How do I increase the pressure of my gas boiler?

aingeal_croi · 03-01-2010 09:19AM #1

Hi there my gas boiler is a Potterton Suprima 50l Wall mounted fan assisted balanced flu gas boiler. For the last couple of days it has been making gurgling noises and hussing noises like hot water sizzling off a cold surface very noisy anyhow. About a week or two ago I bled the radators as they were only heating up half way. I have searched the internet about the current problem and seems that at the time I should have increased the water pressure to the boiler? I am looking at the pressure gauge and it is sitting at 0.5. From what I read this is too low? It should be at 1-1.5?? My question is this how do I increase the pressure. Beside the gauge above the unit there is a unit that says "grundfos" with a large screw is this the valve to increase or decrease the pressure? I am aware now also that some of the radiators are cold up top again so my plan is to bleed them again but afterwards top up the pressure. Any Advice please sorry for the long winded post!!!! TIA!

mickmcgee · 03-01-2010 09:37AM

Grundfos is just a pump
Look underneath your boiler and find the mains water in,
Open the valve going to this and let some water into your system,

1/1.5 should be ok,

mick

lods · 03-01-2010 10:05AM

I have a small in-line tap in my hot press that allows me to add water into the system to bring up the pressure.

aingeal_croi · 03-01-2010 10:45AM

Hi there I have no tap underneath the boiler but the boiler is located on the first floor and the hot press is on the third floor. In the hot press there are three pipes going into the hot water cylinder the two outter ones have a "close" arrow and bright red tap on the two outside pipes. Then running up the corner of the cupboard there is a similar looking tap that runs into a red BBQ gas bottle shaped unit and there is a picture on the side showing a tap with a water drip coming from it. would that be the tap?

Alkers · 03-01-2010 11:21AM

It should be beside the boiler as you would want to watch the gauge when you open the tap. Only takes a few seconds to fill up

03-01-2010 11:33AM

You may find your boiler is tank fed, if you have bled the rads and there has been no change in pressure, then i would say it's tank fed, Gary.

aingeal_croi · 03-01-2010 11:33AM

God this is the most frustrating thing ever! I know the problem how to fix it..confident I can do it but just finding a tap...there is no tap, lever, or anything!! just a grundof pump beside the pressure gauge with a big screw very similar to this:

aingeal_croi · 03-01-2010 11:37AM

Hi Gary saw you posting on a couple of other threads you seem a man in the know! I have a feeling it is tank fed too as in our attic there is a water tank now in the hot press just below the tank there is a big bulbous looking metal conpartment with a pipe running in and out of it with a red tap could that control the pressure to the boiler?

03-01-2010 11:41AM

This is a filling loop: http://www.google.ie/imgres?imgurl=http://www.idealboilers.com/fault_assistant/images/filling_loop_closed.jpg&imgrefurl=http://www.idealboilers.com/fault_assistant/isar_filling_loop.html&h=170&w=180&sz=16&tbnid=RjVxyZJhhf0hYM:&tbnh=95&tbnw=101&prev=/images%3Fq%3Dfilling%2Bloop&hl=en&usg=__P1nEaCIhKww9zeBDux5any2SIdE=&ei=v3JAS6j1A-SNjAe0lPGADg&sa=X&oi=image_result&resnum=5&ct=image&ved=0CBsQ9QEwBA

They are normally found under the boiler as posted or in the hot press with the hot water cylinder, sometimes installers like to hide
them, if the boilers is tank fed then in the hot press there should be a red wheel head valve (http://www.genesis7.co.uk/images/valve.jpg)with a large brass non return valve (http://www.gasman.fsbusiness.co.uk/images/antibrav1.JPG) in line with it, Gary.

aingeal_croi · 03-01-2010 11:55AM

ok so up in the hot press there is a brass pipe that goes up into the water tank there is a red tap like this

and then it diverts out at up in a solid U shape to the red tank the size of a bbq gas bottle directly below the tap is a connection that looks like the second picture

aingeal_croi · 03-01-2010 11:56AM

Just seen you edit gary that is exactly what it looks like but what would the red bbq looking bulbous little tank be for? Or is that beside the point?!

aingeal_croi · 03-01-2010 12:00PM

So if I turn that red wheel head and get another pair of eyes on the pressure gauge I should see a change in the pressure meter above the boiler? Do I need to have the boiler running?

03-01-2010 12:02PM

If it's this: http://www.tradingdepot.co.uk/external/commerce/1/gfx/hires/ALTEXPKIT12LT.jpg

then this is for taking up the expansion of the heating water as it gets hotter, Gary.

aingeal_croi · 03-01-2010 12:05PM

yep it looks exactly like that without a gauge (as far as I can see) is that the little tap that I should be playing round with?

