This article concerns the Design, Supply, installation, Balancing and commissioning of a full high quality MVHR (mechanical ventilation and heat recovery system)
MVHR is the premium standard to home ventilation with excellent recovery rates of energy from 90 to 96%.
Like everything in life the premium brands offer better heat recovery rates, quieter systems and longevity with back up service and filters easily available.
When we talk about quality systems we are specifically talking about the following.
- A quality machine, well built substantial unit from a long standing brand. Passive rated by the passivhaus institute preferably.
- This machine is then connected to distribution manifold which have build in silencing features and further enhanced with the use of attenuators.
- The ducting connected to the manifolds and then to the room plenums should be 90mm to reduce air restriction and have anti bacterial and anti static inner layer.
- The ceiling Plenums should be none restrictive and maintain the air as straight as possible to reduce friction and thus noise. As should all fittings.
- All ducting in the cold spaces should be insulated or within the thermal envelope of the building.
Lets talk cost
1. Design Cost
The design should be completed as soon as possible within the Design build process. This is to ensure the routing of duct work and positioning of the machine is suitable.
Ventilation is usually considered during the build process for the first time.
The sooner this conversation happens the better, but as a minimum when the complete structure is open timber work with all exposed. We can design most systems around the given structures. The cost of design work is usually included within the purchase price of a full ventilation system. If you were to identify this as a single cost for a 4 bedroom home it would be 480e £417 approximately.
2. Machine cost
The machine must be sized at least 20% higher capacity than required. We specify our machines at 40 to 50% higher. This further enhances the optimum performance of the machine.
So for a 4 - 5 bedroom home machine cost would be 2500e £2173 approximately.
For a 5- 6 bedroom home machine cost would be 3400e £2956 approximately.
There are cheaper machines available in the market but you honestly pay for what you get.
3. Air Ducting cost
We supply all fittings required to install a full ventilation system. Our unique system is based on 90mm semi rigid ducting. The system is fully tested by British research establishment and is listed under SAP appendix Q for BER assessment. The fittings have been designed to allow a simple and straight forward installation for the professional and the self installer. The Duct fittings have unique air straightening features reducing air turbulence and noise. The manifolds have noise suppression features reducing noise transfer by up to 45%. The connections to the manifolds allow air volume to be adjusted while the machine is running to provide accurate air flow to each room. Other systems are based on adjustment on the ceiling outlet which caused noise due to high pressure in the ductwork. Also adjustment for the air volume at the manifold is easily done with the simple turn of a valve to obtain the correct air flow.
So for a 4 - 5 bedroom home ducting cost would be 2600e £2260 approximately.
For a 5- 6 bedroom home ducting cost would be 3200e £2782 approximately.
The controller should be positioned centrally and offer all the controls required by the home owner. But should be easy to read and display all the values. It can record all the readings. For download for further analysis.
The cost of a Genvex touch screen controller is approximately 366e £318
4 . Installation cost
Installation is important and for a system to operated correctly you must follow the design drawings. But in saying that your builder can install or it can be self installed. The fittings are simple to use and the the S90 semi rigid ductwork is manageable with one person but simpler with 2 people.
Giving a finite cost is difficult and it depends on the layout and structure of the house so much.
But to give a guideline:
A 4 - 5 bedroom home cost would be 2500e £2174 approximately.
For a 5- 6 bedroom home would cost 3100e £2696 approximately.
The system here is for an approved ductwork system required under NZEB and the national bodies for regulations.
5. Testing and commissioning
Commissioning is a crucial aspect of installing an MVHR system. You’ve spent all that money installing it, and now you need to make sure the airflow is correct to each room to run quietly and efficiently. Your Building certifying Engineer will also want to see a certificate of performance.
Beware those MVHR suppliers who either don’t offer commissioning, or don’t convey its importance – the fine tuning at the commissioning stage is vital to ensure the MVHR system works properly – and it’s not easy to do without calibrated equipment for measuring airflow.
You can purchase a meter at quite low cost to do rough calibration, but for a certified report the certifier must be approved to preform this for you.
Your MVHR designer will have assigned airflow rates to each individual room in your property at a set rate based on the requirements of Building Regulations Part F .
Commissioning and reporting on the MVHR system will take a competent technician a full day using a calibrated anemometer .
Commissioning also produces the Ventilation Certificate for Building Control compliance.
Commissioning an MVHR system costs approx. 380e £330 for the average m2 home.