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Heat Pumps FAQ

Explore our FAQ section to gain insights into Clade Engineering Systems' heat pump products and services. Here, we address common queries to assist you in making informed decisions about your business's heating and cooling needs.


  • Electrical
  • Mechanical
  • Acoustic
  • Civil
  • Controls
  • Services
  • Buffer

Clade heat pumps have a lead compressor that is inverter controlled which reduces the start up current by giving a "soft start".

The Acer Range is compliant to EN61000 for harmonics – Clade will supply details from the inverter OEM to provide as evidence. The EN61000 compliance question on the DNO application can be ticked.

Anything above 100A is outside of the standard and will require a stage 2 assessment by the DNO in any case. We have a number of reports for the Oak units [link to attached on website] to show the effects of the grid and application of the units in relation to Flicker and Harmonics. Please note: the DNO will have to undertake this assessment as the specific of the site grid stability is the driving factor, not the heat pump.

If there is a constraint regarding harmonic content on a site then we can provide harmonic filtering to support an install, at additional cost.

Clade heat pumps are not currently on the ENA database, this is underway and will be completed in due course. However, it should be noted that ENA listing does not necessarily mean automatic connection approval. It is possible to connect any Clade heat pump as follows;

Installing contractors will have to make a DNO application and the DNO will undertake a stage 2 assessment. This will be supported by Clade with evidence on harmonics and flicker. (Ref. para 6.7 from the ENA guidance Notes )

Cable size is to be calculed by the site electrical Engineer.

Each product has a breaker type and size recommendation. Final design to be approved by the site electrical Engineer.

The Spruce AHU is the only heating and cooling heat pump produced by Clade. In general we have found it easier and more efficient to use separte heating and chilling plant, energy recovery between the two can be done on request.

As standard the Clade heat pumps come as a single unit up to 300KW. The Oak and Aspen ranges can be split if necessary but will require Clade to re-join them on site, this will involve a high pressure leak test. A charge will be made for site works on a case by case basis. Above 300KW up to 600KW the heat pumps will be delivered as split and close coupled on site. If there is any separation between evaporator and compressor units there will be a similar charge for site works.

Yes for most products these are available on request.

COPs are provided against standardised ambient, flow and return temperatures. These are calculated value which have been verified against field data and therefore represent a realistic value that can be expected on site. However, final COP is dependent on actual ambient conditions, how the heat pump is used and system temperatures.

SCOP is calculated to ISO14825 for each heat pump.

Actual site SCOP will depend on location, flow and return temperatures as well as the heating system operation. An average UK SCOP is given for each heat pump.

Yes, all Clade units come with an integral export pump which is VSD controlled.
This can be changed for additonal head if required.

Clade heat pumps keep a stable flow temperature by varing flow rate.

Clade provide a generic description of operations here [link]

or, a master controller can be purchased which will take care of everything up to the buffer. The BMS only needs to provide an enable signal.

All Clade units come with leak detection on board. In the event of a leak of refrigerant the unit will shut down, vent the compressor housing and alarm as necessary.

Hydrocarbon heat pumps have ATEX rated separation inside with leak detection and safe shut down capability.

For site considerations there is generic guidance available from our website.

All Clade heat pumps are available in light or dark grey as standard. Other colours and finishes are available on request.

Achieving a 30C return from a heating and hot water system is necessary for the efficient operation of a CO2 heat pump. This can be achieved in a number of ways, however we recommend using our standard schematic and DESOPS. This centers around using PIC Valves, pressure pump control, plate heat exchangers and correctly sized terminal units. Further info here

The water side pipework should be protected from frost, not doing so can cause damage to heat exchangers, pumps and pipes which would not be covered under warranty.
If enabled the heat pump will circulate water and provide heat, otherwise glycol, trace heating etc. should be provided.

The water system should be maintained to BS 8552

Standard schematics are available for single and multiple heat pumps, hot water only or hot water and space heating.

Clade master controller for mulitple heat pumps provides full control at a reasonable price.

Burst discs should be used to protect the heating system from high pressure refrigerant release.

Acer fan guards can be used to prevent debris entering the fans.

Heating and hot water systems can be connected to Clade heat pumps as per the standard schematics.

Buffer sizes can be found here. The design of the buffer should protect stratification as much as possible by minimising flow. Our standard schematic shows our recommended method.

Our standard schematics show multi unit systems. In general they should be connected to headers before the buffer.

The Clade master controller provides multi unit control up to the buffer.

