boiler rising close to 3bar and dripping trough prv

scamalert

Anyway it has been happening like this think since my family bought house 8 years ago, boiler was serviced once as needed new board to heat water, but not sure about dripping issue was it apparent then. now dripping small amounts of water happened each year but didnt take much notice of it, as it wasnt much of an issue, anyway called my gas company, engineer comes over and says need to have pipe for prv leading outside meaning punching hole trough wall and expansion vessel 18L size into hot press upstairs .


Now boiler is vokera mynute 14e, and pretty sure 100 houses in estate have the same and did read manual and its one of those that can either have or not pressure release valve on outside, further its a b$tch to even take off the panel the way everything is squeezed in the kitchen.


Anyway engineer fip flapped about needing those and replacing some valves due to how long it wasn't serviced etc, but has done 0, basically call plumber was his answer.


Now in the past i thought that few drips were due to condensation gas and hot water pipes close by, but this year seems whenever its on, it goes to 2.8-2.9 bars and starts dripping trough pressure release valve.


Now ive no clue what causes it to spike close to 3 bars as imagined it should cut off or be configured to do so to prevent raising pressure automatically when heating is on.


Any advice as drilling hole outside im not fond of the idea.

Your safety valve must terminate in a safe manor which is outside pointing towards the ground, this should of been done when the boiler was fitted.

Your expansion vessel on the boiler is not doing it’s job hence the drip/spike and increase in pressure this should of been identified during a service, if the boiler vessel is defective then usually the easiest answer is to fit a secondary vessel in the hot press but you must first have the boiler vessel checked as it may just need pumping, have your heating water checked for contamination as a defective vessel can be a sign of contaminated heating water that can damage the boiler over time.

scamalert

thx for breaking it down, none was done as imagine engineer expected to just do annual service even thou explained issue on phone when called for one.

guess having pvr to outside 20 odd years ago wasn't strictly required either and same is mentioned on boilers manual.

now im guessing costs do to all the works would be close to 500e, but would rather save up until next year and get new boiler fitted, rads cleared of any gunk and more energy efficient.

is there a way theoretically to just drain one rad to where pressure would be like 1.3 once it goes close to 3 bars, as i know its supposed to be closed system and shouldn't top up itself without opening main valve for refill ? as temp fix. For time being

John.G

scamalert wrote: »

thx for breaking it down, none was done as imagine engineer expected to just do annual service even thou explained issue on phone when called for one.

guess having pvr to outside 20 odd years ago wasn't strictly required either and same is mentioned on boilers manual.

now im guessing costs do to all the works would be close to 500e, but would rather save up until next year and get new boiler fitted, rads cleared of any gunk and more energy efficient.

is there a way theoretically to just drain one rad to where pressure would be like 1.3 once it goes close to 3 bars, as i know its supposed to be closed system and shouldn't top up itself without opening main valve for refill ? as temp fix. For time being

If the the make up *main valve" is shut off and tight and assuming that the expansion vessel is defective or full of water due to no pre pressure then after the boiler cools down the system pressure should theoretically fall to zero because water is in compressible and the boiler shouldn't even fire if that pressure is < 0.5 bar.
You might note the pressure with the boiler cold and that will tell a lot, ie leaking make up or a auto fill valve maintaining pressure in the system.

scamalert

fires automatically or manually all the time, just checked and its been off for couple hours and pressure is at 0.3, thou i think ive seen it at 0 at some points, will need to keep an eye on that but it never has issues firing up.

I def would felt better when engineer was over if he replaced the valves as limescale buildup from water over the years and mentioned some get perforated as well would be routine job, but as said before after taking single look at it, said just get a plumber before he will touch it.


All in its not massive issue, as boiler is old as the house and just to wait till summer to get new installed, as more tlc is needed round the house with plumbing and other maintenance which would be better added into single bundle as cost goes for these works. Appreciate for response.

John.G

scamalert wrote: »

fires automatically or manually all the time, just checked and its been off for couple hours and pressure is at 0.3, thou i think ive seen it at 0 at some points, will need to keep an eye on that but it never has issues firing up.


All in its not massive issue, as boiler is old as the house and just to wait till summer to get new installed, as more tlc is needed round the house with plumbing and other maintenance. Appreciate for response.

