why does my gas furnace always spews water from the pressure relieve value(hot water heat)?
Answers:
There are a couple of reasons: First, check the water pressure gauge to see if it is above 30#'s(setting on boiler relief valve), and if it is, use the drain that should be near the bottom of the boiler to draw off some water until pressure reads about 20#'s. If it is below 30#'s, then you may just have a leaking relief valve(it happens, they have just a metal to metal seal. If the valve keeps blowing off, I would then replace the expansion tank, but be careful, it may be waterlogged & very heavy, and will also spray water all over if you attempt to remove it without shutting off the boiler and relieving the pressure. If both of those things don't work, I would replace the boiler feed/fill valve as it may be letting too high a water pressure into the boiler (it should be preset at 12#'s). That is really all the things that can go wrong with a boiler relief other than having an undersized expansion tank to begin with, but if that were the case, than it would have been blowing off the relief valve almost from day 1. If you are not comfortable with all this, call a plumber. Hope this helps,
Steve
Other answers:
your relief valve is in need of change The srping is weak
your relief valve is in need of change The srping is weak