It’s a wee bit nippy up North!

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Published: 01 April 2016


Geothermal and Dimplex do it again… read on about how they’ve won the Domestic Ground Source Project 2016, held at the Town Hall, Birmingham in January.  
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Alan Bell, owner of the house situated in Kincraig, Scotland approached BRE Scotland in August 2014, looking for a recommendation for a company to install a ground source Heat-pump, using a Burren (river) beside his house, as the heat source. 

​“When you get shortlisted it is very good PR but if you can win an award it gives the company very good credibility. We also won another HP category in 2013 for our commercial monitoring systems. Over the years we’ve put forward 12 different entries and am pleased to have been shortlisted as well as win on the night. 
We already have projects, in 3 different categories, for the 2017 event. 
The collector design in this installation pushes out the boundaries beyond industry standards in which we are achieving higher than normal CoP's. We have even improved on this design since within some commercial installations…” Thomas Vaughan, Managing Director of Geothermal 
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Built 20 years ago, this house was very forward thinking with high levels of insulation and under floor heating. It was heated with an oil boiler existing heating system comprised of a 15lt copper cylinder and an open vented system with expansion above. 

Why this solution?
The oil usage records for the previous 3 years were obtained, to establish that the actual energy consumption of the building was. The run times of the existing system were calculated, resulting in the monthly and daily requirements of DHW used for the year. Records of the water temperatures of the Burren for the past 5 years to establish the lowest water temperature available as a heat source.
The Burrens water levels were also monitored, to establish the low level flow rates. It was also proven that the Burren had not frozen over in the previous 20 years. It was at this point, when all the above data had been calculated, that an average water flow temperature of 2.5 degrees C and a COP of 4 at W35 was achievable.
It was decided to install a Dimplex S1H11ME , which is a high temperature HP. Due to the design parameters it was pertinent to install a system that would achieve a higher COP than a normal temperature HP. The installation is currently on target to make a saving of 5.47 tonnes of Co2 per year.

What was installed?
  • 2 x Kw energy meters on the hydraulic side
  • 1 x electricity Kw energy meter installed on the power supply
  • Temperature sensors on the HP flow and HP return 
  • Sensors on the DHW temperature and Collector temperature - where data is extracted from
The installation was situated in the basement, alongside the existing boiler, which meant it was ultimately designed as a bivalent system.

Key Milestones and Timings
The complete install was set up to be complete in 10 days. However, due to unusually heavy rain, the water level rose from its normal level of 1 meter to over 2 meters. For safety, it took an additional week to ensure the safety when installing the Collector.
Geothermal have a policy of ensuring clients are without hearing or DHW for no longer than 4 hours, during installation. So they complete installation and switching off of the existing systems happens in the early part of the days, allowing the integration of the existing system to be carried within the shortest possible time.

How does it work?
The client, and his local plumber were given a short run through on the day of implementation. This explained all the settings that were recommended. The filters are shown, to allow for basic maintenance requirements.
Five days later a call is made for another run through, just in case the client needs any adjustments to suit their specific needs.

The customer’s feedback
The customer is delighted with the HP and the installation. The boiler was only required for 35 hours throughout the cold Scottish winter. The house is extremely comfortable, and operates with flow temperature which is 10 degrees lower than the previous system.
After 2 months, an inspection was carried out to ensure that all settings were being optimised for achieving the highest COP. Filters were cleaned and flow rates are checked.
There was a small amount of air getting trapped in the collector, due to the fact the collector is a slinky. A slight increase in operating pressure moved this air and the efficiency when even further improved.
Having monitored the system over the winter, it’s proved to be performing event better than anticipated and such are getting even better heat transfer than the industry norm.

Figures
During sub-zero temperatures the lowest flow temperature from the collector was 4.9 degrees C
An external temperature of 1.5 degrees C had a collector flow of 5.1 degrees C
An external air temperature of 8.6 degrees C resulting in collector flows of 8 degrees C
The average flow temperatures achieved have a COP of 4.5 with heating water flow temperature of 40 degrees C

If you think you have a project/product worthy of winning the National ACR&HP Awards 2017 please visit
www.acrheatpumpawards.uk or contact Juliet Loiselle on julietl@warnersgroup.co.uk