Can heat pump anti freeze valves replace glycol
In cold climates, protecting heat pump systems from freezing is essential to ensure efficient operation and prevent damage. Traditionally, glycol has been used to lower the freezing point of the water within these systems, though anti-freeze valves offer a genuine alternative, automatically draining the system when temperatures drop below a certain threshold.
They cost about the same as one 20 litre tub of glycol but need no ongoing maintenance and don't reduce system efficiency. We only supply anti-freeze valves for projects where they're suitable and won't affect the heat pump warranty, so you can use them with confidence when they're the right fit.
This article looks at why anti-freeze valves are a strong alternative to glycol in heat pump systems, weighing up the advantages and disadvantages of both to help you decide on the right freeze protection strategy for your project.
The Drawbacks of Using Glycol in Heat Pump Systems
Most heat pump installers will be familiar with glycol, and if you've worked with us through our MCS Umbrella Scheme or attended our heat pump training, we've likely recommended glycol as part of your system setup. While glycol is commonly used, it's important to be aware of a few downsides:
Cost: Glycol can be expensive, and typically, multiple containers are required to fill a heat pump system adequately. A 20-litre container of glycol costs around £200, meaning that using several tubs can significantly increase the overall cost of the system.
Maintenance: Glycol needs regular testing and replacement to ensure it continues to function effectively. If you need to drain the system, the glycol must be replaced, which adds ongoing maintenance costs. This is something we've covered in our heat pump training, as it's crucial to factor in maintenance when considering system longevity and performance.
Performance: Glycol is a viscous liquid, and even when diluted with water, it can reduce the efficiency of a heat pump. This increased viscosity means the system has to work harder to circulate the fluid, which can impact overall energy efficiency.
Toxicity: Glycol is toxic if ingested, so great care must be taken when draining the system to avoid contamination.
Inta Zero Anti-Freeze Valves
What Are the Benefits of Anti-Freeze Valves?
Anti-freeze valves are designed to drain down a heat pump system if the temperature of the heating circuit (not the outdoor temperature) drops below 3°C. Each valve contains a small sensor that triggers when the heating circuit falls below this threshold, meaning the system would have to lose power and the pumps stop running, or we'd have to enter a new ice age, for this to happen. Similarly to glycol, this is done to prevent the heating system from being damaged in cold conditions. Here are the benefits of using anti-freeze valves:
Cost: A pair of anti-freeze valves costs around £250, and unlike glycol, only one pair is needed for the system.
Maintenance: The valves are a fit-and-forget product, requiring no maintenance and should still be working in 7-8 years.
Performance: Anti-freeze valves serve as an alternative to glycol, meaning your heat pump system will work more efficiently thanks to the fluidity of water.
To find out more, we've put together a short video explaining the benefits:
What About the Heat Pump Warranty?
Many installers are concerned about the possibility of invalidating a heat pump warranty by using anti-freeze valves. Thankfully, this isn't the case. Most manufacturers state that there must be anti-freeze protection, without listing glycol as the only option.
In the case of Mitsubishi, here's their stance on anti-freeze valves:
"Anti-freeze valves can be used, but you must ensure the freeze stat function on the FTC6 is enabled."
The Mitsubishi Ecodan has a function whereby when the outdoor temperature drops below 5 degrees, it runs the pumps to ensure the water doesn't freeze. So anti-freeze valves are supported by Mitsubishi when that function is used, which it always is.
Samsung heat pumps can also use anti-freeze valves, but usually require other items alongside them, which can increase the overall cost.
Can You Use Glycol and Anti-Freeze Valves Together?
Some installers have asked about using both anti-freeze valves and glycol for extra protection. This isn't something we recommend. Mechanically, the system would work fine, but it would be a waste of money for your customer and wouldn't add any real value.
Adding glycol to the system would lower the freezing point of the water, but it wouldn't change the temperature at which the anti-freeze valves open. So if the valves were triggered, the system would still drain, wasting all the glycol in the process.
MCS Umbrella Scheme
Whether you're specifying anti-freeze valves or glycol, getting the details right matters, and that's exactly the kind of technical decision our MCS Umbrella Scheme takes off your plate. We handle all the MCS paperwork and compliance, and our expert team designs, supplies, and commissions the system, so you can focus entirely on the installation.
Stock Available
We hold stock of anti-freeze valves and are recommending them to our installers. To find out more, get in touch or download the spec sheet.