# Boiler repressurise? Or how to reset a Worcester Bosch boiler??



## Fletch456 (19 Dec 2010)

Anyone know how to repressurise a Worcester Bosch 24i Junior (or other model) combi boiler? The pressure has dropped and had this problem earlier in the year and can't remember the routine they talked me through.

Failing that do you know how to reset it - pressing the reset button must have to be for a prescribed number of seconds as it's not quite working.

Glad I have a gas fire and an electric stand alone shower.

Thanks

Craig


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## mickle (19 Dec 2010)

There's be a braided hose underneath which is used to fill the heating circuit. It should be left disconnected when not in use but they rarely are. At one end of it is a valve - simply open this valve until the desired pressure is reached.

It sounds like you have a leak somewhere - it's the only way that the system can be losing pressure. Check around all your radiator valves for signs of weepage.


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## zacklaws (19 Dec 2010)

I have a tap from a coldwater pipe into my boiler just above the boiler which I open and when the gauge gets into the green zone, I then turn it off. I have to hold the reset button down for about 5 secs for it to work.

To loose pressure though as "Mickle" says, you may have a leak some where in the system. Alternatively, as what has just happened to me, and I did loose pressure, is to check the pipe to the outside from the boiler to release water from your condenser is not frozen up outside. At the moment it is the no1 call out problem. I had two yards of ice inside my pipe which had steadily built up till my boiler stopped worker.

But having just looked on the Worcester website, I do not think your boiler is a condenser type, so in all probability you may have a leak, but another point is, is the water pipe frozen from the mains, especially if if it is on the inside of an outside wall of an unheated room.


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## Fletch456 (19 Dec 2010)

Sorted. Thanks guys. It was ice in the pipe outside - boiled kettle later and I've heating and am washing the dishes (darn!).

Though it lost pressure once before in the year - I think it was then that they replaced a dodgy fan - (free as it's months old). Perhaps this type somehow loses pressure as a failsafe mechanism.


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## zacklaws (19 Dec 2010)

That's good news.

Anyway as it is a common problem, here is a link which I have just found for anyone else with heating problems, which helps fix the frozen pipe:-

http://www.worcester-bosch.co.uk/homeowner/customer-service/common-winter-boiler-enquiries


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## Fiona N (20 Dec 2010)

I've found my condensing boiler outlet pipe is quite a reliable theermometer - the condensate pipe is short (and lagged) so the temperature has to be below -5C for the water to chill sufficiently on the run down the pipe to start freeze at the outlet. Once it starts, then the icicle sort of works backwards until it clogs the pipe outlet. Quite an interesting process. British Gas (and presumably others) have a fix available in the form of a wire down the pipe which when, it gets cold enough, is heated just enough to keep the water liquid - neat.


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## Globalti (21 Dec 2010)

Newer condensing boilers have a siphon arrangement so that the condensate is released in a rush rather than a constant trickle.


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## GrumpyGregry (21 Dec 2010)

The OP was talking about a combi boiler not a condensor.

You may find that when 'just' repressurising the system, as per mickle's instructions above, all you end up doing is compressing the air which, if you've a leak, will inevtiable be trapped in some of your radiators. Repressurisation (in our 3 storey Bosch Westinghouse combi equiped house) is a two person job. Someone to work the bleed screws on the highest radiators and someone to work the water valve. Coordinated via mobile phone!!!!

And despite two plumbers/engineers best attempts we've never found the leak.


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## mickle (21 Dec 2010)

Filling a system is a one man job so I can't imagine why just bleeding them requires two. 

I did fail to mention that every time a leaking system is topped up the concentration of inhibitor in the water is diluted.

If there is insufficient inhibitor in a system the slightly acidic water will cause galvanic corrosion to occur between the copper pipes, brass fittings and the steel radiators (This produces hydrogen gas. Not air. Air cannot get into a pressurised system through a leak).

Over time the system will lose efficiency as the rads fill up from the bottom with black silt and eventually the rads will develop pin hole leaks and require replacing completely.

Manufacturers of radiators and boilers recommend that CH circuits be serviced every year. Thats a drain, power-flush, rinse, drain and fill. Adding galvanic inhibitor to the filling water. No one ever does it. 

Google Fernox.


If I have to post on this thread again I'll be ******* invoicing someone.


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## SavageHoutkop (21 Dec 2010)

mickle said:


> If I have to post on this thread again I'll be ******* invoicing someone.



So we'll need to start a new thread then...?


