Boiler Blows fuses!!!!

[Caesar]

Hi All

I have a Potterton Profile 80e I think. Firstly the Honeywell Programmer digital type had no lights or even time showing on it. Checked in the airing cupboard where pump and electronic control box is which i think controls the pump, programmer, 3 port valve electrically I think. This received power via a 3 pin plug which plugs into a electric spur. when I checked the 3 amp fuse it had blown. Replaced fuse, power lights plus Clock timer came back on programmer. Started the heating, fan whirred, ignition started to click to ignite then there is a large click which instantly blows the fuse in the 3 pin plug!!! Sorry fr the long post but anybody has any ideas? replaced 3 amp fuse a number of times wiht the same result!!! Many thanks.

 

[BOB D.O.L.E]

pump

 

[Caesar]

Hi Bob D.O.L.E many thaks for your kind reply. How do you check it is the pump thats the problem? Could it not be the Gas Valve or anything like that? Many thanks.

 

[Agile]

Judging by your sequence it well be something else!

But pumps are the most likely statistically.

Easy to check.

Disconnect pump and wire it to a plug with a 3 A fuse and see if it blows when you plug it in.

Only do this if competent.

Tony

 

[BOB D.O.L.E]

Hi Bob D.O.L.E many thaks for your kind reply. How do you check it is the pump thats the problem? Could it not be the Gas Valve or anything like that? Many thanks.

just stick a multimeter on and see if there is conti.

 

[diverdee]

need to test the resistance of the pump between live and neutral pins and make sure there is a working reading 150 ohms+

 

[diverdee]

but the fact that boiler trys to light points maybe to gas solaniod because would imagine pump is already running by the time it trys to spark

 

[BOB D.O.L.E]

but the fact that boiler trys to light points maybe to gas solaniod because would imagine pump is already running by the time it trys to spark

could be but all with coil wiring needs to be checked but not fan has it was working

its hard to diagnose off heresay with this type of fault he will need to go throught the check list with a multimeter

 

[Agile]

Blind leading the blind as usual.

I appreciate that most of the people on here are not professional diagnostic engineers.

I also know that even if I tell you something then you will probably ignore what I am saying.
However, I will still say it although the term "pearls before the swine" comes to mind!

Its not always possible to identify a fuse blowing problem with a low voltage meter. Thats why an electrician has to use a 500v insulation tester.

Of course few people on here will even know much at all about electronics.

Suppose I ask you to email me with the answer to this simple question?

A gas boiler fan measures 44 ohms resistance. You connect it to 230v mains. What current is taken from the mains supply?

Tony

 

[BOB D.O.L.E]

Blind leading the blind as usual.

I appreciate that most of the people on here are not professional diagnostic engineers.

I also know that even if I tell you something then you will probably ignore what I am saying.
However, I will still say it although the term "pearls before the swine" comes to mind!

Its not always possible to identify a fuse blowing problem with a low voltage meter. Thats why an electrician has to use a 500v insulation tester.

Of course few people on here will even know much at all about electronics.

Suppose I ask you to email me with the answer to this simple question?

A gas boiler fan measures 44 ohms resistance. You connect it to 230v mains. What current is taken from the mains supply?

Tony

So after all this rambling trying to impress us all with your big headed knowledge you cant give him the answer because the answer is it cant be given unless you where there and worked on it.

So put all yea fancy big headed words back in there boxes and shut your big fat gob D..ck head.

And the answer to your question is 5.2 amps

 

[diverdee]

ac or dc? sorry agile i agree no point blinding diyers with too much info they dont know what to do with.we just try and point them in right directions.most diy people have a ohms meter but not an insulation tester.and a ohms reading will tell you if there is a constant fault on the item. n its 5.23 why not tell him it should not be on a 3 pin plug too !!

 

[aptsys]

And the answer to your question is 5.2 amps

But is a fan a purely resistive load?

I have a transformer sitting in front of me with a 47 ohm primary resistance, but it definitely doesn't draw 4.89A from the mains

 

[diverdee]

but most boiler fans on dc so total different scenario

 

[aptsys]

Brushless DC so even more of a different scenario

 

[BOB D.O.L.E]

ac or dc? sorry agile i agree no point blinding diyers with too much info they dont know what to do with.we just try and point them in right directions.most diy people have a ohms meter but not an insulation tester.and a ohms reading will tell you if there is a constant fault on the item. n its 5.23 why not tell him it should not be on a 3 pin plug too !!

OK mr technical bu..ll.sh.tt.er and agile try this one

A conductor has a diameter of 2mm for every metre and a lenght of 2 metre a similar conductor is 8 metres long
what would the diameter have to be if the resistance stays the same

easy this one any competent engineer should know this