Central Heating Low Pressure Problem - Plumbers advice needed!!

greg_johnston

Hi,

I'm wondering if anyone can help me. I have a sealed "vokera mynute 14-48 se" central heating system. The pressure is v.low (1/2 bar), so i went about looking for the filling point to top up the system. I found it beside the emersion. There is a pipe from the cold water tank that feeds into the central heating as it comes out of the emersion via a double check value. I opened the gate value of this feed but there was no increase in pressure. My questions are.

1. Will there be enough pressure in the feed from the cold water tank to fill the system?

2. Should the system be filled from the mains as opposed to the cold water tank?

3. Is there a way to check if the value is working and not blocked?

4. Anyone any ideas on how to proceed?

Thanks,
Greg

willah

Are you having problems with heat?

greg_johnston

Hiya,

Sorry for delay in reply!

Yep, having trouble with heating in that the house doesn't really get warm. Its no way near as warm as when as last year.

Thanks
Greg

JamesM

greg_johnston wrote:

Hiya,

Sorry for delay in reply!

Yep, having trouble with heating in that the house doesn't really get warm. Its no way near as warm as when as last year.

Thanks
Greg

1/2 Bar is fine as long as the boiler does not have a low pressure cut out switch.
Have you checked the boiler thermostat ? Are the rads getting as hot as before ?
Jim.

greg_johnston

JamesM wrote:

1/2 Bar is fine as long as the boiler does not have a low pressure cut out switch.
Have you checked the boiler thermostat ? Are the rads getting as hot as before ?
Jim.

ok thx.
The boiler thermostat is up at full. The thermostat in the hall is set at around 18 degrees depending on how cold it is. The boiler seems to fire for a while and then cut off...even though the temperature in the hall hasn't reached the 18 degress mark. So to make sure the house will be warm at night, I would have to leave the boiler on all day as it gradually would build up to temperature.
Greg

JamesM

greg_johnston wrote:

ok thx.
The boiler thermostat is up at full. The thermostat in the hall is set at around 18 degrees depending on how cold it is. The boiler seems to fire for a while and then cut off...even though the temperature in the hall hasn't reached the 18 degress mark. So to make sure the house will be warm at night, I would have to leave the boiler on all day as it gradually would build up to temperature.
Greg

I am not very familiar with gas boilers, but basically, the boiler heats the water to about 70 degrees C. and the waterpump circulates the water around the radiators.
Check the water pipe leaving the top of the boiler - can you keep your hand on it ? If so, then the boiler thermostat may be faulty and the boiler is not reaching the required temp.
If the water is very hot leaving the boiler, is it still that hot when it reaches a radiator ?. Can you keep your hand on a radiator. Or are the rads cool.
Jim.

tapest

Hi
For what its worth.....

I'm having one of that type (combi) installed. Potterson brand. It has a pressure switch and needs about 1 bar pressure feed....mains feed. you ask about tank feed... to get 1 bar pressure from header tank you'd need 10 metres height difference.
BUT Why is your mais pressure so poor....Contact your council and they'll tell you what pressure to expect and any oddities in your area
They can do a test and if the problem is their...no charge otherwise €160 I think
hope this helps
t

JamesM

tapest wrote:

Hi
For what its worth.....

I'm having one of that type (combi) installed. Potterson brand. It has a pressure switch and needs about 1 bar pressure feed....mains feed. you ask about tank feed... to get 1 bar pressure from header tank you'd need 10 metres height difference.
BUT Why is your mais pressure so poor....Contact your council and they'll tell you what pressure to expect and any oddities in your area
They can do a test and if the problem is their...no charge otherwise €160 I think
hope this helps
t

Hi Tapest,
I wondered about the pressure switch, but he says that the system did work OK last year. If there was enough pressure last year, why will it not build up now
Maybe he will find something over the weekend
Jim.

tapest

JamesM wrote:

Hi Tapest,
I wondered about the pressure switch, but he says that the system did work OK last year. If there was enough pressure last year, why will it not build up now
Maybe he will find something over the weekend
Jim.

James
I was refering NOT to pressure in a pressure / sealed system, but incoming mains pressure. If the water pressure entering the boiler is too low then the boiler simply will not fire. A little extra crap in pipe line ( there are still lead pipes out there), like a bit of rust breaking off will do it. Another thing Councils sometimes reduce pressure deliberatly to reduce the risk of leaks developing. Or a small leak somewhere in his neighbourhood might be enough just to drop the pressure that little bit, if he was borderline in the first place. The Council will tell him what pressure they "would like " to have. They have min values. If there is problems unique to his immediate area they'll tell him.They're pretty good like that. Contacting them in the first instance is probably the cheapest option. I know in my case I'm going to get myself a small cheap pressure guage. Even on a piece of hose attached to cold mains water tap will allow periodic monitoring of pressure.