OK, if the system is as I stated above the the PRV should dump ~1.5 to 2.5 litres of water (the expansion amount) each time it reaches temperature so something is making up the lost water?, do you have to top it up from time to time?, if not then then the make up is being supplied by some other method.

scamalert

no never been topped up in years, the heat press where boiler is has lots of valves also there is heating for shower water, only change thats been made one of the valves was opened at some time this summer not by me as the place is a maze not a single marking, to get cold water running from one of the taps in separate bathroom.


just checked again as boiler was on for 15mins and pressure stands at 1.3.Also never mentioned but its always set on to heat rads and water on almost full heat, but never runs continiously more then few hours but rather 30mins bursts for evening/ mornings.but if set manually for hour or so then it climbs up to 2.8/9 bar and starts dripping water drop at a time, never full blown flush.


Id say its losing about 1.5 ltrs a week, but if it was closed loop it would be empty after so many years, as my guess any top-up done was when the house was built almost 20 years ago.

John.G

scamalert wrote: »

no never been topped up in years, the heat press where boiler is has lots of valves also there is heating for shower water, only change thats been made one of the valves was opened at some time this summer not by me as the place is a maze not a single marking, to get cold water running from one of the taps in separate bathroom.


just checked again as boiler was on for 15mins and pressure stands at 1.3.Also never mentioned but its always set on to heat rads and water on almost full heat, but never runs continiously more then few hours but rather 30mins bursts for evening/ mornings.but if set manually for hour or so then it climbs up to 2.8/9 bar and starts dripping water drop at a time, never full blown flush.


Id say its losing about 1.5 ltrs a week, but if it was closed loop it would be empty after so many years, as my guess any top-up done was when the house was built almost 20 years ago.

As stated above then the expansion vessel may be just too small, you possibly have a internal one of 8 litre capacity, as a temporary measure you could just try reducing the max temperature setting by say 10C which should help if running the boiler for prolonged periods, if set at 80C maybe try 65/70C which will reduce the expansion volume and may just stop the PRV from lifting.

scamalert

was thinking the same will try running at half heat to see if it continues, boiler is old so theres no actual temps on the knob just stripes for heat intensity.

John.G

scamalert wrote: »

was thinking the same will try running at half heat to see if it continues, boiler is old so theres no actual temps on the knob just stripes for heat intensity.

Yes try that, that "scale" goes from 40C to 80C so if you start as you suggest at "half" heat, you can gradually increase the set point as required. Reducing the temp by even 10C will reduce the expansion volume by ~ 0.5 litres.

scamalert

well since last post did half temp and just checked now and had about 100mill of water in a pot, thou rads were still hot from heating before so started at 1.3 and went to 2.9 and pvr gave in to leak until it dropped back to 2.5, will leave it at half heat until tomorrow and will checkup if theres any water, but seems its caused by the duration once its running pressure keeps going until pvr kicks in.

So most likely expansion vessel is damaged/to small or couple things together, but totally out of my area expertise nor something id tinker with myself.

John.G

scamalert wrote: »

well since last post did half temp and just checked now and had about 100mill of water in a pot, thou rads were still hot from heating before so started at 1.3 and went to 2.9 and pvr gave in to leak until it dropped back to 2.5, will leave it at half heat until tomorrow and will checkup if theres any water, but seems its caused by the duration once its running pressure keeps going until pvr kicks in.

So most likely expansion vessel is damaged/to small or couple things together, but totally out of my area expertise nor something id tinker with myself.

I know there are a number of issues but the system is definitely getting make up water from somewhere because there is no way that it can keep losing water and have no make up, I hope not but its possibly a hole in the hot water cylinder coil, if the cylinder is located on the landing of a two storey house then
that would account for it, (and having 0.3 bar cold pressure) of course if it was that then it should work in the opposite way and relieve the system pressure back into the cylinder but you should the notice discolouration in the hot water.

Re using a rad as a expansion vessel, I did this as a purely temporary measure in my relations sealed oil fired system in which the expansion vessel diaphragm failed and it was continuously lifting the PRV and he couldn't get a replacement as it happened on one Christmas eve. I shut off the valves on one of the rads after identifying the hot inlet, I then opened the rad vent fully to ensure that the valves were holding and then drained down the rad fully, I then shut the vent and reopened the hot side valve only and it kept the system going until he sourced and fitted a new (12 litre) expansion vessel.
I must re emphasise that this was ONLY a temporary measure, the rads would corrode away in a very short time if being fed with air!.
The rads will also have a short life if water is making up continuously.

scamalert

Yes boiler is on first floor landing, with water tank sitting in the attic.


dunno its a strange one as checked today no leaks of water and pressure sits at 0.8 - 4 hours last time it fired, and its usually set just for 15-30 min duration few times a day which seems keeps issue at bay.


did drain one rad a bit yesterday and water was clean no gunk at all, and in general doing so every year you get a bit of black stuff once starting first time for the season but all radiators then spit out clean water, and havent noticed any discoloration in water.


