Can't repressurise heating system. What am I doing wrong?

Mayo Exile

One of my radiators has gone cold, so I've bled it a couple of times. It's been alright then for a week or so, but then went cold again. Reading other threads I'm guessing its a balancing issue. However my main concern now is that in bleeding the radiator I've dropped the pressure in the system, and I can't seem to repressurise it. .

Maddening thing is I got a plumber in just after xmas to look at this radiator that's acting up again. He was one of the plumbers contracted to install the heating systems in the estate. He repressurised the system in a jiffy!! The reading on the gauge he set it to 1.5 bar when the system was off and cold. Now its driving me nuts that I can't do it myself!! :mad:.

What am I doing wrong or am I missing doing something somewhere? System is natural gas one powered by an Ideal Mini boiler that's in a separate room away from the combination water cylinder and associated plumbing. Some pictures supplied. If anybody needs more pictures, I'll try to get them up as quick as I can. Many thanks in advance.







Note: that's the pressure not long after system is off. It's lower than this when totally cold.

Note to Joey_the_Lips: sorry, this thread will seem to familiar to you, its a continuation of the valve thread (http://www.boards.ie/vbulletin/showthread.php?t=2055606178) I posted a few weeks ago. Could'nt contact a plumber on the estate to do that repressurising job on my heating system as you recommended, as the estate is nearly finished now and the plumbing contractors dont seem to be around anymore).

aujopimur

Open the fillvalve and give the valvebody a few gentle whacks with a spanner.
The brass screw on the left sets the water pressure .
The (red) wheelhead valve may be stuck closed as these are usually of poor quality
The fillvalve should not be used on heating system and should be replaced with a filling loop and disconnected and blanked once the system is filled.

Mayo Exile

Which is the fillvalve? Is that the black knob on the gauge itself?

The fillvalve should not be used on heating system and should be replaced with a filling loop and disconnected and blanked once the system is filled.

Apologies aujopimur. Don't understand. Is that not the filling loop in the top picture?

EDIT: Opened brass screw (water pressure adjustor). It actually came right out at one stage. Screwed it back in again. Opened red wheel and then black knob on the gauge itself (this is the fill valve?). Heard water flowing when the black knob was opened. Pressure on gauge went to 1.2 bar. Closed black knob and then the red wheel. Pressure now steady. Any significance that the brass screw came out?

PeteHeat

Hi,

The valve is an automatic filling valve, nothing wrong with using them on a system properly fitted.

Many plumbers don't like them because if a joint weeps / leaks the system keeps topping up automatically.

Are you sure you didn't close the gate valve on the filling loop (red valve) ?

The black one opens the valve and the screw sets the pressure, close it slowly about 1 turn at a time pausing at each turn to check if the pressure has started to rise.

When the pressure reaches 1.5 bar turn off the main gate valve !!!!!!!!

You must be careful because the "Screw" should have a protective cover on it and I always ask why ? when I come across a valve not plumbed to do job intended (fill automatically).

At this time only the last plumber to work on it can answer that question.

.

Mayo Exile

Are you sure you didn't close the gate valve on the filling loop (red valve) ?

The black one opens the valve and the screw sets the pressure, close it slowly about 1 turn at a time pausing at each turn to check if the pressure has started to rise.

When the pressure reaches 1.5 bar turn off the main gate valve !!!!!!!!

Thanks PeteHeat. As I said, the screw actually came out. Put it back in again. As you hinted at, it mightn't be doing its intended job or maybe not doing any job at all? Opened red valve all the way, then started to open black valve, heard water flowing after roughly 3 turns, pressure rose, then closed black fully, then the red one fully. Pressure stable at 1.2 bar.

I had tried this procedure previously (opening red valve, then black, (didn't go near pressure screw though, didn't know what it was!)) in attempt to raise the pressure, but nothing used to happen, so maybe the pressure screw WAS faulty, jammed shut maybe?

The red and black valves should always be closed, only being opened if you need to fill the system? How does automatic filling work?

Sorry for repeating myself, my knowledge on the subject is limited! Just want to make sure I understand you and that you know what I've done!!

Joey the lips

To be honest I hate dispise and lothe autofilling vales. It would be worth your will getting a plumber in on this for 2 reasons

1. Get s/he(have to be pc) to replace the filling valve with an combi filling loop that way you get rid of the dodgy gate valve as well. The combi filling loop comes with a non return valve so is a lot easier to use

2. Any leaks in the system cannot be masked by the auto filling valve meaning for example the life span of your rads wont be drastically reduced.

I appreciate at this time money is tight, but feel if you chage this to the filling loop it might show up what i think is another problem and this migh result in your heating working come winter!

Best of luck

Mayo Exile

Thanks Joey. So whats in the top picture is not a proper filling loop? Have I done the right thing (opening red, then black, then closing black, then red). It seemed to work now after that pressure screw was adjusted (came out!). Same procedure never worked before. You are right though the system needs checking out maybe. Has worked without fault up to now.

One other thing now I remember, I had bathroom fully tiled before xmas, the tilers took off the radiator to do the job. They told me to get a plumber (they knew one they said, foolishly now with hindsight I told them to contact him to check everything) to check the system and the said person was gone before I got home, while the tilers where still there!! Did he come at all I wonder? I noticed the pressure on the gauge was low after that! They must have lost water out of the sytem taking it off and putting it on again i'd say?

