Hello,

I was having trouble getting heat to the top floor of my house. I bled the lines and a whole bunch of air and crud came out, then ran clear. When I opened everything up again I saw that the pressure Guage on the furnace said 35 pounds.

If I shut the intake water off I can get to that 8-12 PSI but the second I open the main water line it goes to 35. I do have a Watt ETX-30 that says it does pressure but I'm not sure if that could be the problem.

Any help or direction is greatly appreciated,

Thank you.

If the gauge is accurate your t and p valve is seized and must be replaced
While the boiler is drained i would replace the gauge and empty the expansion tank fully or install a new one
Also replace the auto feed if you have one

Please excuse my ignorance.
What is a T and P valve?

There is NO T - P relief on a boiler, merely a P relief.

Your pressure relief valve 'should' have opened at 30 #.

One or more or all of the following are NFG:

PRV

Gauge

Auto fill valve

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Just to be sure.

That's on my water boiler. The issue I'm having is the pressure from my furnace.

A T-P relief valve will be found on a fuel or electric fires water heater, temp relieves at 210 degrees, pressure at 125 or 150 psi. A temp release is required so that the water does NOT become superheated under pressure.

A seam rupture on pressurized superheated water vessel is a CATASROPHE since the pressure immediately drops to zero (atmospheric) and the superheated water INSTANTANEOUSELY flashes to steam occupying 1,700 times the volume = BOOM.



A hydronic boiler for heating purposes operates at 8-12 psi and 180 degree water. It has a pressure relief valve set at 30#.

It has a gauge, a compression tank (called an expansion tank), and may or may not (probably DOES) have an auto-fill pressure regulating fill valve.



If, repeat IF, there is a coil inside the hydronic boiler to supply hot water (with or without a holding tank) said coil / tank then has a SEPARATE T-P relief.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

if there is only a coil, it has a pressure relief valve.
if the coil feeds a storage tank then the tank has a temperature/pressure relief valve.

he pressure has to be adequate to lift the water above the level of the upper radiators. A tall building with the boiler in the basement MIGHT need more that 12 psi.

packy,


correct

again




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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Help me understand why a water heater needs a T & P relief valve whereas a hydronic boiler only needs pressure relief.

A water heater will only have superheated water when the thermostat malfunctions. A boiler could have superheated water if the thermostat malfunctions, though not superheated to the same extent because of the lower pressure. But super heated nevertheless. So why no requirement for temperature relief in a boiler?

the severity of the 'explosion' at 30 psi in a boiler versus the explosion at 150 psi is like night and day

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

temperature relief valve relies on new water flowing into the device to cool it down so the lowered temperature allows the valve to turn off. A boiler has a "feed valve" which would NOT introduce cooler water so the temperature device would be ineffective.