myson boiler

[greengrass]

Header/expansion tank that serves boiler



When the boiler is off the header tank overflow is ok and water inlet ball valve stops water level to around 35mm below the overflow,so ruled out the valve washer.

However, when the boiler switches on and the pump is running it causes overflow from the header tank to flow. She now has the cleanest patio in the area. What could cause the top up of the tank via it seems the only source points to the boiler vent pipe.

Myson marathon 80 circa 1996 and a floor mounted unit. Se's a widow friend of the family who is too far away for me to check it out.

Many thanks in anticipation.
Greengrass.

 

[Boilerman2]

With the heating on & the pump running, have a look in the header tank see if the water has become hot, also cheack that no water is running from the loop over expansion pipe into the tank, if all is OK

try carefully bending down the ball valve arm, to lower the "cold" water level (when the system heats water expands into the header tank, so there has to be sufficient room in the tank to accomodate it the cold water level should be around 40mm above the cold feed outlet at the bottom of the tank, thereby giving plenty of room for expansion without overflowing

 

[greengrass]

With the heating on & the pump running, have a look in the header tank see if the water has become hot, also cheack that no water is running from the loop over expansion pipe into the tank, if all is OK

try carefully bending down the ball valve arm, to lower the "cold" water level (when the system heats water expands into the header tank, so there has to be sufficient room in the tank to accomodate it the cold water level should be around 40mm above the cold feed outlet at the bottom of the tank, thereby giving plenty of room for expansion without overflowing

adding thanks to your reply as you can see, once again thanks
Greengrass.

 

[Agile]

The settings described are totally wrong.

Cold the level should be about 100 mm !

Tony

 

[Boilerman2]

As long as the cold water level is just above the cold feed outlet it is fine, if too high the tank MAY overflow when the water heats which the OP is complaining of by suggesting 40mm I was allowing a margin for error
at the end of the day we are arguing about a small amount of water!!