How Can I Fail?
1. Size the system based on previous experience with BTUs (British Thermal Units) and ignore Prestyl’s sizing calculator.
Far infrared systems “heat” objects and surfaces; these do not heat the air. BTUs are an air-volume based energy measurement which is not directly convertible to surface areas. Prestyl’s Sizing calculator takes into account all surfaces and incorporates correction factors for window and door surfaces, which do not store as much energy as other surface areas.
(Comparable to traditional “heat losses”)
2. Ignore the floor
Concrete floors are ideal for storing far-infrared heat. To prove this, we can look at outside brick or concrete slabs; these surfaces will stay warm for many hours after the sun has gone down. To optimize a concrete floor for heat-energy storage we need to insulate it (similar to in-floor radiant heat).
To explain how this works in simple terms we compare this with a cooking pan. We heat a pan on the stove and when we take it off the pan is very hot; this is because the pan and everything in it stores the heat-energy. After we take it off, we put it on an insulated pad to keep it warm longer. Over time, the pan will cool off. This happens because the heat-energy is transferred from the pan to other media (air or objects).
We experience three kinds of heat transfer:
- The first is radiation; when you hold your hand near the pan you can feel that it is radiating heat-energy. This radiation causes some of the “heat losses” or cooling of the pan.
- The second is convection; cooler air moves past the pan’s surfaces and takes away some of the heat.
- The third is conduction; heat travels from the hottest to the coolest surface. The better the insulation value of the pad, the lower the conductive heat-losses, and the longer the pan stays warm.
If we put the pan on a large cool surface, the “conduction” component will become the most significant “cooling” (heat transfer or heat-loss) factor. If we place the pan on a cold metal counter, it would cool off in just a minute or two, and possibly 5 minutes on a stone counter. The same is true for an un-insinuated concrete slab; most of the heat it stores would simply conduct to the outside environment and the heating system would constantly work to replace the lost heat.
In contrast, a properly insulated floor would retain the heat-energy for long periods of time, and in many cases the Far-infrared heating system is only active during less expensive “off peak hours” and is off during expensive “peak hours”. During the “off” time, the floor releases its stored energy and gets replenished during the “on” time.
3. I have a large warehouse and the floor is insulated, but I cannot heat my shipping manager’s office; why is this?
In your scenario, since you have a continuous slab floor, you are unintentionally trying to heat the entire warehouse with only the heating system in the shipping manager’s office. You are heating the concrete floor in your shipping manager’s office, but your installer did not take into account that the entire warehouse shares the same slab. Though the building may be insulated at the perimeter, your tiny heating system is trying to heat the entire warehouse through what is known as “conduction”.
To optimize heating efficiency, you will need to line the manager’s office floor with a thin layer of insulation and cover this with a few inches of concrete or wooden floor boards. Once the heat transfer to the rest of the building has been stopped the system will work as designed.
4. I have a brand new building with a properly insulated floor but I cannot get the building to warm up; the building actually feels cooler, not warmer.
When concrete is fresh, it contains massive amounts of moisture (water). Depending on the soil and soil prep, it may take several months for the concrete to dry out. Infrared (of any wavelength) helps dry out the wet floor, but as the water evaporates, you are actually experiencing evaporative cooling. The drying/curing time with IR heat is typically 1/3 of the concrete’s natural drying time and as soon as the floor is dry the system will perform as anticipated.
5. I did a room addition and ducted my existing heating system into this room but I could not get it warm enough. I decided to add one small IR panel since I figured I only needed 1/3 of the heat to correct my problem. Why doesn’t this work? It works at my friend’s house.
Unfortunately there are too many variables (unknowns) that we cannot address in a pre-formatted answer. Due to these unknown variables, “adding “just a little bit of heat” is a trial and error process. The only way we can guarantee that the Far-infrared system in your addition will work properly is to use the sizing calculator and assuming that there is no primary heat source. In fact it may be better to cap off the air duct (unless required for AC) since the cool air from the home’s primary system may actually cool the surfaces and have a negative impact on the Far-IR system.
6. I tried heating my outdoor patio; I used the calculator but it did not work anywhere near what l expected; what am I doing wrong?
- First of all, the low-intensity Far-infrared heating systems sold by Prestyl today are intended (and approved for) indoor use only.
- Secondly, you included the floor, doors and windows in your calculations, but did not include the 60+% open space (no walls, just outdoor space).
In an outdoor environment there are many factors that need to be included in the equation: Such as heat losses through conduction to the outside of the structure, conduction to the ground around, the lack of storage facilities (only the floor and walls can store energy, not the open space), excessive cooling due to outdoor air movement and the wind-chill factor.
You would probably need 10 – 15 times the amount of panels to have the people feel reasonably comfortable, which would make outdoor applications not a viable or cost effective. A shortwave high temperature IR system (gas or electric) will probably be more practical in your situation.