Hi all. I have an oil-fired tankless hot water setup (Kerr Comet) with my aquastat set at 180-160-10. When I run a bath for my daughter, the water starts to run cold long before the furnace kicks in to heat the domestic water back up. I've tried setting the aquastat up a bit on a trial basis (190-170-10) and it doesn't seem to be much better. The house heats well, but we consistently have to run the water to luke warm, turn it all off and wait 5 minutes to finish putting water in the tub. Mind you, there's only 6 or 8 inches of water in the tub by the time I'm finished, and it's only hot enough for a 2 year old; not exactly scalding (P.S. The "anti-scald" feature of the faucet is set at it's lowest for most hot). I've tried pushing the mixing valve to send less cold, and it seems to make the hot hotter, but no real chance when it starts to get chilly again. I live in Atlantic Canada and winter can get pretty chilly, but summer or winter I have the same problem. My furnace cleaner says that he thinks it's the mixing valve, but I'm not so sure; the mixing valve seems to be doing what it's supposed to in response to me changing it's position. Does anyone have any insight? Thanks so much in advance.