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Posted by Brian on Tuesday, 19 August 2008, at 7:19 p.m.,
in response to Geothermal Troubleshooters in Denver, CO area, posted by Terry Ten Eyck

Terry,

Have you checked all the connections to the boiler and in the box? A loose wire can cause an intermittent breaker fault. Try using a different circuit, typically the control supply is just 110v and normal amperage you should be able to plug in to a different outlet on a different circuit to see if it is a problem with the boiler. In my system I had a bad breaker that would trip early. I replaced the breaker and the problem went away. If it still blows the other breaker and if all the wiring looks good, have the installer replace the boiler controls or the boiler until he fixes the problem.

It is not unusual to have ignition and burn problems at your altitude. I had a boiler that would back fire and have control problems. I had to change the burner, expand the air intakes and change the baffling in the boiler. I also had to protect the air intake from being subjected to high winds.

Does your system have floor temp sensors and outdoor air temperature input? Does your controller work off air temperatures? Do you monitor the internal log temperature so you can see what is happening to the thermal mass temperature of the house?
What type of controller are you using and how is it programmed.

Another issue is that log cabins have a significant thermal lag built in to the logs. You get about 1 hour of thermal lag per inch of log thickness, this is a relative number because it is delta t dependant. The larger the diameter of the logs the bigger that thermal lag will be. The mass of the logs will cool before cooling the house significantly and then you have a huge cold thermal mass to heat against when the system finally sees the inside a temperature cooling off it is too late to recover without the house being uncomfortable.

Often in homes with high floor thermal lag, high wall thermal lag, high basement thermal lag the controller is not capable of handling, understanding and deciphering the information to make good decisions. An example, the temperature outside suddenly falls and the logs start absorbing the cold. The controller has to understand this situation and start heating against the coming thermal wave front hours before it gets to the inside of the house or the house will suffer significant temperature fluctuations.

High thermal load on the heating side can reduce the ability to get adequate hot water from some systems if these problems coincide. How is your system plumbed?

If your system was designed for your home by someone that understands these relationships and installed it properly it should not have a problem maintaining the temperatures. It is very common for the installer of in floor heating systems to be from a standard HVAC and or plumbing background and for them to not properly understand, design, install, and control the systems correctly do to all the dynamic interactions of the system. Read through all the posts on this forum and you will see many system problems due to poor initial system design and installation.

Brian

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