URGENT - Gas/Hydrogen Buildup - NEW Central Heatng Systm.

[Archie]

URGENT problem, if you are able to suggest a solution to me. Many thanks. Archie

BACKGROUND: Reputable central heating installer. Complete new central heating system, boiler/pipes/radiators. Combination condensing gas boiler, sealed system. Standard Copper pipes (25mm). Radiator thermostat valves. The whole system recently installed totally new.

PROBLEM: There is a steady, continuous, build up of hydrogen gas in the system, which results in a steady rise in system pressure as shown by the boiler gauge (about 0.1 bar every 2 days).

What is causing this steady, persistent build up of hydrogen gas in this completely new system?!!

NOTES: The sound of small gas bubbles is clearly heard in ONLY ONE radiator valve (noise stops when this valve is closed), however, the gas build up still continues.

System has been drained three times so far, also 2 times inhibitor strength in the system.

Boiler's fresh water inlet valve was changed, just in case it was letting fresh water into system from the mains.

First gas investigation -> gas from a radiator burnt strongly ->

ie hydrogen gas.

Is it possible for air to get into system - even though system is under pressure?!

After 3 times draining the system over 2 months, residue FLUX cannot be causing this problem!

Is one radiator valve causing this due to oil leakage of some sort? I'm just guessing.

Is this caused by the boiler?

Is something leaking into the system? oil/grease/flux/air/fresh water/metal powder? . . .

Is something corroding?

Out of frustration, I am about to ask the installers to take the whole system down! Based on your experience, what is the most likely cause of this problem?

[Andrew Heggie]

Sounds like an aluminium heat exchanger in the boiler.

An electrolytic corrosion reaction involving the boiler heat exchanger and other metals in the system, cured by one of the fernox inhibit chemicals added to the system.

AJH

[Archie]

"Andrew Heggie" wrote: | | >Is something corroding? | | Sounds like an aluminium heat exchanger in the boiler. | >

| >Out of frustration, I am about to ask the installers to take the | >whole system down! | >Based on your experience, what is the most likely cause of this | >problem? | | An electrolytic corrosion reaction involving the boiler heat exchanger | and other metals in the system, cured by one of the fernox inhibit | chemicals added to the system. | | AJH

Andrew, many thanks. Have you seen/heard this before?

I understand your explanation - this boiler has Aluminium exchanger, but the current setup has TWICE the inhibitor concentration in it - ie it has X100 Sentinel inhibitor at 2x concentraion . . . Unless you believe this is different.

NOTE: Water/gas solution => When bleeding the radiators, the extracted water is CLEAR, but has a fizzy/foam/froth apperance which clears after a few seconds - this is why we guessed it was caused by residue flux in water -> ie acidic flux residue generating hydrogen gas in water - but there's a lot of gas over 2 months for this to be still valid IMHO anyway. Cheers.

[Andy Dingley]

Just to check an obvious problem before going for the oddities -- you _have_ removed the filling loop, haven't you ?

-- Do whales have krillfiles ?

[Archie]

"Andy Dingley" | wrote: | | >There is a steady, continuous, build up of hydrogen gas in the | >system, which results in a steady rise in system pressure as | >shown by the boiler gauge (about 0.1 bar every 2 days). | | Just to check an obvious problem before going for the oddities -- you | _have_ removed the filling loop, haven't you ? |

Andy - what do you mean please? - I hope these points further clarify:

*** BOILER: Glow-worm, combi condensing boiler, model = 30CXi The water mains top-up inlet valve (fresh water inlet to system - visible underneath boiler), is Closed (turning up clockwise) - it is a blue cap valve (the only user operated valve).

*** Boiler PRESSURE GAUGE: Sealed system - system pressure (boiler gauge) goes up approx 0.1 bar every 2 days. AFTER bleeding radiator gas, system pressure RETURNS to original value - suggesting that gas build up is the cause for pressure increase. Example: After a week, systm pressure is now 2.3 bar, however, it will go down to 1.1 as soon as I bleed the radiators to let the gas out - the lowest press. reading (1.1 bar) is almost reproducible.

There's always a slight (0.1 bar) pressure fluctuation due to water heat up & cool down for central heating - this is normal and seems reasonable.

[Lawrence]

Lawrence

usenet at lklyne dt co dt uk

[Andrew Heggie]

I had a similar problem but 5litres of fernox seemed to cure it, although mine is not a pressurised system. I would have kept bleeding the radiators but for a poster here, mentioning hydrogen, made me go and check with a cigarette lighter ;-).

I am afraid you will have to wait for a more plumbing au fait poster to pop up, Ed S or Andy H will probably know best.

AJH

[Ed Sirett]

This is all very strange.

1) Inhibitor has been used. 2) The GW is a condensing boiler so its not an Ally heat exchanger. 3) Sentinel X100 prevent corrosion even if there is Ally (unlike Fernox MB1)

I can only suggest a through flush out using a new system cleanser intended for totally new systems. One of the Sentinel products is suitable but I can't remember which one. The cleanser is designed to deal with flux residues.

Is it also possible that the 'draining down' is only partial due to the layout of the system?

The only other possibility is a leak from the mains into the primary in the secondary heat exchanger in the boiler. This would show as a pressure rise in the boiler even if you isolate the boiler (assuming the releif valve and expansion vessel is in the boiler).

[John]

"Ed Sirett" wrote in message news: [e-mail]...

AFAICR the DHW heat exchanger of this boiler is a stainless steel plate exchanger so there are only two mains water to heating circuit potential contact points. If the pressure rise was due to leakage into the system it would be via one of these. Its unlikely to be this but as an acid test try closing the cold water inlet valve (blue) to the boiler for as long as you can over a few days except when you actually want to draw hot water. From what you said in the thread about igniting the issuing gas it does sound like hydrogen from galvanic corrosion but "some" of the accumulation could be dissolved air coming out of solution at elevated temperature. On this score repeatedly refilling with fresh water will only exacerbate the problem. If you can get hold of some pH indicator paper you could check that the water is not acidic at all. I would look for a pH above about 8 but a chat with Grace-Dearborn (in widnes I think), who make Sentinel would be fruitful. It is possible that you have two coincidental conditions - a small crossover leak which should be dealt with by Glow Worm under warranty, and the accumulation of gas is simply a slow clearing of the dissolved air which could take more than a few days or even in extreme cases over a week. If you do decide to give the system another clean I think you will need X300 but take advice from Grace-Dearborn and try the test of shutting off the cold inlet for a few days first to gain a more complete picture before you do.

[Archie]

Many thanks guys and I am watching this newsgroup like a hawk almost every minute for everyone's insight/suggestions/experience.

Complications happen in clusters . . . and so I was unable to phone Sentinel & Glow-worm yesterday/today . . . But, yesterday, I emailed both companies and haven't had a reply yet. Tomorrow I'll phone Sentinel (GE Chemicals), Glow-worm and british gas heating to get serious with this story . . .

I used to have yards of litmus (spell?) paper, but now that I want some I find none . . . perhaps DIY or Gardening shops?

[Andrew]

In article , Archie writes

//// I though you said 'Reputable heating company' in your opening post ? We don't think they are here.