03-01-2010 12:13PM

If your system is tank fed then gravity decides the pressure in the system when cold, depending on the hight of the tank, the higher the tank higher the reading on the boiler.
With the boiler off I would open the valve and have someone watch the gauge to make sure there isn't mains water coming into the system, once your happy that it's not mains then leave that tap open, if a boiler is tank fed and the water is switched off then the boiler has no protection for running low of water, Gary

03-01-2010 12:20PM

That chrome flexible pipe is the filling loop, have a look at the first picture or take a pic yourself of your installation to confirm, if you do have a chrome filling loop then with someone in front of the boiler fill up the system to 1.5 bar, bleed the rads and keep refilling to 1.5 bar till you have bled all the rads, run the boiler and keep an eye on the boiler until your happy there is no more pressure loss, Gary.

aingeal_croi · 03-01-2010 12:20PM

So if I turn on that tap and see the gauge move is this ok? Or should the tap then be turned off? If I turn that tap on and the gauge does not move then should I leave that tap on? Only trouble is there is not flexible chrome loop near to or attached to that pipe it is a solid brass pipe just in a U shape

03-01-2010 12:38PM

To clarify, there are two ways your system can be fed with water, via a tank which would have the red valve with a large brass non return valve on the same pipe in line with it, if you were to open this red valve i would expect the gauge to stop at a low level ie.. 0.5 bar when cold, if you have this set up then i would leave the red valve open.

The other way is via a filling loop which is a chrome flexible connection which should be left shut at all times unless toping up water pressure like now, if you open this the water can shoot up quickly depending on the pressure of the incoming mains, you have to be carefully as you can put to much water in and over pressurize the system and cause other problems, so have someone in front of the boiler to give you feed back on whats happening, Gary.

aingeal_croi · 03-01-2010 12:47PM

thats great cheers for that Gary will report back once I have done my bit of DIY!!

03-01-2010 12:55PM

aingeal_croi wrote: »

So if I turn on that tap and see the gauge move is this ok? Or should the tap then be turned off? If I turn that tap on and the gauge does not move then should I leave that tap on? Only trouble is there is not flexible chrome loop near to or attached to that pipe it is a solid brass pipe just in a U shape

If your not sure, don't open it and get someone in, if you are able to identify the correct fittings and your happy then thats a good thing, but you would be probperly best to leave any thing you open off once you have sorted the problem out until you get someone to look at it to identify things for you.
If you can put up some pics then that would help, the pictures you posted earlier look like the fittings for a tank fed system, but i would be reluctant to advise you on precisely what to do in case i give you the wrong advise, Gary.

Martron · 03-01-2010 01:02PM

i am having the exact same problem in my house. pressure never comes above 0.8

i can bleed the radiators every day nearly as the heat only comes up half way.

now after following all the directions here it has led me to the hot press. i found the brass non return valve but there is no tap in line with it. in fact the pipe runs back up to the tank in the attic i assume. there is definately not a chrome pipe anywhere.

now my tank is in the attic on the second floor and the boiler is on the ground floor so i would have imagined the pressure to be ok. that tap would hardly be in the attic?

Martron · 03-01-2010 01:05PM

also should evry heating system have an expansion tank? as mine does not. as i ewent looking for it one day. all there seems to be is a overflow pipe that runs back into the tank in the attic. ( there is however 2 tanks in my attic . they are both connected and the tank with the overflow pipe also supplies one of the showers)

03-01-2010 01:39PM

Martron wrote: »

also should evry heating system have an expansion tank? as mine does not. as i ewent looking for it one day. all there seems to be is a overflow pipe that runs back into the tank in the attic. there is however 2 tanks in my attic . they are both connected and the tank with the overflow pipe also supplies one of the showers)

In a ideal world you would have a separate small tank feeding your boiler which would mean your system was a open system and happily replenish any water lost and pressure wouldn't be a factor,
or you would have a sealed system filled via a specially designed filling loop and you would need over 1 bar for the system to work properly.

In Ireland there is a strange mix of the two, the feed for the heating system is taken of the main tank with the idea of the non return valve stopping the heating water from reaching the tank, the pressure for filling the system comes from gravity and must pass threw the non return valve which can cause a Resistance effecting refilling of the rads.
No manufacture i know off have designed boilers to work on this type of system, boiler are either mains fed pressurized systems or tank fed open systems, installers tend to cut out the safety devices to detect low pressure (below 1bar) this isn't a problem as long as the supply from the tank is not shut off.

Long story short if you have a semi-sealed heating system then i would convert it to a mains fed system with a filling loop,refilling is easier and any leak problems on the system would be identified but make sure the safety device for sensing low pressure is repaired, Gary.

Martron · 03-01-2010 01:46PM

so there is no way in topping up this system so. it will just operate at that pressure?

