help for novice to drain down and refill system properly

[markyhud]

Hi. I have had loads of noise when my hot water turns on for months now. Like a gushing, trickling kettling noise. A mate who is good with all things like this suggested we drain down the system as it would probably be full of sludge. So did this yesterday and

. Water was jet black!!!! Like 100 pints of Guiness. The house is 12 years old and it has never had any sludge remover or inhibitor fitted.
With this in mind I want to drain it down again, add the cleaner, leave a few weeks, drain and add an inhibitor. Just wanted to check if I'm doing things here in the right order. I believe it is an open vented system, conventional boiler (ideal classic).

1. Isolate tank in loft
2. Attach hose to downstairs rad and crack this open
3. Open bleed valves on upstairs rads and then the same downstairs
4. When drained close all bleed valves
5. Open valve in loft to fill header tank and leave to fill
6. Open bleed valves downstairs first one at a time so they fill and work my way upstairs.

This is the order we did things yesterday but since then i am thinking of the following. The diverter valve has a position for "flushing only" (didnt touch this yesterday) Should I move the lever to this position before draining and will this drain water from the coil in the hot water tank in the airing cupboard? If this is right do I open the bleed valve close to the hot water tank to aid in flushing?
Also when the system fills when do I bleed air from the pump and this bleed valve in the cupboard?
Also I have seen that the boiler should be off. I take it this means not firing and so knock the electricity off yes? Also just read that the pump should be set to manual. The pump is a Grundfos Selectric and has no manual controls.
Any tips for a novice would be great?

 

[jase158]

4.1 (if possible) clean tank before refilling (as any dirt in tank will work its way into system slowly)
4.2 add cleaner through small tank in attic before refilling

boiler off at switch and turn programmer off

to do properly, push divertor valve to side and make sure it stays there by pushing up for 5 seconds (flushing)

air valve open when upstairs has been drained down and before you drain down downstairs.
And open air valve again when system is full, once full start boiler up and keep opening air valve every 10 minutes ish to get all the air out.

nothing to do with pump except unscrew the screw on front once you have refilled to let air out, once a little bit of water comes out then screw back in. (make sure you dont drop screw, can be very bouncy)

further more....

1. you may get an air lock in system when filling, to get rid of this you may have to redrain and refill. (if done properly you shouldnt get an air lock) less likely as you have a open vented system.
2. make sure you have drained all radiators, any radiators that have pipes that come directly from upstairs will have to be drained from the lowest point of that pipework.
3. with cleaner in the system try turning pump to level 3, check small tank in attic if there is water coming out of pipe, turn pump back down. try turning up and down a few times to try and create some turbulance.
4. tap the radiators (in bottom middle) once a day whilst cleaner is in to get rid of built in sludge
5. take heads off of radiator valves and make sure pins come back up when pushed down, if not loosen by pushing pin up and down a few times, if still not working, try using wd40
6. open lockshield and trv valves all the way, but write down how many turns for each valve so you can put back after.


hope this helps

 

[markyhud]

Thanks for all the info and tips. Just a few queries though (forgive me as cant get the multi quote thing working)

to do properly, push divertor valve to side and make sure it stays there by pushing up for 5 seconds (flushing)

Not sure about this. So I just move it across to the "flushing only" position but have to hold it for five seconds. Is this still with the electric on and will it move the valve??

air valve open when upstairs has been drained down and before you drain down downstairs.

Is this the bleed/auto vent next to hot water tank I was referring to? I thought downstairs drained first as that is where the hosepipe is attached to. And will it drain from the coil through the pump as this is in between the HW tank and diverter valve?

take heads off of radiator valves and make sure pins come back up when pushed down, if not loosen by pushing pin up and down a few times, if still not working, try using wd40

Are these the pins with the plastic covers that just prise off? If so I did'nt realise that these push up and down. What is the purpose of that?

open lockshield and trv valves all the way, but write down how many turns for each valve so you can put back after.

They are all fully open in the first place. Should they not be??

 

[markyhud]

D'ooohhh just realised what I said there....of course upstairs is going to drain first due to gravity!!! So i open that bleed screw/vent thingy after the upstairs rads have emptied yes?? When will i know this has happened though?? Sorry for all the questions I just want to be able to do it myself

 

[dontknowitall]

When to open the bleed screw - when will you know - when there's no water coming out when you open it. If a hiss of air, probably means you're going to be safe.