All Clade heat pumps come with: acoustic housing for the compressors, inverters, leak detection, export pumps and BMS connections.

In addition to the required safety valves and pressurization equipment of the LTHW system it is strongly
recommended that a bursting disc is installed to the system to protect the system from increase in
pressure from the high- pressure CO2 system should the plate heat exchanger fail.
CO2 refrigerant within the heat pump operates at 100-120 bar, protection for plant and equipment on
the LTHW side of the system is advised to mitigate any sudden variations in pressure.
Burst Discs consist of a thin membrane which is designed to break and open when the specific level of
differential pressure rises above the resistance limit that the disc was originally calibrated for, so as to
allow for the excess pressure to vent out safely.
System configuration, plant locations and servicing routes will need to be considered when locating the
burst disc on the system. It is therefore the responsibility of the designer/installer to specify the type and
location. On multiple Acer installations one burst disc on the common primary pipework maybe deemed
Burst discs are designed to be installed between two flanges. Please refer to manufactures instructions
for installation information.

Clade heat pumps are designed for full duty at -5C ambient. They will operate in the range -10 to +25C. Below and above that operation may be compromised by reduced capacity.

Clade operate hot gas defrost strategies which does not export heat from the building or use direct electrical heat. This is the most efficient defrost available.

Larger units use a rolling sectional defrost which will keep heat production and temperature available at all times.

There should be a minimum of 800mm clear space from the evaporator coil where air is inducted.

In general the more space the better the air flow and the more efficient the heat pump.

The air flow at maximum capacity is given in each product info.

The calculated sound power levels are given for each heat pump in the technical information.

The final sound pressure depends on the envrionment the heat pump is in and is therefore site specific. However we give 1m and 10m indicative levels in the product information.

We are unable to provide overall acoustic harmonic data as our component manufacturers do not supply this.

Most site evaluations can be done using our sound power and pressure information.

Clade can engineer a heat pump to virtually any noise requirement. As standard we offer;
Compressor acoustic housing standard on all units
Acer and Birch low noise models
Silencers for approximately a 10db reduction as an option
Additonal fan banks if necessary

The footprints of each heat pump are available on each product page

The evaporator coils will produce condensate from the air, unlike a boiler this is not contaminated and can be directed to a soak away or drain.

V- block heat pumps drain underneath and Acer / Birch models have a pipe connection.

The weights of each unit is given in the product information. For structural purposes weight distribution should be taken equally over the sub-frame.

The minimum clearance around any Clade unit is 800mm along the evaporator and 1.2m infront of any doors for access.

The location of drains and connection points is available on each product page, summarised below.

Heat pumps can be enclosed behind fences for security or visual impact. Minimum clearances should be ahered to [link] and free air flow should be maximised.

BACnet is available as standard.

A BACnet connection to a BMS is available the standard points available are;

Data on the heat pump is available via two routes; integration with BMS [link] or via Clade Cloud. Clade cloud is a subscription service that offers detailed data and control of single and multiple heat pumps for optimisation purposes including live COP.

As standard Clade use Siemens and RDM controllers.

Heat pump efficiency is a product of location, refrigerant choice and system operation.
The BMS should control the heating system to provide optimal conditions for the heat pump, e.g. for CO2 this is to return 30C at all times.
In addition heat pumps should be well maintained with the evaporator kept clean and good air flow availability.

Clade provide a specific controller for multiple heat pumps [link] and the standard schematics show the recommended mechanical arrangement [link]

Yes, full project services are available here.

Clade have a full design team who can provide advice or full design up to and including stage 5. Learn more.

Please read this blog on successful project delivery here.

Get in touch today and our team will help you with this.

Standard delivery is by lorry equiped with a hi-ab which will deliver to kerbside ground level.
Contract lifts can be managed by our projects team under a separate contract.

Small units are kept on stock whilst larger heat pumps are built to order and take 16 to 18 weeks.

Yes, we have partnered with Plug Me In to provide this. More information here.

Our design services team can assist with PSDS or other funding applications

Yes we guarantee performance where we have oversight of the design and commissioning phases. These are the two critical control points for successful implemenation. Please get in touch for more info on this.

Here’s a link to our standard T&C’s.

No. Using traditional buffer tanks in domestic hot water (DHW) generation often comes with a number of challenges – these include space requirements, difficult installation and complex controls.

As such, we’ve developed a No Buffer DHW solution. Our approach is simpler, cheaper and more efficient than traditional methods. This makes it ideal for businesses who want to upgrade their DHW systems.

Head to our No Buffer DHW PDF to learn more.

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