Heat Loss Survey Case Study: Choosing the Right Heat Pump Flow Temperature Before Installation
Heat Loss Survey Case Study: Choosing the Right Heat Pump Flow Temperature Before Installation
Heat Loss Survey Case Study: Choosing the Right Heat Pump Flow Temperature Before Installation
Heat Loss Survey Case Study: Choosing the Right Heat Pump Flow Temperature Before Installation
Heat Loss Survey Case Study: Choosing the Right Heat Pump Flow Temperature Before Installation
UK Heat pump Help Technical Team
Independent Heat Pump Engineer
We thought we needed a heat loss survey. What we actually got was a plan for our entire heat pump installation.
This homeowner contacted UK Heat Pump Help because they were considering an air source heat pump installation. They knew they needed a room-by-room heat loss calculation, but they also had plenty of questions. What size heat pump did they actually need? Which radiators would need changing? What flow temperature should the system be designed around? How much should they realistically spend? And perhaps most importantly, would spending more money on the heating system actually save enough on running costs to make it worthwhile? That's where our Technical Heat Loss and Pre-Installation Review started.
More than somebody measuring the rooms
An experienced heat pump engineer visited the property and completed a full room-by-room heat loss assessment, but the visit wasn't simply about measuring walls, windows and radiators. We also looked at the existing heating system and discussed exactly what the homeowner wanted from their new heat pump. By the end of the visit, they had a much clearer understanding of the property's heat loss, the likely heat pump requirement, which radiators needed changing, potential system upgrades, different design flow temperatures, likely installation requirements, approximate additional costs, and what they should be asking prospective installers to provide. The homeowner could now approach installation companies knowing what they actually wanted to buy.
Should the system be designed at 50°C, 45°C or 40°C?
This became one of the most useful parts of the assessment. Rather than simply choosing a design temperature, we showed the homeowner what the different options meant financially. A system designed around a lower flow temperature can generally allow a heat pump to operate more efficiently, but achieving that lower temperature can require larger radiators and additional changes to the heating system. So there's a balance to strike: how much should you spend today to reduce your running costs tomorrow?
Option 1: designing around 50°C. This required fewer alterations to the existing heating system, meaning a lower initial investment. However, the heat pump would generally be expected to operate less efficiently than the same system capable of heating the property at a lower flow temperature. It was the lower cost installation option, but not necessarily the lowest running cost option.
Option 2: designing around 40°C. We then looked at what would be required to design the property around approximately 40°C flow temperature. This required significantly more work. Larger radiators and other heating system improvements would have increased the initial investment by approximately £3,500. The system should then be capable of operating at lower temperatures, potentially improving heat pump efficiency. But when we compared the additional investment against the estimated reduction in running costs for this particular property, the payback period was too long to make the extra £3,500 particularly attractive to the homeowner. Spending money to save energy only makes financial sense if the saving justifies the investment.
Option 3: the compromise at 45°C. Designing the system around approximately 45°C required some additional radiator and system upgrades, but considerably less than designing everything around 40°C. Based on the estimated costs and potential energy savings for this particular property, the additional investment was expected to pay for itself in around two years. After discussing the options, this was the design the homeowner chose. Not the cheapest installation. Not the lowest possible flow temperature. But the option that made the most sense for them financially.
Lower isn't automatically better
It's easy to say heat pumps are more efficient at lower flow temperatures. That's true in general, but it doesn't automatically mean spending thousands of pounds getting from 45°C to 40°C is a sensible investment. Imagine spending an additional £3,500 to reduce your annual energy bill by a relatively small amount. Technically, you've created a more efficient heating system. Financially, you may never recover the investment within a timeframe that matters to you. That's why we don't believe heat pump design should simply be about chasing the lowest possible number. We'd rather ask where the sweet spot is between installation cost, efficiency, comfort and return on investment. For this homeowner, that sweet spot was approximately 45°C. For another property, it could be completely different.
The homeowner knew what they were buying before speaking to installers
This was arguably the biggest benefit. Before the assessment, the homeowner knew they wanted a heat pump. Afterwards, they understood what heat pump system they wanted. They could approach installation companies with a much clearer specification and have more meaningful conversations about heat pump sizing, radiator changes, design flow temperature, system alterations, controls, expected performance and installation price. Instead of receiving three completely different quotations and wondering which installer was right, they had an independent design to compare those quotations against.
This is why our heat loss survey is different
A heat loss calculation is important, but on its own it's ultimately just a set of numbers. Our Technical Heat Loss and Pre-Installation Review is designed to turn those numbers into practical decisions. We don't just want to tell you your property loses a certain amount at the design temperature. We want to help you understand what size heat pump makes sense, which radiators need changing, what different flow temperatures would require, how those choices could affect efficiency, what additional investment may be worthwhile, what the practical installation will involve, and what you should be asking your installer.
Get the design right before choosing the installer
A heat pump is a significant investment, and once the pipework is installed, the radiators are changed and the equipment is sitting outside your house, fixing a poor design can become expensive. That's why there's a strong argument for getting independent technical advice before signing an installation contract. Understand the system first. Understand the compromises. Understand where your money is best spent. Then find the right company to install it.
