Vokera gas boiler pressure guage dropping frequently.

[Deleted User]

I posted this in 'Techie Forum' and helpful advice says I should post here instead.  Neil_Jones and neilmcl have replied with advice on the Techie Forum.  I'm not sure how to delete the post there but I'll put a note to say that I have now posted here, thank you:

I'll be glad of help as you have helped a lot before (very much appreciated) regarding Vokera boiler problems.
I have had three  parts replaced and boiler fully serviced earlier this year.  This time there is no error code.
Now, although I can see no sign of a leak anywhere at all in the boiler or pipes,  the pressure guage (not the hot water one with the picture of a tap on it) keeps dropping when the heating is on.  The heating was not on much at all during the summer.  With the cold weather my boiler is on for heating every day now and really is needed.  To keep the guage at or just  above 1 I have to turn the knob to let water in, very briefly, every two to three days now.  If  don't  do this the dial goes away down far below 1 and I don't  want the heating to cut out.

If it can be avoided I would try not to have a gas safe engineer out again.  I'm concerned I may need a new boiler.  Parts and labour this year have, in total, cost over £400.

If you can help, please,  my questions are: Is it safe for me, in the circumstances, to keep topping the water up so frequently to keep it safely just above one and can anyone suggest why the pressure guage keeps dropping so soon after being topped up?

Thank you for any help and information.

Crimson 

Here is my last post on Techie Forum:  "

Now posted on the In My Home Forum but, for your helpful answers above Neil_Jones and neilmcl, I am checking as much as I can.  Access to radiators is difficult because of fixed radiator covers but, as far as I can see, the 'knobs are in the right position.  Inside the TRV is at 3 except the one in the hall which has none and comes on all the time when the others are on.

The kitchen one is off as, with cooking, the kitchen is never cold.  I'll experiment as advised and see if I can find anything.  Outside there are two pipes:  I think one is from the bathroom and nothing is dripping from it and the other, from the kitchen which I think must be from the boiler, is also not dripping.

I appreciate your time and helpful replies here.   As advised, I won't post here any more as I have just posted the question on the In my Home Forum and will, as helpfully advised,  look there for any more insight.  I have a good start thanks to you and I'll see what I can work out.  After a really cold snap the sun is actually shining now so the heating probably won't come on until later.  Having just put water in this morning and the dial is at 1.5 I have a bit of leaway for now.  Thank you again.

Crimson. 

Jeepers_Creepers

Hi Crimson.

You have a leak.

The question, where from? There are three main routes (I think): 

1) From a radiator or other part of the CH pipework. You have checked for this as much as you can, and if the leak was above floor level you would have noticed it by now. So it's either below floor level or not there at all.

2) It's from the Safety Discharge Valve in the boiler. This should only open if the system pressure goes UP to around 3 bar. The valve then opens and dumps the excess water & pressure out a 15mm copper pipe heading to the outside of your house. Once opened, these valves then tend to dribble... 

You need to find where this pipe exists your house and see if the pipe end is dripping. If it is, there's your answer.

3) It's from another part of your boiler, and the only bit that can do this without showing itself as a visible leak under your boiler is the main heat exchanger. A leak here will find its way out of your boiler via the condensate pipe - the 22mm plastic pipe which probably also heads out your house and points to a drain. This is major. But unlikely - phew...

So, please find the 15mm discharge pipe and see if it's dripping. 

(Another indication - note the pressure reading when the boiler is COLD. Now watch what this does for the first 10 minutes when you turn on the boiler to heat the rads - does it go UP? )

[Deleted User]

Thanks very much, JeepersCreepers.  As far as I can see there aren't any signs of leaks at the radiators - although the fitted cabinets make it a bit difficult. 20 minutes after the heating went on the bar was still the same and had not gone up - it usually goes down after about 2 or 3 days.

The pipe outside my kitchen window shows no sign of leaking at all as, although it has been raining this week, it has been cold, dry and very sunny today

Under the boiler (on the worktop) it is dry and no sign of leaking from the boiler.

Your reply, and the others, have been really helpful.  I'll now try to switch radiators off over a few days one at a time to see if it makes any difference to the guage level going down. 

Although I am out of my depth I think I can follow the instructions and see if any of the individual radiators is responsible.  The only one I cannot turn off is the small radiator in the hall - when the heating is on it is always on and there is no TRV on that one.

Thank you again for this very useful help.

Crimson

Jeepers_Creepers

I was really hoping it would be the pressure discharge pipe as that's probably the most common fault and usually straight-forward to sort. However, since the pressure doesn't go up when the boiler fires up from cold to hot, it's less likely to be that.

I also doubt it'll be a rad that's to blame - water losses like you mention would have left a very obvious clue, all over your floor.

I suspect, therefore, it'll be a leak from a pipe that's out of sight - so probably under your floor. You aren't lucky enough to have a foundation void large enough to crawl around in?

If it's a cracked or corroded main exchanger, the leak would be coming out (hidden) via the condensate pipe. Can you see where that is outside - plastic 22mm, probably white? Whilst the boiler is running, there will be slugs of 'water' coming out this pipe normally, so you'd really have to monitor it when the system is cold and has not been running for a while - if water still comes out, that's a leak. 

