Sorry guys but those in line heaters are useless. I had one before I went TM on my Cheyanne 3, I gave up on it after a couple of weeks struggling to get a decent hot flow, which when it came lasted for about 30 seconds before losing it again. It seems they just dont work fast enough to cope with the flow. The water needs to remain in the unit to heat up, but quickly empties when you pull the trigger to be replaced by cooler water. You then have to let this heat up and so, on. Tried lots of ways to prime the thing, but it couldnt cope. It ended up taking longer to try and get a hot water flow than to clean the carpet.
Dave.