Wallstar Oil Fired CH Boiler Problems

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Wallstar (in cavity) oil fired boiler CH system installed about 7 years ago, and has performed without a single problem until recently. I have to hold my hand up and admit that it hasn’t been serviced since 2000 (!).

Initial symptoms were that it would not restart after a period of shut-down, i.e. overnight. Once lock-out was over-ridden manually, it would restart and fun fine until next time. Everything pointed to oil starvation (air in clear burner feed hose). It should be noted that the boiler is mounted about 2.5m above ground level, and the tank is on the ground.

I have replaced the (extremely dirty) tank filter, one-way valve and nozzle. Also cleaned the photocell. Still the same, so I suspected the fuel pump (an Italian 'Delta' unit). After stripping down I noticed the small key that takes the drive from the motor shaft to the main pump inner rotor was extremely worn, allowing the rotor to slip. As a temporary fix (i.e. wanted to make this was the problem before I forked out on a new pump!) I made a new key, and reassembled the pump, having also cleaned the filter. Hay presto, within a second or two of starting, fuel sprayed out the bleed like I’d never seen before and the fuel hose was full – no air.

Sorted, or so I thought…. now, the burner ignites, runs for about 4 – 5 seconds, then flames out, followed by reigniting a couple of seconds later, and flaming out again after 4 – 5 seconds, then locks out. This happens exactly the same every time I try to start it.

Now I’m completely stumped and desperate! Any advice would be really appreciated.

Thanks in advance.
 
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It seems as if you have fixed one problem and caused another.

I suggest you check the connections to the photocell and back to the controller?

Perhaps even connect the photocell externally and shine a torch on it?

Can you measure the burner pump pressure and confirm the pump pressure stays up when the burner is on?

Tony
 
A possible cause is a faulty photocell.

I don't know the spec for this component, but as a sanity check you could measure the resistance when covered and again when exposed to bright light.

Oh bummer - Agile got there first.
 
get a new pump (danfoss bfp21 l3) 7 years for a delta is quite long enough. and new drive dog.
in fact just get it serviced. twill be easier...
 
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Well I've just serviced a boiler for the first time in 13 years, everything fine except the blast tube was a bit burnt round the edges. No problem with the pump.
 
Er, it seems as though he's already done more than would be done in a service. Just to satisfy my curiosity willhelm - what do you think the problem is likely to be? Some dirt where it shouldn't be? Something out of adjustment? A faulty component?
 
Problem now fixed!

Just wanted to say thank you for all your advice, it really is appreciated.

I did measure the pump pressure of the existing pump, and discovered that although it initially reached around 7 bar (normal), it soon dropped off to around 3 - 4 bar and air was observed in the pressure line to the gauge. At this point the burner went out. I suspect that the wear caused by the worn out drive key was allowing pressure to drop at the pressure side of the pump. I therefore bit the bullet and fitted a new pump, and set the pressure to the manufactures specs. Hasn't missed a beat since..... fingers crossed!

Many thanks once again.
 
As I said yesterday:-

"""Can you measure the burner pump pressure and confirm the pump pressure stays up when the burner is on?"""

Tony
 

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