Radiators off for decoratin - Inhibitor & mixing inhibit

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Hi,

I took two radiators off for decorating, I have put one back and filled due to cold weather. Yet to put the other one back on. I have decided it would be good to add inhibitor due to having diluted the system, and by replacing the second radiator I will be diluting it even more.

Only thing is I can't be sure what inhibitor was previously used. When the boiler was installed in 2004 (long before I owned the house) Sentinel was used according to the warranty document for boiler. Although the previous owners had a loft conversion in 2006 and two radiators were added, so the system may have been drained and refilled then, and possibly a different (or maybe even no) inhibitor used!

I was going to use Sentinel Concentrate, and my questions are:

What are the consequences of mixing two different makes of inhibitor? I know it is not advised, but what are the side effects?

What is the best way of getting it into the empty radiator, which is currently off the wall and empty. Can I inject it into one of the bottom inlets and is the concentrate gel thick enough not to run out when I reconnect it?

It is a sealed system with combi boiler.

Regards
 
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JPC

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are the rads new'ish...with the bleed and blank nuts on the sides at the top ? if so hang the rad and connect it..open a nut and inject it in the top, then close the nut and open valves as normal and vent/bleed the air out
 
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Yep, new radiators.... well 4 years old.

The bleed pin is set in what looks like a silver nut, and there is one at the top on the other side (but with no bleed pin).

Are you saying take this entire nut out or just the bleed pin and inject the sentinel? If I take just the bleed pin out and inject using sentinel concentrate in a caulk gun with the supplied adaptor the air will need to be displaced to make room for the gel, so I was going to leave the radiator disconnected where the valves are, but am worried the gel will flow out, or is it thick enough not to flow out for five minutes whilst I re-connect it!

Also, as I can't be sure what, if any, inhibitor is in the sytem what are the consequences should the one I choose (sentinel) be different from the one already in the water?

Regards
 

JPC

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mixed inhibitor will be fine
hang the rad...doing the valves up
undo one of the silver nuts and inject.
do the nut up
open the rad valves and refill with water

air displacement worries you have wont be a problem if u undo a nut as desc...

you may want some ptfe to redo the nut up
 
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Nice one... cheers.

Just that you read mixing inhibitors from different manufacturers is a no no, but nowhere does it states what the consequences are of such an action.

So if I understand correctly, if I take the entire nut off then the air will simply be displaced via the same hole as I'm injecting into, where as I guess if I take out just the bleed nut and use the adaptor which forms a seal the air would need somewhere else to escape.

PTFE tape around the screw thread on the blanking nut? Is that correct?

Regards
 
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Mission failed.

Got the empty rad on, but the Sentinel kept running out of the radiator despite taking the blanking nut out and opening the bleed valve on the opposite end. I tried to use a funnel with length of thin plastic tubing pushed down inside the radiator.

I do have a filling loop and have heard that it can be injected this way. Any ideas how to do this please?
 
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I do it this way (after experiencing what happened to you).

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 isolation 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.

(iso valves are a couple of quid... google for picture)
 
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Thanks for tips.

I've opted to purchase a Sentinel Rapid Dose valve for the filling loop (or maybe get the one you use in the rad) then buy the rapid dose X100 in the can and inject it that way.

I can't seem to find a drainage point for my sealed system. There are none on the radiators.

If I use the radiator dosing point apparently it can be left in place on the rad in place of the blanking nut and one can refill in the future if needed.

Anyone used the rapid dose? Is it messy?
 
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Re: drainage point... sometimes there are none...

Article I wrote for somebody shown below... for a combi boiler...

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: Fix hosepipe to a drain pipe on one of the downstairs rads (or might be a drain off point near boiler) 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 else thinking everywhere is empty.

If no visible drain point then you'll just have to choose a low radiator and close both the TRV (switch it to off or lowest setting) and lock shield valve (this then means that the rad is cut off from the circuit). 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 on rad to allow air in). Be ready to tighten connection as water fills paint tray as rads hold a lot. When rad is empty you can then think about rest of water in circuit (under pressure still!). Obviously if you now open the lock shield valve or the TRV then water will spurt out... what can you insert or attach to this? 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 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 with other end connected to some plastic 15mm pipe (or tucked into some waste pipe and fed outside). It’s just about getting the water out and diverting to a drain or garden.

TOP TIP: If a rad is taken out but the flow and return 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). Google some pics to see what one looks 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, either via pipework at TRV or by taking bleed valve out and putting in top of rad)..

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.
 
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