I have purchased the pipe freeze kit SF 2500R and I am not too happy with it. I have a service company and I tried to use it several times by applying the heads at the required distance on the pipe and spray the heads as the machine turns on. I work on buildings only and I may have a flow issue there might be some kind of slight passing at the isolation valves. Do the isolation valves have to be completely off or is there a little tolerance of flow that will freeze eventually? Is there any suggestions or secrets to this tool that are not in the literature that you might have?