Gas Central Heating and Radiators

B_Rubble

Dear Anybody,
I think I need to Bleed my radiators. Some of my rads are lovely and hot, some not so hot and others cold. All the DIY forums seem to indicate turning off the central heating system/pump before bleeding. Does this mean simply turning OFF at the control panel. i.e. on my pomerton boiler control panel you can set the system to ON, TIMER, ONCE, or OFF. Do I simply set to OFF and bobs your uncle or is there some other control for the 'PUMP'.
Secondly, the last time I tried to bleed one of the radiators it did not improve things. I got the key, loosened the bleed nut, Out came the water (no noticeable air hiss), Radiator still cold. Have I unwittingly turned something off on my (very complicated looking) system. I'm thinking particularly about a KNOB on my system called a MYSON combi loop. When I turn it anticlockwise, i.e. towards (+) I can hear water flow as if i have relieved an enormous pressure. What does it do? Please see picture below (The knob i am referring to is the white one in the upper right hand corner of the picture)
Any help/advice much appreciated

10-10-20

That's the fill valve for the heating system. When you open it is simply fills up the system to the required pressure, and you should then close it off again afterwards.
Any guidance I've ever received on bleeding a radiator system has advised that the whole system be hot but not on. You bleed the rads as normal and then you makeup any difference or loss afterwards by opening the fill valve again.
If the system is continually loosing pressure or getting airlocks, then you will need to get it checked by a plummer.

B_Rubble

Many thanks, So i run the system 'til hot water through the system. Then turn it off at the control panel. Then bleed. If needs be (although I dont know how to determine this bit) i can top up the system using the fill valve?
thanks 10-10-20

crosstownk

Check your pressure gauge located near the boiler (usually). A good guideline is approx 1 bar when the system is cold. Briefly opening the valve in the pic will increase the pressure a little bit

B_Rubble

Thanx crosstownk,
Aint got no pressure guage unfortunately, just loads of pipes. It reminds me of the george pompidou centre in paris.
Can't figure it out at all, at all. Some rads hot, Some not so hot (cold, lets face it). I installed a new second thermostatic shower about a year ago, and prior to this I turned all knobs off and on, to isolate the hot and cold supply lines from the jetforce pump that came with the house. Maybe I messed up things then (the shower is working beautifully btw).
I tried bleeding the rads that dont heat up but no improvement. It's nearing that time when the phone is lifted and the number of the local plumbperson is dialled. I DO get really annoyed that i can't do this stuff myself though. Anybody know a course in plumbing for forty something people who aren't in the trade?
anyway cheers again.

JamesM

If you don't have a gauge, you should have - look around a bit more. If it really is not there, then you do need that plumber. He will fit a gauge and, if you ask, will ballance the system and show you how to keep it topped up.
Jim.

GreeBo

Depends on what you mean by cold rads:
1) cold at the top but nice and warm at the bottom
2) warm at the top but cold in a triangle pattern from the bottom up
3) just not warming up at all.

1) needs to be bled, the top is full of air which doesnt conduct the heat as well as water does

2) rad is full of sludge which again doesnt conduct the heat, system needs to be power flushed (or rads replaced) This problem shouldnt just appear overnight.

3)Probably an airlock or the system needs to be balanced. If you google "central heating radiator balancing" you should find the info required. Its a time consuming job.If its an airlock I would shut off all the other rads except for one cold one and turn on the heating. Then try bleed it, you might get lots of water before you get the air out.

Good luck.

B_Rubble

Thanks all seems like some excellent tips. I'll givem all a bash.

jamesM: I cant find the gauge anywhere. I think a plumber is the next step.

GreeBo: It is no. 3 Just not warming up at all. Some time ago I tried turning off all rads but the offending one and bleeding it, but seemed to be bleeding for too long so i stopped. Maybe a bigger airlock now? I'll get a plumber to balance the system and work from there.

Many thanks again

crosstownk

Depending on the type of boiler, you may have to remove some of the panels to see the gauge. Usually the gauge is located on the flow pipe - close to the boiler. Have a look at the outside of the external wall to which the boiler is mounted - you should see an 'overflow' pipe. Usually the gauge is mounted internally, close to this pipe.

JamesM

You may need to fill the system, but if you cannot find the pressure gauge, it is better not to open the fill valve. If the pressure goes too high, you will have water squirting from the safety valve. Maybe this time get the plumber and try to learn from him.
Jim.

B_Rubble

Gauge was (as suggested by crosstownk) behind a panel below the control panel. It seems to be measuring 2.5 bar at the moment of checking (i.e. the heating has been on for 1hr and the needle is just at the interface between green and red). I will check it when the system is cold and get back toyawl!;)

crosstownk

FWIW, I always bleed when the system is good and hot, which means that the pressure to expel the air is greatest.

Let us know how the pressure reads when cold.

JamesM

B_Rubble wrote: »

Gauge was (as suggested by crosstownk) behind a panel below the control panel. It seems to be measuring 2.5 bar at the moment of checking (i.e. the heating has been on for 1hr and the needle is just at the interface between green and red). I will check it when the system is cold and get back toyawl!;)

From what you say, the system has plenty of water - don't open the fill valve. You said that when you bleed, water comes out immediately. - There is no air. You may need to balance the system See "Stickys"
Jim.

B_Rubble

Dear crosstownk/James,

crosstownk: I checked the gauge cold and it has dropped to about 2.0bar which is one third into the green zone from the red zone.

crosstownk and James: Seems to be a mixed opinion the more you read regarding bleeding the system. Some say cold when bleeding some say hot. Personnally i can see the logic behind the hot bleed with regard to increased pressure but then i'm not an expert in this area.
There is also varying opinion on air in the system. Some say you must bleed for some time to get the air out?
Anyway I think I'll get 'an expert' in and maybe watch how to balance the system for the next time.

many thanks one and all.

Now where's my golden pages

JamesM

B_Rubble wrote: »

Dear crosstownk/James,

crosstownk: I checked the gauge cold and it has dropped to about 2.0bar which is one third into the green zone from the red zone.

crosstownk and James: Seems to be a mixed opinion the more you read regarding bleeding the system. Some say cold when bleeding some say hot. Personnally i can see the logic behind the hot bleed with regard to increased pressure but then i'm not an expert in this area.
There is also varying opinion on air in the system. Some say you must bleed for some time to get the air out?
Anyway I think I'll get 'an expert' in and maybe watch how to balance the system for the next time.

many thanks one and all.

Now where's my golden pages

If the pressure is at 2.0bar when cold, and there is no air at the top of the rads, trust me, there is enough water in the system. If the layout is very spread out, then you may need to balance the rads, make sure that the circulating pump is at full speed etc. Do you have the original system which used to heat OK, or a bungalow - rads spread out all over the place, or an extension added on ?
Jim.

B_Rubble

The setup i have is a two storey semi-D arrangement. Seven rads upstairs and five downstairs. Don't know if the pump is at full speed. In fact i dont know where the pump is. There is a large red object/casing with the word ZILMET written on it (it looks like a fat red discus) and is located behind the lower panel (i.e the one i removed to see the gauge). This red object takes up most of the space behind the panel. Behind the red object there is a black box with I think MYSON written on it. The red object has the words "working pressure 3.0 bar" writtten on it. many thanks in advance

JamesM

I presume that the red object is the expansion vessel. Myson is the circulating pump. See if there is an adjustment on it - fast / slow, or maybe 1, 2 or 3 speed. After that, try turning off the hotest rads and see if the others get hotter etc. If there is some effect, then go about the usual balancing, as described somewhere
Jim.