Glow worm hideaway boiler possible kettling help

[Gazza51]

i have a really strange problem with my glow worm hideaway 60 b boiler I hope someone can offer advice on. Since putting fernox f2 boiler silencer in to quell some minor kettling noise which was only moinir hissing on heating up rather than banging etc, now when the boiler has reached or is reaching its set heat output (boiler only set to half way) there is a sound of tricking gurgling water/air passing through the boiler/pump. This then passes to the nearest radiators in the hall and dining room producing a trickling gurgling sound in the radiators but I never find any air in the radiators. The situation is even worse if the boiler is up to temperature and you stop the pump allowing the boiler temperature to climb further and then start the pump again, the noise of trickling/gurgling water is terrible and alarming.

I have checked for water leaks by tieing up the fe tank float for 5 days and the water level stays the same. There are no signs of water leaks around the boiler either. I have checked to make sure that when you drain water from the system the water level in the fe tank falls. I have also checked that there are no blockages at the feed T to the system using a magnet. I have placed a cup under the vent pipe for 2 days and no water is in the cup so I guess no pumping over. I have placed a cup of water under the vent when the pump starts and initially a small amount of water is sucked up but released as soon as the pumped water reaches equilibrium. The hot water is gravity fed and the boiler is heating up the water tank as normal.

Turning the pump speed up to 2 helps the problem as the boiler doesn't reach the temperature set at the boiler stat very often compared to when the boiler is cycling more on speed 1. When the tricking/gurgling starts it diminishes as soon as the water temperature in the boiler starts to fall. When the boiler heats the water up form cold it is silent until it reaches the higher water temperature set on the boiler stat. When the boiler cycles in and offer around the boiler stat temperature the problem is worse.

As I can never find any air in any in of the radiators is the boiler experiencing localised steaming due to kettling which the fernox f2 boiler silencer is making worse and pushing through the pump to the radiators in the dining room and hall. Fernox say it should improve heat transfer and break larger steam bubbles down into small ones during kettling. How could these steam bubbles be reaching the radiators before they cool? Should I just drain down and refill my system without the f2 or could I have sludge in the boiler that is boiling and then being pushed round into the nearest radiators? The problem is really peculiar.

 

[simond]

It's an old boiler and is probably full of limescale.

When this happens some parts of the heat exchanger get much hotter, quicker, than other parts. The design was intended to get uniformly hot all over.

Ultimately this differential temperature will cause thermal stresses enough to write off (crack) the heat exchanger.

The boiler silencer just changes the surface tension of the bubbles, it doesn't address the core problem.

Another but unlikely problem is that the gas rate is too high (not an expert on Hideaways, I know I've scrapped a few but can't remember their construction), would be worth getting a qualified person to check. Alternatively, you can turn the thing on from cold and use the gas meter dial and a stopwatch, there are tutorials on the internet. Compare the amount of gas being used to the Hideaway manual for your model.

 

[Gazza51]

Yes I think lime scale will be present but the problem never occurred until I put the fernox silencer in other than some minor kettling which resulted in some hissing, steam bubbles never made it to the two rads before if this is what I can hear. I have a BG contract so yes they are booked to come round to service the boiler and take a look but I just want to be prepared with some facts just in case they try to sell me a £800 + power flush. Would it be worth putting in some sentinal x400 in case it's sludge build up as when I first put the boiler silence in a few weeks later black sludge appeared in the fe tank and I bailed it out, it has not returned since. Or should Put fernox f3 in to try and clean it then drain and refill with fresh inhibitor or is it worth trying some sentinal x200 boiler silencer in there as this is supposed to stay in and loosen lime scale over time. Can I add the sentinal x200 with the existing fernox f1 and f2 or should I drain and refill first?

 

[Agile]

If you have black gunge then I think you should address that first with X400 for five weeks or X800 for two days.

Then add X200 if there is still a problem or just X100 inhibitor if not.

Tony

 

[JohnD]

The boiler silencer just changes the surface tension of the bubbles

Well that's odd. I could have sworn it used to be described as descaler, and I wondered how it worked. Some retailers still use the word
http://www.screwfix.com/p/sentinel-x200-boiler-descaler/43140 "A unique, life-long system treatment for the elimination of limescale and boiler noise" but Sentinel don't.

The manufacturer says noise is "most often caused by a thin layer of deposit on the heat exchanger. Sentinel X200 Noise Reducer is extremely effective in solving this problem, whilst simultaneously helping to restore boiler efficiency" but how can it improve efficiency if the scale is still there?

