Author Topic: Boiler on the blink, help needed :) (Read 7547 times)

sinto · « **on:** 29 January 2016, 01:33:50 pm »

I have a vokera linea 24 but it's been losing pressure on a daily basis. Top it up at night to the 1.5 bar recommended pressure but by the morning it's at zero

I have checked boiler forums and the like and they go on about the prv and a vessel but they're not very clear on how to check these (or maybe I'm reading them wrong)
I can't really afford to call out a plumber at the moment but as I read into this it doesn't seem that hard to do.

Are there any guys on here that can give me any idea what to do in layman's terms to resolve my issues.

Thanks in advance,
Colin

esetest · « **Reply #1 on:** 29 January 2016, 01:48:52 pm »

I,m not a heating engineer , but a leak would also cause the pressure to drop , Pm Slim Willy , he is the man .

sinto · « **Reply #2 on:** 29 January 2016, 02:05:08 pm »

Quote from: esetest on 29 January 2016, 01:48:52 pm

I,m not a heating engineer , but a leak would also cause the pressure to drop , Pm Slim Willy , he is the man .

Meant to say earlier that I've checked all radiators and pipes for leaks and there is no sign of any water or air coming out.

Cheers, I'll pm slimwilly

chaz · « **Reply #3 on:** 29 January 2016, 03:42:20 pm »

have you checked outside where the PRV pipe vents?

slappy · « **Reply #4 on:** 29 January 2016, 05:04:43 pm »

I am not a heating engineer but I had similiar problems with a Baxi a few years ago, pressure would drop over a few weeks. To solve the problem I had a new pressure vessel fitted, I would not have done the job myself as the engineer had to remove quite a few parts to get at it.
If it isn`t that it might be a leak as others have said, finding the leak is the fun part.

locksmith · « **Reply #5 on:** 29 January 2016, 05:22:50 pm »

When our pressure vessel blew every time you tried to fill the system, water pissed out the bottom of the boiler and the pipe outside and it wouldn't pressurise at all.

evesdad · « **Reply #6 on:** 29 January 2016, 08:19:52 pm »

To check if expansion vessel needs re-pressurising top boiler up to just over one bar when the system is cold. Put the heating on and watch the pressure gauge..if the pressure rises over 3bar then the vessel is flat. Pressure relief valves start letting water out of the system at 3 bar, so when the system cools down again water has leaked out of the system so the pressure goes down to zero. The pressure relief pipe should goes to outside so you don't notice any leaks. On your boiler the pressure relief pipe is the one to the left hand side closest to the front of the boiler see if you can find where that goes to and if it has been dripping. Expansion vessels can usually be pumped back up but prv may need replacing.

midden · « **Reply #7 on:** 29 January 2016, 11:59:11 pm »

Quote from: evesdad on 29 January 2016, 08:19:52 pm

To check if expansion vessel needs re-pressurising top boiler up to just over one bar when the system is cold. Put the heating on and watch the pressure gauge..if the pressure rises over 3bar then the vessel is flat. Pressure relief valves start letting water out of the system at 3 bar, so when the system cools down again water has leaked out of the system so the pressure goes down to zero. The pressure relief pipe should goes to outside so you don't notice any leaks. On your boiler the pressure relief pipe is the one to the left hand side closest to the front of the boiler see if you can find where that goes to and if it has been dripping. Expansion vessels can usually be pumped back up but prv may need replacing.

also if you can get to the expansion vessel valve undo cap when cold, press valve in to release air and if water comes out its knackered. I learned that when mine went and as above my system was running passed 3bar which alerted me to the problem

crickleymal · « **Reply #8 on:** 30 January 2016, 12:35:33 am »

On ours we had problems with the pressure. The pressure vessel had a normal car tyre valve so I replaced that and then pumped it up to about 1.5 bar. Seems ok now. The engineer who came out when it broke down with a different fault didn't comment anyway.

evesdad · « **Reply #9 on:** 30 January 2016, 05:30:48 pm »

Quote from: midden on 29 January 2016, 11:59:11 pm

Quote from: evesdad on 29 January 2016, 08:19:52 pm
To check if expansion vessel needs re-pressurising top boiler up to just over one bar when the system is cold. Put the heating on and watch the pressure gauge..if the pressure rises over 3bar then the vessel is flat. Pressure relief valves start letting water out of the system at 3 bar, so when the system cools down again water has leaked out of the system so the pressure goes down to zero. The pressure relief pipe should goes to outside so you don't notice any leaks. On your boiler the pressure relief pipe is the one to the left hand side closest to the front of the boiler see if you can find where that goes to and if it has been dripping. Expansion vessels can usually be pumped back up but prv may need replacing.

