Post by carrickknot on Nov 25, 2009 19:26:42 GMT -6
We installed our Watts Radiant heating system and electric boiler over the summer, so 2009 is our first fall/winter using it. We are heating 3000 sq ft at an average room temperature of 70F. At boiler start-up October 12, 2009 , we began monitoring our kWh and external temperatures daily to determine a consumption base line and external temperature correlation. We have noticed a great fluctuation in kWh usage from day to day. We are interested in what others may have experienced with a house of similar size. We live on Vancouver Island. Thank you
Post by Watts Radiant on Nov 26, 2009 16:07:13 GMT -6
The first thing to note when running your radiant system is to not pay attention to the air temperature too much. The air temperature in a radiant system will typically be lower than with a forced air system, yet maintain a higher level of comfort. So you might find that even 68 degrees is comfortable.
With regard to controlling the system, we typically recommended that you find a temperature you feel comfortable, and just let the system run. With a forced air system, you have quick response and can get away with fluctuating the set temp up and down as desired. With radiant, the system is much slower responding, and to control it like a forced air system usually leads to undesired results and wasted energy.
Since systems and construction varies tremendously, it is difficult to say what a "typical" kWh consumption would be. We do have a software program called RadiantWorks that can determine the heat loss for your house, and estimate the amount of energy it should take to heat it.
Since this is your first year, you might just set the system as described above, and let it roll through the heating season. That way, you'll have a definite benchmark to go by.
Post by Kolyn Marshall on Nov 30, 2009 13:09:02 GMT -6
There are several factors that may contribute to un-even operation.
1. Almost all radiant systems will have a relatively high start load. This is due to the system having to bring the mass temperature up. This process can take as long as a week, depending on construction profiles and current weather conditions.
2. Mass construction. Is the floor a frame floor, or a slab-on-grade? The greater the mass, the greater the thermal fly-wheel effect will be (the ability for the mass to coast).
3. The outside temp. As we move into winter, the outside temperature typically does not stay constantly cold, it swings. In Missouri we can have mornings in the 20's and be in the mid 60's by the afternoon. This can cause a radiant system to operate inconsistently. As winter becomes more "constant" then the system operation will become more constant.
Most radiant systems will cycle less than a traditional forced air system, but will run longer when they do operate. It's hard to compare the two solely based on run cycles.
In the end you really won't know how the system is performing until you begin to gather several months worth of utility bills. Once these start to come in then you will be able to see how many kwh are actually being consumed.