# Upgrade to condensing boiler - do I need to clean the gas oil tank?



## smokey (28 Nov 2010)

We are replacing our boiler with a condensing boiler. Our fuel tank is 1/4 full of gas oil which we will empty before filling with kerosene. Do we need to clean out the tank, and if so what is involved?


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## hopalong (28 Nov 2010)

i have an old oil boiler and was considering the same idea,(replace with condensing one).the other option being to change to gas.can i ask if you considered gas and also how much the new condenser system cost.


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## smokey (28 Nov 2010)

Piped gas not available here & didn't consider getting tank. Cost of job just under €3k which includes boiler, pump, provision & installation of new twin-walled flue through roof area & making good. Zoning to space & water + 3 TRVs etc. a further €1.5k. Grants recoverable through seai - see their web page for details


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## smokey (29 Nov 2010)

*Upgrading Boiler - do I need to clean out gas oil tank?*

Problem solved. Tank needs to be fully emptied of gas oil (diesel) and sludge but thorough cleaning/scrubbing not necessary. Thanks all.


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## hopalong (29 Nov 2010)

thanks.


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## cathalcjb (26 Mar 2011)

smokey said:


> Problem solved. Tank needs to be fully emptied of gas oil (diesel) and sludge but thorough cleaning/scrubbing not necessary. Thanks all.


 
Smokey, did you just tip the tank over and drain the diesel? I'm looking to do the same thing very soon. 

I reckon once I have it  drained down by burning it off I'll be left with maybe 50 litres of gas oil. Could be less, I don't know, I'll have to do the maths. I take it I need to empty this out somehow, and clear the line to the existing boiler. I imagine even a slight mix wouldn't be good for a pristine new burner.


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## salaried (31 Mar 2011)

Smokey is it dangerous to use gas oil with a condensed boiler. I just had a new condensed boiler fitted last week. I rang our oil company today to top up with kerosene only to be told we have been using gas oil for the last few years. Can this damage our new boiler.


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## DGOBS (31 Mar 2011)

Your condenser will not run on gas-oil, it will be sooty, smokey and create lots of carbon monoxide, you MUST change to kero....your installer should have made you aware of this


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## salaried (1 Apr 2011)

DGOBS, We only have the condenser a week and it is working away fine, We have 9 rads working from it and so far no problems. Are you saying if we are using gas oil that it should not work at all. By the way we were not asked if we were using kero or gas when we had it installed, Also I specifically asked the oil company for kero on our first fill and apparently we were given gas oil since, I only realised this when I asked them yesterday. The tank is almost empty now so in your opinion would it be wise to run with it for a few days and then order the kero. From Smokeys post it looks like if sludge is a problem I am in trouble already. Will this damage my new condenser after having it for only a week.Thanks for your advice so far DGOBS, Regards, Salaried.


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## Shane007 (1 Apr 2011)

Salaried,

Remove all traces of diesel from tank. Do not mix the two fuels. Pump pressure for kerosene is much lower than that required for diesel, so when trying to burn diesel at lower pump pressure will result in diesel not completely broken up into tiny particles and therefore will not burn properly, resulting in sooting. It is a heavier fuel than kerosene.

Immediately remove all remaining diesel, clean inside of tank, remove all diesel from oil line, filter and oil pump in burner. Refill with kerosene, SERVICE and COMMISSION boiler and it should be fine. Do not continue to burn diesel.


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## salaried (1 Apr 2011)

Shane, our oil line is running under our extension, through our back and onto the tank. We have just put down new tiles in our extension and a new expensive patio out the back, How do I remove all diesel from our oil line. Seriously worried and sick of this guy right now, First he destroyed our kitchen and now this.


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## Shane007 (1 Apr 2011)

Use an oil suction pump, or a small air compressor to blow it through. 

If oil line is going under floor of extension, make sure you do a pressure test on the line to ensure there are no leaks in the line.