What ya think J ?? I may be way of the mark of course
t


PS I just noticed you're on line...anothervinsomniac
t

JamesM

tapest wrote:

James
I was refering NOT to pressure in a pressure / sealed system, but incoming mains pressure. If the water pressure entering the boiler is too low then the boiler simply will not fire. A little extra crap in pipe line ( there are still lead pipes out there), like a bit of rust breaking off will do it. Another thing Councils sometimes reduce pressure deliberatly to reduce the risk of leaks developing. Or a small leak somewhere in his neighbourhood might be enough just to drop the pressure that little bit, if he was borderline in the first place. The Council will tell him what pressure they "would like " to have. They have min values. If there is problems unique to his immediate area they'll tell him.They're pretty good like that. Contacting them in the first instance is probably the cheapest option. I know in my case I'm going to get myself a small cheap pressure guage. Even on a piece of hose attached to cold mains water tap will allow periodic monitoring of pressure.

What ya think J ?? I may be way of the mark of course
t

Hi T, I know that you were talking about the mains supply and the OP had asked about connecting to the mains. But, he says that the connection at the moment is to the cold water tank. I was wondering how there was enough pressure for it to work last year, and not this year.

PS I just noticed you're on line...anothervinsomniac
t

We had friends in last night. They went home at 1.00 and we started watching the Rugby match which we had taped. I must have checked out boards during that time Got to bed about 3.00
Jim.
PS Hey, vinsomniac ! That's good - we were sipping some red wine

greg_johnston

JamesM wrote:

Hi T, I know that you were talking about the mains supply and the OP had asked about connecting to the mains. But, he says that the connection at the moment is to the cold water tank. I was wondering how there was enough pressure for it to work last year, and not this year.

Hi,

1. I've checked the heat with my hand on both the feed from the emersion and those of the radiators and they seem hot. It takes a long time for the system to get hot though as the boiler seems to fire and then switch off, even though the temperature on the termostat in the hall has not been reached.

2. I'm convinced that there is not enough pressure from the cold water tank to top up the system. I've had the value from the tank to the heating open and have not noticed any increase in pressure.

The gate value from the emersion to the rads seems to leek a drop now and again and i believe this is why there is a v. gradual loss of pressure.

So, it seems like there is two problems. 1. how to i top up the system...(pressure is in the red part of the guauge) and 2. why is the boiler not firing continually till the temperature is reached.

Greg

JamesM

greg_johnston wrote:

Hi,

So, it seems like there is two problems. 1. how to i top up the system...(pressure is in the red part of the guauge) and 2. why is the boiler not firing continually till the temperature is reached.

Greg

The boiler should fire continuously until the boiler stat reaches its set temperature - NOT the stat in the hall. The boiler may come on many times before the hall stat reaches the temp you have it set at. In fact it may never reach the temp you want, if you set it too high.
If the rads reach a temp where you cannot keep your hand on them, then everything is probably working OK. There will always be a slow drop in pressure in the system as water is lost from leaks. Some leaks you will not see, they are so slight.
Jim.

tapest

Just in case ..
I'm going only on what you say here, assuming you know your system(having traced pipework)...although most combi boilers should be mains fed requiring pressure you wont get from header tank
I have come accross combis used as part of a conventional system...Possible way to tell is if boiler heats domestic water as needed, ie turn on hot tap and boiler fires up immediately.
Anyway
"2. I'm convinced that there is not enough pressure from the cold water tank to top up the system. I've had the value from the tank to the heating open and have not noticed any increase in pressure."

pressure from the cold water tank will not change. You are adding water to the system when cold and not when the water has heated up and expanded ???
t

greg_johnston

JamesM wrote:

The boiler should fire continuously until the boiler stat reaches its set temperature - NOT the stat in the hall. The boiler may come on many times before the hall stat reaches the temp you have it set at. In fact it may never reach the temp you want, if you set it too high.
If the rads reach a temp where you cannot keep your hand on them, then everything is probably working OK. There will always be a slow drop in pressure in the system as water is lost from leaks. Some leaks you will not see, they are so slight.
Jim.

Hi Jim,

Thanks for that. The stat in the hall is set at 20ish...the stat on the boiler is up full. The rads in the house will reach a temperature that I can't put my hand on...thats only if I have the heating on all day.

