How to turn a lovley old house with solid walls into a warm efficient home



HEAT RECOVERY Installation

Two duct runs are required. One supplying fresh air and one extracting stale air. The extraction is from wet rooms - bathroom, kitchen, toilets utilty, en-suite, and the supply is to all other rooms.It is clear that to install a full MVHR unit requires a good deal of disruption to a home, specifically because of running the ducting, so if you are not undertaking major work it is worth careful consideration about pipe runs, where they will go and how they will look. I really don't like seeing utilities 'boxed in' so set myself the task of hiding all the ducting in floors, stud walls etc. so that it would be totally invisible. I chose to use solid section ducting - a mix of 125mm round and the 60mm  x 206mm rectangular sections that would help me achieve hiding drops in stud walls. Where necessary, to get through awkward areas I also used short sections of flexible duct, but these need to be kept minimal.

After too much deliberation I chose to buy my unit from Nuaire. Their LH1 model would just about cope with the size of my house, but I chose to buy the LH2 so it was not having to work close to flat out all the time.

MVHR manufacturers will be happy to advise on which of their units would suit your house size based on plans you send them.

As part of the purchase the Nuaire technical team would create me a layout plan for the ducting, but as I knew where I wanted to hide the ducts I created my own layout plan for the ducting and sent it to the Nuaire technical team for approval. They approved my layout, so all was good.

Heat Recovery unit, nuaire, eco, home, green, renovatoinI would use domus plastic ducting made by polypipe. This can all be purchased separately, but I ordered all mine via Nuaire.

It's always exciting to receive big boxes! The original unit was damaged in transit. I contacted Nuaire and they had no problem organising me a replacement.

The unit is large and has all the ducting holes blanked off so the most appropriate ones can be opened up for use.

I decided on the best location for the main unit would be in the roof of the new extension. I also knew that the trussed rafters would make fitting the unit very tight, so its precise location and orientation needed checking. As it was heavy and awkward to lug into position I used the box it was delivered in to make a replica and tried it in various positions between the rafters to ensure I would have enough space to fit it and access it.

It is very tight to access, but I eventually chose its position. I could now start layout out the ducting.Heat recovery unit, eco, home, green deal, renovation

Domus Ducting, heat recovery, eco, green deal, renovation

125mm round and 204 x 60 rectangular ducting can be mixed and matched using this system. I used the round throughout, only turning to the rectangular where needed, usually the drops down to the first floor.

Domus supply a special glue that fits a skeleton gun. I glued and also taped the joint with aluminium tape so as to ensure no leaks.

Heat recovery, ducting, eco, green deal, mvhr

Running the ducting to the upstairs rooms is no great problem as it can all run through the lofts. Finding suitable locations to drop the ducting down to the ground floor ceilings is trickier, particularly if you don't want to have to 'box in'. To access the main lounge below, I decided to cut out a section of plasterboard from an existing stud wall. I would have just enough space to cut through the noggins and slide in some 204 x 60 ducting.

Cutting through the noggins without causing too much damage to the wall was a pain in the butt. However, as I wanted it all to be invisible I slowly chibbled away.

Once the plasterboard is glued back in place nobody will ever know!Heat recovery ducting

Running the ducting through the loft areas was fairly straight forward. The pipe needs supporting along its length, and if it is running through a cold area it needs insulating. the silver foil / bubblewrap style insulation came with the pipe, but I would also give it a good layer of loft insulation over at a later date.

Though straight forward, there is quite a lot of work cutting, joining and taping the ducting, and cutting holes in walls, floors and ceilings as necessary. The whole job is quite time consuming. I also had to cut two 125mm holes to the outside in order to push out the stale air and draw in new fresh air. I made these in the gable wall that I planned to re-render.

Details to follow on connecting up the system and balancing the airflows.

MVHR ducting, eco

heat recovery installation

MVHR installation, eco, green deal

In the ceiling of each room the ducting terminates with a vent that will be either extracting or supplying air from/to the room.There are several designs but in my case both extract and supply vents were the same. It is worth considering the location of such vents a part of you design. You would not wish, for example a supply vent directly above your bed. Though the vents are designed not to push the air straight downwards it is not impossible you might feel a very small effect in a large room if ceilings are very low.
Heat recovery vent








© Christopher Thompson