# A basic central heating question.



## Dave7 (17 Jan 2021)

Fairly modern system (maybe 4 years old)
Worcester combi boiler.
Pressure drops during c/h (winter) time, maybe every 8 weeks.
Had the installer out.
Had Worcester out.
Both spent a long time before declaring 'no problem'.
Anyway........my query.......
This morning the pressure had gone again. 
I topped it up, reset it and all was well......for an hour. Then it went off again.
Pressure was full.
I pressed reset and it was ok.
Been ok for 3 hours now.
Was this just a blip or indicate a problem ??


----------



## mistyoptic (17 Jan 2021)

Is there water dripping from the pressure relief valve? Ours failed on our Worcester boiler last year with a bit of scale preventing it from sealing properly


----------



## Dave7 (17 Jan 2021)

mistyoptic said:


> Is there water dripping from the pressure relief valve? Ours failed on our Worcester boiler last year with a bit of scale preventing it from sealing properly


Doesn't appear to be any leaks.
The Worcester engineer reckoned all was fine..


----------



## bikingdad90 (17 Jan 2021)

Put the heating on full pelt, really high. Does the pressure rise to above normal levels (2bar+) ? If it does, go outside and check and the pipe and see if it is leaking. If it is then there is a good chance your expansion vessel has gone and need replacing.


----------



## Lookrider (17 Jan 2021)

If the engineer said it's all fine ..then please believe him 
In the cold of night water will contract ( as do all things at lower temps ) because it contracts in a sealed system the volune of water gets "smaller" thus implying that there is a drop of pressure on the gauge 
This is normal 
If you put the heating on you will see the pressure will go up as the water heats up it expands putting pressure on the gauge ...switch it off and the pressure will drop again 
Winter is not the best time to check pressures as it is fluctuating as the boiler tends to be in use more 
The engineer will know a pressure drop due to a leak somewhere ..and he says it's fine 
He will put some leak sealer in if you ask him too 
get a compatible one for the heat exchanger within the boiler..again the engineer will advise compatibility


----------



## bikingdad90 (17 Jan 2021)

A pressure increase or decrease staying between 1.0 and 2.0 is normal operating range and like @Lookrider says is to be expected. 

If it is pushing over 2.0 bar then then you potentially have a problem. If the opposite happens and the pressure is slowly dropping to below 1.0 bar over time as opposed to tripping out due to over pressure then it is more than likely a leak/hole somewhere in the system. 

Stupid point to check, you have closed off the pressurisation inlet after topping up haven’t you? If you have left it in the open position then it will let air into the system.


----------



## Lookrider (17 Jan 2021)

Worcester boilers have an "error" code that will be flashing in the display...the manual will tell you what that error code relates too 
You can then tell your engineer who will know more about it ...and can then act on the repair if needed


----------



## Dave7 (17 Jan 2021)

bikingdad90 said:


> A pressure increase or decrease staying between 1.0 and 2.0 is normal operating range and like @Lookrider says is to be expected.
> 
> If it is pushing over 2.0 bar then then you potentially have a problem. If the opposite happens and the pressure is slowly dropping to below 1.0 bar over time as opposed to tripping out due to over pressure then it is more than likely a leak/hole somewhere in the system.
> 
> Stupid point to check, you have closed off the pressurisation inlet after topping up haven’t you? If you have left it in the open position then it will let air into the system.


Yes....it has 2 valves (no idea why) and I closed them both after topping up.


----------



## Dave7 (17 Jan 2021)

Lookrider said:


> Worcester boilers have an "error" code that will be flashing in the display...the manual will tell you what that error code relates too
> You can then tell your engineer who will know more about it ...and can then act on the repair if needed


Thanks, will look at that.
Not seen any such messages but will check again.


----------



## ColinJ (17 Jan 2021)

Dave7 said:


> Not seen any such messages but will check again.


These things are not subtle! My (different make) boiler lost pressure and shut down completely with *F1 *flashing on the display. F1 = loss of pressure fault.

My system holds its pressure for about 5 weeks, after which it slowly loses a little pressure over a few days, and then it suddenly loses the remaining pressure overnight. Very odd!


----------



## cm2mackem (17 Jan 2021)

Just had the same with my boiler, expansion vessel gone, most can be topped up with a bike pump, mine had a very small hole in the bladder, £40 to replace , shop around first quote was £90, 30 minute job no need to drain system but the old vessel will need draining before removing.