Re: Leaks: see below post,
Thanks,
Greg

greg_johnston

tapest wrote:

Just in case ..
I'm going only on what you say here, assuming you know your system(having traced pipework)...although most combi boilers should be mains fed requiring pressure you wont get from header tank
I have come accross combis used as part of a conventional system...Possible way to tell is if boiler heats domestic water as needed, ie turn on hot tap and boiler fires up immediately.

Hi t,

I've traced the pipework and am certain the system is filled from the header tank. (See attached pics)

tapest wrote:

pressure from the cold water tank will not change. You are adding water to the system when cold and not when the water has heated up and expanded ???
t

If I open the feed from the header tank to attempt to fill up the system. There is no increase in pressure. I have tried to do this when the system is on and off, but to no avail.

Any ideas on how best to proceed???
Thanks,
Greg

Emersion.jpg

Header Feed.jpg

JamesM

greg_johnston wrote:

Hi t,

I've traced the pipework and am certain the system is filled from the header tank. (See attached pics)



If I open the feed from the header tank to attempt to fill up the system. There is no increase in pressure. I have tried to do this when the system is on and off, but to no avail.

Any ideas on how best to proceed???
Thanks,
Greg

Emersion.jpg

Header Feed.jpg

Just looked at your photos. I presume that you have checked that the pipe coming through the wall is from the tank in the attic. Are you sure that it is not from the mains ? You have a gate valve and a non return valve - it looks like a normal sealed system.

Tapest, I thought that if there is a pressure switch and the pressure is not high enough, that the boiler would not fire at all ?
What about the water pump - is it circulating properly ? Is it at the low speed ? If the pipe coming out of the boiler is hot, and the water is circulating properly, then the rads should be hot- it should be as simple as that .
Jim.

tapest

JamesM wrote:

Tapest, I thought that if there is a pressure switch and the pressure is not high enough, that the boiler would not fire at all ?
What about the water pump - is it circulating properly ? Is it at the low speed ? If the pipe coming out of the boiler is hot, and the water is circulating properly, then the rads should be hot- it should be as simple as that .
Jim.

JamesM

Agree 100%
t

towbar

Can you hear air been circulated in the system?

Any of the radiators noisy?

Have you a picture of the pressure guage?

2000ad

Hi all,

I've searched and read through all the old threads I could find on boilers and pressure it turns out that I have a similar issue to Greg -

My gas boiler on the ground floor is showing 0.2 bar.

The boiler is fed water from a cold water tank in the attic, through a copper pipe that goes through the hot press. This copper pipe only appears to have a a single "valve" on its path, and that is located in the hot press and looks like the one Greg pictured:
https://us.v-cdn.net/6034073/uploads/attachments/63973/36176.jpg
There are no other pipes intersecting this pipe, from what I can see it goes straight into the gas boiler, and there are no other apparatus attached to the pipe, e.g. there is no expansion tank.

I decided I would try to increase the pressure by opening this valve in the hot press, but I found that it was already fully open (fully turned anti-clockwise and the nut is not stopping it btw).

Back to the water tank in the attic and I noticed that the ball cock was not securely mounted from outside the tank. When I stabilised this, I got the water to rise in the tank by a couple of inches. I think this may have caused the pressure gauge on the bolier to increase slightly, but it's still around the 0.2 mark.

Now my questions:
1. Does this sound like a normal set-up? Does 0.2 bar sound about right for a (fairly large) tank in the attic of a 2 story house?
2. Is the pressure of 0.2 ok or should I be worried? The heating works ok, but I have noticed that it switches on and off a little bit too frequently - every minute or two.
3. Should the valve in the hot press be open or closed? I'm thinking it should be closed, which would allow the hot water in the system to expand and increase the pressure.

thanks in advance.
AD

greg_johnston

JamesM wrote:

Just looked at your photos. I presume that you have checked that the pipe coming through the wall is from the tank in the attic. Are you sure that it is not from the mains ? You have a gate valve and a non return valve - it looks like a normal sealed system.

Tapest, I thought that if there is a pressure switch and the pressure is not high enough, that the boiler would not fire at all ?
What about the water pump - is it circulating properly ? Is it at the low speed ? If the pipe coming out of the boiler is hot, and the water is circulating properly, then the rads should be hot- it should be as simple as that .
Jim.

Hi James,

Yep, thats definately from the tank in the attic and not the mains. The mains has only two feeds, one for main sink and one for the header tank.

Proabably still have enough pressure (0.4ish) to allow the boiler to continue to fire without tripping the switch. The rads are hot as normal...just seems to take longer...ie..there are more boiler start/stop cycles that I remember previously, therefore it takes longer to heat up the house. I figured this had something to do with the pressure.

Re: Low speed of pump: will check if I can adjust that.