And, if you get it wrong, you're not going to flood the house - few teaspoons of water at most, unless you're not paying attention.

 

[jase158]

ok
you will know when the upstairs rads are bled because they will have no more air coming out of them.

"to do properly, push divertor valve to side and make sure it stays there by pushing up for 5 seconds (flushing)

Not sure about this. So I just move it across to the "flushing only" position but have to hold it for five seconds. Is this still with the electric on and will it move the valve??"

turn electric to boiler off and boiler off and timer off first before starting any work leave off until system is full again, valve should still turn if you push valve even if no power.
normally on these valves it needs to be pushed acrossed and pushed up and hold for 5 seconds and it will stay in the same place, you may just have to put in the "flushing" position if not you will need to be kept in the flushing position for the whole time you are draining down somehow.


take heads off of radiator valves and make sure pins come back up when pushed down, if not loosen by pushing pin up and down a few times, if still not working, try using wd40

Are these the pins with the plastic covers that just prise off? If so I did'nt realise that these push up and down. What is the purpose of that?

No the valves you are talking about is the lockshield valves the valves i mean are the valves that are turned up and down, have numbers on them 1-5 usually or 1-7. These valves have a rigged bit underneath the head, this can be turned anti clockwise to undo them. Sometime you may just have 2 lockshields on each side, if so just turn them anticlockwise as much as possible and leave open whilst cleaning.


open lockshield and trv valves all the way, but write down how many turns for each valve so you can put back after.

They are all fully open in the first place. Should they not be??


Some systems need to be balanced the reason for this is because certain radiators may get hot before other radiators, having some valves partly closed balances the system out so that it heats up evenly.
however if your valves were all open before you did anything the chances are that they wont need balancing.

air valve open when upstairs has been drained down and before you drain down downstairs.

Is this the bleed/auto vent next to hot water tank I was referring to? I thought downstairs drained first as that is where the hosepipe is attached to. And will it drain from the coil through the pump as this is in between the HW tank and diverter valve?


If you have auto vent, then no need to touch this at any point, as this will do the work for you

if you have the manual vent this will help drain the coil and will get the water from the pipes to as it is a direct connection to the pipework, open when draining down, (after the upstairs rads are drained down) and close again when air stops coming out.
when system is filled open again untill a little bit of water comes out.

start up system and re open again untill a little bit of water comes out.

Wait 10 minutes and re open again untill a little bit of water comes out.

repeat until no more air in system (no noise/ rattling)

 

[markyhud]

Wow mate thanks for taking the time to answer all my queries. That's really informative thanks. I am just on my way out the door to work but i have one more query about this auto vent thingy. I will post tonight and try and get a pic but thanks again!!

 

[AWheating]

make sure you drain from all radiators/low points in the system aswell as drain off cock ontop of boiler to ensure its all out as leaving cleaner in the system can cause problems.

 

[markyhud]

make sure you drain from all radiators/low points in the system aswell as drain off cock ontop of boiler to ensure its all out as leaving cleaner in the system can cause problems.

So after all the rads are empty I do this. I have looked at my boiler and just above there looks to be a drain valve like on the radiators. Is this it?

 

[markyhud]

This is the automatic vent. I know that because the screw sheared off yesterday when i tightened it and I had to buy a new one. I didnt even know these invented til then.This has been a crash course!! Thing i cant understand is how this self vents. I presume it is via the little holes but to manually bleed this I have to undo the slot head/screw nipple. Should this be as tight as I can get it then or just tight so it doesn't leak. plus it hasnt helped all these years by draping facecloths over it to dry them. I think I should be ashamed of myself for that one. So could i have been occluding this vent for the last few years??

 

[AWheating]

So after all the rads are empty I do this. I have looked at my boiler and just above there looks to be a drain valve like on the radiators. Is this it?

yes the drain off above the boiler will need draining too. So once you have the cleaner in and run for a couple of weeks dependant on the cleaners instructions you want to drain from all point to make sure you remove all the cleaner. Its best to drain when water is hot, but be warned that you may get burnt if you are not carefull. I would use a hoes clip to secure your hose pipe to the drain off tap and then you wont get and nasty suprises if you leave the hose to open the vents etc....

