Any oil system experts out there??

[andyw]

Hi everyone,

I'm looking for some advice on a problem with our oil boiler system.

We have a self-build with a new condensing oil boiler from Elco Klockner and underfloor heating. It is feed by through a glass viewing filter in turn fed by a lifting pump / reservoir (not air tight sealed). Externally there is a fire cutout valve. The pipe to the tank is approx 50m and the boiler is 1m higher than the tank outlet. The pipe is 8mm plastic coated copper and runs underground in a black duct. We've a high water table, so any crack in the ducting means there is a good chance the pipe is sitting in water.

Every few months, the boiler starts stopping, and my perception is its more so in colder & wet weather. Also, it 'seems' to stop more at the weekends, when the only difference in that room I can think of is that the Washing Machine / Tumble dryer are running more. The heating / water programme is the same.

There is no evidence of air bubbles / condensation / dirt in the filter. Also, apart from one time when the tank emptied, the filter vessel has not run dry, ie oil appears to be available to the boiler. I've asked the oil supplier is they've had any bad batches - again no problem.

Elco have been out several times under warranty.

On the first visit, the filter in the burner nozzle was blackened, and they replaced. They also replaced the boiler oil pump as it was broken.

2nd visit replaced the complete burner assembly, again, nozzle black, and it worked well for a few months after that. On a the main boiler burner.

3rd visit, new nozzle filter, has worked well over the summer till now, when over the last few weeks its began stopping lots - eg Sunday 10 times. Only once per day Mon & Tues.

Anyway, Elco and the builder say the problem lies with the supply pipe / pump /tank install, not the boiler. Tank / pipe installer says boiler problem not pipe. Me, I'm stuck in the middle surrounded by 'experts' who don't know what to do next.

I was wondering if anyone had any ideas - could the oil be too cold / viscous into the boiler, could the boiler be susceptible to room temp / humidity. What sort of things could cause the blackening of the nozzle filter.

Any thoughts / help much appreciated.

Could anyone recommend a good oil engineer in the Reading area?

 

[Jenx]

Hello Mate, sounds like you have a Tiger-Loop or something similar lifting the oil up to the burner, yes ?

The blackening nozzle does point to slighly poor combustion, which could be allied to the same problem...

Without sitting in front of it and going through all the proper testing procedure, I can't be certain of being correct... but I'd start looking at the 'Lifting' system ( Tiger Loop or similar ) first-off.
Sounds suspiciously to me like its intermittently starving the oil-pump ( on the burner itself ) of fuel , bringing about a 'dirty burn' through stop/start ignition sequencing.

Can you hear the tranny kicking in periodically, generating spark , at the times when the problem is prevalent ?

I'm a long way from you bud, otherwise I'd nip round & fix it for you....
The 'top'dogs' round your direction used to be Hartwells ( the BP Oil distributor, ) but I don't know if they've maybe been taken over by someone else nowadays.

PM me if you need further assistance.. I'll do my best to help ya !


(Editted to add this bit) : Its already trashed one oil pump, correct ?
99 times from 100, the burner oil pump will die when its Starved of oil. Its a gear pump, and is lubricated by the fuel oil running through it.
Has your filling elevator system got a return line ?
( how many flexi-hoses connect into the oil pump at the burner ... ? )


Alun

 

[andyw]

Hi Alun,

thanks for the helpful response.

The oil lifter has no tiger loop, it's a 3litre BM Control:
http://www.ibhs.co.uk/product.asp?numRe ... &PT_ID=166

There was a mess up early on in the install; the boiler people were supposed to supply an internal lifting pump, but did not, and the boiler was running on it's standard sucking pump for a few intense days starting to dry out the floor screed. Originally they claimed it would be OK for the distance and level change.

So after a couple of days it stops working. Some problems with joints on the pipe connectors where identified and fixed, and ditto the need for an external pump. Unfortunately, it would have taken a couple of weeks to get it from Germany, so I arranged for the BM box to be fitted the next day.

The system ran fine then for a week or so, and then stopped with no oil in the viewing filter ie it had been starved. The tank was empty and no-one had told me it would be taking that much oil to dry the screed.

Filled up tank, and had intermittent working then broken internal pump.

They replaced the pump, removed the outside tiger loop, as the lifting reservoir does the same function. The system would not work properly with a feed back into the lifter pump, so we only have an outlet connected.

Every since the tank was refilled, I have never seen the filter glass empty of oil, so can't see how the internal pump is being starved, though that I think is the suspicion of the boiler people.

 

[Jenx]

Hi Andy ...
Again, without actually 'seeing' it, its a little more tricky...
However - lets see f we can do a 'work thru' and alleviate the fault.

1. Don't assume that because you think you can see oil in the line-filter bowl, that there's actually oil present. - They discolour in days, and its not the first time that someone has thought there was oil present, only to find that there in fact was not.

