soldering an air separator into central heating

[shortplank]

I'm battling trying to get an air separator (one of these) soldered successfully. The issue I think is that I just can't get it hot enough. I'd initially connected it via solder ring connections however wasn't convinced they'd joined correctly. Sure enough both leaked when the system was connected up. I've re-drained the system, but using a standard butane/propane blow torch I can't get it to the point that solder will melt on it.

Has anyone got any tips or suggestions?

thanks

 

[Hugh Jaleak]

Whats your soldering experience like? Number of factors that could have caused it not to take properly first time round, insufficient heat is one. Also, if there is water remaining in the pipework at the point you are trying to solder, it will never take. Secondly, if the joint has already been attempted, it is extremely difficult to get it to take on a subsequent attempt, the pipework is too dirty from the previous attempt for the solder to take.

Personally, I'd ditch the air sep and make a H with the pipework, it'll do the same job if done properly. If your blowlamp is struggling, then get a decent one before attempting anything else, 22mm pipework will need more heat than 15mm, obviously.

 

[shortplank]

thanks. My experience isn't huge but I've done a number of standard pipe joins which have been fine. I'm 99% sure there isn't still water in the system, it's been drained from a downstairs radiator, 3 way valve is manually open and I've checked the bleed point on the pump which was dry. I think it may just be too dirty and I was thinking of removing it and just joining it up without it. The blow lamp is handling standard 22mm joins absolutely fine.

The background is that the system didn't have an expansion pipe, just a feed pipe so I've added a new expansion pipe in and used the air separator to join it to the system. It'll end up almost like a 'H', but with the flow to the pump continuing horizontally for a short period before dropping vertically (see attached).

 

[Hugh Jaleak]

Provided the R/H upward leg of that diagram is the vent (22mm), and there is 150mm min between the vent and cold feed, then there's no reason it shouldnt work.

Pipes need to be spotlessly clean for the solder to stick, I always use wire wool then flux, (Laco), as belt and braces. Not sure what blowlamp you're using, but if you do a fair bit of plumbing, its worth the investment in a decent torch, the cheap ones will struggle to get bigger work hot enough without melting half the surrounding area at the same time.....

 

[shortplank]

thanks. They'll be about 90mm between the feed and vent, yes the r/h is the vent.

 

[Hugh Jaleak]

Edit. Yes, maximum 150mm apart. Got it the wrong way round, teach me to multitask....

 

[shortplank]

hmm, ok. My understanding was that they needed to be a maximum of 150mm apart?

 

[picasso]

You had a combined feed and vent (probably for a reason) what was wrong with your system that you wanted to install an air seperator?

 

[shortplank]

There was expected pressure build ups in the pipes, several plumbers have suggested that it needs a seperate vent pipe to alleviate this

 

[picasso]

Was the cold feed in 22mm ?

 

[shortplank]

Cureently yes. One of the issues is when a number of the rads have turned off (all but one have thermostatic valves) the pipes ar often clunking. Having talked to a number of plumbers the next thing to try was adding a seperate vent pipe.

If this does make things worse then the system can be returned back to a combined vent/feed relatively easily.

 

[picasso]

Sounds more like you need an automatic bypass than messing with the vent/feed.

 

[shortplank]

Sounds more like you need an automatic bypass than messing with the vent/feed.

that was going to be my next step after putting in a vent

 

[bazdaman]

It should be your first step!

 

[shortplank]

There's a little bit more to it than what I've said in this post, I haven't explained it all as I was initially asking specifically about the solder/air separator issue I had. Having moved in a couple of months ago it seems there are a number of issues with the system: I'm making once change at a time (this vent pipe isn't the first change) to resolve the issues and as mentioned above I've talked everything through with several plumbers. I probably shouldn't have only mentioned the pressure build ups above, sorry. Due to the layout of the system I cannot easily fit a bypass in without lifting the floor boards which I wasn't in position to do this week. That'll happen when I have some help in a few weekends time.

thanks for everyone's help