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## bstop (1 Apr 2011)

A small amount of gas oil well diluted with kerosene will not cause any problems in your boiler. I have done this and you will not cause any harm to the burner or boiler.


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## villa 1 (1 Apr 2011)

+1


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## Shane007 (1 Apr 2011)

bstop said:


> A small amount of gas oil well diluted with kerosene will not cause any problems in your boiler. I have done this and you will not cause any harm to the burner or boiler.


 
First of all, it will depend on how much a small amount is. Cold weather can make diesel separate away from the kerosene and not burn correctly as diesel becomes heavier with cold weather.

Condensing boilers will come with an Enhanced nozzle, either EH or ES unless of course it is above 1.00 USGal. This is a much more finer nozzle than diesel nozzles such as S or H and requires at least 16bar pump pressure to force the diesel through, especially in cold weather. Normal nozzles will only require on average 12bar pressure for diesel. Condensing burners will come with a factory-set pump pressure on average of 8.5bar pressure, far too low to atomize diesel through an EH or ES nozzle.

By putting diesel through an ES or EH nozzle at low pump pressure, the following will likely happen:

1. No damage should occur to the flame chamber boiler walls (as long as not for prolonged period).
2. Due to incomplete combustion of un-atomized fuel, sooting of the boiler WILL occur, leading to inefficiency and ultimate lock out of the boiler.
3. As a direct result of incomplete combustion, damage or buckling of the baffles will likely occur.
4. Nullification of the manufacturer's boiler warranty.

For what it takes to remove, why not do so? If a job is worth doing, do it right in the first instance. Less down the line possible complications, call backs and ultimately less unhappy clients!


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## villa 1 (1 Apr 2011)

jeez lads, we're taking here about a domestic 10mm diameter oil supply pipe!! How much fuel are we taking about here!!
Approx, 10m x 3.14 x 0.005 x 0.005 x 1000 = 0.785litre.


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## Shane007 (1 Apr 2011)

Does the diesel in the oil tank not count?


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## villa 1 (1 Apr 2011)

I presume the diesel and sludge would have been removed.


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## Shane007 (1 Apr 2011)

Sorry, I thought bstop well diluted the gas oil with kerosene. I would have presumed he did this within the oil tank.

Remember from the bottom of an oil tank to the bottom of the outlet will be about 65 litres. This will not be used under normal usage and will be mixed.


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## bstop (3 Apr 2011)

Shane007 said:


> Cold weather can make diesel separate away from the kerosene and not burn correctly as diesel becomes heavier with cold weather.
> 
> Kerosene is mixed with Diesel to reduce waxing in extreme cold conditions.
> I have never heard that it separates under these conditions. Kerosene and Diesel are very similar fuels. Kerosene is more highly refined than Diesel. Mixing the two together gives a blended fuel which is commonly used in very cold countries.


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## Shane007 (3 Apr 2011)

Gas oil & kerosene behave very differently under cold conditions. For instance, gas oil, at 0°C, begins to cloud due to the parafin content within it. When temperatures of -10°C occur, it begins to solidify and block the oil filter. This is known as its gel point. This is where I have come across the separation from kerosene. Where the fuels have been mixed in the oil tank, the heavier parts with more viscosity solidify and block the filter. By opening the filter, you will see that it can contain more gas oil than kerosene, therefore separation. Just because you have mixed the fuels does not change the chemical make up of their components.

The second main difference between both fuels is their viscosity and it too plays a very important part of the fuel & burner. This is why gas oil is referred to as 35 second oil and kerosene as 28 second oil. A given amount of each fuel takes 35 or 28 seconds respectively to pass through a given opening. It is the reason why gas oil requires a much greater pump pressure than kerosene.

In colder temperature regions of the world, oil burners that use gas oil will have pre-heaters built into the ignition process to pre-heat the gas oil before it enters the nozzle, similar to a diesel engined vehicle. They will also take precautions such as insulating the fuel lines, etc. Just mixing with kerosene will NOT suffice.