by now guessing it might be damaged collapsed exp vessel in boiler, as seems if firing it up takes less then an hour for pressure to climb to almost 3 bars and pvr kicking in.


boiler setup pic

John.G

Just to go back to this mysterious make up again. In some older systems there was another small tank adjacent to the big tank in the attic, this small tank (Feed and Expansion Tank) kept the system topped up by gravity, some systems were then changed to sealed systems and one (normal) system fed from the mains had a pressure reducing valve with pressure gauge and a flexible hose with isolating valves at both ends, after topping up the system to 1 to 1.5 bar, both valves were closed and the flexible hose was then supposed to be removed. The other conversion from gravity to sealed still utilized the small tank. the vent line was blanked off, the cold feed had a NR valve fitted and was then teed off into a expansion vessel. I don,t know which system you have but it should be relatively easy to establish this and see what is/or isn't isolated on it. I believe some systems didn't even have a separate feed and expansion tank but used the same (big) tank.

Wearb

Where does this pipe go?
Is this valve on or off?

John.G

Wearb wrote: »

Where does this pipe go?
Is this valve on or off?

Looks like a semi sealed system, if the NR valve below that gate valve is just removed then the system becomes a gravity fed combined cold feed and expansion system, problem solved? but as you say needs checking out to see where that pipe goes to in the attic, if it goes to a dedicated header tank then should be ok?

I have never really understood why you need a semi sealed system, if the feed and expansion (like my own system) are combined then that cures any potential pitching problems and has often been put forward here as a fix for pitching problems. All the houses in my estate have just the combined feed and expansion but when bord gais installed a boiler in a neighbours house they made the system semi sealed. Have you any views on this?.

Wearb

John.G wrote: »

Looks like a semi sealed system, if the NR valve below that gate valve is just removed then the system becomes a gravity fed combined cold feed and expansion system, problem solved? but as you say needs checking out to see where that pipe goes to in the attic, if it goes to a dedicated header tank then should be ok?

I have never really understood why you need a semi sealed system, if the feed and expansion (like my own system) are combined then that cures any potential pitching problems and has often been put forward here as a fix for pitching problems. All the houses in my estate have just the combined feed and expansion but when bord gais installed a boiler in a neighbours house they made the system semi sealed. Have you any views on this?.

I have always thought of combined f+e as a bit of a bodge for a poorly designed system. They are much poorer at getting rid of air. They probably also create low pressure zones when pump runs. I expect that with normal f+e the low pressure zone can be much easier reduced by by the f+e pipe. I know that causes pump over.

Semi sealed allows for more pressure in the system and most likely overcomes the problem of taking air in through rad valves and perhaps aav,s.
I suppose the reason for not going for a fully sealed (from open) is the saving in time and equipment on the filling side. Especially if a small leak required the fitting or an automatic fill valve.

As an aside, I don’t think a combined f+e is allowed with a boiler stove/back boiler.

scamalert

sry guys been out most day, just returned will have to check on that valve 2morrow and see where it leads.

scamalert

well looked up today and theres correction 4 as seen one is higher then rest valves connected to water tank in the attic 3 of them rubber ones and one copper, thou theres small bedroom in attic and just feet away it has radiator as seen in pictures, theres no other tanks in the attic besides main water one seen in picture.

John.G

scamalert wrote: »

well looked up today and theres correction 4 as seen one is higher then rest valves connected to water tank in the attic 3 of them rubber ones and one copper, thou theres small bedroom in attic and just feet away it has radiator as seen in pictures, theres no other tanks in the attic besides main water one seen in picture.

My Laptop doesn't display pictures too well, what is the rectangular "shape" which is either perched on top of the water tank or is situated behind it?....there seems to be a white "plastic" pipe attached to it.
Is the red valve above your cylinder open? and see if you can trace it up to the attic to see if its the copper pipe that you referred to above.

scamalert

the white pipe on the side seems like some sort overflow protection it stands about inch above max water level and one besides red float fills water tank, not sure about highlighted pipe as it goes into the floor but by the looks stands straight under boiler.

thou took not the best pic but pipe above water tank in grey foam seems idle, maybe some sort of mains water connection to fill tank up fast.

John.G

scamalert wrote: »

the white pipe on the side seems like some sort overflow protection it stands about inch above max water level and one besides red float fill water tank, not sure about highlighted pipe as it goes into the floor but by the looks stands straight under boiler.

thou took not the best pic but pipe above water tank in grey foam seems idle, maybe some sort of mains water connection to fill tank up fast.

