The capacitor across the line and neutral of a gas boiler I'm working on has gone short circuit. It's a 0.047uf 240v foil type. Can I replace it with a 2.5uf 400v of similar type capacitor?

 

The capacitor across the line and neutral of a gas boiler I'm working on has gone short circuit. It's a 0.047uf 240v foil type. Can I replace it with a 2.5uf 400v of similar type capacitor?

No. It must be a class-X.
(but you didn’t state what voltage supply your boiler uses, local regulations may differ - my answer is correct for my location)

 

Welcome to AAC!

No. You cannot replace a 0.047μF capacitor with 2.5μF.
Remove the capacitor and see if the boiler still works.

If your line voltage is 230VAC, replace the capacitor with 0.047μF/400VAC.

 

No. It must be a class-X.
(but you didn’t state what voltage supply your boiler uses, local regulations may differ - my answer is correct for my location)

Thanks, it is a class X as I recovered it from a disused fridge/freezer live/neutral. (The boiler is 230v). It's the difference in values of the capacitors that concerned me, 0.047uf and 2.5uf. What difference would this make, if any...?

 

Thanks, it is a class X as I recovered it from a disused fridge/freezer live/neutral. (The boiler is 230v). It's the difference in values of the capacitors that concerned me, 0.047uf and 2.5uf. What difference would this make, if any...?

One is 5 times the value of the other.

The question is, "What is the function of the capacitor?"
Does the boiler run with the capacitor removed?

 

If the capacitor is across live and neutral, it is just there for filtering so its value will be unimportant.
If that is the case, then the boiler will run with the capacitor removed as @MrChips suggested that you test. If it does, then a 2.5uF capacitor will do no harm, but don't go thinking that you can go around replacing any capacitor with one five times its size!
2.5uF will give you a bit of power factor correction for the pump.

 

One is 5 times the value of the other.

The question is, "What is the function of the capacitor?"
Does the boiler run with the capacitor removed?

The boiler works fine with or without the capacitor. So why is the capacitor there in the first place, (google tells me it's a spark supressor) and what electrical difference, if any, would no cap, .047uf cap and 2.5uf cap make?

 

So why is the capacitor there in the first place, (google tells me it's a spark supressor) and what electrical difference, if any, would no cap, .047uf cap and 2.5uf cap make?

If the capacitor is across live and neutral, it is just there for filtering so its value will be unimportant.

2.5uF will give you a bit of power factor correction for the pump.

 

Excellent, thank you for your help