how to test a pump ?

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hi there,

I remember reading something on this forum about how to test a boiler pump.

it's one of these Worcester 15-60 Pump Head 87161135940 Worcester 15-60 Pump Head 87161135940

the manual is http://www.bhspares.co.uk/wp-content/themes/RevampV3/manuals/Worcester Bosch/RD 532i.pdf

on page 24 there is a diagram on how to adjust the flow rate, the screw on this looks corroded, could this be related to the flow not flowing ?

Basically I switch the boiler on, it heats up but gets too hot (flow temp) goes above 88degrees and it switches off the flame, won't activate the fan until it cools down again on switch on.

I check the flow pipe coming out of the heat exchanger and it's mildly hot but gets cool before going down to the main split pipe for hot water/ central heating.

A plumber mate told me that when the boiler is switched on the pressure guage should twitch up a little when the pump kicks in. mine doesn't it just sits at 1.5 bar.

When it gets hot, above 100 degrees flow, there is a knocking noise, I guess air is trapped somewhere.

I've bled the radiators lots, refilled plenty, open the relief/release valve and it streams out into the street.

thanks
 
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By removing the centre screw put a cloth underneath to catch any water coming out. You can put a screwdriver in to see if the pump is turning.
Or give it a twist to see if it is stuck.
Other possibility is if it is spinning is that the impeller is not actually connected to the shaft so not moving any water.
Also a blockage in the system.
 
thanks dcawkwell,

I did try that, removed the centre screw and felt around but it didn't seem to be turning.

There was a kind of tranformery humm coming from it, and it started to get quite warm over a few minutes. I guess it's not turning, or blocked as you say. I tried to turn it with needle nosed pliers, but it didn't want to move.

I guess I'll drain the whole system tomorrow and remove the pump for inspection.

Would the pump come on for hot water demand as well, or just central heating ? I assume it has to come on in order to pump the flow through the heat exchanger.
 
pumps gone.
You would see the central shaft spinning.


thanks dcawkwell,

I did try that, removed the centre screw and felt around but it didn't seem to be turning.

There was a kind of tranformery humm coming from it, and it started to get quite warm over a few minutes. I guess it's not turning, or blocked as you say. I tried to turn it with needle nosed pliers, but it didn't want to move.

I guess I'll drain the whole system tomorrow and remove the pump for inspection.

Would the pump come on for hot water demand as well, or just central heating ? I assume it has to come on in order to pump the flow through the heat exchanger.
 
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yeah i thought that, so I gave it a final bash and turned it really hard.

free'd it up and now it works!

got my eye on a spare part anyway to replace it when it does finally kick the bucket.

cheers again mate
 

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