Initial filling pressure on a gravity hot water boiler.

Markus_2

I have a gravity hot water boiler (very old system) and had to drain it to remove radiators while refinishing floors in my home. When I refilled it it seems the reduction valve (which is rated for 12psi) doesn't work and the system fills to city water pressure (aprox 35-38 psi). The pressure gauge on the boiler is pretty simple, however it has the word "Danger" at the 30 psi line giving me a subtle hint that city water pressure is too high to run it at.What pressure do these typically run at? Any help would be appreciated. Thanks.

Empire_2

Fill Pressure

Yes the fill Valve is bad and needs to be replaced. 1 psi will raise the water level in the boiler roughly 2.34 feet. Generally preset at 12 psi from the factory, this will raise the water to 30 feet or so. Fine for most 2 story dwellings.

Markus_2

Thanks Empire, guess I'll go drain some water out.

jerry scharf_2

think of it as flushing the system!

Marcus,

You've been steared correctly.

Since you need to drain the water again, why not take the opportunity to flush the system as well. You could add a cleaner (George seems to like Rhomer products!) or not, but open the valves wide and see if you can get some benefit from all the water going down the drain.

jerry