can not get pressure below 22lbs

mark anderson

Forced water,oil burner.Cast iorn radiators.

The pressure relef kept going off eveytime pressure hit 30lbs.

Changed the flow valve and put in a 30extrol.

I dropped the psi to 8 lbs and walked away. come back next day and the sytem is at 22lbs. The system water is hot and running.

I did turn down the pressure setting on the flow valve below the preset 15lbs.

Once I changed the setting I drained a little water bringing the pressure to 8 lbs. The flow was giving it water till it reached 15 lbs(cold) I figured ok! I can live with 15lbs.
Next day it is at 22lbs (hot)

Whats the problem here

Many thanks in advance.

Unknown

Not a problem

Water expands when you heat it.

The extra volume goes into the expansion tank; compressing the air in there.

This causes the pressure to rise.

It's supposed to do that.

Noel

mark anderson

Shouldnt the pressure stay the same due to the expandable

Shouldnt the pressure stay the same due to the expandable diaphram?

What would be a normal for cold and a normal reading for hot?

I appreciated your reply.

scrook_2

system pressure

Unless you have 3 or more stories of radiation over the boiler set the pressure reducer valve to fill it to 12 psi cold and it shouldn't go over 20 psi hot. A larger Extrol tank would keep it from rising that much, but 20 psi, give or take a little, hot should be fine. The Extrol should be pressurized to 12 psi too, prior to install.

David Sutton_3

if your feeder is..

on the suction side of the circ, and not at the point of no presure change , when the circ comes on it will drop the presure at the point of the feeder and it will add water to your system, make sure its where your extrol is so where you hang your tank tee the feeder in there and the presure will not vary

Unknown

No, not exactly

When cold, at the precharge pressure of 12 PSI, the bladder will fill the entire tank. When the system water expands into the tank, filling it halfway, the air pushes back on the water. When the water pushes the diaphram into half of the tank (to make room for the expansion) the air pressure HAS to go up. The same amount of air in half the space would push back on the water, and show more pressure on the gauge.

When the system cools, the air pressure pushes the water still, and the water leaves the tank to keep the balance. When the bladder gets fully extended, the pressure in the tank will be back at the starting point.

Noel

ScottMP

expansion tank

Switch to a number 60 expansion tank, a 30 is just to small to handle the volume of cast iron radiators.

I had this happen to me years ago and changing to a 60 tank allways took care of it.

Scott

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jose

also

He should also make sure the aquastat/high limit is set correctly, too much heat will also create too much pressure.

joe_14

pressure


your static fill pressure should be set to accomodate the height of the highest radiator. around 12 psi for two stories 18psi for three stories. and yes you should use a bigger tank than a #30 you have a large volume of water. use at least a #60 or #90 before you insatall the tank pump it up to match your system fill pressure this will give you the prpoer volume of the tank


good luck

joe.g

mark anderson

You people know your stuff !!! I have a three story house with

I have a three story house with the boiler in the basement.The top of the highest radiator is 25' above the boiler.

There is 10 large cast iron radiators with cast iron pipes (old steam). my 1/2 pipe comes out of the radiator and terminates at the extrol.So i have no idea if its at the suction end of the circulators.

It has one standard Taco with three zones.

Thank you all very much,im very impressed.

Jim_47

water pres rising

Does it stabilize at 22lbs?
If it goes above it and dumps, is there a tankless coil leaking into the boiler water intermittenly?
I recently had one that only leaked during the heating season. Problem went away last april only to retur a month ago. Had customer shut off feed to coil and rising pressure problem did not happen over night. Coil had a pinhole leak that only showed up during the heating season.

mark anderson

No tankless coil