Boiler flue inspection point (and central heating inhibitor) query

[Giles Mann]

Hi everyone.

I have a couple of boiler/CH related queries.

I had an engineer come round to re-pressurise the expansion vessel fairly recently, as the CH pressure kept rising drastically; causing the PRV to activate. He fixed this issue but said that the boiler was not technically serviceable due to a lack of inspection point on the flue elbow.

The boiler is an Ideal Independent C24 and going through the manual I cannot seem to find anything on this kind of inspection point. I have read about probes being used from outside but access is an issue. I have attached a couple of photos of the top of the boiler - I am wondering if the small black screw cap has anything to do with this.

Also, because he drained the expansion vessel (and from the several times I had to top up the system), I am wondering if I should top up the inhibitor. He said it should be alright if enough was put in to begin with but unfortunately, having moved in a year ago, I don't know what had been done before. It seems that test kits available are for specific brands (and again I don't know which would have been used).
I am just concerned about the inside of the radiators corroding over time. Would my best bet be to bite the bullet; drain the system and add inhibitor?

Really appreciate any advice as central heating is definitely a bit out of my comfort zone for DIY.

 

[CBW]

If the engineer didn’t know, he should have contacted Ideal technical for assistance, they would have told him how to sample to flue, or asked on here in the gas forum.

Regards the inhibitor, it all depends how much you have been losing and topping up. If only a week, I’d say it’s fine, if a week or more I’d go with adding inhibitor - certainly wouldn’t do it any harm.

 

[Hugh Jaleak]

Boiler servicing is one for the Gas Engineers, I cant see a test point on the flue where it should normally be located, but there may be other methods of doing the required checks. The black cap is unlikely (in my view) to be a test point, possibly an air vent.

Inhibitor, you cant really overdose it, I'd drain a few pints of water off, add another bottle and top system up to required level again. If you've other issues like kettling in the boiler, cold spots in rads or poor circulation, then it's time to get a bit more involved, but if system is working ok, just add inhibitor.

 

[flameport]

drain the system and add inhibitor?

Drain enough only to add the inhibitor - it's not desirable to drain everything as that then means refilling with fresh water which will contain dissolved oxygen, the very thing that will increase corrosion.

 

[Giles Mann]

Thank you for your responses. I am going to call Independent myself and ask about inspection point.

As for inhibitor, I am going to get some Sentinel X100 and add it via the Magnaclean. The Sentinel product is one of the recommended ones in the manual - although I cannot know if this was the one added previously.
Should I be concerned about the potential of mixing two inhibitor types?

 

[Daveydub]

The little black cap on the top of boiler will be sampling point

 

[Daveydub]

This is the Ideal Isar but same principle

 

[ianmcd]

The black cap is the sampling point , not a flue inspection as you called it, it is how with a Flue gas analyser you can test how the boiler is burning, nowt to do with inspecting the flue, your install is fine, adding another litre of inhibitor will not do any harm but if you can, use the same brand as is already in there , not always a good idea to mix them

 

[CBW]

The black cap is the sampling point , not a flue inspection as you called it, it is how with a Flue gas analyser you can test how the boiler is burning, nowt to do with inspecting the flue, your install is fine, adding another litre of inhibitor will not do any harm but if you can, use the same brand as is already in there , not always a good idea to mix them

I knew this, but wasn’t sure if I was able to quote this on open forum?

 

[ianmcd]

I knew this, but wasn’t sure if I was able to quote this on open forum?

Sorry mate wasnt getting at you in any way, really sorry if it came across as that pal , honestly didnt mean to

 

[CBW]

Sorry mate wasnt getting at you in any way, really sorry if it came across as that pal , honestly didnt mean to

I know you weren’t mate, no harm, no foul. Didn’t come across as anything.

 

[Giles Mann]

I have bought a Sentinel X100 test kit (obviously might be completely pointless, as I don't know if that was used).
If it shows that it is fine, I will do nothing. If not, I will drain the system and add new inhibitor. I don't want to do more harm than good by potentially mixing inhibitors.
Does this sound reasonable?