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## Fiona N (21 Dec 2010)

mickle said:


> F
> I did fail to mention that every time a leaking system is topped up the concentration of inhibitor in the water is diluted.
> 
> If there is insufficient inhibitor in a system the slightly acidic water will cause galvanic corrosion to occur between the copper pipes, brass fittings and the steel radiators (This produces hydrogen gas. Not air. Air cannot get into a pressurised system through a leak).
> ...



I have a British Gas CH 'inspection' each year and so far, what with replacing the 'old' boiler, new radiator in the bathroom, replacement radiator in office and big new radiator in the kichen and new radiator in the airing cupboard (to replace the hot water tank as a heat source for airing clothes), I have managed to have the system drained every year I've been in the house. Given the (low) quality of the radiators and fittings used when the houses were built about 15 years go, I can't see the next few years being any different.


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## Gixxerman (21 Dec 2010)

I have a Worcester Bosch 12Ri. When it was fitted 7 months ago, I was aware of the condesate pipe freeze issue, so I got the installer to route it inside the kitchen (where the boiler is) and into the sink drain. It is a tiny bit of an eyesore having it in the kitchen, but at least it will not freeze up. My mate has his boiler in the garage and every year he has problems with the condensate pipe freezing. I have heard that if you make it a 2" pipe instead of the normal 3/4" pipe, it wil not freeze even if outside. There is also the solution of adding trace heating to the pipe, which normally comes on at 5 DegC or less.

I have a bit of an issue with my system in that there is a gurgling sound from the magnaclean in the airing cupboard. It only does it when starting from cold, and is worse if just using water heating on it's own (it has a 3-way valve). Once the system has been running for an hour or 2 it is fine. I assume (afterall I am no expert) that by this time any air in the system has been expelled by heat expansion into the F+E tank (it is not a sealed system).
The bathroom radiator always seems to have air in it as well (I think it is the last in the line and nearest to the pump / hot water cyclinder).
It was filled with fernox when they fitted it, so it should not be the hydrogen issue mentioned above.
Any ideas anybody?


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## subaqua (21 Dec 2010)

mickle said:


> Filling a system is a one man job so I can't imagine why just bleeding them requires two.
> 
> I did fail to mention that every time a leaking system is topped up the concentration of inhibitor in the water is diluted.
> 
> ...



of course all the gases ( oxygen nitrogen etc) dissolved into the solution , as water is great for this, when it is in the supply pipes to your house from the reservoir has to bubble out of solution at some point. 

http://www.nigelhewitt.co.uk/diving/maths/pp.html shopws the physics behind gases dissolving into a liquid. 

the rest is all bang on the nail. although be warned if the system hasn't been flushed since day 1 you may end up fixing lots of leaks when you have power flushed it. some boiler manufacturwers also don't recommend flushing the heat exchanger in their boiler. I have a bypass loop and isolators fitted to avoid this problem, its great when you work for a large M&E engineering contractor


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## mickle (21 Dec 2010)

Gixxerman said:


> The bathroom radiator always seems to have air in it as well (I think it is the last in the line and nearest to the pump / hot water cyclinder).
> It was filled with fernox when they fitted it, so it should not be the hydrogen issue mentioned above.
> Any ideas anybody?




Fernox doesn't last forever. According to the manufacturer it should be replaced regularly. 

A little leak in an open system is more likely to go un-noticed. Over time the inhibitor drips slowly away to be replaced automatically with fresh oxygenated water (when a sealed system loses pressure it must be filled manually).

My last house had a leak at a rad valve which occurred only when the radiator was warming up and was so slow that the drip evaporated before it could reach the floorboards. Three or four such sneaky leaks would soon cause the inhibitor to be diluted below a useful concentration. 

Or. Your bathroom rad might be first on the circuit and capturing air generated by pump cavitation. 

Another possibility; if the system isn't designed right the pump could be sucking in a gulp on start-up through the expansion pipe.

That'll be £119.47 please.


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## Gixxerman (21 Dec 2010)

Thank you.
I take the hint, sorry for being a bit cheeky expecting free advice.
You must get it all the time.

I hope you forgive me if I do not send the payment .
I can offer to return the favour if that is any good.
If you need to know anything about gas turbines and their associated control systems or any electronics queries, I can help you out with them.


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## mickle (21 Dec 2010)

Cool.