 

[jase158]

View attachment 3840



This is the automatic vent. I know that because the screw sheared off yesterday when i tightened it and I had to buy a new one. I didnt even know these invented til then.This has been a crash course!! Thing i cant understand is how this self vents. I presume it is via the little holes but to manually bleed this I have to undo the slot head/screw nipple. Should this be as tight as I can get it then or just tight so it doesn't leak. plus it hasnt helped all these years by draping facecloths over it to dry them. I think I should be ashamed of myself for that one. So could i have been occluding this vent for the last few years??

chances are that their wasnt massive amounts of air in the system, so putting stuff over it doesnt matter too much, also the manual valves are usually closed during normal operation, these are only opened when the system is filled.
and you have an air vent in attic which dispells air from the system. so no not too big a problem, stick that flanel back over it, lol

the automatic air valve has a flap inside which opens when air is in the system and shuts when water hits it.

these should be left open at all times to expell all air, however I have had a couple of these leak on me before, so perhaps open it when filling up and close when finnished.
no water should come out of these.

I am giving you this advice as you say this is an automatic valve, however i have never seen one like this before, so taking your word on that. it does look like a manual one to me, when you open it does it leak water?

if it is an automatic valve then you only need to open it 1 full turn, no need to completely open it. leave it open after boiler has been switched off and shut again after you have refilled and tested system. If still loads of air in system after you have filled and tested then leave open for 24-48 hours with hot water and heating on to try and get rid of all air in system.

 

[markyhud]

chances are that their wasnt massive amounts of air in the system, so putting stuff over it doesnt matter too much, also the manual valves are usually closed during normal operation, these are only opened when the system is filled.
and you have an air vent in attic which dispells air from the system. so no not too big a problem, stick that flanel back over it, lol

the automatic air valve has a flap inside which opens when air is in the system and shuts when water hits it.

these should be left open at all times to expell all air, however I have had a couple of these leak on me before, so perhaps open it when filling up and close when finnished.
no water should come out of these.

I am giving you this advice as you say this is an automatic valve, however i have never seen one like this before, so taking your word on that. it does look like a manual one to me, when you open it does it leak water?

if it is an automatic valve then you only need to open it 1 full turn, no need to completely open it. leave it open after boiler has been switched off and shut again after you have refilled and tested system. If still loads of air in system after you have filled and tested then leave open for 24-48 hours with hot water and heating on to try and get rid of all air in system.

If I turn the bleed valve about half a turn anti clockwise water runs from it. I did manage to vent a little air doing this the other day after refilling. I only know it is an automatic vent as that is what it had on the packet of the new one I bought. So I can't leave it open so that is why i was confused as to why it is called automatic. It seems to work just like bleeding a rad

 

[markyhud]

yes the drain off above the boiler will need draining too. So once you have the cleaner in and run for a couple of weeks dependant on the cleaners instructions you want to drain from all point to make sure you remove all the cleaner. Its best to drain when water is hot, but be warned that you may get burnt if you are not carefull. I would use a hoes clip to secure your hose pipe to the drain off tap and then you wont get and nasty suprises if you leave the hose to open the vents etc....

Good tip that but I will be able to self treat any burns as I am a paramedic!! Lol!! Will this just refill with rest of the system. No special trickery etc involved. Will this be the pipe that takes water from the boiler or does this not really matter

 

[jase158]

Good tip that but I will be able to self treat any burns as I am a paramedic!! Lol!! Will this just refill with rest of the system. No special trickery etc involved. Will this be the pipe that takes water from the boiler or does this not really matter

boiler will fill automatically yes, no special trickery needed.

"Will this be the pipe that takes water from the boiler or does this not really matter"
Bit confused, what do you mean?




yes it is a manual one then. open after first floor is drained down and like said before open up after system full and before boiler fires up.

 

[AWheating]

the boiler pipework will refill when the rest of the sytem refills. on tip i would give you is once you have refilled the system and vented all points inclueing the A/C pipework and pump i would turn the system on with the boiler stat at 0, set clock to hot water only and turn boiler stat up and allow the pump to run but turn back down before the boiler fires up. then go to A/C and vent the pipework again. Do this a couple of times and it should help remove any air, if your boiler fires up with air inside or no flow you may get overheating and damage. Once you have done it a couple of times and removed the air set for heating and hot water and allow the boiler to fire. (If you have an auto air vent in the A/C then ignore the venting A/C pipework bit.


does this make sense?

