Vaillant Ecotech Plus 831 - isolating

[oldguy]

Hello,

I want to fit a new radiator in my existing system. My plumber removed the old one and capped of both pipes (JG speedfit end caps on existing copper). To do this he closed something on the boiler, then released pressure at the old radiator valves, whatever he closed created the vacuum in the system so he could simply cap off the pipes. He then simply re-pressurised.

I now want to fit a new radiator with valves but don't want to drain the whole system - I don't have inhibitor etc etc.

What did he close on the boiler? Flow and return valves? Are they the outer pipes on the bottom of the boiler - 22mm?

If I close these, i then need to release the pressure but how 'easy' is this if i just put a bucket on the end of the one of the capped pipes and release the speedfit cap? and is a bucket big enough? (with a cloth around pipe to avoid spraying water everywhere....
Or can i just open one rad bleed to lower the pressure first?

thanks in advance

By the way plumber can't come out due to COVID!!

 

[Deleted member 267285]

Is this new radiator exactly the same size? Upstairs or downstairs radiator? You can close off the valves under the boiler, and drain through a rad pipe, a builders bucket should be big enough.

 

[Elkato531]

On an 831, it would be the outer 2 valves (22mm). A 4mm allen key is the best tool to use. Boiler iso valves can be prone to leaking but I've never had a problem with the newer Vaillant ones. Before you do this, make sure all your radiators have been bled and any auto air vents on the system are closed. You shouldn't lose more than a pint or so of water before the vacuum stops the flow.

 

[oldguy]

Is this new radiator exactly the same size? Upstairs or downstairs radiator? You can close off the valves under the boiler, and drain through a rad pipe, a builders bucket should be big enough.

Thanks. It is two new radiators replacing one smaller one - 1st floor with boiler (house is on four levels - G, 1, 2, 3)

So I intended to 'T' off both the existing flow and return that went to the one radiator and split to two new ones.

Like the attached sketch - Is the orientation of the 'T's ok ?



If I close the valves and bleed the pressure out of the system from another radiator bleed screw (will take a while?) - then i can take off the speedfit end caps as otherwise they would go off like a bullet + water everywhere...?

 

[oldguy]

On an 831, it would be the outer 2 valves (22mm). A 4mm allen key is the best tool to use. Boiler iso valves can be prone to leaking but I've never had a problem with the newer Vaillant ones. Before you do this, make sure all your radiators have been bled and any auto air vents on the system are closed. You shouldn't lose more than a pint or so of water before the vacuum stops the flow.

Already asked Chris_W above, but.....best way to release the pressure out of the system once I've isolated the boiler? The old radiator was removed along with valves and speedfit endcaps fitted to pipes - so i canlt jus open the old valve.....Bleed another rad? Will take ages?

thanks

 

[Elkato531]

A few methods possible. There should be a drain point somewhere on the heating pipework. I often loosen a joint on another radiator valve somewhere with a drip tray under it.