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gungaabayar

Im planning to do some DIY plumbing in my one bedroom flat which has currently S plan open vent CH and HW system (with 5 rads and heat only boiler)

1. Drain off the system
2. replace 2 old rads with new one
3. replace old style bypass valve (lockshield gate valve) with new Auto Bypass Valve
4. refill with inhibitor

I replaced one old rad week ago and refilled the system with X400 cleaner. had no problem to change the rad, but I didnt refill properly cos no water comes to any rad. I must've made something wrong, called a plumber and he back filled, by the way cold feed is not blocked. he said just air lock inside a pipe.

so what I am aware of when draining off and refilling the system this time? Ive read so many times like drain off and refill it.

I just wanna know following things before I start my DIY plumbing next week

how to drain properly (obviosly I will drain all rads , openig all vent point)
a) Do I have to open zone valves manually when Im draining the system? (I didnt when Im draining week ago)

b) in order to stop cold feed to the system do I have to close gate valve of the feed tank with the ball valve open or leave ball valve up position with the gate valve open (means emptying feed tank)?

c) do I need to drain boiler as well and how?

How to refill properly:
d) Do I have to leave all rads' vent OPEN before start refilling?
e) Do I have to leave ZVs open manually during refilling? ( I didnt leave them open during refill week ago)f) Do I have to leave rads drain valve open until water reaches to that point?

so what else Im should be aware of not getting airlock which happened to me last week?

any advice is very helpfull

many thanks
 
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Hi there, yeh make sure power is off as by opening the zone valve would call for heat and don't leave Rad vents open when filling unless you can make sure you won't cause a mess lol
 
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kris said:
Hi there, yeh make sure power is off as by opening the zone valve would call for heat and don't leave Rad vents open when filling unless you can make sure you won't cause a mess lol
Click to expand...

yep, definitely power will be off.

have to leave ZV open or not? I will be very carefull during refilling making sure no mess will happen,

Thinking if leaving rad vent open eases water go to the rads,
cheers
 
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in regards to air lock , I would fill your system via a drain valve with a hose pipe from an outside tap, the pressure will clear it, obviously you cant leave it on long as it will overflow your header tank and I don't know the condition of your overflow , so maybe get someone else to keep an eye on that whilst your in control of the tap? , I wouldn't touch the gate valve on the header tank as they are prone to snap internally leaving it closed if you have a stopcock to the float valve then turn that off,,
 
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Staffy85 said:
in regards to air lock , I would fill your system via a drain valve with a hose pipe from an outside tap, the pressure will clear it, obviously you cant leave it on long as it will overflow your header tank and I don't know the condition of your overflow , so maybe get someone else to keep an eye on that whilst your in control of the tap? , I wouldn't touch the gate valve on the header tank as they are prone to snap internally leaving it closed if you have a stopcock to the float valve then turn that off,,
Click to expand...

Thanks for your tips
There is a stopcock there. Im thinking turn that stopcock off and using water vacuum to suck all water and gunk from the feed rank and drain it might be good idea to not blocking feed pipe? Just being cautious.

Cheers
 
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gungaabayar said:
I was thinking water left in the system might cause airlock during refilling system,
Click to expand...

quite the opposite with that way of thinking, air locks happen because air is introduced into the system and cannot naturally escape , pipe work in these sort of systems should be installed with "rise to vent " in mind but things get in the way and some times prevent this and air gets trapped , therefor if air isn't introduced into the system in the first place there cannot be an airlock, It all depends on what work your doing on the system and at what level , i.e if your doing something at ground level and its going to take awhile like pipe alteration then I like as much water out as possible , if your doing something on say 3rd floor then you only need to drain down to that level,
 
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Staffy85 said:
quite the opposite with that way of thinking, air locks happen because air is introduced into the system and cannot naturally escape , pipe work in these sort of systems should be installed with "rise to vent " in mind but things get in the way and some times prevent this and air gets trapped , therefor if air isn't introduced into the system in the first place there cannot be an airlock, It all depends on what work your doing on the system and at what level , i.e if your doing something at ground level and its going to take awhile like pipe alteration then I like as much water out as possible , if your doing something on say 3rd floor then you only need to drain down to that level,
Click to expand...

in my case it is one bed flat, 5 rads which are all same level, 20ish cm from floor.

Flow and Return pipes are in the loft so all rads get reached from roof.

so when starting to refill, water from head tank first travels to return pipe. so in order to get rads filled water has to raise to the loft pipes then go to rads.

in this kind of layout, anything I need to be aware of when I refiil the system?
 
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I always open motorised valves it seems to be the times I forget I get air locks.

As an example a job I have drained fully 3 times for moving rads etc, twice it has filled beautifully the third it air locked a pig and the reason it air locked was because I left the motorised valves shut where as the 1st 2 times I opened them. So even when I opened them the water in the pipes were held in place by trapped air.
 
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I always try & drain fully, plus open motor valves, may be my imagination but I find it helps refill easier with less chance of air locks! If I'm worried of air locks I'll risk the Bung method but only for 3 ports or trv's etc
 
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Millsy 82 said:
I always open motorised valves it seems to be the times I forget I get air locks.

As an example a job I have drained fully 3 times for moving rads etc, twice it has filled beautifully the third it air locked a pig and the reason it air locked was because I left the motorised valves shut where as the 1st 2 times I opened them. So even when I opened them the water in the pipes were held in place by trapped air.
Click to expand...

Leave rads' vent valves open as well? ( until water come out of the vent valve?
 
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