Paul Greengrass, Product Development Director from DiversiTech International, answers some questions on mounting an ASHP unit.
Correct siting and mounting of an ASHP unit is a critical factor influencing system performance, customer satisfaction, and long-term reliability.
Q. What are some of the key considerations when deciding how to place an ASHP unit?
ASHPs must be allowed to breathe to allow the unit to perform efficiently. If the airflow is restricted, this will lead to inefficiency and unnecessary wear on the compressor. Maintain manufacturer’s recommended clearance to sides and rear and allow a discharge zone in front of the fan. Planning compliance should be considered during initial survey and not left to paperwork at the end.
Q. What kind of base is required to ensure stability?
Get the base right. The mounting base must support the unit through its operational life. Movement will lead to vibration, refrigerant stress and noise transfer. A concrete slab (minimum 100mm thickness) on compacted hardcore needs to be installed level. It needs to be raised slightly above surrounding ground to prevent pooling water. Anti-vibration feet will greatly reduce any noise that the unit makes. DiversiTech recommends the FLEXI Lite Slab kit as it is a cost (and time) effective alternative to a concrete base.
This solution comes complete with rubber mounting anti-vibration feet (2 or 3-foot options) and is available in a range of sizes (175mm thickness inclusive foot). This kit can be delivered to site and constructed easily, and is a fibre reinforced concrete coated slab independently tested to varying weather conditions and exposure to chemicals.
Q. Can ASHPs be mounted on a wall?
Wall brackets can work well on sites with limited space – or when you need to raise the unit. The wall must be structurally sound and load bearing. DiversiTech brackets are flat packed and easy to assemble. The crossbar (complete with spirit level) allows the uprights to be spaced exactly as required and include wall spacers to help level the unit.
These brackets are powder coated in a scratch resistant textured finish and undergo a complex weather protection process to combat corrosive environments. Condensate trays are available to fit most standard units when considering a drainage strategy. They are available in a range of sizes and colours with two or three-arm versions – with different load capacities.
Q. What can you do if an uneven ground mount surface is the only option?
In some cases, structurally sound wall mounting and a flat level ground mounting surface is not available. The Baby Sumo adjustable rubber support anti-vibration feet are the ideal solution when you need to support units on uneven or sloping surfaces. They have an adjustable height between 160-210mm and are made of SBR vulcanised UV-stabilised recycled rubber compound with internal glass fibre-reinforced polypropylene.
The support surface features a substantial contact area offering a stable and secure base which prevents water stagnation and seepage.
Q. And after the mount?
External pipework needs to correctly insulated in a tough UV-stable PVC-coated external grade product. This will ensure that heat loss is at a minimum, and that the efficiency of the heat pump is maintained. Pipework running from an externally placed heat pump into a property is equally vulnerable to cold bridging and heat loss and should be insulated adequately.
In summary
For contractors, air source heat pump installation is as much about positioning and mounting as it is about pipework and wiring. A well-sited unit delivers quieter operation, better efficiency, easier servicing, and fewer call-backs — all of which protect reputation, profitability and lower electricity consumption for the homeowner.
Treat the outdoor unit as a critical piece of plant infrastructure, not an afterthought. Get the base right, give it space, manage noise, and plan pipework intelligently… and the system will perform as designed.
Image: DiversiTech
