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The installationof the heat recovery system is a straight forward operation following the plan provided. Where possible the installation should commence with positioning of the central air unit and then working away from the unit with each of the duct runs. It is better if each duct run, whether it be extraxt or supply, be completed in its entirely before starting the installation of the second duct run. This avoids confusion with the possibility of supply extract rooms or vice versa.
Step 1 Central Air Unit
The central air unit should be mounted on a board slightly larger than the unit itself. Inspection of the underside of the air unit will show a condensate drain this will need to be connected to an internal plumbing drain or taken to outside via a soffit to a gutter.
A hole should be cut in the mounting board aligned with the location of the drain. Position the mounting board and fix to the joists.
Assemble the mounting cradle in accordance with the instructions supplied.
Note that the assembled mounting cradle slopes along its length and to one corner. Fix the cradle to the mounting board with its lowest point at the end of the board where the hole for the condensate drain has been cut. Align the cradle, so that when the air unit is mounted to it, the condensate drain will align with the hole cut in the board. Screw the cradle in position on the board.
Route the condensate drain tube from its drainage point back to the central unit, ensure that it is below the level of the base of the air unit, passing through the hole in the board. Lift the air unit on to its mounting, but before lowering into its final position connect the condensate drain tube, tightening the compression nut to make a watertight connection.
Step 2 Connection to outside
The fresh air and exhaust connections to outside are best made before the duct runs to the rooms as access can be limited, especially to soffits if the unit is in the eaves of the house. Outlets may be roof trminals or grilles for gable wall or soffit mounting.
Where the ducts in a warm roof contruction the fresh air inlet duct must be insulated to prevent moisture condensing on its surface.
The standard ESP REGA roof terminal provides a free area of 20.000mm² and is provided with an adaptor to connect 100mm, 125mm or 160mm ducts. The unit is available ic terrecotta or anthracite finishes and includes an integral lead flashing to suit slate or tile roof.
In some cases it may be preferable to use the roofing suppliers integrated roof outlets for reasons of aesthetics but these must provide an equivalent free area to the size of the duct connections from the unit to outside.
Multiple outlets may be used if a single outlet with the required free area are not available. In this case Tee pieces and reduces will be required to make the duct connections. A typical standard outlet to suit soliu vent has an area of 8000mm². For use with a 125 outlet duct 2 units would be required with a 125/100 reducer. For a 160 outlet duct 3 roof units would be required with two 160/100 and a 160/100 reducer.
Grilles may be used as gable wall outlets or soffit vents. Grilles are available in sizes to suit the duct outlet diameters and in various colours to suit brickwork. Standard colours are white, grey, terrecotta and cotswold stone.
Where the grilles are installed in the soffit the space may be restricted for routing the duct over the wall plate. A flexible rectangular duct is available for use in these situations, these are two sizes 200mm x 60mm or 220mm x 90mm.
Step 3 Duct installation to rooms
The installed unit makes the ideal point for starting the installation of the duct systems. Work away from the unit and complete the installation of one complete duct run before starting
Make the connections to the air handling unit with worm drive clips for both insulated and plain ducts.
Plain Aluminium Ducts
ESP REGA Aluminium Bendable duct air are ideal for use in domestic ventilation systems. They are lightweight, self supporting without spring back and may be easily formed to bends or offset negating the use for purpose made bends. Unlike wire spiral type flexible ducts aluminium bendable ducts do not materially increase air flow resistance when compared to rigid ducts.
Aluminium bendable ducts are supplied in 4 metre lengths compressed to 1 metre for transport. Fully extent the duct before use. This is best carried out by two people, allow the duct to twist whilst extending.
The duct should be cut to length using sharp bladed knife, not serrated. Joints to the body of tee, connectors and reduces can be made using taped joints only. On the branches of tees or the smaller end of reducers it is more convenient to use the worm drive wire clips joint apply a single layer of tape to the spigot of the fitting, this give a resilient surface for the clip to grip rather than a metal to metal joint.
When joining tees to reducers use a short length of duct, 100mm is sufficient, as a coupler, then tape the joint using PVC tape.
Insulated Aluminium Ducts
ESP REGA Insulated Aluminium ducts provided two functions. They provide thermal insulation to prevent heat loss from the air in cold locations but more importantly prevent sound trnsmission through the duct whether from the air unit, from outside the dwelling or from one room to another.
The inner aluminium tube is perforated to allow waves in the duct to expand and dissipate. This means that the outer aluminium/polyester membrane is the air sealing tube, if this is punctured it must be repaired using PVC or foil tape to maintain air tightness.
Joints made to fittings should use the worn drive wire clips. To make a joint, firstly fold or slide back the outer sleeve to allow access to the insulation. Cut back and remove the end section of insulation for a distance of some 75mm, do not cut the inner aluminium tube. Slide the outer sleeve back over the inner aluminium tube, the fit the worm drive clip over the outer sleeve so it rest 25mm from the end of both the bendable inner tube and the membrane outer. Apply a layer of PVC tape to the spigot of the fitting, slide the end of the tube over and tighten the worm drive clip clamping the outer sleeve and inner tube securely to the fitting.