also if you can get to the expansion vessel valve undo cap when cold, press valve in to release air and if water comes out its knackered. I learned that when mine went and as above my system was running passed 3bar which alerted me to the problem

Doesn't always mean its knackered. If you can still pump the water out of the other side and pump the vessel up to about 0.8 bar you should be ok. You need to have an open end on the system somewhere to pump the water out of the vessel to pressurise it properly.

sinto · « **Reply #10 on:** 01 February 2016, 07:45:55 pm »

Quote from: evesdad on 30 January 2016, 05:30:48 pm

Quote from: midden on 29 January 2016, 11:59:11 pm
Quote from: evesdad on 29 January 2016, 08:19:52 pm
To check if expansion vessel needs re-pressurising top boiler up to just over one bar when the system is cold. Put the heating on and watch the pressure gauge..if the pressure rises over 3bar then the vessel is flat. Pressure relief valves start letting water out of the system at 3 bar, so when the system cools down again water has leaked out of the system so the pressure goes down to zero. The pressure relief pipe should goes to outside so you don't notice any leaks. On your boiler the pressure relief pipe is the one to the left hand side closest to the front of the boiler see if you can find where that goes to and if it has been dripping. Expansion vessels can usually be pumped back up but prv may need replacing.

also if you can get to the expansion vessel valve undo cap when cold, press valve in to release air and if water comes out its knackered. I learned that when mine went and as above my system was running passed 3bar which alerted me to the problem

Doesn't always mean its knackered. If you can still pump the water out of the other side and pump the vessel up to about 0.8 bar you should be ok. You need to have an open end on the system somewhere to pump the water out of the vessel to pressurise it properly.

Done all of the above checks I think,

I've discovered....
Vessel needed air,
Pipe outside is leaking warmish water,
Still won't really pressure till I run the system,

So, going with above I reckon it's a new prv

So 8ve got another couple of questions if you don't mind.....
Are these easy to replace?
Is it on the water side of the system, is there a stopcock or similar that I use or just drain the system,
Thanks again in advance.
Colin

evesdad · « **Reply #11 on:** 01 February 2016, 08:31:33 pm »

its on the heating side open the old one up to release system pressure whip the old one out and stick the new one in a bit sharp and you won't have to drain the whole system. forgot to say before you whip the old prv out make sure its open and pump the expansion vessel up to about 0.8 bar.

sinto · « **Reply #12 on:** 01 February 2016, 08:37:01 pm »

Quote from: evesdad on 01 February 2016, 08:31:33 pm

its on the heating side open the old one up to release system pressure whip the old one out and stick the new one in a bit sharp and you won't have to drain the whole system.

Brill

It's sounding easy to do but I'll have some towels/rags underneath when I do it.
So, some water should come out depending how quick I can replace it?

Read somewhere else that I could try screwing in the front screw and back again to see if that sorts it but I'm not to sure

evesdad · « **Reply #13 on:** 01 February 2016, 08:50:52 pm »

I've never had much luck trying to get them to re-seat.

sinto · « **Reply #14 on:** 01 February 2016, 08:55:14 pm »

Quote from: evesdad on 01 February 2016, 08:50:52 pm

I've never had much luck trying to get them to re-seat.

If you've had no luck, I don't fancy my chances

sinto · « **Reply #15 on:** 01 February 2016, 09:43:15 pm »

Scratching head.......

Been talking about *Pressure Release Valve* (PRV)
Manual I downloaded says *Automatic Air Release Valve* (AARV)
But picture in manual says CH Return Valve
(See pic attached)

Totally confused as to what to order now

evesdad · « **Reply #16 on:** 01 February 2016, 10:18:10 pm »

Have a look for makers part number 1806 its on a different picture to the one you are looking at, one end of it fits on to the safety outlet pipe in your picture. Sorry I can't copy the picture from my work laptop onto here. key number 27 in parts diagrams.

chaz · « **Reply #17 on:** 01 February 2016, 10:19:53 pm »

The AARV should be at the top of the heat exchanger, it might have a knurled knob that must be loose so that any air in the heat exchanger can vent, The PRV is the safety valve, so if the presure rises to 3 bar it vents to the outside , the other valves are service valves and can be closed so you don't have to drain the whole system, if you close them make sure they are open before pressurising the system (I dont know how or when you do the expansion vessle?) the filling loop is used to fill the system to 1 to2 bar.

sinto · « **Reply #18 on:** 01 February 2016, 10:38:44 pm »

Another pic (pic1)
I presume were talking about the one on the left?

