Technical data

8
4. Installation
Note: Before actioning any installation observe the 'Safety information' in Section 1.
It is essential that the following installation guidelines are followed carefully.
The installation must conform to all relevant construction and electrical codes and comply with the
requirements of the Microgeneration Certification Scheme (MCS) MIS3005 ’Requirements for Contractors
undertaking the Supply, Design, Installation, Set to Work Commissioning and Handover of Microgeneration
Heat Pump Systems’
Any electrical work required to install or maintain this appliance should be carried out by a suitably
qualified electrician in accordance with current IEE regulations.
Any plumbing work should be carried out to local water authority and WRC regulations.
4.1 The Golden Rules of Installing a Heat Pump
1. A ‘D’ Type MCB should be used for the heat pumps power supply. If this is not available a ‘C’ Type
can be used on single phase units fitted with smart starts.
2. Connect the heat pump using only plastic pipe.
3. Use the Vent-Axia recommended purge pump for purging the ground arrays and heat pump.
4. On the underfloor heating manifold(s), remove the thermal mixing valve(s) if fitted.
5. On the underfloor heating manifold(s), don’t fit electric actuators to more than 75% of the zones.
6. Remove the chrome screws on the water pumps, and check that both pumps are running, and
moving water before turning on the compressor (25 MCB on the unit) (See section 5.3).
7. Do not install the heat pump adjacent to or beneath bedrooms or noise sensitive areas.
8. Read this manual fully before commencing installation.
9. Do not connect the heat pump to a thermal store without consulting Vent-Axia first.
4.2 Underfloor Heating Schematics
The following section includes typical schematics of how a heat pump can be connected. Only the load
side is shown i.e. the heating distribution system. It is important to note that the schematics are only
general arrangements and hence do not illustrate all required valves or fittings.
On the underfloor heating manifold(s) remove any thermal mixing valves, if fitted.
To avoid the heat pump from short cycling, it is important that the underfloor is capable of accepting the
minimum load from the heat pump.
The easiest way to do this is simply to have some zones left “open” – i.e. without electric actuators. These
zones will still require thermostats so can call for heat when required. In houses, the best zones to chose
are ensuite bathrooms, and hallways, neither of which are likely to be overheated.
To avoid short cycling of the heat pump the smallest actuator controlled zone (plus all the open zones on
that manifold) should be capable of absorbing the minimum thermal load of the heat pump. This
minimum load is approximately 25% for single compressor heat pumps.
If a fully controlled zone system is required, then a buffer vessel will be required (ideally a two connection
tank). This can result in a lower overall efficiency of the system (due to the higher temperatures, pump
electricity usage, etc) and hence Vent-Axia would always advise that the ‘open zone’ method of avoiding
short cycling is used.