Riello RDB / Grant Vortex Eco 15/21 puzzle

[DetlefSchmitz]

We have a Grant Vortex Eco 15/21, with Riello RDB burner, fitted around 15 months ago. When it stopped working recently, we called in the original fitters who messed us about something wicked, ordering parts and fitting them at random. After about a month with no heating, I decided enough was enough and took it into my own hands. As there was no oil pressure, I ordered and fitted an oil pump, which fixed the problem. I had the opportunity to purchase the commissioning tools without too much personal outlay, so I went ahead and got a smoke tester and a combustion gas analyser. I already had an oil pressure gauge from maintaining an earlier boiler.

So I set up the oil pressure according to the manual, and then set up the CO2 level to 12.5% as specified.

What I found was that if I used the test point in the flue I got really lousy CO and smoke measurements (5). But if I use the test point in the front cleaning door and set to 12.5% CO2, the CO/CO2 ration is 0.0000, and the smoke is barely above 0.
So my question is, why are the combustion measurements in the flue test point so far off? It's a balanced flue in a chimney, and I pushed the probe around half way in.

 

[Johntheo5]

The exhaust temperature is only 77C in one test and 164C in the other, did you wait for the boiler to heat up properly in the first test, also take the two tests one after the other, if the first test was taken with a cold boiler, possibly some fuel droplets burning off if solenoid valve leaking past during purge period??. Suggest taking both tests at ~ 77C and ~ 164C.
Also check oil pressure while purging and when firing.

 

[roguetrader]

Are you really running your boiler on heavy oil?

 

[Exedon]

First thing at less than 2 years old it's still under warranty If your installer was Grant registered its 5 years,
That's assumes you had it serviced at correct interval.
I take it your flue is the red system? If so the flue really has to be as warm as possible to get correct readings.
Plus has as been noted above heavy oil?

 

[DetlefSchmitz]

The exhaust temperature is only 77C in one test and 164C in the other, did you wait for the boiler to heat up properly in the first test, also take the two tests one after the other, if the first test was taken with a cold boiler, possibly some fuel droplets burning off if solenoid valve leaking past during purge period??. Suggest taking both tests at ~ 77C and ~ 164C.
Also check oil pressure while purging and when firing.

Both attempts at adjustment were made with the boiler having reached a settled temperature, with the gas composition readings not changing. In each case the air was adjusted to try to reach 12.5% CO2. At the front cleaning door this was achieved with almost negligible CO and smoke, whereas trying to get 12.5% CO2 in the flue raised the CO and smoke and produced a CO/CO2 ratio of at least 0.004 (the limit for condensing boilers). According to Grant the temperature must taken in the flue and must be between 75-85 C. They also say that the gas composition 'may' be taken at the test point in the front cleaning door. So the temperature of 164 C is artificially high because it was taken at the wrong place.

So I would be quite happy with the settings at the front cleaning door, and using the corresponding temperature at the flue.

I just find it hard to understand why the flue gas composition should be different, as it should be the same gas.

Perhaps the probe point in the flue is allowing a mix of flow and return gas, as the probe has to pass through the outer part of the flue. This would, of course, reduce the level of CO2, but I am not sure whether the available measurement fittings could prevent this.

 

[DetlefSchmitz]

Are you really running your boiler on heavy oil?

I think so - I'm using kerosene.


HCOTEG12260 - Technical Background on Oils: Light and heavy oils

Descriptions of Mineral (Hydrocarbon) oils
Light Oil

Benzole and benzene
Cumene
Ethylbenzene
Motor and aviation Spirit
Petroleum ether
Rosin spirit
Solvent or heavy naphtha
Styrene
Tetralin and decalin
Toluole and toluene
Turpentine, dipentene and pinene
White spirit and special solvents (e.g. special boiling point spirits )
Xylole and xylene ( including ortho-para and meta-xylene)

Heavy Oil

Anthracene oil
Burning oil (kerosene)
Coal tar
Creosote oil
Diesel oil
Fluxing oil
Fuel oil
Gas oil
Lubricating oil
Medicinal paraffin
Switch gear and transformer oil
Technical white oil

 

[DetlefSchmitz]

First thing at less than 2 years old it's still under warranty If your installer was Grant registered its 5 years,
That's assumes you had it serviced at correct interval.
I take it your flue is the red system? If so the flue really has to be as warm as possible to get correct readings.
Plus has as been noted above heavy oil?

