Thanks for all the input everyone.
I have spoken to my dealer, he is talking of charging me to fix it, so I wanted to get some more info before dumping any more money.
haven't noticed increase growth around area yet, but will keep an eye out for it.
The stuff from gt Globe industries looks like the stuff I have.
My dealer also mentioned it may be due to unsettled ground, just not sure if I want to wait another year to find out!
Not sure of the temp drop to the house, but I will look into it. I was told to expect about 1 degree C drop over 100ft, I think I am at 115ft or so. Does that sound about what to expect? If I see much more drop, I probably have a problem?
I was at work during the install, but I imagine it is a bit shallower on the exposed patch and gets deeper as it runs under my driveway. I'll have to ask my dealer for more details.
I am just outside of Ottawa, crazy cold winter, but a happy wife who suffered through inhumane temperatures last year when we were heating with oil.
Good luck on the experiments guys!