Bleeding radiators, need to adjust water pressure

John Ketterman

You may have a pressure-reducing valve that looks something like this (copy and paste the link into your browser):

http://www.pexsupply.com/categories.asp?cID=304&brandid=#

It should be just where water from your water supply is fed into the heating system. Raise the pressure by turning the screw on top of the valve clockwise. Watch the pressure gauge and go to about 12psi, and then a few more psi if really needed.

Remember that the above process will only increase the psi, so don't overshoot if you can avoid it. If you need to back off, turn the screw the other way and then let some water out using the faucet at the lowest point of the system.

Less common pressure-reducing valves look like the ones below:
http://www.blueridgecompany.com/radiant/hydronic/451
http://www.houseneeds.com/Shop/HeatingProducts/HydronicHeating/Watts/WattsBoiler12WaterfeedValve.asp

Kevin_48

Bleeding radiators, need to adjust water pressure

We have a gas furnace, a gas water heater and radiators throughout a two-story house. We haven't been getting heat upstairs - the radiators are cold.

I tried bleeding the air out. I heard the hissing when I opened them, but after a few seconds the hissing stopped and no water came out.

The pressure on the furnace is at about 6 lbs., which I understand is probably too low. There are several pipes and valves in my basement, but none are labeled so I don't know which one to turn and how far to turn it in order to (safely) increase the pressure and hopefully get the upstairs radiators to fill with water.

I know that this is difficult to answer because nobody else can physically look at the pipes and valves in my basement, but what should I be looking for? Thanks in advance.

Weezbo

do not add water to the boiler while it is hot and you

do not know the integrity of the temp pressure indicator.

instead , check the pipe temps with a heat gun. turn the boiler off and let it alone for about an hour... the differential pressure in cold and hot water will change the pressure reading on a gauge and depending on the rooms ambient temp it should also change the temp reading on the gauge.

It sounds like you may have a fastfill or regulator that would be a gizmo that came off after the cold water to a 1/2 inch valve to a backflow preventor to the fastfill (regulator) to another valve to the boiler....often it is piped into a T near the expansion tank(captive air) .

sometimes you may on a larger sytem have a valve ahead of it and after it with a copper pipe that comes out of a t over the top to another valve down by 90 to another T on to the pipe feeding the boiler ...that is a bypass for filling boilers from cold or empty instead of running water thru the regulator... do you see anything that looks like what i described?