after people move in, can mean returning to first fix. Not easy in an occupied property. The NHBC class ventilation problems as serious defects, which means registered builders are liable for repair costs for ten years. As retrofit experts we fix poorly designed systems on a weekly basis, so we know the true cost of a free design can be a lot more than you think.

Considering the risks, ask yourself if a free designer will..

  1. Study your plans to identify fire protection walls, so the correct counter measures can be specified to safeguard the escape route? Measures that could save a life, avert catastrophic legal damages and pacify nervous building control officers. Our designers understand approved document B..

  2. Check the prevailing wind direction and the proximity of boiler flues and chimneys to make sure the air you pull in is safe to pull in. Our designers routinely specify traffic pollution filters in air quality management areas or if asthma is an issue for occupants..

  3. Provide acoustic calculations to ensure the air vent in your bedroom doesn't whistle, hum or carry sounds from the street. Environmental Health Officers are not easily pleased and the conditions they impose override the planning department. We can provide attenuation reports for the complete MVHR system if needed.

  4. Speak to your frame manufacturer, structural engineer and/or joist or steel beam supplier to check required holes are not too big or too close together. To ensure structural integrity our designers specify steel fletch plates to shore up timbers prior to drilling.

  5. Liaise with your roofing contractor to ensure your roof terminals match the tile shape, size, design and colour? Our designers monitor the progress of your project to ensure the right terminals are installed in the right place and at the right time, which can be weeks ahead of the MVHR install.

  6. Calculate air flow rates, produce a commissioning certificate, comply with Building Regulations Part A (structure), Part B (fire safety), Part C (moisture control), Part D (toxic substances), Part E (acoustics), Part F (ventilation) and Part L1A (airtightness). Our designers also apply CIBSE and NHBC best practice and follow Passivhaus guidlines.

Free design vs. Workable plan

A free design generally means a 20 minute AutoCAD session adding supply and extract pipes to your drawings. You get what is best described as quick 'proposed design' sufficient to work out approximate material costs, rather than a workable plan, which normally involves multiple design revisions by the time your architect, builder, interior designer and MVHR installer are all agreed. Try following a free design when you install the system and you'll soon discover the shortcomings. Every project has site specific challenges, including pinch points, limited plant room space, structural obstructions or a tricky ceiling datum that's defined by window heights. Solving these challenges without ugly boxing-in takes extensive product knowledge and construction experience, neither of which come for free. One way or another you're going to pay for design.

Why Solarcrest?

Solarcrest employ a qualified architect with over 1000 successful designs completed to date, utilising the latest premuim quality 75mm, 90mm or oval radial ducting. He works alongside an install manager with over 30 years construction experience, including hundreds of successful MVHR installs. Both are qualified Passivhaus designers, which means they can review your insulation, airtightness, moisture management and acoustic strategies too if needed. It's our concientious designers, our experienced install teams and our first class customer service that makes Solarcrest a preferred partner with so many top manufacturers. But don't take our word, see what our clients say or ask the manufacturers.

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