I fear it's time to call out the pros, tho'...

[Deleted User]

Jeepers_Creepers said:

I was really hoping it would be the pressure discharge pipe as that's probably the most common fault and usually straight-forward to sort. However, since the pressure doesn't go up when the boiler fires up from cold to hot, it's less likely to be that.

I also doubt it'll be a rad that's to blame - water losses like you mention would have left a very obvious clue, all over your floor.

I suspect, therefore, it'll be a leak from a pipe that's out of sight - so probably under your floor. You aren't lucky enough to have a foundation void large enough to crawl around in?

If it's a cracked or corroded main exchanger, the leak would be coming out (hidden) via the condensate pipe. Can you see where that is outside - plastic 22mm, probably white? Whilst the boiler is running, there will be slugs of 'water' coming out this pipe normally, so you'd really have to monitor it when the system is cold and has not been running for a while - if water still comes out, that's a leak. 

I fear it's time to call out the pros, tho'...

That is very helpful, thanks Jeepers_Creepers, although it is not what I hoped to hear.  With the boiler running, and radiators on, no slugs of water seem to come out of the small white pipe  which is outside the kitchen wall.

I'll keep a good lookout on it  - and for any signs of water leaking.  Because of expense, and difficulties generally with  this awful virus and (necessary) related restrictions, I'll keep very carefully topping up to mark 1 before it goes so low that the heating/boiler cut out.  I know, now and from neilmcl's helpful post previously, that this can 'dilute all the inhibitor in the system' so I will have to get a gas safe person to investigate. 

Many thanks indeed for your helpful advice.

Crimson

Jeepers_Creepers

The condensate pipe should be sending out slugs of water at regular intervals when your heating is on - but they are quite easy to miss if you ain't looking. You could place a container under it to check. (The liquid is a mild acid - it won't take the skin off your hands, but pour it away carefully in any case...)  The trick, tho', is to work out if there's extra water coming out due to a leak - near impossible! You could only check this with the boiler off (so it doesn't produce condensate), and with the pressure dropping (indicating a leak).

What kind of pressure gauge does the boiler have - analogue or digital? Are you SURE the cold starting pressure doesn't jump during the first 5 minutes of running? (On some digital displays, the pressure reading is replaced by a temp reading so can't be monitored). 

Yes, regular topping up dilutes the inhibitor and also introduces small amounts of dissolved air each time - neither a good thing - but in reality these wee top-ups are small in relation to the overall system volume. You can almost certainly keep doing this (provided the leaks don't get worse) for a few months until - HURRAH! - the vaccine is rolled out and Spring is in the air!

(If it is a leak from a pipe, it hopefully shouldn't be causing much harm under your floor either - do you have a suspended floor or is it solid?)

[Deleted User]

Thanks Jeepers_Creepers.
I have the non digital/older  type.  When getting really low I put the 'tap' on (barely seconds) to just over 1 - never over 1.5 on the manual dial.  It's been really wet here a lot lately but yesterday and today are cold, bright and very dry.   (Frosty this morning so warm water and food out for the birds!)  Where the 'pipe' comes out under my kitchen window outside there is a border of about 2 feet of white stones replacing a previous grass border.  When it rains they go a dark shade of white!  It's  definitely likely that the slugs of water come out and dry out or evaporate quickly so I never see them.  I would notice a drip or a puddle.

My wee linked bungalow was built (approximately) in 1986 and I think the floors are solid.
YES ... a huge hurrah  for the vaccine, the spring and more normality.  All the jobs needing to be done, on hold at present if not really essential, can then be done ... one at a time.

Your replies have been extremely helpful and reassuring.  Keep safe and thank you (and the other posters) for all your time and much appreciated help.

Crimson

-

bris

It could be a cracked heat exchanger which leaks into the condensate pipe. Impossible to spot under normal circumstances.

You would need to keep the boiler off so it doesn't generate condensate then disconnect the condensate pipe from under the boiler and see if it drips into a bucket.

[Deleted User]

Thanks, bris.  IF I can delay, safely keeping an eye on things in the meantime, I'll be glad to wait until 'things' are back to normal.  I was worried in case I would be damaging the boiler and causing more problems, by topping up to keep the pressure at 1 to 1.5.  At the same time, it's cold here, I don't want to leave myself without heating.

Like most people on their own I'm, of necessity, keeping a list of non essential jobs (things which I can't do myself in case I make them worse) to be done, one at a time, once the restrictions can ease safely and we are all more back to normal.

It's good of you to reply, thank you.

Crimson

southcoastrgi

If your boiler is the same age as your bungalow it won't have a white condense pipe 

Jeepers_Creepers

Ooh, good point Coastie. 

Crimson, is that white pipe made of plastic or white-painted copper? Ie, could it be the safety discharge pipe? Is it 15mm or 22mm?

Anyway, good chance you can nurse your boiler along until you are happy to get a plumber out.

If your floors are solid and the pipes are buried in them, it might be worth going around all the rooms every now and then to check there isn't a damp patch appearing.

The pipes that go to the rads - where do they come from, the floor or the wall? Are they copper (metal) or plastic?