Whilst on the other hand, kerosene can withstand temperatures of -30°C and generally does not have the same issues as gas oil. The other issue is that kerosene does not contain FAME (fatty acid methyl esther) and as of 1st January 2011, as an EU directive, there has been an increase of 40% of FAME in gas oil throughout Europe. This also introduces a whole other issue/problem and another reason why not to use gas oil in home heating oil systems.


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## DGOBS (3 Apr 2011)

Shane, think what you will find on this type of subject as always in Ireland is the attitude, 'ah sure that'll be alright' rather than people adopting what is the best approach, whats recommended by the manufacturer and considered industry best practice, hence why almost every oil tank installation in the country is not to regulation and the vast majority of gas installs are on 'semi-sealed systems' 

Here Shane, have a loan of my brick wall to keep banging your head off (btw +1 shane)


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## Shane007 (3 Apr 2011)

There was an American poet/educator, Henry Longfellow, who once said "It takes less time to do a thing right than it does to explain why you did it wrong". 

How right he was!


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## bstop (4 Apr 2011)

We are talking about a few parts per thousand of impurities here i.e. a few liters of diesel in a 1000 liter tank. The fuel is delivered to the tank from a truck which supplies diesel and kerosene through the same supply hose. Any delivery can result in slightly impure fuel being supplied to the storage tank. Advising anybody to have their tank and feed pipe cleaned as suggested is excessive and is adding needless cost to them.


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## salaried (4 Apr 2011)

Bstop and Shane, I really appreciate your opinions and thank you both for taking time out to offer them. Bstop I would prefer to take your approach as it the less expensive of the two but when I have to commision the boiler they will know full well that I ran gas oil through the boiler at some stage albeit a tiny amount. Shane I think it would be best to empty the tank and start fresh as you said, I am sure the both of you know your stuff but having gone from one disaster to another in the past 8 weeks I dont have the patience for another mess, Thanks for the input lads, Also thank you DGOBS and Villa.


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## Shane007 (4 Apr 2011)

My point is always get somebody who is certified and registered to do the job in the first instance. A competent OFTEC engineer should always do the job right. If your installer fitted a condensing boiler running on gas oil, I would very much doubt if it has been commissioned with a flue gas analysizer and set up to suit site conditions. I would also very much doubt if your boiler passport has been filled out correctly and returned to the manufacturer, therefore leaving you with no manufacturer's warranty whatsoever. If an OFTEC engineer was used, you have a definite comeback through OFTEC in Dublin.

With regard to excessive and needless costs to the customer, it takes me approx 3 to 4 minutes to attach my compressor to the oil line at the oil tank and disconnect the flexi-hose from the oil pump in the burner, place in a container and switch on the compressor. This is not an extra cost to the customer but part of the service which should be standard practice. You are going to the trouble of removing the gas oil from the bottom of the oil tank anyhow! As DGOBS says, perhaps if more best practice was applied, unhappy customers such as Salaried would be a thing of the past.

Salaried: By having your boiler commissioned, not only will you receive a manufacturer's warranty, but you will recoup the cost of having it commissioned in savings in oil, running cleaner, more efficiently and less further complications down the line. See http://www.ofteconline.com/locatecompanyIreland.asp for a registered technician.


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## Shane007 (4 Apr 2011)

Typical cost for commissioning boiler and certifying boiler passport when works not carried out by the engineer are €70.00 + VAT @ 13.5%.


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## mcusack (11 Oct 2014)

Liffey Oil provide a fuel swapping service. They will take away your existing GasOil (diesel) and replace with the same amount of Kerosene. They charge €150forthe service. When this is done there will be a small amount of diesel left in the bottom of the tank below the level of the outlet pipe. The new kerosene will float on top of that because it is much lighter and will not get sucked into the flow to the boiler. Once you have changed the oil in your tank you then have to bleed whatever is left in the line between the tank and boiler. The boiler fitter can do this.


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