----------



## cyberknight (17 Jan 2021)

I am having the exact same issue , i rang up british gas home care and was told until the lockdown ends they will not even come out as i can repressurixe it to make it work even though i need to do it 3 times a day.


----------



## newts (17 Jan 2021)

What pressure are you filling up to?


----------



## Dave7 (19 Jan 2021)

newts said:


> What pressure are you filling up to?


Not sure who your question was directed to??
I fill it till the needle stops.... which is on the green, about 3.
Incidentally it has, strangely, been working fine since. Maybe (hopefully) it was just a blip.
It will still need topping up every 3-4 weeks which, after reading other posts, I can live with.
With the old boiler I don't remember it ever having such a problem.


----------



## PaulSB (19 Jan 2021)

Dave7 said:


> Not sure who your question was directed to??
> I fill it till the needle stops.... which is on the green, about 3.
> Incidentally it has, strangely, been working fine since. Maybe (hopefully) it was just a blip.
> *It will still need topping up every 3-4 weeks which, after reading other posts, I can live with.*
> With the old boiler I don't remember it ever having such a problem.



I guess we have the same or very similar boiler, a Worcester Bosch, though ours is 10 years old.

In that time I've topped it up once myself. It's been serviced annually and so the engineer may have topped it up then so no more than 10 times in 10 years.

Every 3-4 weeks sounds far too often to me. I would continue to try and find the problem and fix it.


----------



## dave r (19 Jan 2021)

Dave7 said:


> Not sure who your question was directed to??
> I fill it till the needle stops.... which is on the green, about 3.
> Incidentally it has, strangely, been working fine since. Maybe (hopefully) it was just a blip.
> It will still need topping up every 3-4 weeks which, after reading other posts, I can live with.
> With the old boiler I don't remember it ever having such a problem.



I think 3 is too high, our old one was topped up to 1.5 then topped back up when it was down to 1, we've had a new boiler recently and haven't had to top it up yet.


----------



## MrGrumpy (19 Jan 2021)

My last house had a combi , used to lose pressure as well. Maybe 2/3 times a year, I was pretty sure there was a leak of a radiator. Very very small. Bit of a pain, to be honest but other than that not an once of bother !! If losing it every few weeks then you have an issue. Check all rads for small leaks as well.


----------



## Lookrider (19 Jan 2021)

Did you do the " go to fix" of bleeding all the radiators 
Surprising how this minor issue can play havoc ....but is an easy fix


----------



## mistyoptic (19 Jan 2021)

dave r said:


> I think 3 is too high, our old one was topped up to 1.5 then topped back up when it was down to 1, we've had a new boiler recently and haven't had to top it up yet.


This is the advice we were given by the engineer too


----------



## ColinJ (19 Jan 2021)

Dave7 said:


> I fill it till the needle stops.... which is on the green, about 3.
> Incidentally it has, strangely, been working fine since. Maybe (hopefully) it was just a blip.


Too high - that's usually the pressure at which the boiler has to start venting excess pressure through the pressure release valve!

And don't forget - the pressure usually goes up by about 0.5 bar when the heating is on.


dave r said:


> I think 3 is too high, our old one was topped up to 1.5 then topped back up when it was down to 1


I do mine to 1.5 and if I need to bleed the radiators it then drops a little. It goes up to around 2.0 when the boiler is in use.


----------



## newts (19 Jan 2021)

Dave7 said:


> Not sure who your question was directed to??
> I fill it till the needle stops.... which is on the green, about 3.
> Incidentally it has, strangely, been working fine since. Maybe (hopefully) it was just a blip.
> It will still need topping up every 3-4 weeks which, after reading other posts, I can live with.
> With the old boiler I don't remember it ever having such a problem.



3 bar is too high for topping up, when the boiler heats up the pressure rises even further & the pressure relief valve opens.
Topping up the heating circuit is normally done when the system is cold, 1-1.5 bar (dependant on boilers user instructions).
when the system heats up it'll be around 3 bar.


----------



## slowmotion (19 Jan 2021)

Pinhole leaks are often the cause of lost pressure. Most people installed combis in systems that originally had conventional boilers. With a conventional system, any water lost by tiny leaks goes un-noticed because the feed and expansion tank replaces it. When the system is a pressurised one, those tiny un-noticed leaks are enough to cause a loss in pressure.


----------



## MrGrumpy (19 Jan 2021)

Yep , was our issue. Microbore pipes to rads . Hopeless !!


----------