Checked that number 27 (pic2) it's called a HEATING COCK (pic3) on the manual!
This is screwing me up

I really do appreciate your time and effort in helping me but I'm just getting really confused and scared of buying the wrong part

sinto · « **Reply #19 on:** 02 February 2016, 12:34:24 pm »

Thanks evesdad, thanks your help.
Should I be replacing pic1?
To stop it dripping water out the pipe to the outside?
I'm guessing I just need to drain the air in the vessel at the valve on top, replace this part (pic2) and pump up air in vessel again?
Therfore no water being lost via the boiler when I do this?

sinto · « **Reply #20 on:** 02 February 2016, 01:18:48 pm »

Quote from: chaz on 01 February 2016, 10:19:53 pm

The AARV should be at the top of the heat exchanger, it might have a knurled knob that must be loose so that any air in the heat exchanger can vent, The PRV is the safety valve, so if the presure rises to 3 bar it vents to the outside , the other valves are service valves and can be closed so you don't have to drain the whole system, if you close them make sure they are open before pressurising the system (I dont know how or when you do the expansion vessle?) the filling loop is used to fill the system to 1 to2 bar.

Thanks chaz,
I think I've been a bit mixed up with all this.
It's leaking through the pipe outside, takes about 40 mins to build up any pressure (just about 1 bar) to be able to use the boiler, then it loses pressure overnight. So I think it's as I've quoted above, prv replacement job.
Will empty the vessel so no pressure on the prv, take out and replace, pressure up the vessel then hopefully it should work?
Thanks, Colin

chaz · « **Reply #21 on:** 02 February 2016, 09:03:29 pm »

It's a while since I worked on gas and not registered now so don't do it any more. On most combi's there are 6 or 7 conections, there's the central heating flow (1) and return (2) pipes these are 22mm, mains cold in (3) 15mm, (the filling loop will go from this to the heating pipe), DHW (4) 15mm domestic hot water, this goes to the taps, the pipe from the PRV (5) 15mm to the outside, and the gas pipe 22mm reduced to 15mm (depending on pipe run) if its a condensing boiler there will be a (plastic) pipe going outside to a drain.
You shouldn't have to do anything with the expansion vessle as long as its ok, its there so when the water expands on heating it has somewhere to expand into. If the diaphram is damaged then it won't work and when the water expands the only place it can go is out of the PRV, then when it cools there's not enough pressure for the boiler to work?
You should be able to pressurise the system in a few seconds if the system hasn't been drained by opening the valves on the filling loop there may be two one ate each side if the loop,(as its should be removed to prevent contamination but never is).

sinto · « **Reply #22 on:** 02 February 2016, 09:26:05 pm »

Quote from: chaz on 02 February 2016, 09:03:29 pm

You shouldn't have to do anything with the expansion vessle as long as its ok, its there so when the water expands on heating it has somewhere to expand into.

I put some air in it. It shouldn't be full of air then?

If the diaphram is damaged then it won't work and when the water expands the only place it can go is out of the PRV, then when it cools there's not enough pressure for the boiler to work?
that seems to be what's happening
You should be able to pressurise the system in a few seconds if the system hasn't been drained by opening the valves on the filling loop there may be two one ate each side if the loop,(as its should be removed to prevent contamination but never is).I put the boiler on and it pressured after a while, but don't know if it'll stay up in pressure, looks like I'll be looking at a new diaphram then?
Oh that's way past my diy skillset

chaz · « **Reply #23 on:** 02 February 2016, 10:32:58 pm »

this is off youtube.
https://youtu.be/KeO2gswQQe4

sinto · « **Reply #24 on:** 03 February 2016, 10:58:37 am »

Ahh well another day.....
After replacing the prv and getting a tad wet I left it last night and woke up to the pressure being at zero.
Thought I'd try and top up the water using the filling loop, heard some water go through and pressure went up a few red lines but not much

So looks like I'm on the blower to a costly repair man to come and sort it