Last August, we paid a licensed firm to install 1500 sq ft of oak flooring on two levels of our home. In November, gaps started to appear and as they grew bigger there became tears along the seams of the boards. It looks like a piece of paper when you tear it with ragged edges. Every board now has a gap between it. Many are significantly larger than a dime. Several of the boards have split through the center of the boards. We also installed hardwood in the kitchen which is my biggest concern with the water getting into the cracks. The firm claims this is normal. I do not believe that this is normal. The firm said they can fill the cracks and apply another coat of poly and extend the warranty. I cannot see how by adding another coat of poly solves this problem. Many of the cracks have shrunk with the weather becoming more humid but my fear is that this same thing is going to happen once again when the humidity subsides. I don't know what to ask the firm for and I am looking for any help. I have a house full of furniture that will need to be moved as well as all new baseboard trim that was installed after the floors were put in which it appears that I would be responsible for moving & removing.

If the homeowner does not maintain a constant relative humidity level and temperature, then gapping in solid wood floors is going to happen as the flooring will expand and contract with changes in the temperature and humidity. This is normal and not considered a defect. It is covered in the NOFMA manuels and publications. There are times when gapping is not normal. Only a highly skilled inspector can ascertain the difference.
https://www.nofma.org/Portals/0/Publica ... ps_R6b.pdf
https://www.nofma.org/Portals/0/Publica ... isture.pdf

It's the homeowners responsibility to maintain "normal living conditions" year round. Seasonal movement is to be be expected with a solid wood floor. Check into having a humidistat put on your hvac, otherwise it sounds like you need to run a couple of humidifers in the winter to replace the moisture being sucked out by heating the home.

The gaps should start closing up as it is a few days from summer, if in August, the same conditions which it was installed in, unless you have change something with the ambient conditions in your home.

If it was installed "wet" it very well can shrink, and not close the gaps. That is what acclimation to living conditions is all about. Moisture meters are mandatory, not a luxury for installers. Along with educating, their clients about wood floors and constant humidity levels, from acclimation, to yearly use.