I don’t have a hot water heater, the water is heated through furnace. When I run the shower, I get nice hot water for a long time, but when I swithc the water to the tub, it turns cool/cold within seconds. A friend of mine suggested that the diverter valve (Symmons system) may need to be replaced, but I couldn’t get it out (it would not just pull out).
What do you think the problem is, and if it IS the diverter valve, how do I get it out?