Draining/refilling heating system help

[Shaun-UK]

Hello. I need to remove a radiator in an upstairs bedroom and cap the pipes for a month. I have a baxi 105 he combi boiler and I just need some advice on draining the system and refilling it.


Before draining the water from the radiator do I release the pressure from the system? and if so how?

... and I just need to know how to refill the system correctly. I was once shown by my plumber but can't remember. I am sure it has something to do with the 2 taps either end of the filling loop but the tap I thought it was won't move at all. So any advice on how to fill the system to the right pressure will be great.

I know I should get help from my plumber but he is on vacation and I have a plasterer round at the weekend so I need to do it myself.

Many thanks

 

[Goldspoon]

Turn boiler off (ideally at fused spur). Do not use boiler at all if no water in CH circuit.

If you can find a drain point on a radiator: Make sure the drain point is on the same floor or lower than the item you want emptied for working on (unless a full drain down and then you need to find a drain point on the lowest part of the system). Fix hosepipe to this drain point (with a clamp/jubilee clip unless you live dangerously) and drain off an amount of water to outside drain or garden (you'll see combi boiler pressure drop from whatever it is, likely between 1 bar and 2 bar... eventually to zero). Keep draining until you have emptied the rads (you will need to open the rad air bleed screws - starting at the top of the house and gradually working down - to allow air in, which in turn allows water out the hosepipe - essentially you are getting rid of a vaccum that would otherwise prevent draining). Take care that you are not just draining a "drop down leg of pipework" - this is okay but don't then go and work somewhere elsewhere on the circuit thinking everywhere is empty. Note that draining down can take quite a while. To check a rad is drained first open the air vent to see if water comes out from the top. If no water comes out then open its drain plug if it has one – if it does not have one then you can carefully start to undo one of the bottom valves from the pipework (with cloths and a water collection tray underneath of course). If anything other than a “last dribble” is apparent then nip the nut tight again sharpish and continue draining.

If no visible drain point METHOD 1: Then you'll just have to choose a low radiator and close the valves at each end of the rad (if one is a TRV then switch it to off or lowest setting). Then carefully drain the ONE rad only - by loosening the connection between the rad and the lockshield valve and letting the water flow into a paint tray or something suitable (open bleed valve at top of rad to allow air in). Be ready to tighten connection as water fills paint tray - rads hold a lot. When rad is empty you can then think about the rest of the water in the circuit (under pressure still!). You could dribble it all into a paint tray from the valve at each end of the empty rad but that will take forever. If you open either valve then water will spurt out the circuit... what can you insert or attach to these valves (you will have to drain water from both pipes and not just one)? To attach anything you might have to remove the rad or bend the pipework a little (otherwise rad is just in the way). For example on the TRV next to my desk now I could insert 15mm pipe (inc. olive and nut from a 15mm iso valve or compression fitting) into the TRV, tighten it up and then attach garden hose to that with a jubilee clip... then switch on TRV and water will be off and away. If it’s a big thread then a wash machine hose will likely fit (tucked into some waste pipe and fed outside or connected to a hosepipe using a small length of 15mm copper). It’s just about getting the water out and diverting to a drain or garden.

If no visible drain point METHOD 2: Method 1 does require care – bending pipework near any fittings can cause close by joints to misbehave and start to drip/leak! I therefore often prefer the following method: Turn off the rad at both ends then remove one of the top two nuts (one is likely a bleed and one a blank). This only works if they are 1/2 " threads. Screw a 15mm iso valve in (with some PTFE tape on the thread) and then add a short length of 15mm copper to the other end of the iso valve. From this you can drain (attach hosepipe to it and lead pipe outdoors). Only works if 1/2" thread and you want to bleed rads or pipework on a higher floor or level.

TOP TIP: If a rad is taken out but the flow and return pipes are left still pressurised then be aware a TRV can open if the temperature in the room drops enough due to frost setting sort of thing..

When re-filling you do this using the combi boiler filling loop (boiler still off) or a combi boiler filling key (as on my Worcester Bosch). Google some pics to see what these two methods look like. Stop at 1 bar pressure and then bleed downstairs rads (so water filling from bottom of house upwards)... pressure will drop so top up to 1 bar and bleed again and continue this bleeding all rads inc. upstairs. When no air in all rads pressure up the system to what it should be (likely 1 bar to 2 bar - check your boiler manual). You should add some inhibitor (early in this process - add inhibitor whilst drained down).

I add inhibitor via a rad: take out the top bung (like the air bleed screw but just a blank). Insert one end of a 15mm iso valve and gently tighten. On other end of iso valve is small length of copper pipe connected to small length of hose and then funnel. Pour inhibitor into funnel which then flows thru hose and past iso valve into rad (make sure iso valve open lol). You may need to open opposite air bleed valve to allow air to escape as inhibitor enters. One can add inhibitor like this at any time - just drain down some water, add inhibitor to a upstairs rad, then refill.

