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.
[automerge]1575972423[/automerge]
Also need to check the fire valve, are they all operated by the method push button to close manually and pull to reset open

 

[SJB060685]

These are supposed to be very good. Not tried one myself but know a lot of oil guys swear by it. Running a new line is not as straightforward as you might think. You would need a strainer at tank, a isolating valve before inline filter and fire valve, all of which will be ideally bushed together rather than a load of fittings and ideally a new burner hose, which I’m sure you’re aware is installed inside boiler casing. If someone was to run a new line then it’s either compression fittings with pipe inserts or flared fittings, NO soldered joints allowed.
I believe some older types of fire valve are wheel head but these have an internal metal fuse that once melt its new valve time. KBB is what we always used as you know these are a simple push back in to reset.

 

[richard3009]

Think we're ahead of the game here, I'm suspecting a fully gunked up acrylic filter in the Teddington valve wash out and away. With it being borderline restriction I just get the feeling that's my culprit, trouble is I have no daylight until Saturday, shall upload photos of a five year unserviced filter.

 

[SJB060685]

If theres a blockage anywhere downstream of the tank I'd expect it to be in the narrowest part of line, ie valves. If you're going to check check everything and obviously don't wash out with water, use neat kerosene from tank.

 

[richard3009]

Just one point after the bowl has been removed off the underside of the valve filter rinsed with clean kerosene, I assume you fill the bowl with it slightly not sealed to purge the air or is there a bleed screw on them, I don't want to sort all that air at the boiler end. Only three tight points on the system tank valve, fire stop valve and boiler flex valve, the horrible bulkhead 90 is long gone.

 

[SJB060685]

Some filters have bleed screws on them. Alternatively crack the compression fittings slightly. Always bleed at pump as well

 

[richard3009]

There is a fibre washer on the underside best be armed with a replacement too.

 

[SJB060685]

Always have replacement seals yes, o rings, washers, olives etc whatever you're working on

 

[Best]

I wonder are all the valves turned on plenty of turns, including the valve at tank?
Also oil hose not kinked in?
Either of those can cause problem you describe.
But the fact the oil filter hasn’t been checked means it is pointless to speculate until that is cleaned.
Alarming that your service engineer didn’t check that when replacing oil pump and at services.

 

[richard3009]

Just ordered an identical tank valve so I can simply swap the filter inside and stick on a fresh seal, it has to be well sludged in so many years, both valves are levers and fully open

 

[SJB060685]

Replace that strainer/filter at tank and check everything else downstream as well. Like best said above this should all be checked and replaced during routine servicing, perhaps it's time to find a decent engineer.

 

[richard3009]

Not possible to change anything upstream of the tank valve surely with 1200 litres sat there

 

[SJB060685]

You can replace the strainer/filter at tank no problem but to change the whole valve you would have to wait until oil runs out. I've known some snatch it with a little oil in tank but not 1200 litres, insurance companies could go mad and if you were to lose that amount of oil the environment agency would hold you accountable and that's a hefty clean up fee.

 

[richard3009]

Ok just the filter/strainer in the valve bowl, yep that's what I'm doing, wow I could just image releasing a 1200 litre head of kerosene, Christ that would have me in a slight tizz

 

[SJB060685]

Like I said it's worth finding a decent engineer, a good engineer is for life. You being an electrician means you have got a good grasp of things already however unless you have FGA, pressure gauges and a smoke pump etc then what you can safely and efficiently do is limited

 

[richard3009]

Sat having my tea tonight and can hear the oil pump is get more and more distressed, I was thinking to myself any minute now that's going into lock out and it did. So now I've nothing to lose I'm having that filter off to look torch in hand absolutely persisting it down, tank valve closed, cracked it open clean as a whistle I mean spotless fuel in bowl a few grains but nothing serious. Opened the tank valve and flushed the main outlet into a bucket a good litre. Refitted the filter bowl and bled off the air valve opened. Back at boiler closed flex valve and uncoupled from pump, open valve zero flow, popped outside to check the fire valve pressed the reset and it clicked hmmmmmm, back inside no flow, desperation gob around fuel line blow hard release and fuel flows slow but we have fuel, Couple line back up and reset lockout. Open bleed air bolt and she bubbles for 10 secs then pure high pressure fuel. It's been running as sweet as a nut for the past hour. Either fire valve or I was airlocked. All I can taste is kerosene small price to pay, happy days.

 

[Best]

Fire valves are very easily blocked. You need your entire oil line flushed.
It is best to remove the fire valve to flush the open ends of pipe to give good flow for flushing and to avoid a lot of crud just blocking fire valve.
Oil pumps won’t last long when oil line is nearly blocked

 

[SJB060685]

You would get air into system any time its opened. You might of dislodged some crap or an airlock, time will tell. If the pump wasn't bled when it and motor were replaced I dred to think what a FGA would say.

 

[richard3009]

I think the fuel line is spotless by the looks of things no sludge or even discoloured fuel in the filter, doesn't need replacing. Airlocked I'm not convinced you tend to get flame waffle, I reckon that fire valve was half closed and the pump was sucking like buggery for fuel. Every time it shut down on reaching the high temp stat it had time to refill the flexible hose as it would equalise the (pump created vacuum), then the whole scenario starts again.

 

[SJB060685]

Again I'm impressed with your knowledge. You are correct, air in pump can cause an unstable flame, it also wont start at all, it depends on how much air is inside, if it's only partly restricting the pump outlet to pressure line it might as you say waffle, if its fully blocking then you wont get anything through.

 

[SimonG]

Love the smell of kerosene in the morning, not so sure of the taste

 

[richard3009]

Had my fair share of that when the bulkhead 90 valve leaked for weeks before I sussed out where it was from, horrible design, drilled through bulkhead and fitted an inline hose valve, sorted.

 

[SJB060685]

How far away is the fire valve? I've come across crushed lines or kinked hoses a few times where burner ignites, runs then flame goes out and then by the time it tries to ignite again enough fuel has come through for ignition. If your burner is coming up to temp and then shutting down through stat then I imagine it's at least a couple metres

 

[richard3009]

When I say its shutting down via the stat Im talking about the heating phial as designed, so my bolier water is circulating around the rad circuit trying to reach room stat target, if my circulation water reaches the boiler heater stat target, it will shut down the burner but keep the diverter in heat position. As for the fire valve outside i need to check where its stat phial is parked it may be touching a pipe

 

[SJB060685]

The phial for your fire valve should be clipped above the burner. Its purpose is to protect the flexi, although if there was a fire hundreds of degrees c will be reached in seconds. And yes if its resting against a hot surface then you will getting nuisance tripping.

 

[richard3009]

it should stop 1200 litres of kerosene being added to a runaway fire, anyway thanks for the help just pleased to have it working as designed. A faulty boiler in winter is a bloody nightmare, always learning and just about understand this model inside out.