Glycol Heating Systems
Why using a steam to glycol heating systems?
If you use steam directly or water alone in a coil in contact with fresh air, you are looking for trouble. Indeed, any problem with the drainage of the condensate in a steam coil or no-flow situation in a water coil can cause your coil to freeze when outside air is well below freezing temperature. Once the coil has frozen, it needs to be replaced in most cases. This is not only very costly but you can be without heat during an extended period of time. To avoid this situation, engineers use a mixture of water and glycol to bring the freezing point of the mixture below usual freezing point. Depending of the application and geographical location, a freezing point of 0oF can be acceptable in some case while -40oF would be required in extreme conditions. We typically see glycol concentrations between 20% and 50% for building heat applications. Glycol types most often used are ethylene or propylene.
Inconvenient of working with glycol solutions
High glycol content will drop the freezing point further down but will also reduce the efficiency of the heat transfer. Water has a great heat transfer potential with a specific heat of 1 Btu/lb*F but this specific heat drops when using glycol solutions. For example, a 50% ethylene glycol solution will have a specific heat of 0.8 around 90oF (heat transfer properties change with temperature). This means you will need to circulate 20% more liquid to get the same heat transfer than if you were using water only. On top of that, glycol is more viscous than water so it is a little more difficult to circulate. Bottom line is you will need more pumping power with a glycol solution than with water. However, this is a small problem compared to freezing a fresh air coil.
You will also need a glycol pressurizing tank to maintain the pressure of your closed loop if some glycol solution is lost along the way because of leaks or maintenance on some components.
How is glycol heated?
When steam is not available, glycol can be heated indirectly using hot water in a plate and frame heat exchanger. However, in large facilities like hospitals and universities where steam is readily available, the water/glycol mixture is typically heated indirectly using a shell & tube heat exchanger. And this is where Maxi-Therm comes into play.
If you are using water only or a water/glycol mixture, Maxi-Therm offers the perfect steam to glycol heating systems solution sized to your specific needs. Being our standard vertical flooded heat exchanger package or our complete turnkey HVAC skidded system (see our Ultimate Package Solution), we size all the components for your specific application requirements. With our vertical flooded patented design, we are able to provide factory assembled and tested systems that will save you energy, floor space and maintenance headaches. We have also factory wired and tested control panel options to make sure operation of the system is simple, optimal and safe.
Contact your local exclusive representative to learn more about our steam to liquid heat exchanger packages for building heat.