Baxi boiler, re-pressurising.

DaireQuinlan

I have a Baxi boiler, Megaflow system HE IE.

Had it serviced the other day, but the guy couldn't find the repressurisation feed valves so left, saying it had to be re-pressurised. It's a closed system, the filling loop is the standard braided silver line with two valves, one at either end. The pressure dial, with the boiler off, reads about 0.1 bar or so.

I opened up both values, and the pressure dial climbed up to about 0.5 bar and stayed there. We have pretty bad mains pressure, we're at the top of a hill, so it's possible that's as high as it'll get.

The problem is, once I turn ON the boiler and the pump starts up, the pressure reading drops down to about 0.2 bar and sits there, only to go back up to 0.5 bar when the boiler turns off. As it runs and the water heats up it might go to 0.3 bar at most. When the pump stops it can drop to 0.1 bar again. It doesn't seem to be consistent. Is this expected behaviour ?

D.

Dtp1979

DaireQuinlan wrote: »

I have a Baxi boiler, Megaflow system HE IE.

Had it serviced the other day, but the guy couldn't find the repressurisation feed valves so left, saying it had to be re-pressurised. It's a closed system, the filling loop is the standard braided silver line with two valves, one at either end. The pressure dial, with the boiler off, reads about 0.1 bar or so.

I opened up both values, and the pressure dial climbed up to about 0.5 bar and stayed there. We have pretty bad mains pressure, we're at the top of a hill, so it's possible that's as high as it'll get.

The problem is, once I turn ON the boiler and the pump starts up, the pressure reading drops down to about 0.2 bar and sits there, only to go back up to 0.5 bar when the boiler turns off. As it runs and the water heats up it might go to 0.3 bar at most. When the pump stops it can drop to 0.1 bar again. It doesn't seem to be consistent. Is this expected behaviour ?

D.

If you were able to re pressurise the boiler, why couldn't the Service engineer do it?
.5 isn't high enough. Try topping it up at midnight when nobody else is using water.

DaireQuinlan

I wasn't there when the engineer was doing the service, and the person who -was- there didn't think to ring me. That said, it's not too hard to find so I'm inclined to think he just wasn't bothered ...

The user manual says that anything over 0.2 is enough, in fact it directs you to open the valves on the filling loop until the pressure hits 0.2 and then close them again, so I thought 0.5 was probably an OK pressure? It's more the behaviour once the boiler is turned on that's puzzling, the sudden drop in the pressure reading.

Prior to doing this I bled all the rads, opened up the valves, closed them again, ran the boiler for a bit, turned it off, waited for it to cool down, opened the valves again, still 0.5, closed off the valves, and still that same behaviour when I turned it on again.

beldin

Mine does the same, pressure is at 1 bar but when the boiler starts up the pressure can drop.

If it works fine at .5 bar then go ahead and run it.

Calibos

Mine stays at about 0.2 as well. Don't recall seeing a header tank in the attic for it so it doesn't seem like it's semi sealed, yet at the same time I've never come across a filling loop pipe either.