Condensing Boiler - water top-up query

[Buckster]

wonder if anyone can help please

we had a condensing boiler fitted about 2 years ago - its a "sealed system" - although my plumbing knowledge is zero - so probably all condensing boilers have to have a sealed system

anyway the question is with regards to having to top-up the water round the system

every 4 weeks or so - the pressure drops from the required minimum of 1 bar down to about .6 of a bar or so - perhaps 5 weeks or so.

I can't see any water leaks - although thats not to say there aren't anywhere that I can't see.

(1) should I be worried

(2) where is the water going ? leak ?

(3) steam that comes out of the boiler outlet to the outside world - is that where the water is going ? IE I know that condensing boilers obviously give off steam - hence the name - but where does that water that produces the steam come from ?

ps to top up - I have to open 2 taps up - and it really takes a pretty tiny amount to get back up to 1 bar - perhaps a 1 second burst of water or so.

thanks for any help,

Best Regards, Mark.

 

[Berserker]

Sounds like a slight leak. I'm no expert, but steam coming out of what should essentially be an air/combustion gas vent suggests one of two things - (1) you have a condensation problem, or (2) there's a slight leak inside the boiler.

Like I said though, I'm no expert so hopefully someone else will be able to provide more accurate information.

One thing I will say though is that I need to top up my sealed system maybe once every two years - certainly not every four weeks. The only time I had to top up regularly was when the installation was new.

 

[ANDARIAL]

On a condensing boiler there should be a overflow/pressure relief pipe about 3/4 inch in diameter going from the boiler to the outside,sometimes into a drain.
Put a container under that and see if it is catching any water.If so you .you `MAY` need to get a plumber in as the expansion tank may have a hole in the membrane.
If you are not too bothered about topping up the water,keep doing that as a new tank could be a £100+fitting
Am not a plumber but i work on site so may not be entirely accurate
Bottom line is if you are worried get a pro plumber in to have a look

 

[FlyingFish]

If your topping up by such a small amount every 5 weeks then I'd say thats not far from normal for this time of year.

If your seeing lots of steam out of the flue then thats good, the more the merrier. It means your boiler is working efficiently and condensing for longer, which is good

You may want to set the heating dial ( front of boiler ) to a lower setting. If this is too high that could account for the topping up every month or so. Ever watched a pan start to boil? Small air bubbles created, same effect can occur in your boiler, the auto air vent removes that air, and over time the pressure will drop, you are using water. Different systems use water at different rates they are all different, and used differently.

There are various reasons/faults why a system can drop pressure. But for what your seeing, I would not worry

Mick

ANDARIAL

Nice try m8 nearly there Its a combination boiler ( or any sealed sytem ) that has a copper outlet pipe, that discharges from the prv.. A condensing combination boiler will have this too, and also a plastic condensate pipe...This condensate pipe discharges water under normal running ( heating normally on ).
PRV outlet pipe normally discharges to the ground safely, a condensate outlet normally discharges down a waste pipe or soakaway.

Expansion vessel problems are a different ball game. Start at 1bar, run heating, pressure goes to 3bar, prv dumps water, heating cools at end of cycle, pressure now drops below 1 bar. Instant water loss from one heating cycle.

 

[Nobski]

Do you have to bleed the radiators much over this time. If you do you will need to to top up the inhibitor in the water that stops the rads from oxidising (or something like that)

.

 

[moon man]

yoy could get a maintenance plan for £12 a month including a service thats over £50 anyway we had a heat exchanger plus circuit board done last year and it would have been £1100

ours steams but only top pressure up once a year maybe

 

[Buckster]

thanks very much to all of you

when I said steam - I meant the condensed stuff that should come out at al times - not sure what you call it I call it steam but perhaps there is a different term

from what I heard the more steam the better as it meant the boiler was working more effeciently ?

 

[Boycey]

If your topping up by such a small amount every 5 weeks then I'd say thats not far from normal for this time of year.

If your seeing lots of steam out of the flue then thats good, the more the merrier. It means your boiler is working efficiently and condensing for longer, which is good

You may want to set the heating dial ( front of boiler ) to a lower setting. If this is too high that could account for the topping up every month or so. Ever watched a pan start to boil? Small air bubbles created, same effect can occur in your boiler, the auto air vent removes that air, and over time the pressure will drop, you are using water. Different systems use water at different rates they are all different, and used differently.

There are various reasons/faults why a system can drop pressure. But for what your seeing, I would not worry

Not much I can add - that answer has the ring of a heating engineer about it...? I have the same issue with my boiler, needing to top up quite often at the moment; one of those slightly irksome but necessary tasks to try and keep Winter at bay!

thanks very much to all of you

when I said steam - I meant the condensed stuff that should come out at al times - not sure what you call it I call it steam but perhaps there is a different term

from what I heard the more steam the better as it meant the boiler was working more effeciently ?

It basically is steam, or 'vapour' at least - won't actually contain any water from inside the heating system (unless there's something very wrong), it's the cooled exhaust gases or 'products of combustion' from the burner. Paradoxically, a non-condensing boiler won't form this vapour because it pumps out the POC at a much higher temperature (they have not been passed over a secondary heat exchanger, so have not cooled and don't form vapour plumes). So, any moisture being vapourised in this way is basically just formed from the moisture in the air rather than in your pipework (hopefully).

Or, the short answer: yes, sounds like your boiler is fine; it's going to be working ruddy hard in this weather though, poor thing.

-Alex