I'm doubly confused now, are you certain/sure that there is only one tank up in the attic, it looks like one tank with the three pipes is sitting on the attic floor and another tank is actually sitting on top???. as its jutting out over the lower one.
Re the red valve: The pipe from that goes upwards into the attic? from the hot press. Is that valve (in the hot press) open or shut.

Edit: Sorry for confusion, I copied picture to another Laptop and i can now see that it is one tank! (surprise surprise) and what I think you have is that the two plastic pipes are feeding the cold water supply to the hot water cylinder and bath/wash basins/toilet etc and the copper pipe probably goes down through the attic floor and is connected to that red gate valve and NR valve and is the cold water make up to the boiler re the cylinder coil, and that you have a semi sealed system.

scamalert

No def no other tank heres better picure, checked the valve and it seems you can only turn it clockwise. Not sure if it means its open or closed thou as it comes to plumbing ive no clue tbf.

John.G

scamalert wrote: »

No def no other tank heres better picure, checked the valve and it seems you can only turn it clockwise. Not sure if it means its open or closed thou as it comes to plumbing ive no clue tbf.

Yes, it means that its in the open position and appears to be supplying the make up water to the boiler via the NR valve & cylinder coil so at least we now know where the make up is coming from. It still doesn't address your problem though, just removing that NR valve would stop the PRV from lifting but I cannot recommend it as the make up water is coming from the same tank that supplies domestic cold water which could be become contaminated, normally there is a separate small tank that does this job.
In the long term you have two choices, either get a RGI to check out the boiler internal expansion vessel which may only need re pressurising or get a plumber to install a external expansion vessel downstairs somewhere with a pre pressure of 0.5/1.0 bar.

scamalert

was just going to post that, about whats next regarding pressure but you have answered it, seems like expansion vessel seems like most obvious short term choice, then again prob will wait till next year and get new gas boiler, as guy from board gais said he wont even service it because theres no outlet to outside for pvr.

John.G

scamalert wrote: »

was just going to post that, about whats next regarding pressure but you have answered it, seems like expansion vessel seems like most obvious short term choice, then again prob will wait till next year and get new gas boiler, as guy from board gais said he wont even service it because theres no outlet to outside for pvr.

I was just thinking again...... using one of your rads as a expansion vessel (see post 12) may be preferable to making up water continuously until you can fix your problem and may cause far less corrosion damage, and you dont have to be collecting the PRV leak off in a bucket, if you are considering it try and use a double rad to give you a bit of capacity.

scamalert

read through manual and it has internal expansion vessel of 4.5l - seems really small.


EXPANSION VESSEL fig. 1
Due to the compact design of this appliance,
removal and/or replacement of the expansion
vessel may require the appliance to be removed
from the wall, if this is deemed impractical, an
external expansion vessel may be fitted to the
return pipe as close to the appliance as possible.




anyway the way boiler is fitted its basically trapped, as i still remember guy bruising his knuckles just to get cover off last time it was serviced, fitting external one with 18l capacity most likely would solve the issue completely as house has 9 radiators across 3 floors and that size internal vessel seems just to small, putting this repair of just because theres one leaking sink in one of the bathrooms that will need to be fixed
so all together will require plumber for to do few works, so looking at good chunk of cash that will need to be put aside.


thanks again for helping to troubleshoot the issue, as water does drip but its into bowl and isnt really much hassle, but will need to be fixed eventually to have external pvr to outside none the less just to future proof it.

John.G

4.5 Litre is very small, I thought the smallest internal ones were at least 6 if not 8 Litre, the 18 Litre will certainly solve your problem and even though a 12 Litre would suffice you can't over size a expansion vessel.

Dtp1979

scamalert wrote: »

was just going to post that, about whats next regarding pressure but you have answered it, seems like expansion vessel seems like most obvious short term choice, then again prob will wait till next year and get new gas boiler, as guy from board gais said he wont even service it because theres no outlet to outside for pvr.

Yea I came across this lately too where Bord Gais refuse to service a boiler because the prv isn’t piped out. What kind of nonsense is this??

scamalert

Dtp1979 wrote: »

Yea I came across this lately too where Bord Gais refuse to service a boiler because the prv isn’t piped out. What kind of nonsense is this??

I know regulations change all the time, but i was very specific on the phone about issue, that it was fix not service and guy didn't even got told about what call was for even gave specific model of the boiler so prob knew way it would be setup. and after talking about vessel valves and needing direct pvr i was like so can you do any service, and he says no cant touch it. like wtf might as well came and said call a plumber, hoping 99euro wont appear on my bill as ive got 0 done and morning wasted, for advice to get plumber.