Cross Contamination in a Gas Flue

FTimon · 07-12-2015 11:35AM #1

Hi
I have two Potterton gas boilers. I recently had them serviced. I was charged 450 euro to fix an external gas leak. He shut down the boilers on the basis I have cross contamination in both flues and repair cost 3-4 k to replace the 2 flues. The boulders were installed in 2010. Can the Flues not be resealed at the joints? Does this seem ok?

Dtp1979 · 07-12-2015 04:06PM

FTimon wrote: »

Hi
I have two Potterton gas boilers. I recently had them serviced. I was charged 450 euro to fix an external gas leak. He shut down the boilers on the basis I have cross contamination in both flues and repair cost 3-4 k to replace the 2 flues. The boulders were installed in 2010. Can the Flues not be resealed at the joints? Does this seem ok?

Either your not explaining it right or your being screwed by a cowboy. What did he write on the gas cert he gave you when he shut down both boilers? Can you post pics of the flues and perhaps measure the distances between them?

FTimon · 08-12-2015 02:53PM

I no not think it is cross tamination between Flue 1 and Flue 2 but within each flue. Distance between them is 8-10 meters

Exact Language "Cross Contamination in Both Boiler Flues" this was in the notification of Hazard"

In the Declaration of Conformance:
Boiler 1: Flue Gas Analysis "Co 5774 ppm Co2 12.8% Co/Co2 Ratio 0.450
Boiler 2: Flue Gas Analysis "Co 484 ppm Co2 12.9% Co/Co2 Ratio 0.0038

FTimon · 08-12-2015 03:41PM

Wont let me post photos as i am a new user (FLue sticks about 9 inches to 12 inches out if the wall is black / round and in the flew part is about 6 inches

Wearb · 08-12-2015 07:27PM

Did you seek a second opinion?

FTimon · 09-12-2015 08:43AM

I have called another plumber but I would like to understand what the problem is.

Dtp1979 · 09-12-2015 01:27PM

FTimon wrote: »

I have called another plumber but I would like to understand what the problem is.

Keep us updated. What plumber 1 is saying is that the flue outlet gas is mixing with the air intake. Very unusual that both boilers failed though. Did he hand you a printout of the flue gas reading ?

roy rodgers · 09-12-2015 02:21PM

What fuel are you burning?
I wonder if the boilers have been converted

Dtp1979 · 10-12-2015 02:01AM

roy rodgers wrote: »

What fuel are you burning?
I wonder if the boilers have been converted

Well spotted Roy. I'd say that it!

FTimon · 10-12-2015 09:43AM

LPG

roy rodgers · 10-12-2015 03:02PM

FTimon wrote: »

LPG

That's the problem I'd say.

The boilers haven't been converted from natural gas to lpg.
They could be still done by a GOOD rgi. But I have seen boilers that weren't converted do a lot of damage to the boiler it really depends on how long they have been that way..
What make of boiler are they?

FTimon · 10-12-2015 07:59PM

Potterton promax Combination He plus. They have been running for 5 years. The last guy who serviced them never said . But not sure if he had a gas analyser

roy rodgers · 10-12-2015 10:27PM

FTimon wrote: »

Potterton promax Combination He plus. They have been running for 5 years. The last guy who serviced them never said . But not sure if he had a gas analyser

Them boilers come from the factory set up to burn natural gas and I don't think you can adjust the gas valve on them just looking at the manual there.
There should be a data badge on the boiler some where, it could be on the underneath of the boiler. It will tell you what gas it is set up to burn on that.
Under no circumstances you should use them boilers if that's the case. I know it's been working away for the last 5 years but it only takes seconds for that amount of carbon monoxide to kill you.
The problem I came across with boilers burning lpg that haven't been converted was that they burn a lot hotter and I have seen flues melt from the inside out heat exchanger buckle the frame also buckle and it turned out that it be cheaper to change the boiler than try and replace the parts.
Now that was the most extreme but that what happens

Dtp1979 · 11-12-2015 03:13AM

It's frightening that this hasn't been spotted by an Rgi yet.