I am not a CH expert ... I'm sure somebody will chip in if I am wrong or have missed anything

 

[swidders]

No, you don't need to reduce the pressure to the system. Close the valves to the radiator (you will need a decorators valve cap for the thermostatic one to ensure closure) and undo valves from radiator, using a shallow tray to catch water that will escape from the rad. Have buckets ready, and when you can, lift the rad from its wall brackets and carefully empty into bucket (there will be sludge so take care since not easy to clean up), and carry it upside down.

Flush through outside using a hose ASAP and store upside down!

Re-use this forum when you want to rehang, fill and repressurise the system.

 

[Goldspoon]

If he does not wish to cap the pipes then I agree. If the valves can be left in place then no need to reduce the pressure. Sometimes one might have to remove the valves - as I did the other day in readiness for a rad removal to be followed by new stud wall. Then you will have to drain down (or pipe freeze).

 

[swidders]

Hi goldspoon

We posted our replies simultaneously, so wasn't being critical. All in all, we agree, which, since we are both right, we must!!

 

[Shaun-UK]

Re-use this forum when you want to rehang, fill and repressurise the system.

The only thing is I wont be rehanging it for about a month. The plan is for me to remove the radiator and cap the pipes. Then I will have a plasterer in before painting the walls. Then a plumber will be here to hang a new radiator on a different wall.

So I need to be able to pressure the system up and use it untill the plumber can come round.


To Goldspoon, I have an idea about bleeding the system but what i want to know is how to fill and pressurise my system using the filling loop/taps. Your post says "pressure up the system" but I am unsure how to do this exactly.


1 point to add. If I am just removing a small upstairs radiator do I need to drain the system? Can't I just drain the radiator itself and cap the pipes? then just turn the boiler on and add some pressure to the right amount?
Thanks again.

 

[swidders]

Sorry, I misunderstood what you meant by capping - didn't think you meant permanently. Out of interest, how are you going to do this (endfeed, speedfit ot compression?)

 

[Shaun-UK]

how are you going to do this (endfeed, speedfit ot compression?)

Sorry you lost me there mate

I was planning on undoing a pipe at the radiator and draining what I could. Then actually cutting the pipes and cap using push on copper caps. The reason for this is that the pipes are in the way of some timber which I need to remove that is screwed into the wall (part of some bizzare boxing round the pipes).

I have removed a radiator in an emergancy (long story) by hacksawing both pipes and capping with copper caps. We got abit wet but it seemed to work and the system didnt lose much pressure at all. I have considered doing this again but I would prefer to learn a better method

Thanks again

 

[Goldspoon]

To Goldspoon, I have an idea about bleeding the system but what i want to know is how to fill and pressurise my system using the filling loop/taps. Your post says "pressure up the system" but I am unsure how to do this exactly.


.

Google a pic of a filling loop. All a filling loop is is a link between a cold mains pipe and your central heating circuit. When you open the "link" you blast water into the CH system pipework. You keep doing this until the pipework pressure gets to 1.5 BAR pressure (or whatever pressure your boiler instructions say but usually 1.5 BAR is average). It will have one or two off on levers on it. Open lever/s to make this happen (and watch guage!).

 

[Goldspoon]

1 point to add. If I am just removing a small upstairs radiator do I need to drain the system? Can't I just drain the radiator itself and cap the pipes? then just turn the boiler on and add some pressure to the right amount?
Thanks again.

You have to drain the system to below the level of the rad that you are working on. If you just drain the rad then it will just keep refilling from the pipework. If you switch the rad off at both ends then the rad can be drained. But the pipework will still be under pressure and when you cut the pipework all hell will let loose (water spraying everywhere and it can be black and dirty and smelly with inhibitor).

 

[Shaun-UK]

Ok thanks Goldspoon, I take it the same applies if the pipes to the rad come upwards from the floorboards?

What I shall do then is drain the system from a downstairs rad.

Oh btw, whats this inhibitor you say about? Do I need some of it bearing in mind a plumber will be round in a months time?

 

[swidders]

Then actually cutting the pipes and cap using push on copper caps.

These push on copper caps are referred to as speedfit, and can be plastic since you're never likely to see them again and don't have to look pretty.

The only advice i can give about using these is to use a pipeslice to cut the pipe instead of a hacksaw - quicker, easier, neater/cleaner cut, and rounds off the end of the pipe making it less likely to rip the rubber seal when you push the fitting on. I tend to spray a bit of silicon into the fitting, but it's not really necessary.

Inhibitor is added to prevent the chemical reaction between water, copper and iron (radiator) which causes sludge to build up which is the bane of most systems. Not to use it for a couple of weeks shouldn't be a problem, but not good practice. Just make sure your plumber uses some when he completes his work - it's not expensive (about £20 should cover it)

 

[Goldspoon]

(about £20 should cover it)

Can be as cheap as £6.50 for a cheap brand... £12 for Fernox brand... that's for about ten to twelve rads.

 

[Goldspoon]

Ok thanks Goldspoon, I take it the same applies if the pipes to the rad come upwards from the floorboards?

Yes... go to floor below and find a rad/suitable point and drain

 

[swidders]

Quote:
(about £20 should cover it)


Can be as cheap as £6.50 for a cheap brand... £12 for Fernox brand... that's for about ten to twelve rads.

I've been robbed!!!