Heat pump know-how ensures efficiency

A substandard system is made good with installer and manufacturer working together to provide the client with the best possible solution.

About the project

  • 10 year old property, Peterborough
  • Existing heat pump system with inexplicably high running costs


Resolve the reasons for the system using so much electric, create a system which that is simple to operate and maintain, that ensures high
comfort levels and will have a long operating life.


WPL 25 and WPL-A 07 heat pumps working in a cascade to provide heat for a 200ltr STH 210 Plus buffer and 300ltr SBB 302 hot water cylinder.

The heat pumps were installed with weather compensation sensors to ensure maximum efficiency by modulating flow temperatures based on external temperatures. Domestic hot water runs off the larger heat pump, enabling the smaller heat pump to keep feeding the buffer for room heating, even when heating hot water. This ensures minimal room temperature fluctuations when drawing hot water and quick reheat times for the hot water tank.

Project planning is key to getting the right result

JMR assessed and planned the project meticulously with support from STIEBEL ELTRON.

“We began by placing sensors around the home for 3 weeks prior to install to ensure correct sizing of the units with the homes heat loss” says Mark Denman of JMR Heating and Energy. “The Results showed an 18Kw heat loss at -3 outside. The current set up was 8Kw higher
than required, which explained some of the excessive running costs. When we looked at the pipework we found another reason: most of it was undersized and poorly designed.“

This thorough and careful approach to checking the project requirements implemented by JMR was supported by their choice of partner. “Our involvement with the project started as early as the design stage,“ says Jack Hiley from STIEBEL ELTRON, “This allowed us to offer JRM
access to the wealth of technical experience and expertise in our business to help them design the perfect solution for this application. We aim to make heat pumps easy for our partners and end consumers. In fact we call our whole heat pump concept HPEasy, to encompass the way that our products and services work together to make for faster, simpler installations. This project showcases both the way we work with out partners to achieve this and how our range of highly integrated components and controls that work seamlessly together to deliver robust, high quality systems which are easy to use.”

A particular focus for the client was to ensure that future maintenance would be easy and the plant room was designed with that in mind. “Having a good level of space to work in with a plant area for the equipment meant the system could be laid out and designed incorporating the existing pipework that could be retained. This enabled us to have enough space to allow for maintenance between the equipment and plenty of isolation points to minimise the need for complete drain downs of the system. Everything that will require future servicing is easily accessible and we have ensured that engineers will be able to deliver optimal results by making sure they won‘t having
to work in confined spaces,“ said Mark.

Designing the system to run with weather compensation on an open loop through 5 underfloor heating manifolds meant that JMR could could ensure plenty of water volume for the heat pump to work at low temperatures for the most efficient operation. STIEBEL ELTRON‘s ISG system provides the ability for the system to be controlled and monitored via an app from anywhere in the world, allowing both extra flexibility for the homeowner and extra insight for maintenance engineers.