Anything over 2.5 bar you're getting to close to the magic number of 3 bar where the safety valve is fully opened and emptying your system water to outside (hopefully),
Setting the pressure in a heating system is only a issue for a sealed system filled from the mains by a filling loop, if you have a tank fed boiler then the tank will replenish any water lost and the reading on the guage will only show the effect of gravity on the water and then as it heats up it may show movement on the guage.We have an expansion tank in the attic
most gas boilers are designed to be used on pressurized sealed systems and mains water fed, because of this most gas boilers come with a 3 bar safety valve fitted inside them, if there is to much pressure building up in the boiler this valve will open and release heating water stopping any further increase in pressure in the boiler, these valves should be plumbed to a safe place.which I think takes the place of the "emptying outside" function.?
If a 3 bar safety valve is not plumbed to a safe place ie... to outside , then when the valve opens it will empty under the boiler flooding any area the boiler is in, this would be a bigger concern if the water was at i high temperature and someone got burnt, Gary.As a by-the-way, when you say "hopefully", what would happen if the system water could not empty outside or into an expansion tank - would the pipes burst?
If a 3 bar safety valve is not plumbed to a safe place ie... to outside , then when the valve opens it will empty under the boiler flooding any area the boiler is in, this would be a bigger concern if the water was at i high temperature and someone got burnt, Gary.
Setting the pressure in a heating system is only a issue for a sealed system filled from the mains by a filling loop, if you have a tank fed boiler then the tank will replenish any water lost and the reading on the guage will only show the effect of gravity on the water and then as it heats up it may show movement on the guage.
most gas boilers are designed to be used on pressurized sealed systems and mains water fed, because of this most gas boilers come with a 3 bar safety valve fitted inside them, if there is to much pressure building up in the boiler this valve will open and release heating water stopping any further increase in pressure in the boiler, these valves should be plumbed to a safe place.
Unfortunately i have the answer to that, it's because they don't want the walls stained from contaminated water when the safty valve leaks, Gary.My pet hate is safety valve outlets. Countless times I have seen them terminated out of building at head height, so If they do go and your unlucky enough to be walking by, you get a face of very hot water. the hard work was done by drilling hole out, why can't they be run toward the ground and at a lower position?