Heatslave 20/25 surge

[richard3009]

My Worcester 20/25 is producing an intermittent surging noise, I reckon it's a similar noise to when I have had air in the fuel line after fitting new fuel hose. Could this be fuel starvation noise from clogged fuel filter. I'm told the fuel filter at the tank has not been changed since install 7 years. Blower motor is brand new and so is fuel pump.

 

[SimonG]

Who fit the fuel pump?

 

[SJB060685]

If you had a blocked strainer at tank or inline filter or pipe etc you would not have ignition. Using a vacuum gauge you can see if theres any restrictions before fiddling with pipe work but I assume you don't have one and from what you said I'm assuming the burner ignites and doesn't go to lockout.

 

[richard3009]

Burner is not locking out, just intermittent buzzing/vibrations that come in waves around 20 secs apart, new parts fitted by oil tech

 

[SJB060685]

Burner is not locking out, just intermittent buzzing/vibrations that come in waves around 20 secs apart, new parts fitted by oil tech

Is the oil line gravity or under suction (tigerloop)? Where is this noise you hear located?

 

[richard3009]

No tiger loop on system pure gravity and head, hard to pinpoint the noise location

 

[SJB060685]

Hmmm 🤔. Without hearing it or pinpointing the rough area it's hard to say

 

[SimonG]

Something not tightened up when new parts were fitted.

 

[SJB060685]

A possibility SimonG yes. Possibly the grub screws holding pump in place. Was the pump coupling changed at time of pump and motor?

 

[richard3009]

Noise is from the oil pump just listened with ear to screwdriver, all is tight checked, not sure how old burner nozzle is could a clogged nozzle cause it

 

[SJB060685]

Pump housing rubbing on motor housing, fan impeller rubbing on burner housing?

 

[richard3009]

No it's got me beat all bearings nice and smooth fan is clear of cowling, I will have the filter off at the weekend plus fit a new burner nozzle, then get a combustion test re done. The only other thing I can think of is a baffle plate wobbling and it's carrying through the boiler chassis.

 

[SJB060685]

It seems strange that this is only since motor and pump replacement. Would usually indicate the problem lies there somewhere. Did you change pump coupling at same time? A blocked nozzle is not going to cause this problem, it will just not atomize fuel or have an aggressive start. Baffles tend to weld them selves in over time rather than become loose and rattle but it could happen, baffles do fall apart over time exposed to the high temperatures inside chamber and can fall down into chamber.

 

[SimonG]

An engineer is not going to put a new pump on without a new nozzle

 

[richard3009]

There was a new plastic pump coupler in the box that has been fitted, the old coupler he passed me and said put that somewhere safe you may need it one day. If an oil pump is sucking on a vacuum due to a clogged filter surely it's going to get noisy, that's my thinking.

 

[SJB060685]

Yes you are right there, the pump will whine if there is a restriction but like I said I'd be expecting other problems as well if that were the case

 

[richard3009]

Yes and I suppose it would be more of a whine, not a lot more I can check really, could be something worked loose around the flue area, think I will take a look at the baffle plates at the weekend for any obvious rattles

 

[SJB060685]

If you had a restriction and fuel problem I'd be expecting burner lockout or stop and start. 30ft of oil line holds very little oil. Running a few litres off at burner into a container and seeing if theres a loss of flow at any time will show if theres a problem. Apart from that then all the obvious should be checked first.

 

[richard3009]

It sounds like it could be in the burner box area what's inside there is it just a void.

 

[SJB060685]

So it's not from the pump as you originally thought but the combustion chamber. Is it a conventional flue and if so when was it last swept or flue draft tested? If the filter at tank hasn't been replaced in 7 years I expect the flue hasn't either

 

[richard3009]

Just going to get an oil boiler tech to come out and give it a full check from top to bottom. Flue is straight out the back through the wall, 12 inches at most

 

[SJB060685]

Ok. Can you update us on what the problem is if you find it, it might be something I've overlooked or forgotten

 

[richard3009]

I've had a really good listen to it for 10 minutes definitely the oil pump in waves, another thing when it starts up it takes around 30 seconds for it to start whining, enough time to draw a vacuum in a 20 meter supply line, I'm leaning toward restricted flow making the pump work really hard, but not enough to lock out the bolier

 

[SJB060685]

I'm impressed at your knowledge Richard, few people have your understanding as a general homeowner. Like I said above vacuum gauge, the longer the line, the more valves, bends and restrictions etc all increases resistance which all add up. Running a few litres off at burner is also a good way of determining flow. Remember the average domestic oil boiler only burns a couple litres of fuel an hour, so if you were to draw 5 without restriction then that's a sign it's all good.

 

[richard3009]

In the event of restricted flow would it be easier to simply install a new fuel line, or are there good clearing methods. Lines cheap enough.
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Also need to check the fire valve, are they all operated by the method push button to close manually and pull to reset open