As far as the warranty goes, it is one year unless you realised that the little brochure they give you, on page 6, has one sentence that says you can extend your warranty by a year if you can find them on the internet and register the boiler (even though the fitter registered it separately). The fitter informed me with glee that I had made a stupid mistake by not reading the 'How to work your boiler' brochure, and it was going to cost me hundreds of pounds as a consequence.

Yes it is the red system. I don't think I could have left it on much longer, and it certainly seemed to reach the temperature than Grant require.

For light/heavy oil see above reply.

 

[muggles]

Kerosene is classed as light oil as far as analysers go, unless your particular one is different. What's that phrase again, a little knowledge can be a dangerous thing

 

[Exedon]

We are Grant registered installer's if indeed your installer did register boiler with Grant that counts for 2 year warranty.
As I said if installer's are registered with Grant 5 years.
We never ever use analysis point on boiler as you cannot get efficiency readings there always on flue.
Dont know the settings on a tpi 709 but on our equipment kero is a different setting from heavy oil.
Check starter section of flue ok I've seen them left not centralised and not fully tightened down.

 

[Johntheo5]

The above tests looks like one taken before the condensing section, the other after, judging by the gas temperature differences so one might expect the same analysis apart from the exhaust gas temperatures?.

 

[DetlefSchmitz]

Kerosene is classed as light oil as far as analysers go, unless your particular one is different. What's that phrase again, a little knowledge can be a dangerous thing

Yes it seems that I was wrong to believe the government web site. There seem to be different definitions of light/heavy oil depending on why it's being defined. So kerosene is defined as 'extra light' according to DIN 51603-1.

It is rather like electricians and the different meanings of high and low voltage! And their 'Danger - Low Voltage' signs.

I accept your dig at my trying to learn a new discipline.

 

[DetlefSchmitz]

We are Grant registered installer's if indeed your installer did register boiler with Grant that counts for 2 year warranty.
As I said if installer's are registered with Grant 5 years.
We never ever use analysis point on boiler as you cannot get efficiency readings there always on flue.
Dont know the settings on a tpi 709 but on our equipment kero is a different setting from heavy oil.
Check starter section of flue ok I've seen them left not centralised and not fully tightened down.

Unfortunately, it was Grant that told us that we were not covered. Maybe they recently changed their terms and conditions. Dunno. As I replied above, I was clearly wrong about heavy v light oil as I found the wrong definition, and I've now set the light oil option. Unfortunately TPI are not very helpful on the definition. I guess most of their sales are for gas boilers.

Anyway what I found was that the flue probe needs to be right at the back, and the cleaning panel test point needs to be pushed to the back and then forward by about a centimeter. Using these two positions I get the same gas readings. This may support your suggestion, I will take a look.

So I now have 12.5% CO2 as specified, 6 ppm CO, CO/CO2 ratio 0.0000, efficiency 97.4% (this time remembered to connect the ambient probe) and flue temp of 89 C. This last reading is higher than I hoped but still within the tolerance Grant allow. I will check it again soon.

 

[DetlefSchmitz]

The above tests looks like one taken before the condensing section, the other after, judging by the gas temperature differences so one might expect the same analysis apart from the exhaust gas temperatures?.

Yes, as I mentioned above, I have now found positions for the probe in the test points that give the same gas readings in both positions. I guess this is the kind of thing a regular user (of the test equipment) would do without thinking about it.

 

[DetlefSchmitz]

Many thanks to all who replied. It has been very helpful.