Re: Filling the system: as the pressure continues to decrease, are there any suggestions on how best to fill up the system? Willl I try connecting the garden hose? Run a new feed from the header tank mains feed?

Thanks,
Greg

JamesM

2000ad wrote:

Now my questions:
1. Does this sound like a normal set-up? Does 0.2 bar sound about right for a (fairly large) tank in the attic of a 2 story house?
2. Is the pressure of 0.2 ok or should I be worried? The heating works ok, but I have noticed that it switches on and off a little bit too frequently - every minute or two.
3. Should the valve in the hot press be open or closed? I'm thinking it should be closed, which would allow the hot water in the system to expand and increase the pressure.
thanks in advance.
AD

I would think that, if the system was set up that way and is working OK, then things are fine.
If you look at the valve in Greg's photo, you will see a non return valve this side of the gate valve. It is just a fitting thicker than the pipe. You will probably have one as well. This stops the water going back into the pipe and tank, and builds up pressure when the water in the system expands.
Jim.

JamesM

greg_johnston wrote:

Hi James,

Yep, thats definately from the tank in the attic and not the mains. The mains has only two feeds, one for main sink and one for the header tank.

Proabably still have enough pressure (0.4ish) to allow the boiler to continue to fire without tripping the switch. The rads are hot as normal...just seems to take longer...ie..there are more boiler start/stop cycles that I remember previously, therefore it takes longer to heat up the house. I figured this had something to do with the pressure.

Re: Low speed of pump: will check if I can adjust that.

Re: Filling the system: as the pressure continues to decrease, are there any suggestions on how best to fill up the system? Willl I try connecting the garden hose? Run a new feed from the header tank mains feed?

Thanks,
Greg

I don't think that the pressure will decrease, unless a pipe is blocked and water cannot get into the system. If there was enough pressure for the switch from the beginning, nothing should have changed. The lack of heat may be something else. Has the boiler been serviced / cleaned recently ? If it is dirty, or not burning efficiently, you may not be getting a good heat transfer to the water. If the boiler thermostat is working correctly, it only switches off when the water in the boiler reaches the required temperature. The minute the temp drops it switches on again. Regular stop starts should just mean that there is very little variation in the temp - the temp in the boiler barely drops, and the stat switches in and the boiler starts heating again.
If when the heating is turned on initially, the boiler runs for a long time, without the boiler stat turning it off, then maybe the boiler is not generating enough heat - get it serviced.
If the boiler switches off before the rads build up enough heat - there is probably a circulating problem.
Jim.

Shades799

Well lad\lassies,

Another poor unfortunate here, same problem. Removed a radiator to plaster a hall, when I put it back up it was badly airlocked. I bled it and now the pressure in my pump (Vokera Mynute 14se) is down to 0 and the manual says it should be between 1 and 1.5. There is no filling loop on my system and my hotpress looks like the attached pics. It's f*cking baltic here since Thursday!!

Any ideas for me would be hugely appreciated!

http://www.twitpic.com/rmg5u
http://www.twitpic.com/rmg7m
http://www.twitpic.com/rmga7

I was messing around with dials to no avail. From what I've read in other posts I think the wheel that should do the job is number 3, but I can only get that to turn about 30 degrees. I have opened up number 4 a few times and some air comes out but no affect on the pump. Finally I've flicked number 6 a few times and I heard water flowing through the pipes but again no affect on the pump and now when I flick this leaver nothing happens.

I've also bled the radiators again but no affect.

I'd love some help lads. I'm stonewall broke coming up to Christmas and can't really afford a plumber!

Thanks

towbar

does this help - maybe there is a filling loop at the boiler


http://www.howtomendit.com/answers.php?id=29687

greg_johnston

Hi Shades799,

I think your right...number 3 looks like the most likely candidate. Make sure that the screw locking valve under the stop cock is open (not sure about plumbing terminology) ...i.e. the line of the screw is in the vertical and not horizontal (closed).

If thats not it, another option is to gentle tap the stop cock while turning it, this might free it up.

Also, I think there is a reset button on the front of the boiler at the bottom right. You take off a black plastic screw cap and push the grey cross shape switch in to reset it.

Good luck,
Greg

PS Update to original issue with low pressure.
I added a new rad a while back and when I connected it up low and behold the system filled up from the top up valve no problem until it reached 1/2 bar and then it stopped. So, just about enough to keep the system runing.

markgdub

Hi all,

I am having a similar problem with my boiler.

The pressure gauge is 0.5. Apparently it won' fire until it is at a minimum of 1, according to the only man I could find who services Ariston boilers.

I can't find the valve to top up the pressure. I've a similar boiler layout to the poster above, with the Tweet Pic links.

All help,tips and pointers welcome.