Do not use insulated duct to make the final connection to the room grille, always use a coupler to terminate the duct run with a short length of plain aluminium duct. This is easier to form and will not make fitting of the grille more difficult.
Rectangular PVC Ducts
Rectangular Ducts are used in confined spaces, normally as vertical runs in stud walls routed through the first floor to the ground floor rooms or as horizontal runs in false ceilings below floor slabs.
Joints between rectangular ducts and fittings are simply push fit but should be sealed with a couple of layers of PVC to ensure ait tightness.
The duct can be cut to length using a fine tooth hacksaw or a small angle grinder.
Joints between aluminium bendable ducts and the circular adaptors of the rectangular duct should be made using worm drive clips.
In the loft space the lightwei9ght ducts can simply rest on the floor joists. They are supporting so will not sag between supports.
Vertical duct runs should be held in place using pounched metal banding or cable ties. Clips are available for use with the rectangular PVC ducts but these are only really useful on flat horizontal surfaces so in most situations such as the underside of beam and block floor puncehd banding is a better alternative to overcome the height differences.
Once the extract and supply duct runs are completed to all rooms and the connections for fresh air and exhaust to outside are made the only part of first fix remaining is the provision for electrical cables.
A 3 amp fused supply should be made to the location of the central air handling unit.
Control cables will be required from the location of the air handling unit to selected location of the system controls. Bear in mind that Heat Recovery Ventilation system are designed to run continiously with littlen need for constant adjustment, therefore a suitable site for the controls can be the airing cupboard or similar location. Generally two 4 core and earth 1mm² cables will cover the normal requirement for the control cables will depend on the type of unit and the optional items added e.g summer bypass, humidistats, remote boost switching etc. Instructions for these are provided separately.
First Fix Completion
If power is available run the system to check that there is air movement from all room ducts and that it is in the right direction. Exhausting from 'wet' rooms and bringing fresh air to bedrooms and living rooms.
Check that the tails of all room ducts are in the correct location and showing below ceiling level. The location of the duct tails should be marked when the ceiling boards are fitted but it is worth taking some reference measurements to prevent possible future problems.
Once Boarding is complete the final operations can be completed. These are installing ceiling or wall grilles, making electrical connections and texting and balancing the system.
Locate the position of the duct tails in each room and cut holes for the ceiling grilles. The hole size for a 100mm connection is 110mm and for a 125mm connection 135mm. It is important that the holes are close to this diameter and as circular as possible to ensure a good fixing for the grilles.
Pull the tails of aluminium duct through the cut holes and trim the duct so it extends 50mm below the ceiling.
The room grille is permanently fixed to the ceiling and sealed to the duct using adhesive and for this purpose a fillet of non solvent based grab adhesive should be applied to the body of the ceiling grille and to the back of the flange that will be in contact with the ceiling.
Hold the end of the duct and slide the grille body in to it, once fully home compress the duct to push the grille finally into position in the ceiling, retain with 2no 6mm x 25 screws.
Each 100mm ceiling grille is provided with 3 filters, fine, medium and coarse density. These filter the air but are also used to balance the air flow through the system.
At this stage only fit a single coarse filter to each grille.
Ideally the system should be balanced using air flow meter but if such an instrument is not available comparative air flows may be tested by using a large light gauge polythene bag to test the speed that the bag is inflated or deflated at each inlet or outlet.
Make the final electrical connections to the unit and controls and run the system at maximum. For greatest accuracy ensure that all windows and doors are shut as this will replicate most closely the conditions under which the system will normally operate.
Generally the air inlets and outlets closest to the system will have the greatest flow rates, in an unbalanced system, and those furtest away the least.
Check the air flow volumes at all of the outlets and note the air volume to each room, whilst doing this make sure that the direction of the flow is correct. Once the room measurements have been taken the rooms outlet with excessive flow should be fitted with medium or fine filters as required to reduce the flow rate. This will have the effect of incresing the air flow in other areas that may have reduced volumes. In some cases it ay be necessary to use more than one filter.
In larger kitchens and living rooms the outlet or inlet may be via a 125mm duct which will be terminated with an air valve rather than the diffuser grille. Adjustment of the air flow through these valves is achieved by rotating the centre disc to open or close the air passage, once adjustment is complete the locknut on the inside of the air velve should be tightened to prevent movement.
When the air flows are balance to suit the room requirements fit the grille covers, fitting them so that the legs of the grille cover align with the screws retaining the grille body to hide the fixings.
Make a note of the type and quantity of the filter used in each room grille so that when they are removed for the cleaning the correct filters are returned to each location.
ESP Ecocent Success
Another success for ESP and its unique Ecocent domestic hot water system!
This 12 house development in Winchester managed to reach the desired Code for Sustainable Homes rating (carried out by NHBC) target because the Ecocent provided a major boost for the green credentials of the development.
This is just another reason why the Ecocent is a must for any new development. Please feel free to call us for further details.