CH system, Fernoxed, no leaks, produces air/gas..why?

[hendenne]

My CH system is 9 years old, it has an MHS condensing boiler.

The boiler is serviced annually by an industrial engineer experienced with the installation/maintenance of this type of MHS boiler.

There are 22 rads plus towel rail. The bathroom ladder towel rail on first floor continuously gathers 'air'.

The 4 rads on the second floor do not gather air nor does any other rad to any great extent.

There are 2 air release valves fitted in pipework at floor level on second floor.

The newly replaced expansion tank holds the system to a minimum 0.5 bar, this pressure rises to 2 bar when heating.

There is no obvious water loss and 2 tubes of Fernox were added 3 months ago.

There is always quite a gurgle at the boiler when the boiler starts and water begins circulating.

I have no idea where this 'air' is coming from but wonder if I could fit an automatic release valve to the towel rail to avoid the regular venting of trapped air?

Other comments about how/why/what to do are welcome.

Thanks for reading this.

 

[45yearsagasman]

Do a test to see if the gas is in fact hydrogen. When venting an affected rad hydrogen can be collected in an inverted tin and then you can apply a lighter to see if it's hydrogen. If positive then your inhibitor levels need to be corrected. Unlikely to be air as you have described a sealed system.

 

[hendenne]

Do a test to see if the gas is in fact hydrogen. When venting an affected rad hydrogen can be collected in an inverted tin and then you can apply a lighter to see if it's hydrogen. If positive then your inhibitor levels need to be corrected. Unlikely to be air as you have described a sealed system.

Thanks for your quick advice.

I'll have to wait a few days to get enough 'air' collected to test burn.

BUT your comments caused me to reconsider if I have added enough Fernox to the system and I think probably not.

There has not been a regular checking of the water/gas of the system.

I added 2 Fernox F1 gel in March thinking that should be enough but have just read that 1xF1=10 rads.

I calculate that all our rads add up to about 40 single panel rads so perhaps I need to add another 2 F1?

I see that there is now a Fernox F1 Express aerosol version and it's less expensive than the tube of gel, do you have any opinion on this?

 

[45yearsagasman]

I've only ever used the liquid inhibitors and not so much the gel type. You cannot overdose with F1(being sensible) I've never used the aerosol product.

 

[hendenne]

I've only ever used the liquid inhibitors and not so much the gel type. You cannot overdose with F1(being sensible) I've never used the aerosol product.

THANKS AGAIN.... 2xF1 to be purchased.

 

[hendenne]

Do a test to see if the gas is in fact hydrogen. When venting an affected rad hydrogen can be collected in an inverted tin and then you can apply a lighter to see if it's hydrogen. If positive then your inhibitor levels need to be corrected. Unlikely to be air as you have described a sealed system.

Another question please: do you have any thoughts about the two auto vents already on the system?

They are sited at floor level on 2nd floor, 1.4mtrs above top valve of towel rail/rad that collects air/gas but 0.6 mtrs below tops of rads on 2nd floor.

Should these auto vents actually auto vent air/gas or do they just disturb it so that it settles in smaller parts in rads?

The auto vents each have a small red cap which when unscrewed is not venting air/water. The main body can be turned but again nothing is vented.

Thanks again.