How to MIG weld a water jacket heat exchanger for a wood stove

[gaz1]

Do you guys realise that the guy that started this thread was a newbie and this was his first and only post!

He's probably been scared off by now by your arguments over the design of back boilers. Please knock it off!

theres no arguments here other than showing some errors or forgotten errors to do with that sort of system here in the uk

but the system is still in use even today and people should be very aware of what they are dealing with when dealing with those systems

but since you mentioned the old back boilers in the chimney they are prone to boil due to there design of straight up to the cylinder and back down

the issue with them is no sediment collection tank other than the back boiler itself and that can block up and thats when they can explode

they are also not a serviceable part either ( but could be with a sediment tank )

the danger lies when they arnt used due to central heating and then fired when needed as they can be blocked

a degrading one is noticeable due to longer heating times needed the more it blocks up

 

[Jelly_Sheffield]

He's probably been scared off by now by your arguments over the design of back boilers. Please knock it off!

I mean if he didn't realise what he was getting into when he asked the question, and decided that he might be biting off a little more than he could chew (moreso on all the not welding bits), that probably isn't such a bad thing.

Either that or he is sitting back with a big grin after putting the wooden spoon back in the drawer,

Equally possible... "I want to build a DIY fired heater/pressure vessel" is (and should be) almost guaranteed to be a controversial forum post.

(Apart from in Model Engineering circles, where the controversy is instead on how to get a test certificate for insurance if you dare innovate in any way.)

theres no arguments here other than showing some errors or forgotten errors to do with that sort of system here in the uk

I would say there has definitely been some disagreement over specifics... (what constitutes an explosion, whether a fusible plug is going to cause an accident or prevent a bad one being worse, whether radiator placement matters in a system, etc.)

But I think you're right that every party to those disagreements has agreed on the core bits of:
- use a vented system that is fail-safe,
- design that system properly, it could be very dangerous if you don't,
- tar formation will get worse with reduced temperatures so cleaning of flues becomes a more critical issue.

but the system is still in use even today and people should be very aware of what they are dealing with when dealing with those systems

They're already very rare, with only an estimated 1.3% to 0.9% of homes having (not necessarily using) one, and those being removed at a rate of about 16% (of the remaining number) a year.

It's very foreseeable that anyone buying a house with one fitted (especially a DIY one) won't understand them at all, and may do manifestly stupid things to them out of ignorance.

Back boilers, waste heat recovery all work in a domestic setting but must be a vented system, safety valves and fuseable plugs are all prone to failure

I would wholeheartedly agree it must be a vented system and did suggest the principles set out in Approved Document G as a great place to start understanding the requirements to design that system two pages ago.

My concern (and reason for suggesting of a fusible plug in addition to a properly designed system), is that as these systems get rarer, the likelihood of future owners making dangerous modifications to the vented system is only increasing...

One could argue that Obviously Harmful, Foreseeable Future Stupidity (that would be a good acronym to slip into a safety management system) warrants an additional Layer of Protection.

 

[addjunkie]

I would wholeheartedly agree it must be a vented system and did suggest the principles set out in Approved Document G as a great place to start understanding the requirements to design that system two pages ago.

My concern (and reason for suggesting of a fusible plug in addition to a properly designed system), is that as these systems get rarer, the likelihood of future owners making dangerous modifications to the vented system is only increasing...

One could argue that Obviously Harmful, Foreseeable Future Stupidity (that would be a good acronym to slip into a safety management system) warrants an additional Layer of Protection.

No matter what happens in any environment, there will always be someone who will fiddle with things. And no matter how many layers of protection, how many Hazop studies, or legislations are put in place you will never change that!

I once saw the aftermath of a big D type boiler that had gone bang, when it wasn't properly operated/maintained. Not what you want in your living room. Superheated high pressure steam getting out of its pipework isnt pretty!

 

[nickk]

I used a schraeder valve off an inner tube,jubilee clip around a 1” spigot that was already on the boiler when I rebuilt mine,the pipe fitting was already fitted,I welded it to the new back boiler I fabricated from 4 mm Dunbar plate. Pressurised to 2 bar,which I thought was 100% overload for a 2 bed cottage height.