 

[jase158]

the boiler pipework will refill when the rest of the sytem refills. on tip i would give you is once you have refilled the system and vented all points inclueing the A/C pipework and pump i would turn the system on with the boiler stat at 0, set clock to hot water only and turn boiler stat up and allow the pump to run but turn back down before the boiler fires up. then go to A/C and vent the pipework again. Do this a couple of times and it should help remove any air, if your boiler fires up with air inside or no flow you may get overheating and damage. Once you have done it a couple of times and removed the air set for heating and hot water and allow the boiler to fire. (If you have an auto air vent in the A/C then ignore the venting A/C pipework bit.


does this make sense?

good tip cheers may try that in future

 

[targett]

Just wanted to check if it's the same theory when I have a closed system?

 

[jase158]

Just wanted to check if it's the same theory when I have a closed system?

similar but no need to turn off small tank in attic (as you dont have one), can just drain down.

you will need a special kit to put chemicals in or if you have a towel radiator then when system has been drained, close the drain off valve and put cleaner/inhibitor in towel radiator before refilling. Or if you can find a manual/ automatic air valve, you may be able to take this off and put cleaner in there.

now to refill you need to find the filling loop and fill up in little stages, fill so that the pressure is up to 1 bar. then go and bleed all radiators and open air valve in airing cupboard, you may need to top up pressure several times. when full make sure boiler is up to 1 bar and start boiler up.

Do not let pressure go above 1 bar. do not try to fill up higher so that you don't have to go up and down the stairs so many times, do not leave filling loop open when you are not looking. pressure will go up very fast and will cause damage if too high.

if you have a combi you will also have no valve in airing cupboard as this is built in boiler so no need to do anything with this and automatic/ manual air valve will be in airing cupboard or attic. Find this first, normally highest point of central heating.
think i have covered everything.

think about what you have to do, ask questions if not sure about anything.

 

[markyhud]

turn the system on with the boiler stat at 0, set clock to hot water only and turn boiler stat up and allow the pump to run but turn back down before the boiler fires up.

Makes perfect sense and thanks but this bit is the only bit confusing me. When you say let the pump run is this the pump upstairs in the A/C? Will this run with the boiler set to 0? Or is there a pump in the boiler?? I don't understand turning the boiler stat up and down before the boiler fires. Is this a split second thing? I'm sorry if I'm missing something obvious here

 

[jase158]

????? confused
which post do i say let the pump run?

 

[markyhud]

????? confused
which post do i say let the pump run?

Sorry for confusion mate it wasn't you it was AWheating

 

[jase158]

Makes perfect sense and thanks but this bit is the only bit confusing me. When you say let the pump run is this the pump upstairs in the A/C? Will this run with the boiler set to 0? Or is there a pump in the boiler?? I don't understand turning the boiler stat up and down before the boiler fires. Is this a split second thing? I'm sorry if I'm missing something obvious here

there should be 5 parts to your central heating, atleast 4 need to be on for your boiler to fire.
1. boiler thermostat
2. cylinder thermostat (wont have if you have combi boiler, will need a tap open to fire up hot water instead)
3. room thermostat
4. electrical switch- usually under boiler or in airing cupboard
5. programmer

so what AWHeating is saying is, turn your boiler down to 0, turn electrical switch on and set programmer on to hot water only. then turn your boiler up, you will start to hear boiler going through process to light. just before it ignites turn off again usually about 3-5 seconds can be different for each boiler.
then go upstairs vent from air valve, come back down and repeat.

I am not 100% sure on this but i don't think you need to with combi boilers as they have an automatic air valve built in.

 

[markyhud]

Excellent. Makes sense that as i can hear my boiler making a ticking noise just before it fires. I think I have it all covered now and so when the weather gets a tad colder in a few weeks (when it snows!!) I am going to follow all the top advice and add the cleaner to circulate for a few weeks. I only have one more question and it might sound a bit daft but here goes.......when that air vent/ bleed nipple sheared the other day it got me thinking...should I replace the bleed nipples in the rads with new ones?? I'm scared that after 12 years and the cycle of draining and bleeding they may weaken and be prone to shearing too. Is this something that could happen or am I just developing some sort of plumbers OCD??

 

[jase158]

well you can do this, completely up to you, I have never had them shear except when tightened too hard.

but its up to you.

problem is, how far do you go, replace radiator valve, replace pump, place three port valve, replace air valve, replace bleeding valves, where does it end. well all depends on your money and confidence