Heat pump expert Bob Long tackles unnecessary complexity in heat pumps and the systems in which they operate
This article is fuelled by the nightmare week I have had at the mercy of an electronics-control issue, and extremely poor support from the heat pump manufacturer.
Although the system under examination has more than its fair share of complexity, locating the problem was quite straight forward, as the fundamental fault lay with the DHW supply pump not running.
The symptom according to the fault code, read from the sophisticated controller, showed fault codes pertaining to: – ‘high temp’ trip, and ‘high pressure’ trip (refrigerant), which was to be expected with a non-functional water pump.
The resolve from here should have been quite simple. Ascertain why the circulating pump is not running, and by remedying this, the high temp and high pressure faults signals would go away.
These simple steps became more difficult with realisation of the DHW pump being variable speed, powered by an inverter and controlled by the main circuit board embedded within the heat pump cabinet.
Visual examination showed nothing obviously noticeable, such as a blown control fuse or similar, and while the machine was idle, a further fault code appeared. This time indicated a ‘communication error from expansion module 3’!
So, we now know what the problem is, but fixing it has quickly become a completely different issue.
A call to the manufacturer’s agent came up with nothing and a google search revealed that the ‘expansion module’ could not be configured without indexing the pass code for ‘technician’ into the main programmer control box. After indexing the pass code, the communication interface can be re-configured.
A simple task if you work for Bill Gates, and a classic case of ‘each to their own’, as even the all-powerful Mr Gates would probably struggle to solder a few plumbing pipe together.
One begins to wonder what on earth a plumber/heating system installer is actually expected to know, by delving into this level of electronic, computerised sophistication.
At this time of writing, I am still awaiting the manufacturer to respond with the elusive ‘pass code’, and my client is heating a £2m dwelling with electric heaters!
While we are trying to convince a sceptical audience on the merits of energy efficient heat pumps, the manufacturers seem to be completely disconnected from the problems we experience, and the merits of simplicity breeding reliability.
Much of the complexity is due to efforts made towards reduced power usage, and an industry that thinks computer electronics is the answer to everything.
Economics in all areas of energy usage have great merit, but when complexity overtakes reliability, it is time to take stock of where all this is leading.
Installers should be able to regard a heat pump as nothing more than heat source, powered by electricity, producing large quantities hot water, CHEAPLY!
If heat pump manufacturers succeed in this relatively simple task, there will a warm future for users and installers.
Being an engineer with many years of refrigeration system design experience to draw upon, I am surprised that heat pump manufacturers do not optimise the operational COP through basic refrigeration principals, ensuring good system efficiency.
Trying to optimise upon the relatively small energy consumption of ancillary equipment, such as pumps, fans is a very secondary consideration, and appears to be the source of much complexity.
Main power usage is consumed by driving the refrigeration compressor and in almost every heat pump examined, the potential operational COP could be significantly improved by manufacturers addressing simple design issues, improving performance and removing complexity.