2. Ensure the line filter is 'aired'. - usuallt two screw-vents on the metal part on top.

3. Ensure the valve at the tank is fully open.

4. Ensure the firevalve ( I'm assuming its a dead-weight type with a wired fusible link to somewhere close to the boiler ? -- usually a steel wire and pulleys / linkages, + a fusible two-piece plate, joined with low melting-point alloy or solder ) is fully open and free-flowing.

5. At 1 Mtr above the tank outlet --to--burner height, I'm a bit surprised that anyone saw the need for a seperate oil lifter. The Burner's own oil pump will lift that up, no problem.

There is, however a little 'proviso' in that.
In order for the burner to 'lift' fuel, it would ideally have a suction AND return line, back to the tank.

There is a way to 'short-cut' that procedure however.
I would try this - Take the 'lifter' out of the equation entirely.
Don't be concerned with the 50mtrs linear distance from the tank to the boiler - thats irrelevant as long as the line is clear.
its the 1mtr 'head' that we are concerned with overcoming, and the boiler's pump will do it, but in the absence of a complete return line to the tank, we have to 'cheat it' a little bit, which will allow the pump to perform perfectly well.
Doing this as even a 'temporary trial' will attempt to 'prove' a fault, which is what we're trying to do.

Try this:--
Where the oil line 'terminates' close to the boiler ( or Lifter ), -- change the coupling out for a Tee-piece,
Then, have TWO flexible oil lines from the burner's pump, connected back to this tee, one from the pump's inlet (which is in use already) and one from the pump's return port, which at present will be plugged.
The burner will be fitted with a pump from Danfoss or Sunstrand or similar, and there's quite a few plugged ports on it... the inlet & return ports will be marked, usually with arrowheads actually 'in' the casting or similar, and will be 1/4" connections ( larger than some of the other 1/8" Connections for the pressure gauge temporary connection etc, which is used by the commissioning engineer, then re-plugged )
This will than have the effect of replicating the full return line, and at 1mtr suction-head, should work perfectly. ...............

........Remember that after doing this, the oil pump will require to be 'bled' also.
This is a case of connecting a small length of hose to the little bleed-nipple ( same size hose as is used for Gas 'U'Gauges )....
and the easiest way is to remove the solenoid coil from its stem on the oil pump, slacken the hex of the bleed nipple and attempt to start the boiler.
It will of course, run to 'Lockout', because of the solenoid being removed.
( A little note here - put a phillips screwdriver or something similar through the hole of the solenoid coil when its off the boiler. -- Electro-magnetic coils are strange little creatures... if they don't have something to 'act upon', the magnetic field that they generate themselves, actually starts to damage themselves, if there's nothing for it to act on... the 'phillips' provides this. )
You may have to repeat this procedure a couple of times, until there's no air coming... only a steady stream of fuel.
Nip the venting-nipple's Hex back up, replace the solenoid coil, and reset the Lockout button, and she'll fire up.

This will have now taken the oil-lifter completely out of the equation altogether.
At 1 Mtr Negative head -- there was no need for it to have ever been there in the first place. They ( lifters ) are a notorious source of niggly problems like the one you're experiencing.
If you had a 'big lift' to do, fine.. but you don't.
The 'experimental change' in piping up the supply can be 'reversed' again in a matter of minutes, back to the way it was.

I'm willing to go as far as to say, by doing this, and ensuring your oil line from the tank in, is clear and free-flowing, by checking it at the filter, the firevalve, & somewhere up near the boiler ( possibly where you you fit this Tee I'm suggesting ), your problem will be cured.

Couple of more points need mentioning. : --

6. I've assumed your on 'Kerosene' ( 28 Second Domestic heating oil ) and not Red Diesel ( 35 Second Oil or 'Gas Oil ).
-- Kerosene is much less likely to be affected by increased viscosity or 'waxing' as a general statement.
Diesel is more likely to see the effects, but its not cold enough yet for this to have happened. In all the years I've been involved in this stuff, up in the North of Scotland with its severe temperatures - I have never encountered either Gas Oil or Kero suffering a viscosity problem. Yes, diesel can 'wax' on a motor vehicle, but this is almost universally down to wind chill as opposed to 'static temperature'.. the vehicle moving through the cold air, or in the case of big HGV's, the vehicle being parked overnight in an extremely windy location and the slight 'venturi' effect of air-speed increase under the vehicle, causing a 'windchill'. Not with Dometic fuel suply installations.

7. You've now had a 'complete burner' replacement - correct ?
The problem is still prevalent - correct ?
The 'original' saw off a burner oil-pump -correct ?
--- The problem isn't a "boiler problem." Its a fuel-delivery issue.

8. "Interpreting the Signals & Signs"
(a) Dirty Nozzle. - I assume you mean 'sooty' on its 'nose'
Its an indication of 'repeated poor starting', caused by a 'late-ignition' in the startup cycle. - Indicative of fuel starvation.