Wearb · 11-12-2015 08:51AM

It is also frightening that the last guy was so confident in his misdiagnosis that he was willing to have the op spend €3,000 or €4,000 to fix a problem that probably doesn't exist.
Even after spending that amount, the problem would still have been there.

jimf · 11-12-2015 09:11AM

I don't do gas as all on here will know but this is scary reading

FTimon · 11-12-2015 11:06AM

The two boilers are LPG so that not it

roy rodgers · 11-12-2015 12:34PM

FTimon wrote: »

The two boilers are LPG so that not it

Whats on the data badge? If you could post a picture of the data badge it would really help.

FTimon · 12-12-2015 10:37AM

Sorry i can not post photos as i am a new users

on the tag with bar code and serial number it is labeled

"Potterton Promax Combi 24 HE Plus LPG"

FTimon · 12-12-2015 11:42AM

Hi Folks - the Label on the boiler is :"Potterton Promax Combi 24 HE Plus LPG". This is part of the tag with serial number and and bar code.

roy rodgers · 12-12-2015 12:13PM

Ok we'll go with that.
On the flue gases printout what is the O2 at and what is the excess air at?

On position of the flues is there anything obstructing the flues would they have a min clearance of 600mm from walls hedges or balconies

FTimon · 12-12-2015 01:36PM

Roy Thanks

Obstruction: Flue 1 None Flue 2: when bushes grow and have leaves within 600mm but just about.

Flue 1: (intake O2% 19.5 - XS Air % ####.#) (Combustion O2 1.5% - XS Air% 7.5)
Flue 2: (Intake O2% 16.1 - XS Air % 335.9) (Combustion O2 1.4% - XS Air % 7.2)

FTimon · 12-12-2015 01:37PM

PS The temperature was set to max also

roy rodgers · 12-12-2015 03:07PM

There's not enough air for full combustion.
It's starting to look like the flues are a problem with the air intake well under 20%
Now I'm wondering if the right flues were used. Ones for condensing boilers and not ones for SE boilers.
There is a reason for the cross contamination and the rgi should be able to explain why it's happening before the 3 to 4k quote.
If it is the flues they can be replaced without to much hassle.

Are the flues going directly off the boiler to the outside individual?

FTimon · 12-12-2015 03:52PM

The boiler with worst readings is about one meter directly to the outside, with one 90% Bend. The second one is about two meters. I would have assumed the replacing a flue would not be that expensive. Waiting on a second plumber for another quote. Pity i cant post photos of the flue

Wearb · 12-12-2015 05:59PM

You can post photos by uploading them to Dropbox or Facebook etc. and providing a link here. You will have to manipulate the link, so that it doesn't look like a link. Eg put in a dash instead of a dot or PPP instead of www. You will get the hang of it.

FTimon · 13-12-2015 01:46PM

Folks thanks for the help todate - I am still waiting on the second Plumber he was to be here on Friday but must have got delayed.

I have tried to post a link to photos using multiple methods but will not work

1- I notice that when the steam/Fumes are coming out, it can blow down by the intake. In the manual i see options to separate the air intake and the exhaust

Also there is a joint on the Flue the looks corroded (a ring of metal) I assume this is not a standard part (Sorry have been looking at the manual)

Would these not be why there is cross contamination?

Hopefully i will get a more reasonable quote from the second plumber.

As there is not enough air intake - would a new / repaired flue improve efficiency ?

Dtp1979 · 13-12-2015 02:03PM

FTimon wrote: »

Folks thanks for the help todate - I am still waiting on the second Plumber he was to be here on Friday but must have got delayed.

I have tried to post a link to photos using multiple methods but will not work

1- I notice that when the steam/Fumes are coming out, it can blow down by the intake. In the manual i see options to separate the air intake and the exhaust

Also there is a joint on the Flue the looks corroded (a ring of metal) I assume this is not a standard part (Sorry have been looking at the manual)

Would these not be why there is cross contamination?

Hopefully i will get a more reasonable quote from the second plumber.

As there is not enough air intake - would a new / repaired flue improve efficiency ?

You need 50 posts to put pics up. You have 15. Go on and post 35 smiley faces on other threads

roy rodgers · 13-12-2015 03:14PM

Is the inside of the flue plastic or metal?

FTimon · 13-12-2015 03:21PM

Plastic all plastic - it is exactly like the one in the manual for horizontal flue except this joint. (I am posting on other forums so i can put up photos.

FTimon · 13-12-2015 03:21PM

Roy thanks a million by the way

Cross Contamination in a Gas Flue

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