Why would a service engineer drill a hole in flue to check emissions?

[bomitie]

This is the background. I noticed a smell of oil in a small enuite that adjoins my boiler house and went out to boiler house and oil tank to have a look. I could not find any odours of oil anywhere so assumed it had come in window, ie you can get a smell of oil from tank, near the outlet pipe and filter. But I had good look at boiler and noticed a hole drilled in the flue and when it was serviced in July this year I did see the service guy have a probe plugged in. I assumed at the time that hole was there specifically to allow that but when checking today I noticed that a piece of silver tape had been stuck on the flue and the hole looked recent.

I got back to him but he wont admit drilling hole but did say he used it for flue reading. He then said I think the last guy had but there was no last guy as I serviced it myself since 2007 and only got this guy out in Spetember 2019 ie the same guy as serviced it this July. This is it. Boiler is a Grant Vortex. Is this safe and why drill a hole should it not have an easier method to measure emissions?

 

[SimonG]

See it on many an old boiler flue. Bit silver heat proof tape and jobs a good one. Never drilled one myself but utilised many and taped over.

 

[bomitie]

You are a star. Thank you I can do that myself. On looking at flue if I had to test flue gases I might have a look at this screw thingy

 

[Last Plumber]

It's a common practice. Holes and foil tape.
See it day in day out.
I don't know why he didn't use the sample point as you would if there was one installed and it opens OK.
Normally see the hole/tape idea on boilers without a manufacturers effort. Most drill holes I see are in commercial premises.

 

[exedon2]

As SimonG says all very normal drilled more than I care to think about back in the day used to be able to get a stainless steel plug that neatly closed them up.

 

[Gasmk1]

Sample point could be too small for probe on analyser seen this quite often.

 

[Last Plumber]

Sample point could be too small for probe on analyser seen this quite often.

True story!
I too have found that on oil boilers. I think it is because they were intended for the hand pump test which is smaller O.D.

 

[SimonG]

True story!
I too have found that on oil boilers. I think it is because they were intended for the hand pump test which is smaller O.D.

Now those were the days. Still got my wet kit, somewhere.

 

[Last Plumber]

Now those were the days. Still got my wet kit, somewhere.

Still use the pump before upsetting my dainty analyser, just to check the smoke won't make it cough you know.
Have you seen the price of them now?
The one I use was my Granddads originally. It was part of the old draeger kit. Still got that too although the rubbers look like porridge.

 

[bomitie]

Thanks all, sorted got my heat sealant tape and hole now covered. Are you aware that gases will go easiest route out top of flue!!! guess who said that.