 

[Gazza51]

Tony currently the system has fernox f1 and f2 boiler silencer in the water, should I just throw some sentinal x400 in with this to see if it solves the problem first and then drain down and add sentinel x200 and x100 or add some x200 with the fernox f1 and f2 first and see what happens. Will it mix with the fernox currently in the system? If the x200 is actually a mild descaler whereas the the fernox f2 is not my thoughts are descaling is better and may resolve problems. Do you know why adding the fernox f2 might have caused the trickle/gurgling sounds to travel to the 2 rads after being heard moving through the boiler and pump? As previously mentioned before it was put in I only had minor kettling in the form of hissing, surly stream bubbles can not travel 4-5 meters from the boiler to the rad before desolving back into the water? Could the fernox f2 be promoting this by holding the bubbles in suspension?

 

[simond]

Fernox sell a different product to dissolve limescale, called DS3.

Servicing the boiler won't make any difference unless the burner pressure is out.

 

[Steelmasons]

Half a bottle of fairy liquid will sort it.

 

[simond]

And be kind to your hands, too.

 

[gasbanni]

Half a bottle of fairy liquid will sort it.

If that's true and not a mickey take I've never heard of that one !
If it's true how does it work ? If the problems a slug of air that's moving back and forth and not venting to the header tank or rads, I'm assuming it dilutes the slug of air to foam and gets it moving.

At gworm we'd remove boiler stat and boil it to remove air locks !!!! Your way sounds less fearful!

 

[Gas2Air]

He's a prat. Running a Hideaway on pump speed 1? I reckon it's pumping over. He's tried to silence the hex by draining the system, pulled a load of ****e in and is now paying the price, or will be when BG turn up

 

[Gazza51]

Speed 1 has always been fine running only 7 rads and no I've not drained it down since BG did it in 2010 to fit a new rad and they cleansed the system with x400 at the same time then installed F1. Oh and no it's not pumping over if you read my post in its entirety you would have understood the detail. If you can offer advice Gaz2Air then please do so, if you can't then cut out all the gas and air mate and stop being a troll and praying on people's misfortune! If the boilers unrecoverable then I'll just have it replaced no big shakes just drawing on a few experts on this website to see if anything can be done to recover the situation just a shame you have to get through a few trolls to find out. Tony respect your views and opinions, seen a fair few of your replies to people's problems and you generally want to help, keep up the good work.

 

[Gazza51]

The boiler silencer just changes the surface tension of the bubbles

Well that's odd. I could have sworn it used to be described as descaler, and I wondered how it worked. Some retailers still use the word
http://www.screwfix.com/p/sentinel-x200-boiler-descaler/43140 "A unique, life-long system treatment for the elimination of limescale and boiler noise" but Sentinel don't.

The manufacturer says noise is "most often caused by a thin layer of deposit on the heat exchanger. Sentinel X200 Noise Reducer is extremely effective in solving this problem, whilst simultaneously helping to restore boiler efficiency" but how can it improve efficiency if the scale is still there?

Looking at the safety data sheet X200 contains Potassium hydroxide which acts as a water softener hence it breaks down the limescale over time making it soluble in water. Clever bit of water chemistry.

 

[Gazza51]

Well contacted Fernox and they said Fernox F2 is not well suited to the cast iron boiler of the glow worm hideaway and that the noise is definitely steam bubbles being collected by the chemical and being pushed around the system until they condense back into water in the nearest radiators. This is confirmed by the absence of any air in the rads too. The nature of the boiler is such that when the water temperature reaches the boiler stat temperature it cuts out and the temperature of the water continues to rise due to the thermal energy still contained in the heat exchanger so if the heating pump had stopped too when the rooms stat reaches temperature, the water continues to rise in temperature and can reach close to boiling point and generates more steam bubbled due to lime scale. As I have gravity hot water too this heat energy takes time to dissipate so hence if the pump comes back on before the water has cooled back to a reasonable temperature all these steam bubbles are shifted through the system by the chemical which improves heat transfer and reduces surface tension.

The boiler has no pump overrun so I have seen that when the boiler stat is set to the 1/4 position and it reaches this set point the water temperature at the top of the boiler continues to rise as much as +20°C higher than the 60°C set with the boiler stat set at 1/4, so the stat would actually cut out at 3/4 nearly 80°C and the boiler not come back on until it reaches 1/4 again. No wonder there is plenty of steam bubbles being drawn out the heat exchange by the F2 when normally these would just either stay in the heat exchange and condense back into water again or circulate up the gravity feed and out the vent. The F2 promotes better heat transfer between the water and heat exchange too. I have changed the boiler thermostat too just to rule out a faulty one and it behaves the same as the old one.

Fernox have instructed me to drain the F2 out and clean the system with either F3 or F5, flush and refill with just F1 inhibitor to put the system back as it was which just had minor kettling before.