Soldering Wet Pipes

[qubit]

Hello I have soldered dry pipes previously but not wet I was getting ready to solder wet pipes but read somewhere on this forum that I shouldn't because apparently I wouldn't be able to get the pipe dry and should use a compression fitting instead

Do most plumbers use compression to connect to existing (wet) pipes?

Is it okay to use compression on a combi system because I've heard that they shouldn't be used on a pressurised system?

Any help greatly appreciated please

 

[seco services]

where on the systemis the pipe and why can't you get it dry ?

 

[malkie]

If its got water in the pipes DO NOT try and solder you might think its ran but it just leaks you may be lucky but i wouldnt try it,or stick some bread down the pipe and see if it keeps it dry enough to solder

 

[shambolic]

Nothing wrong with compression on a sealed system.

 

[malkie]

I had one yesterday on a 22mm heating pipe and i couldnt get the water out and tried to solder it,i seen it run but as i was about to fill up i went and got a conex and used that and the solder hadnt ran all the way so use conex

 

[qubit]

Thanks for the replies Mr Malkie, Mr Shambolic and Mr Services

Mr Services I would hope I can get it dry possibly using a combo of draining off pipes by turning off supply and turning on taps for about 5 hours then using a wet vacuum to suck out water then stuffing some bread in then drying with tissue paper and such and then by heating the pipe with a blowtorch but according to many on this forum even this may not be enough and I don't want to use all that time and still have a dodgy joint and I'm sure others like yourself have experience of these things so I don't have to go through all that

Mr Shambolic that is very relieving to hear because I saw in some plumbing video a bloke saying compression joints shouldn't be used with a combi boiler because the pressure could push off the olives I doubted it because I know how hard it is to move a tightened olive and I doubt even 3+ bars could move an olive

Could I ask just one more q it should be okay to turn off the boiler valves supplying ch return and flow and continue using the boiler for dhw shouldn't it? (Vaillant Turbomax Plus 828E, looked through the entire instruction manual couldn't find any specific guidance) That would be very helpful because I could leave the ch system off for a long time (to dry a little) whilst continuing to use the hot water thank you very much

 

[ChrisR]

conex

I think he means Compression Conex make the best compression fittings, but they also do solder ones, and everyone makes compression...

 

[seco services]

as you say using a wet vac never had a wet vac let me down on soldering even when pipes in screed and lower than draincock and used wet vac to drain the lower section of pipework.

 

[malkie]

Im sure it wont work if you close the valves and keep the pressure up it needs a flow to let the heat excess push into the system,im sure it will o/heat

 

[qubit]

Wow excellent Mr Services that makes me feel much more confident now

How do you get the vac to seal around the pipe though

 

[qubit]

Wow Mr Malkie you're a very knowledgable person thanks for the reply

I thought that dhw excess heat doesn't go into the the ch system I thought that only occured with the much older boilers (where you left one rad's valves fully opened usually the bathroom to let off the excess heat)

Don't modern boilers let off excess heat through other methods and the boiler pressure is at 0 at the moment does that also apply to dhw I thought the pressure bar only applies to the ch system sorry for the dumb q's you can tell I'm careful with boilers cus if there's a prob in this freezing wheather it's a knightmare

 

[shambolic]

Im sure it wont work if you close the valves and keep the pressure up it needs a flow to let the heat excess push into the system,im sure it will o/heat

The pump overrun will noy be able to push excess heat into rads so will overheat like you said!

 

[shambolic]

You still need water inside the boiler for the hw to work as all you are doing is diverting heat internally round the boiler heating a plate heat exchanger(unless valiant doesnt have one). BUT ADVISABLE NOT TO RUN BOILER WITH NO WATER IN CH SIDE AT ALL.
Do all your soldered joints first then use a compression joint for last connection to water side then you will have no problem.

 

[seco services]

Wow excellent Mr Services that makes me feel much more confident now

How do you get the vac to seal around the pipe though

useally just push the tube over the pipe is enough or hold your hand round the end helps seal it.

 

[malkie]

It is to tell you what pressure is in your system but it must around 1 1/2 its a pressurised system so you must keep pressure in it,most boilers wont work if you have no pressure,ive fitted combis were they dont want rads on just yet and i had to run a few foot of copper from the flow to return on boiler just to let the h/water work it needs to have a flow so it wont just heat up and up until your boiler is in your neighbours kitchen so just be careful