Joey the lips

Mayo Exile wrote: »

Thanks Joey. So whats in the top picture is not a proper filling loop? Have I done the right thing (opening red, then black, then closing black, then red). It seemed to work now after that pressure screw was adjusted (came out!). Same procedure never worked before. You are right though the system needs checking out maybe. Has worked without fault up to now.

One other thing now I remember, I had bathroom fully tiled before xmas, the tilers took off the radiator to do the job. They told me to get a plumber (they knew one they said, foolishly now with hindsight I told them to contact him to check everything) to check the system and the said person was gone before I got home, while the tilers where still there!! Did he come at all I wonder? I noticed the pressure on the gauge was low after that! They must have lost water out of the sytem taking it off and putting it on again i'd say?

Its not whats called a combi filling loop what you have is called an auto filling valve and as the name suggests it fills your system automatically once the system drops to a certain pressure.

darcy.jonny

just a quick one for u . if the screw has fallen out then uve effectivly turned off the valve screw it back in and monitor the guage as you do .

theres nothing wrong with these valves what so ever if correctly fitted and set properly , but i will say the majority of the time ive seen these fitted is due to plumbers installing systems and having gradual pressure drops without any evident leaking so the quick fix is to smack one of these lads on .

Mayo Exile

Thanks for the further replys fellas!

Its not whats called a combi filling loop what you have is called an auto filling valve and as the name suggests it fills your system automatically once the system drops to a certain pressure.

Joey, sorry for yet another clarification (sounding like a right slow witted eejit now!). I've put together another picture to attempt to explain myself as best i can. Sorry! Thanks for being very patient!

Stratocaster

Im not sure if you've solved the problem but as stated in a previous post I would advise removing the PRV, what you have there is a simple pressure reducing valve, its not designed for filling heating systems as a NRV non return valve is not included in the assembly. You'll notice the separate NRV located below the PRV. The reason why these are fitted to a mains fed heating system is for handiness. You can pre set the required pressure and not have to worrie about over pressurizing the system while you initially fill the system. Another reason is sometimes the water pressures not great during business hours so the plumber doesn't have to wait around or spend extra time to fill at a good pressure. The PRV will allow the system to be topped up to the required min of 1bar all by its self.

You should remove the whole assembly and fit a flexible filling loop designed for filling heating systems and this will give you hassle free plumbing. They are real easy to use, one simple flick of a lever and you can top it up, then disconnect from the system completely.

The problem with PRVs is most are set on permanently and should you have a slight undetected leak your system will constantly take in fresh water. When a system takes in fresh water constantly over a period of time it can corrode the metal from the inside out and the weakest metal will go first, the boilers heat exchanger. Seen it happen many times and mostly the cause is a slight leak in the boilers safety valve, you see it all the time, a stain running down the wall below the boilers safety outlet.

While im at it, gate valves should not be used on heating systems they seize up, happens on plumbing also. They get locked up and when you open or close them you strip the threads and the wheel head just turns and turns but the gate wont open or close. One tip I can give if you have them installed is never close or open them fully just back them off a slight bit, will save them from seizing. Lever valves are the only ones that last. They cost more that's why not a lot of plumbers use them.

Stratocaster

Mayo Exile wrote: »

Thanks for the further replys fellas!



Joey, sorry for yet another clarification (sounding like a right slow witted eejit now!). I've put together another picture to attempt to explain myself as best i can. Sorry! Thanks for being very patient!

Ok the red gate valve is your mains supply valve which is not really needed you should open it fully then just close it a small amount to save from seizing. The black wheel head located on the PRV is the on/off valve. Turn it clockwise to close and anti clockwise to open. You will need both open to set the required amount of pressure and fill to the amount. I would advise closing both once set.

The threaded adjustment to the left of the PRV is how you set the PRVs maximum pressure allowance, also located on the spindle should be a locking nut. Once you set the pressure amount you tighten up the lock nut to save people from tampering.

I am not sure with that model PRV but in most cases you tighten the spindle on the left for more pressure and loosen for less but in some case's I have found it to be the opposite. Its up to you to figure out.

On a serious note you shouldn't really be messing around with it as the water pressure can be different at different times of the day so be very careful. If your unsure just close off both the gate valve and the black wheel head and have a plumber look at it.

Mayo Exile

Many thanks for that Stratocaster. Both red and black valves are closed now. Pressure steady.

jimmymook

Hoping someone can help with a similar question. The pressure on my gas boiler is at 0 and needs topping up. The gauge in the hot press is also at zero. I have tried opening the black knob and loosening the screw on top but no joy, no sound of any water flowing and needle doesnt budge. I dont have any red wheel on this system. Any advice appreciated. (Apologies for the crappy photo, I had to use an old mobile.)

PeteHeat

Hi,

Tighten the screw (not loosen it) make sure the smaller black knob is open.

Take care not to over fill / pressurise the system.

.

Joey the lips

Have someone keep an eye on the boiler gage while you fill it. Make sure you do it cold.

jimmymook

Thanks for that lads, will try that this eveing.