(b) Ruined a burner oil pump already - indicative of fuel starvation

(c) If you can be in a position to 'listen' to the appliance, listen for this :
You will probably hear the 'spark' on initial startup. It sounds like you'd expect the spark to sound.. a bit similar to an acr-welder running. It should stop noticeably, once the burner has fired, after a few seconds ( up to maybe about 15 - 20 seconds ). If this sound 're-appears' intermittently, at any point when the boiler's running on a 'stop/start' kind of pattern... and the boiler 'fluffs and puffs a bit' in the noise its making as it burns the fuel ... its getting starved of oil. This would be a very audible, very unmistakeable clue, that once you know what to look for, will be very easy to detect.



If at all possible - try the 'Tee Piece' solution, with suction & return lines, and Eliminate the BM Lifter, just by way of experiment, if nothing else.
I'm near certain that given what you've been able to highlight in the symptoms, and assuming the supply-line is clear, that its the lifting system thats causing you the problem, and its really not something that was necessary to be there in the first place.


Hope that helps you Sir ...
Let me know what happens...
If all else fails - or you don't have the confidence and skills to do this quick changeout to the Tee, Yellow Pages - COMBUSTION ENGINEERS, and try to find one with Shell or BP Ties to the oil supply company.

As before - I will try to help you 'remotely' as best I can !

All the best,

Alun


PS - A thought did also just occur to me .... your supply line is 8mm - correct ?
Ideally this would really be 10mm or better still 1/2" / 15mm....
If it was cut with a wheeled pipecutter and a particularly 'heavy handed' fashion... its quite feasible for that 8mm Outside diameter of the tube to be restricted down a far as only leaving 3 or 4 mm as a nominal bore.
With several potential 'cut ends' over its entire length, you could conceivably be starving the thing of enough fuel.
Its a thought !
It'd be a 'hanging offence' on the part of the installer, but if you have a 3mm hole at the inlet end, and a couple of 3mm holes additionally along the length of the line, the 'full bore' of the tubing becomes somewhat of an irrelevance.
Ideally, it should be 10mm tube, cut with a hacksaw, to maintain the full useable cross-section of tubing bore.

 

[andyw]

Hi Alun,

I've sent you a mail.

 

[Chris Knight]

Alun,

I know nothing about the subject but I am impressed by the helpful and lengthy reply to Andy!

 

[Jenx]

Heh heh, nice one Chris... I don't know much about it either :wink:

Excellent Andy ... I'm still at work at the moment, but will get the mail attended to some point in the evening.

 

[Rich]

Very well explained Jenx, one other small point to check, make sure the valve at the base of the sight glass is open.

Rich.

 

[maltrout512]

Well I haven't read a post like this with so much interest. Topic or off Topic. Looking forward to the out come. Alun I take my hat off to you sir. =D> Andy hope you get a result. (hammer)

 

[andyw]

Rich, sorry no valve on the bottom of the filter glass. Is it to de-aerate?

An update. Following on from points from Alun, I've been talking to OFTEC at length today and sending pictures.

In their opinion, there are 6 problems, 4 are best practice, 2 are non compliance with regs.
1. plumber gave incorrect spec on the stand for the tank - this is not operational nor of immediate concern so will park until the system is fixed.
2. plumber did a dodgy compression / male connection on the tank outlet - easy enough to fix.
3. Plumber didn't put the lifter 1.5m above floor level to gravity feed the boiler - easy to fix.
4. Builder used metal braided pipes between filter glass and boiler - easy to fix.
5. and the braided pipes are too small diameter anyway - easy to fix.
6. Builder left the boiler pump configured as twin pipe despite terminating one at the filter glass - easy to fix.

3,5,6 are felt to cause a loop where the pump is just circulating oil rather than fully supplying the boiler, hence intermittent starvation.

So I need to get all these fixed and then see how things stand. I trust the builder to do their part, not so sure for the plumber and may get someone else to do it and just cough up the money.

Does go to show though, no matter how hard you try, it's pot luck sometimes where you end up with contractors.

Had the plumber back round this afternoon, and to him it was all still boiler problems - electrical says he. Did try and give him hints from OFTEC, but he didn't have a clue.

OFTEC are pretty cheesed off with their member plumber and will be taking it further. Builder is not under their jurisdiction.

Thanks to all for help, esp Alun.

 

[Digit]

Know the problems Andy, that's why I prefer to do the jobs myself.
When we investigated LPG heating I found, not unreasonably, that the tanker driver needed 'line of sight' clearance twixt tank and tanker.
No problem thinks I, we'll have the tank in the front garden, lots of local people do locally.
No! Says Calor gas. Must have it round the back, wants feed pipe buried 60 cms, 40 cms below ground is solid Pembroke stone.
We'll go for oil.
No! Can't have tank there, it'll have to be over there. Give up!
Call another LPG supplier.
'Why not have the tank in the front garden where the driver can see it?' he asks.
Makes you want spit on occasion don't it?

Roy.