Can this be done??

[deccy76]

I`m just about to start doing a fair bit of work on my house and was wondering whether my ageing boiler (Vaillant vcw 242) can be changed from a sealed system to a vented system with a header tank up in the roof. It`s already been changed from a combi system in the past and now it runs a HWC.

It would make life a lot easier for me to remove radiators, work on the system, etc with a gravity fed system than it would with a sealed system (never was keen on that idea). I know some boilers can be used with either set-up but need to know if this one can.

I know this is a step backwards nowadays but I was always a fan of the traditional 2 tank sytem. Any advice appreciated from anybody who may have done this

 

[mysteryman]

I wouldn't do that. Sealed systems have a lower oxygen content than even the best open vented.

 

[nickso]

can't see why it's easier to remove rads on an OV system than on a sealed one.

 

[deccy76]

I appreciate these points but just want to know if it will work as a system, or will the boiler throw a tantrum??

 

[mickyg]

its not recommended, and pointless and backwards. Sealed systems are much easier to work on,you don't even need to drain them for most tasks.

 

[Happyplumber]

Why oh why would you convert a sealed system to open vent ,I can not see any advantages to it at all ,most systems are converted to sealed not the other way around

 

[Boilerman2]

Would you get rid of your car and buy a Horse & Cart? in heating terms this is what you are contemplating. from a DIY point of view Sealed Systems are far superior, no problems refilling, no need to drain down every time you want to change a rad valve give me sealed every time
I really do think you should consider the merits of a sealed system, as the advantages do outweigh the disadvantages

 

[nickso]

to be fair you don't need to drain an OV system to work on it either.

still a pointless exercise to convert it back though.

 

[Boilerman2]

A novice would be wise to drain - those plugs and caps on the vent and CF can go very wrong in DIY hands!!!

 

[deccy76]

We`re getting away from the point here, I didn`t want to start a debate about open versus sealed system. I just asked the question "will it work?" because the open system is my preference out of the two

 

[vulcancontinental]

Why oh why would you convert a sealed system to open vent ,I can not see any advantages to it at all ,most systems are converted to sealed not the other way around

Just one I can think of straight away, no pressure relief valve.

Oh, two things: Combined cold feed and vent or 22mm cold feed and vent gives very few problems - if any at all.

Oh, three things: Less pressure on rad valve or pump glands and on auto air vents - important if there is cheap gear on the system.

None of these considerations are worth changing from sealed to open but they're real enough.

If you're converting from open to sealed add pipework buried in screed and old radiators as two reasons to be taken into account before doing so.

 

[deccy76]

But will the boiler actually run ok with this lower pressure??

A friend of mine has a very similar boiler (I think it was the previous model to mine), and his is fine working in the way I want mine. Just thought I`d ask on here to be doubly sure, but I seem to be banging my head against a brick wall.

Vulcan, thanks!!

 

[vulcancontinental]

But will the boiler actually run ok with this lower pressure??

A friend of mine has a very similar boiler (I think it was the previous model to mine), and his is fine working in the way I want mine. Just thought I`d ask on here to be doubly sure, but I seem to be banging my head against a brick wall.

Vulcan, thanks!!

Thanks are not in order, I don't think you should do it, I was only pointing out some of the things others haven't. I don't know the Vaillant model but if there's a low-pressure cut off the boiler will not work. Get the MI and look. I think Vaillant list the old ones on the site somewhere. Failing that, don't be shy, ring Vaillant, you maybe contemplating using something in a manner it is not designed or intended for.

 

[deccy76]

Thanks I`ll give that a try, cheers for the advice on this one

 

[transam]

I would contact Vaillant , if I remember correctly (???) there were some models that could be converted to an open system ?? I think !

ref sealed or open systems , pro's & con's to both , one of the problems that we often come across is with older people who get a sealed system explaining the filling process can cause problems ect ( personal opinion)
There is also no reason why you cannot have a sealed system that use's or keeps the expansion tank , which would now be the fill tank , providing the boiler is suitable ect done it many , many times with various boilers !