Gas turbine control systems eh?. Would you say that L4S is a "momentary" logic signal which will go to a logic "1" when a unit START is initiated and all the start permissives, including sufficient L.O. pressure, have been satisfied. L4T is the logic signal which will be a logic "1" when any trip (emergency shutdown) condition is detected by the sequencing or application code, such as low-low L.O. pressure, or high-high vibration, or exhaust overtemperature. L94T is the logic signal which will be a logic "1" when a normal, automatic non-emergency shutdown is active and the unit reaches the point at which the fuel is to be shut off. In order for L4 to be energized (go to a logic "1"), L4T must NOT be a logic "1" (meaning there must be no active trip conditions detected), L94T must NOT be a logic "1" (meaning that a normal shutdown is not active and fuel does not need to be shut off), and L4S must go to a logic "1" (meaning that all the start-check permissives must be satisfied, and a START must be active, and all permissives to run the turbine must be satisfied).

Or what?


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## slowmotion (21 Dec 2010)

mickle said:


> Or what?



Nay. A sharp smack with a lump hammer, mate.


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## mickle (21 Dec 2010)

Meh.


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## slowmotion (21 Dec 2010)

...and stick a Megger on the dodgy gas valve solenoid....


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## GrumpyGregry (21 Dec 2010)

mickle said:


> Filling a system is a one man job so I can't imagine why just bleeding them requires two.



the install/commissioning instructions on mine suggest both filling and bleeding may be easier done with two....


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## Gixxerman (22 Dec 2010)

mickle said:


> Or what?



This is engineering porn!
I take it that you haven't always been a plumber / heating engineer. Ex RAF ground crew per-chance?

In summary yes (assuming that you are applying the standard failsafe logic of logic '1' meaning healthy).
You should not be able to start the unit unless all pre-start conditions are met L.O. pressure is just one of them. Our engines has as much as 50 or so pre-start conditions. The I/O count on a typical turbine (with driven unit) is about 500 devices. The whole of the code has to run on a 10ms scan rate, including servicing the I/O.
It looks like you are talking about a quite old control system (relay logic?), or possibly ladder logic on a PLC?
I use modern PLC's that are programmed with high level languages (SCL, STL) or graphical programming languages (FBD, CFC, SFC) and also real-time embedded system programming in c / c++ / assembly. I also write communication drivers, so if you need any help there, you only need to ask.


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## Dan B (22 Dec 2010)

mickle said:


> Gas turbine control systems eh?. Would you say that L4S is a "momentary" logic signal which will go to a logic "1" when a unit START is initiated and all the start permissives, including sufficient L.O. pressure, have been satisfied. L4T is the logic signal which will be a logic "1" when any trip (emergency shutdown) condition is detected by the sequencing or application code, such as low-low L.O. pressure, or high-high vibration, or exhaust overtemperature. L94T is the logic signal which will be a logic "1" when a normal, automatic non-emergency shutdown is active and the unit reaches the point at which the fuel is to be shut off. In order for L4 to be energized (go to a logic "1"), L4T must NOT be a logic "1" (meaning there must be no active trip conditions detected), L94T must NOT be a logic "1" (meaning that a normal shutdown is not active and fuel does not need to be shut off), and L4S must go to a logic "1" (meaning that all the start-check permissives must be satisfied, and a START must be active, and all permissives to run the turbine must be satisfied).




"Well?"
"Er, what does the Z mean?"
"Which one?"
"Any one"


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## zacklaws (22 Dec 2010)

[QUOTE 1271816"]
I woke up to our Worcester combi boiler gurgling away merrily this morning. What's wrong with it?
[/quote]

That was one of the symptoms I had when my condensate pipe had froze over. The boiler probably keeps working untill the pipe is completly full of ice and no where for the condensate to go.

As for fitting a 2 inch pipe instead of a 3/4 inch pipe, it made no difference to me, I ended up with a 2 yard long, 2 inch pipe packed end to end with ice.

I removed the 2 inch pipe, heavily insulated the stump poking out of the wall and it seems OK now, just get up every morning now to remove an icicle up to 18 inches long now from the long overhang of the insulation but the pipe remains unfrozen..


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## cisamcgu (22 Dec 2010)

[QUOTE 1271816"]
I woke up to our Worcester combi boiler gurgling away merrily this morning. What's wrong with it?
[/quote]

We had a similar problem. The boiler man found that the small container that holds the condenser water was full of sand and wasn't allowing the water to drip out. He at first thought that the pipe was frozen.

Hope this helps, or at least points in the right direction.


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## Gixxerman (22 Dec 2010)

coruskate said:


> "Well?"
> "Er, what does the Z mean?"
> "Which one?"
> "Any one"


Nice HHGTTG quote BTW.

Good question though. The Z stands for position in the standard ISA device tagging scheme.
This then has a number of subsequent letters that are qualifiers (e.g. S=Switch, T=transmitter, D=Differential)
For example: ZS123 would be Postion (Z) switch (S) number 123 and ZT456 would be Position (Z) transmitter (T) number 456.

Hope that helps.


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