What to remember when designing your next hydronic plus forced-air system

Hydronics + forced-air systems

People who can afford to build a large custom home often want to have the best of everything — including radiant floor heating. Being involved in the design and installation of many of these types of systems, I have learned some very important lessons.

Most of us who do this type of work do not have access to detailed mechanical blueprints and designs for these homes. Rather we are left on our own to design the perfect comfort system for the new homeowners. With that comes a great deal of responsibility to ensure these homes function as the homeowners think they should. Here are three tips I have learned over the years that I now follow for every system I design.

1. Interview the homeowner. Many times your conversations are only with the architect and the general contractor. When the homeowner is willing to spend four to five times the amount on a hydronic/forced-air HVAC system than he would have on a standard forced-air system, this is one step you do not want to skip.

People have certain expectations of radiant floor systems, included having “warm” floors all winter. This may not be the case, depending on the design and overall efficiency of the home. Being upfront with the homeowner about this is critical.

Talk with him about system reaction time to changes in thermostat settings and about how the cooling and indoor air quality systems integrate with the hydronic systems. These systems are much more complex to operate than just setting a thermostat and humidistat with a standard forced-air system.

2. Keep the system simple. Some of the early systems we installed had many zones of radiant, designed at different water temperatures, connected to forced-air systems with multiple zones of cooling, stand-alone steam humidifiers, etc. One important lesson I have learned is that we are not only responsible for this design but for the future maintenance of these systems.

By keeping the system simple, we not only make it easier for our service technicians to troubleshoot in years to come, we keep the cost of maintenance and repairs to a minimum for the homeowner. We are just now starting to replace major components on systems we installed 15 to 20 years ago and the repair costs surprise some people.

During my interview process, I explain to homeowners that some of these systems are as complex as small commercial building systems and to be prepared for future service-related costs.

Part of a simple design is to keep radiant heating and forced-air cooling zones on the same thermostat. While there are modern controls/thermostats that allow for easier integration of multiple heating zones within one cooling zone, I have found it to be much simpler to try and minimize this situation.

If we allow the homeowner to dictate how the system should be designed, then most of the time we end up with too many zones. Remember, you are the designer and will be held accountable in the future for the ease of operation and cost to maintain these systems.

3. Don’t be the guinea pig! We are all tempted to try the newest and greatest thing on the market. However, when designing systems for large custom homes, this is not the time to try the newest equipment or gadget on the market.

This is a personal opinion of mine that some of you may not agree with, but I prefer to wait a few years before designing a complete system around a new product. I am speaking from experience with a few products I have used in the past that were not quite ready. These types of designs have cost us money to keep running or completely change out.

Clear communication with homeowners about expected performance of their heating and cooling systems will help avoid problems in the future.

Author bio: Brian Stack is president of Stack Heating and Cooling in Avon, Ohio, a family owned residential/light commercial company specializing in hydronic heating. He is currently on the ACCA Radiant & Hydronics Council Advisory Committee and ACCA National Board of Directors.