We thought we needed a heat loss survey. What we actually got was a plan for our entire heat pump installation.
This homeowner contacted UK Heat Pump Help because they were considering an air source heat pump installation. They knew they needed a room-by-room heat loss calculation, but they also had plenty of questions. What size heat pump did they actually need? Which radiators would need changing? What flow temperature should the system be designed around? How much should they realistically spend? And perhaps most importantly, would spending more money on the heating system actually save enough on running costs to make it worthwhile? That's where our Technical Heat Loss and Pre-Installation Review started.
More than somebody measuring the rooms
An experienced heat pump engineer visited the property and completed a full room-by-room heat loss assessment, but the visit wasn't simply about measuring walls, windows and radiators. We also looked at the existing heating system and discussed exactly what the homeowner wanted from their new heat pump. By the end of the visit, they had a much clearer understanding of the property's heat loss, the likely heat pump requirement, which radiators needed changing, potential system upgrades, different design flow temperatures, likely installation requirements, approximate additional costs, and what they should be asking prospective installers to provide. The homeowner could now approach installation companies knowing what they actually wanted to buy.
Should the system be designed at 50°C, 45°C or 40°C?
This became one of the most useful parts of the assessment. Rather than simply choosing a design temperature, we showed the homeowner what the different options meant financially. A system designed around a lower flow temperature can generally allow a heat pump to operate more efficiently, but achieving that lower temperature can require larger radiators and additional changes to the heating system. So there's a balance to strike: how much should you spend today to reduce your running costs tomorrow?
Option 1: designing around 50°C. This required fewer alterations to the existing heating system, meaning a lower initial investment. However, the heat pump would generally be expected to operate less efficiently than the same system capable of heating the property at a lower flow temperature. It was the lower cost installation option, but not necessarily the lowest running cost option.
Option 2: designing around 40°C. We then looked at what would be required to design the property around approximately 40°C flow temperature. This required significantly more work. Larger radiators and other heating system improvements would have increased the initial investment by approximately £3,500. The system should then be capable of operating at lower temperatures, potentially improving heat pump efficiency. But when we compared the additional investment against the estimated reduction in running costs for this particular property, the payback period was too long to make the extra £3,500 particularly attractive to the homeowner. Spending money to save energy only makes financial sense if the saving justifies the investment.
Option 3: the compromise at 45°C. Designing the system around approximately 45°C required some additional radiator and system upgrades, but considerably less than designing everything around 40°C. Based on the estimated costs and potential energy savings for this particular property, the additional investment was expected to pay for itself in around two years. After discussing the options, this was the design the homeowner chose. Not the cheapest installation. Not the lowest possible flow temperature. But the option that made the most sense for them financially.
Lower isn't automatically better
It's easy to say heat pumps are more efficient at lower flow temperatures. That's true in general, but it doesn't automatically mean spending thousands of pounds getting from 45°C to 40°C is a sensible investment. Imagine spending an additional £3,500 to reduce your annual energy bill by a relatively small amount. Technically, you've created a more efficient heating system. Financially, you may never recover the investment within a timeframe that matters to you. That's why we don't believe heat pump design should simply be about chasing the lowest possible number. We'd rather ask where the sweet spot is between installation cost, efficiency, comfort and return on investment. For this homeowner, that sweet spot was approximately 45°C. For another property, it could be completely different.
The homeowner knew what they were buying before speaking to installers
This was arguably the biggest benefit. Before the assessment, the homeowner knew they wanted a heat pump. Afterwards, they understood what heat pump system they wanted. They could approach installation companies with a much clearer specification and have more meaningful conversations about heat pump sizing, radiator changes, design flow temperature, system alterations, controls, expected performance and installation price. Instead of receiving three completely different quotations and wondering which installer was right, they had an independent design to compare those quotations against.
This is why our heat loss survey is different
A heat loss calculation is important, but on its own it's ultimately just a set of numbers. Our Technical Heat Loss and Pre-Installation Review is designed to turn those numbers into practical decisions. We don't just want to tell you your property loses a certain amount at the design temperature. We want to help you understand what size heat pump makes sense, which radiators need changing, what different flow temperatures would require, how those choices could affect efficiency, what additional investment may be worthwhile, what the practical installation will involve, and what you should be asking your installer.
Get the design right before choosing the installer
A heat pump is a significant investment, and once the pipework is installed, the radiators are changed and the equipment is sitting outside your house, fixing a poor design can become expensive. That's why there's a strong argument for getting independent technical advice before signing an installation contract. Understand the system first. Understand the compromises. Understand where your money is best spent. Then find the right company to install it.
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Whether you need help with an existing heat pump, a pre-installation review, cooling advice, servicing or a room-by-room heat loss survey, send us a few details and we'll point you in the right direction.
Whether you need help with an existing heat pump, a pre-installation review, cooling advice, servicing or a room-by-room heat loss survey, send us a few details and we'll point you in the right direction.
Whether you need help with an existing heat pump, a pre-installation review, cooling advice, servicing or a room-by-room heat loss survey, send us a few details and we'll point you in the right direction.
