Boiler pressure help! Vaillant EcoTEC Plus 837

tasticz

Hi all,

I have a question. Is my boiler about to die??

The pressure bar on my digital display and the dial does not seem to be matching. The digital display is showing 3.5bar but the dial gauge is nearly rock bottom...

I tried turning the tap as shown in this video but nothing seems to be happening: - https://www.youtube.com/watch?v=XDZXGm_KY9U&ab_channel=This%26That
You can hear the water being filled once the second tap is turned in the video but no water filling noise for me but the water stops coming out of the tap.



Anyone know what might be wrong? Is it just that the dial gauge sensor is gone? 

Jeepers_Creepers

This has two gauges?! Blimey - how greedy.

Of the two, I'd suspect the analogue gauge as these have small capillary tubes supplying them which can get blocked. Mind you, I don't know why it would read zero as a result... :-(

Is the boiler working? Does the boiler stop working when the pressure falls too low - say below 0.5bar? 

IF the digital reading is correct, you have gorn too high with the fill. If you keep adding more water - as it seems you are - this will be ejected out the safety discharge pipe and you should see the results on an outside wall coming from a 15mm copper pipe. 

I think what I'd do in order to check which gauge is fibbing, is to shut off the top-up tap! and bleed a radiator until you hopefully see that 3.5bar reading fall. If it does, keep going until you reach 1 bar.

Now note what happens when you fire up the CH. Does the pressure rise? If so, to what?

tasticz

Jeepers_Creepers said:

This has two gauges?! Blimey - how greedy.

Of the two, I'd suspect the analogue gauge as these have small capillary tubes supplying them which can get blocked. Mind you, I don't know why it would read zero as a result... :-(

Is the boiler working? Does the boiler stop working when the pressure falls too low - say below 0.5bar? 

IF the digital reading is correct, you have gorn too high with the fill. If you keep adding more water - as it seems you are - this will be ejected out the safety discharge pipe and you should see the results on an outside wall coming from a 15mm copper pipe. 

I think what I'd do in order to check which gauge is fibbing, is to shut off the top-up tap! and bleed a radiator until you hopefully see that 3.5bar reading fall. If it does, keep going until you reach 1 bar.

Now note what happens when you fire up the CH. Does the pressure rise? If so, to what?

Doing it now will post results in 10 mins

tasticz

Jeepers_Creepers said:

This has two gauges?! Blimey - how greedy.

Of the two, I'd suspect the analogue gauge as these have small capillary tubes supplying them which can get blocked. Mind you, I don't know why it would read zero as a result... :-(

Is the boiler working? Does the boiler stop working when the pressure falls too low - say below 0.5bar? 

IF the digital reading is correct, you have gorn too high with the fill. If you keep adding more water - as it seems you are - this will be ejected out the safety discharge pipe and you should see the results on an outside wall coming from a 15mm copper pipe. 

I think what I'd do in order to check which gauge is fibbing, is to shut off the top-up tap! and bleed a radiator until you hopefully see that 3.5bar reading fall. If it does, keep going until you reach 1 bar.

Now note what happens when you fire up the CH. Does the pressure rise? If so, to what?

ok so i managed to bleed a radiator until the digital pressure display fell to 1.0bar. no movement on the dial gauge. 

then I fired up the CH tap for like 5 seconds and closed it and the pressure went to 1.6bar

I have now turned up the heating and it is slowly increasing. it was 2.0 - 2.1bar and going up.I will check the pressure first thing in the month

I think we can conclude that the dial gauge is faulty?

Le_Kirk

tasticz said:

Jeepers_Creepers said:

This has two gauges?! Blimey - how greedy.
Of the two, I'd suspect the analogue gauge as these have small capillary tubes supplying them which can get blocked. Mind you, I don't know why it would read zero as a result... :-(
Is the boiler working? Does the boiler stop working when the pressure falls too low - say below 0.5bar? 
IF the digital reading is correct, you have gorn too high with the fill. If you keep adding more water - as it seems you are - this will be ejected out the safety discharge pipe and you should see the results on an outside wall coming from a 15mm copper pipe. 
I think what I'd do in order to check which gauge is fibbing, is to shut off the top-up tap! and bleed a radiator until you hopefully see that 3.5bar reading fall. If it does, keep going until you reach 1 bar.
Now note what happens when you fire up the CH. Does the pressure rise? If so, to what?

ok so i managed to bleed a radiator until the digital pressure display fell to 1.0bar. no movement on the dial gauge. 
then I fired up the CH tap for like 5 seconds and closed it and the pressure went to 1.6bar
I have now turned up the heating and it is slowly increasing. it was 2.0 - 2.1bar and going up. I will check the pressure first thing in the month
I think we can conclude that the dial gauge is faulty?

What is this?  Did you meant the top up tap?  Hopefully the naughty spell checker changed "morning" to "month" for you and you will check today!

Jeepers_Creepers

tasticz said:

ok so i managed to bleed a radiator until the digital pressure display fell to 1.0bar. no movement on the dial gauge. 

then I fired up the CH tap for like 5 seconds and closed it and the pressure went to 1.6bar

I have now turned up the heating and it is slowly increasing. it was 2.0 - 2.1bar and going up.I will check the pressure first thing in the month

I think we can conclude that the dial gauge is faulty?

As Le Kirk asks, did you open the system top-up tap again? If so, aaargh :-)

The 'cold' pressure should be at around 1bar. Some like it higher, but 1 bar is fine for virtually all boilers and imposes less strain on yer system. 

So, when you then fired up the CH the pressure climber and was last at 2.1 and going up further (see now why you should have started at 1bar?!)

