Boiler internal fuse keeps blowing together with the pump

[vinux]

I got Sime Friendly Format 80E boiler which keeps blowing main PCB fuses and the pump.

Few weeks ago the pump gave up the ghost and it looked like a simple fix so the plumber replaced the pump. The fuse on the main PCB was also blown which I thought was the result of the pump shortening out.

Then a couple of weeks later the same thing happened again. The plumber assumed that it was some faulty batch so decided to use a different brand of the pump.

It was working fine for a couple of weeks and tonight it blew the fuse again.

Not sure if the pump is gone again but I would think that the problem was not with the pump itself from the very beginning and something else needs sorting out.

I can't see any leaks anywhere. The board seems to be dry. If I disconnect the pump and open the tap or switch central heating on then the boiler fires up but obviously the water does not circulate in the radiators.

What could be the problem? Is it the PCB, pump (hard to believe that it would be the 3rd faulty pump) or the wiring? How can I check if the pump is still working?

I have a multimeter, can check various things and understand a lot of these things but really need your help here.

 

[hertsboilers]

It is a 1.6A FB fuse are you sure that you put a correct rate one?

 

[andytw]

Was the correct fuse fitted ? Does it say somewhere that the fuse is an F5a or T3a or something like that.
I once spent ages looking at a TV that I had repaired but continued to blow fuses every now and then. The PCB was marked T3A so I fitted a 3A fuse. What I didn't realise was that that the T designates time delay or slow blow fuse. Once I fitted the correct fuse it was fine.

andytw

 

[vinux]

It is a 1.6A FB fuse are you sure that you put a correct rate one?

It's exactly like the one that was on the board and was working fine for at least 5 years (when I moved into the property).

Maplin product code: GL61R. I can't link to the product directly but it's on this page:

http://www.maplin.co.uk/20mm-glass-time-delay-t-fuses-452

Search for GL61R on this page.

 

[andytw]

Mmm interesting. The T1.6A is a time delay fuse. The manual for your boiler says it should be a F1.6A which is a fast blow. Whilst the T fuse would be the wrong fuse I would have thought it would improve matters.

andytw

 

[vinux]

Was the correct fuse fitted ? Does it say somewhere that the fuse is an F5a or T3a or something like that.
I once spent ages looking at a TV that I had repaired but continued to blow fuses every now and then. The PCB was marked T3A so I fitted a 3A fuse. What I didn't realise was that that the T designates time delay or slow blow fuse. Once I fitted the correct fuse it was fine.

andytw

The fuse packaging does not say F5a or T3a anywhere but it says "Time Delay 1.6A".

And on the fuse itself it says T1.6AL250V

 

[vinux]

Mmm interesting. The T1.6A is a time delay fuse. The manual for your boiler says it should be a F1.6A which is a fast blow. Whilst the T fuse would be the wrong fuse I would have thought it would improve matters.

andytw

Could it be a short circuit somewhere in the wires? Should I try to fit fast blow fuse instead? Is it possible that I burned three pumps by putting the time delay instead of quick blow fuse in and wouldn't the PCB itself burn before the pump? If I disconnect the pump then the boiler fires up ok which I think means that the pump is shortened out at the moment.

 

[andytw]

I wouldn't think the fuse is making any difference. If you had them the other way around then it could be a problem i.e. It specifies a 'T' time delay fuse and you fit an 'F' fast blow fuse.

You say it fires up if you disconnect the pump. Where are you disconnecting the pump ? (At the pump or at the boiler ?)
When the pump is disconnected measure resistance (meter on ohms). between its L and E connections and between it's L and N connections, what readings do you get ?

andytw

 

[JohnD]

you say it "keeps blowing" the pump? What happens to the pump? Does it get very hot (hotter than the pipes beside it)? That usually indicates a seized pump or a blockage, both usually caused by sediment and dirt.

does the heating and hw seem to be working OK?

 

[ianmcd]

I got Sime Friendly Format 80E boiler which keeps blowing main PCB fuses and the pump.

Few weeks ago the pump gave up the ghost and it looked like a simple fix so the plumber replaced the pump. The fuse on the main PCB was also blown which I thought was the result of the pump shortening out.

Then a couple of weeks later the same thing happened again. The plumber assumed that it was some faulty batch so decided to use a different brand of the pump.

It was working fine for a couple of weeks and tonight it blew the fuse again.

Not sure if the pump is gone again but I would think that the problem was not with the pump itself from the very beginning and something else needs sorting out.

I can't see any leaks anywhere. The board seems to be dry. If I disconnect the pump and open the tap or switch central heating on then the boiler fires up but obviously the water does not circulate in the radiators.

What could be the problem? Is it the PCB, pump (hard to believe that it would be the 3rd faulty pump) or the wiring? How can I check if the pump is still working?

I have a multimeter, can check various things and understand a lot of these things but really need your help here.

What different brand of pump ? are you sure it was the pump that was blowing the fuse in the first place ?

 

[vinux]

I wouldn't think the fuse is making any difference. If you had them the other way around then it could be a problem i.e. It specifies a 'T' time delay fuse and you fit an 'F' fast blow fuse.

You say it fires up if you disconnect the pump. Where are you disconnecting the pump ? (At the pump or at the boiler ?)
When the pump is disconnected measure resistance (meter on ohms). between its L and E connections and between it's L and N connections, what readings do you get ?

andytw

I unplug the pump where the wire goes into it (L, N and E).

Measured the resistance, between L and E I get 1.
Between L and N I get 26.

 

[vinux]

you say it "keeps blowing" the pump? What happens to the pump? Does it get very hot (hotter than the pipes beside it)? That usually indicates a seized pump or a blockage, both usually caused by sediment and dirt.

does the heating and hw seem to be working OK?

I don't think the pump becomes hotter than the pipes beside it. Heating and hot water works ok. I didn't see what happened to the pump for the first two times (it just stopped turning and they were shortened out) but the third time I actually saw some smoke coming from the area where the wires go into the pump (plastic cap).

 

[vinux]

What different brand of pump ? are you sure it was the pump that was blowing the fuse in the first place ?

It was Grundfos initially then two Bosch and the last one is Grundfos. I am not sure the pump was blowing the fuse. What else could it be, is there a way to test it?

 

[ianmcd]

What different brand of pump ? are you sure it was the pump that was blowing the fuse in the first place ?

It was Grundfos initially then two Bosch and the last one is Grundfos. I am not sure the pump was blowing the fuse. What else could it be, is there a way to test it?

I am confused , I wondered when you said you had tried a different pump this boiler should have a Myson CP 53 pump only, no other make should be used I have seen Ideal multi-heads being used but wouldnt recommend it but they will fit

 

[JohnD]

it is very difficult to make a pump fail unles it is dry. Even when jammed with sediment or having no flow, the water will help absorb the excess heat for several hours, but they will be noticably hot. Sediment and dirt can also make the bearings wear out, but yours are failing very quickly.

I really wonder what went wrong with yours.