3 port valve odd question

[bigmadkev]

Hi one and all,
Fantastic forum I have used numerous times for my basic diy knowledge and found it so helpful!!

Anyways yesterday I channged my central heating controls and three port valve from switchmaster to honeywell, all is ok and it worked first time to my amazement!!!
Although i had to modify the pipe from the boiler flow to the three port valve I used three right angled hep pushfit fittings. All is ok with no leaks however I am now comtemplating wether to change these for propper copper ones as I do not trust these plastic fittings with
Hot water.
my question is can I remove them without draining the system again? As it is only on the boiler flow I have to change not all three. I can turn the pipe off at the water pump but will any water come out of the honeywell three port valve? Obviously system will be switched off at mains?
So basically will any water come out of three port valve if I disconnect the boiler flow pipe?

Thanks everyone in advance,
Big mad kev
Hope that made sense lol

 

[Armo74]

You will only have to do a partial drain down to change them.

Don't forget to top up with inhibitor.

You have to remember that when installing plastic fittings they effect the integrity of the earth continuity.

When installing them supplementary earth bonding has to be considered.

 

[petertheplumber12]

The answer is yes the three port valve is open on the hot water when no power is applied to it. You can blank off the vent pipe over the F&E tank, and close off the water supply from the F$E tank with a tapered rubber bung. Then let water out of the system at a convenient point until it stops, about 1/2 gallon should do. Then you can open 1 joint at a time without loosing water. I am sure you will understand the negative pressure principle. Like a full bottle upside down with the neck in water. Nothing comes out.

 

[bigmadkev]

Nice one thanks guys, so it looks like il have a partial drain so no big deal,
So to recap I have to switch off supply to tank switch off heating ( then power off ) undo my AB CONNECTION to boiler drain until nothing comes out then I can connect new pipework up,
As for the earth continuity thats a good point!!! Can't believe I overlooked this and let the guy in the shop talk me into plastic connectors!!!!

Hindsight is a wonderful thing

Thanks guys you are stars!!!!!!

 

[petertheplumber12]

Switch off supply to tank sounds dif to what I said but follow stopping supply and capping vent and should be ok.

 

[bigmadkev]

Lol sorry mate you have to forgive me, soif I cap the pipe at the top ( is this the vent pipe ) then that would cause a backward vacuum sort of thing so water will cease to go in valve?
So I will only drain what is in pipework?
Thanks again

 

[bigmadkev]

Also I only need to take off the boiler return pipe not all three, is there anyway I can put valve into manual mode to block valve? Or is it either hw or ch. It is a honeywell v4073
Thanks all again lol

 

[petertheplumber12]

Lol sorry mate you have to forgive me, soif I cap the pipe at the top ( is this the vent pipe ) then that would cause a backward vacuum sort of thing so water will cease to go in valve?
So I will only drain what is in pipework?
Thanks again

Yes and shut off cold water supply from tank (15mm usually) with a rubber tapered plug, they sell them in pairs in all plumbing shops, and I think wicks and B&Q and screw fix. That way any probs and you won't loose much water.

 

[petertheplumber12]

Also I only need to take off the boiler return pipe not all three, is there anyway I can put valve into manual mode to block valve? Or is it either hw or ch. It is a honeywell v4073
Thanks all again lol

It is either hot water or heating or both when at rest it shuts off heating for hot water only any manual use off the lever sets it at both which you don't want. By the way the valve will last longer if you have hot water on at a different time to heating.

 

[bigmadkev]

Superb thanks matey !!! Il crack on with it tomorrow and hopefully all will be ok, lol I just dont trust these plastic fittings what are your view on them? I just have visions of them popping off one day and spraying hotwater everywhere over my house!!!
Also we only use hw or ch not both ( to be honest I didnt realise you could have both on at once ) haha

 

[petertheplumber12]

Superb thanks matey !!! Il crack on with it tomorrow and hopefully all will be ok, lol I just dont trust these plastic fittings what are your view on them? I just have visions of them popping off one day and spraying hotwater everywhere over my house!!!
Also we only use hw or ch not both ( to be honest I didnt realise you could have both on at once ) haha

The reason I don't use plastic is because mice and rats can eat them and cause a bad leak. OH Dear.