Ok, when that reaches ~3 bar, the discharge valves will open and dump the excess. Good chance it'll keep dribbling once the pressure drops again, 'cos that's what they tend to do.

You should confirm all this by monitoring the 15mm pipe on the outside wall - place a clear bag over it and fix using a rubber band.

It sounds as tho' you need your boiler checked for its Expansion Vessel and - most likely - a new discharge valve too...

Anyhoo, report back, please, on pressure and ejected water.

daveyjp

Vaillant do have an analogue gauge, on the later models the analogue one is behind the front cover so you don't know if it has failed until service.

If its reading zero it needs a repair (I've had it done a few years ago under warranty).

However if pressure is rising regardless you have further problems which need sorting.

Jeepers_Creepers

Seems it has a digital one too! As long as the digi one works, I personally wouldn't bother replacing the analogue one - the whole boiler can't be that far from replacement... :-(

Tastics, worth looking at a Vaillant fixed-price repair, tho' check the small print and see it it covers EVs. Also, how old is your boiler?

tasticz

Le_Kirk said:

tasticz said:

Jeepers_Creepers said:

This has two gauges?! Blimey - how greedy.
Of the two, I'd suspect the analogue gauge as these have small capillary tubes supplying them which can get blocked. Mind you, I don't know why it would read zero as a result... :-(
Is the boiler working? Does the boiler stop working when the pressure falls too low - say below 0.5bar? 
IF the digital reading is correct, you have gorn too high with the fill. If you keep adding more water - as it seems you are - this will be ejected out the safety discharge pipe and you should see the results on an outside wall coming from a 15mm copper pipe. 
I think what I'd do in order to check which gauge is fibbing, is to shut off the top-up tap! and bleed a radiator until you hopefully see that 3.5bar reading fall. If it does, keep going until you reach 1 bar.
Now note what happens when you fire up the CH. Does the pressure rise? If so, to what?

ok so i managed to bleed a radiator until the digital pressure display fell to 1.0bar. no movement on the dial gauge. 
then I fired up the CH tap for like 5 seconds and closed it and the pressure went to 1.6bar
I have now turned up the heating and it is slowly increasing. it was 2.0 - 2.1bar and going up. I will check the pressure first thing in the month
I think we can conclude that the dial gauge is faulty?

What is this?  Did you meant the top up tap?  Hopefully the naughty spell checker changed "morning" to "month" for you and you will check today!

Apologies, yes I did mean morning not a month! So I checked in the morning and the pressure was 2.4 bar. The CH is the second tap I believe the filling tap?

Jeepers_Creepers said:

tasticz said:

ok so i managed to bleed a radiator until the digital pressure display fell to 1.0bar. no movement on the dial gauge. 

then I fired up the CH tap for like 5 seconds and closed it and the pressure went to 1.6bar

I have now turned up the heating and it is slowly increasing. it was 2.0 - 2.1bar and going up.I will check the pressure first thing in the month

I think we can conclude that the dial gauge is faulty?

As Le Kirk asks, did you open the system top-up tap again? If so, aaargh :-)

The 'cold' pressure should be at around 1bar. Some like it higher, but 1 bar is fine for virtually all boilers and imposes less strain on yer system. 

So, when you then fired up the CH the pressure climber and was last at 2.1 and going up further (see now why you should have started at 1bar?!)

Ok, when that reaches ~3 bar, the discharge valves will open and dump the excess. Good chance it'll keep dribbling once the pressure drops again, 'cos that's what they tend to do.

You should confirm all this by monitoring the 15mm pipe on the outside wall - place a clear bag over it and fix using a rubber band.

It sounds as tho' you need your boiler checked for its Expansion Vessel and - most likely - a new discharge valve too...

Anyhoo, report back, please, on pressure and ejected water.

Yes, sadly I did reopen the system top-up as I thought that is what you meant by CH. It says CH TAP or something similar in a sticker next to the tap. Did you mean central heating?

Sadly I am not able to see the water come out of 15mm pipe as the outflow from this pipe is going into another pipe which is connected to drain?

Jeepers_Creepers said:

Seems it has a digital one too! As long as the digi one works, I personally wouldn't bother replacing the analogue one - the whole boiler can't be that far from replacement... :-(

Tastics, worth looking at a Vaillant fixed-price repair, tho' check the small print and see it it covers EVs. Also, how old is your boiler?

The boiler is 10 year old now - was hoping it would run for couple more years. lets see!

I will bleed the boiler again tonight to 1.0 bar and then turn heating on and see what it will be in the morning. Hopefully it will be stable. pressure = 2.4bar at the time of posting which is what it was this morning.

Jeepers_Creepers

Yes, CH = central heating.

The cold pressure (tho' it should ideally remain quite stable even when hot) should be set to between 1 and 1.5 for most boilers. I like to keep mine to the lower end of this as it's less strain on the system, and - if there is a teeny leak - will make it slower.

So, system cold. Get pressure to 1 bar. turn on CH (central whatsit...) and see what the pressure does. If it climbs significantly, then good chance your EV needs attention. If it hits anywhere close to 3 bar, then you are going to lose water out that discharge pipe.

The problem with safety valves is that, once opened, they tend not to reseal fully = constant loss of water requiring constant top-ups.

10 years is not old for a good make like Vaillant. If you re going for a fixed-price repair, check the small print - the last one I had (on a GlowWorm but I think it was Vaillant doing the work) stated not covered; main exchanger and EV.  The latter surprised me as it ain't that costly a part, and is usually easy to swap. Anyhoo, check :-)