03-01-2010 03:39PM

If you have a tank fed system then as you draw air from a rad the tank via gravity will top up the system, if you find you are getting no movement when you try to bleed a rad then the water is blocked from replenishing the water level or the tank isn't high enough to push the water to the top of the top rads, the boiler gauge will show the pressure from gravity when cold, but the reading will increase as the boiler gets hotter and the pump kicks in.
If you have a mains fed system you can increase the system pressure up to the required 1-1.5 bar, as the mains would be giving you the extra push to get it up there, Gary.

nilaleonor · 05-01-2010 10:22PM

I have been scratching my head with wonderment and fuming with disdain.
Thank you! Thank you!
I've been looking everywhere for this elusive pressure guage, usually sensibly under the boiler with the water inlet tap right next to it.
Those pics really helped and behold I found the red bulbous thingie and blue inlet tap in the airing cupboard. FANTASTIC! Now I can look forward to rattle free heating with out having to bleed radiators everyday, which incidently would not bleed anymore which really freaked me out as that must be critically low pressure.
Thanks again for a snug time being snowed in tomorrow.
best wishes for the New Year!

nilaleonor · 05-01-2010 10:58PM

Right!
I did as said...ie. turned a blue rectangular tap just before the blue rubber tubing connecting the pipes above the little red bulbous tank in the airing cupboard and you can clearly hear the water gushing through and the red tank expelling air, BUT the needle on the guage did not move till..important it seems...I turned the heating on ( by increasing temperature control in hallway and sometimes the water heat setting min-max black knob on the Potterton Suprima 50l boiler downstairs, if the heating switched off too quickly)
Then the needle moved and I could see the response as I let more water into the system at the blue tap above the red tank.
DO NOT LEAVE THE TAP OPEN!! Bad news likely.... just open for little bits once the boiler is fired up and doing its work. Up to 1 with the black needle is more than enough for my 9 radiators.
BE CAREFUL when you bleed the radiators after this if you have been used to zero pressure, of course the boiling hot water and air spurt out like vesuvius.

Keep checking your boiler as suggested earlier to make sure it is making happy sounds and check your guage. The pressure should remain constant after this.

NB TOO MUCH PRESSURE.....NO WORRIES ....QUICK FIX....BLEEED THOSE RADIATORS TILL YOU GET BACK TO SAFE ZONE UP TO 1.5

GOOD LUCK!
Thanks Peeps, that's saved me a call out for now, touch wood.

nilaleonor · 05-01-2010 11:04PM

By the way,
My old boiler did not have a tap at the inlet one way valve but a screw which you had to turn to 1/4 of a turn to do much the same as the tap. You will hear the water going through. You have to have your screw driver at the ready to turn it back to close it when the right pressure is achieved in the guage.

All in laymans terms, helpful I hope ...

TskTsk · 28-11-2010 12:41AM

gary71 wrote: »

In Ireland there is a strange mix of the two, the feed for the heating system is taken of the main tank with the idea of the non return valve stopping the heating water from reaching the tank, the pressure for filling the system comes from gravity and must pass threw the non return valve which can cause a Resistance effecting refilling of the rads.

Sorry for resurrecting an old thread with a long post, but I have a problem with my Vokera Mynute 14e boiler and would appreciate some advice. It's a tank-fed system with a non return valve in the hot press.

The background is that the heat exchanger sprang a leak a couple of weeks ago and was replaced (as well as the non return valve). Now, when the boiler is on for about 10 minutes a rattling/popping noise comes from the heat exchanger (I'm told this is probably water boiling in the exchanger). We thought the heat exchanger might have been faulty, but it was replaced today and the noise is still there.

Prior to the leak, the water pressure gauge was reading just under 0.5 bar which Vokera say is the minimum operating pressure for that boiler. Now, the pressure reads about 0.25 bar when the boiler is off, and drops to near zero when on. I understood from reading other posts that the pressure should actually increase a bit when the boiler is on. I checked my neighbour's boiler and his pressure is over 0.4 bar when off.

So... I don't seem to have any way to top up the system because it's gravity fed and there's no filling loop. All of the red wheel valves I can see in the hot press are fully open, the flow and return pipe valves underneath the boiler are open, the radiators are fully bled and heat up evenly. The boiler pump was inspected today and although there's a little bit of sediment build-up, it appears to be working fine. If it wasn't working properly, would that explain the water popping in the heat exchanger?

Can anyone suggest what might be causing the problem? I have no plumbing or heating knowledge, but I'm thinking that either there's insufficient water reaching the boiler, or the pump just can't push it through the exchanger fast enough. It's driving me nuts.

Thanks in advance.

youtheman · 28-11-2010 07:18PM

I have a Vokera Mynute 25e, also tank fed.

I did an extension recently and my boiler had to be drained down to allow some extra rads to be installed. Took some time to get it back working correctly when I wanted to re-commission the system.

From your description you seem to suggest that your boiler is 'turning and burning', it's just that it is making some funny noises.

The only think I can suggest is that you bleed the heat exchanger. On mine, on the top right hand side of the boiler, just behind the exhaust flue, there is a bleed nipple. An 11 mm spanner will allow you to open it. If you have some plastic tubing then you can run some water into a bottle just to make sure it is 'air free'.

There is also a three position speed selection switch on the pump. You could adjust it to see if it makes any difference. But you'll have to take off the boiler top cover to get at it (located on the bottom left of the boiler).

Before you get your hands dirty you should RTFM, it might help diagnose the problem.

How do I increase the pressure of my gas boiler?

Comments