replacing old compression fittings with combi install

[InTheBeginning2007]

The CORGI plumber who is going to comission my new boiler said he would prefer me to do the water pipe work as the existing pipework is all done with compression fittings and he wants nothing to do with it.
He suggested replacing it all with solder joints or plastic.
The house is 1965 and I think the CH system dates from then. I suppose he has a point that with the higher pressure in the pipes that a combi uses, it could cause leaks, but I think it is unlikely. Maybe I will have to tighten a joint or too, but I dont think I will have any serious issues.

Has anyone out there got an opinion on this matter?

Am I right, or is the plumber ( he is not long qualified and I would say not greatly experienced)

 

[Bahco]

He has given you good advice IMHO.

The old fittings may not take the new pressure.

Get your blowlamp out.

 

[hi-spec plumbing heating]

He suggested replacing it all with solder joints or plastic.

compression is better than plastic.

 

[InTheBeginning2007]

He suggested replacing it all with solder joints or plastic.
quote]


compression is better than plastic.

my thoughts exactly.

 

[oilman]

I suppose he has a point that with the higher pressure in the pipes that a combi uses, it could cause leaks, but I think it is unlikely.

It uses pressures no higher than the mains pressure (and a lot lower for the primary side) in many water supply pipes to houses. Indeed, if the incoming main is plastic, it is very likely to be a compression fitting which joins it to the stopcock, and the other side of the stopcock is, er, compression.

On the primary side (heating) the pressures are often no higher than would be seen in a gravity fed system (static pressure).

I can understand he might not want to play with the compression fittings, but then he's given you bad information, so I would find someone else.

 

[hi-spec plumbing heating]

it's a combi boiler being fitted cause the pressure is higher than gravity system.

 

[oilman]

It doesn't have to be any higher than you would find in a 3 storey house, except under fault conditions I suppose, but it is still loads less than many mains pressures.

 

[Bahco]

I didn't read the post properly but would renew all pipework and joints on a very old system if I was having a brand new combi.

Saves the need for powerflushing and you then know you have a clean system.

Rip the lot out son!

 

[hi-spec plumbing heating]

your going to upset him

 

[namsag]

Bahco it may save the need to power flush but it won`t be clean it still needs hot and cold flushing..

 

[Bahco]

Sorry, should have said replace all the rads too.

 

[InTheBeginning2007]

Sorry, should have said replace all the rads too.

I will be replacing all rads, but not just yet. I have run the system with chemical cleaner in it (two lots), over the couple of months, and intend to talke the rads off and flush them before the combi is fired up. The pipes are now looking clean inside and the CORGI guy says he doesnt powerflush the system, only uses mains pressure to flush (probably just too tight to buy a powerflush machine).

I am now thinking of replacing the hot and cold water pipes only, and leaving the CH alone. The water pipes are all easily accessable, but the CH is not, and the pressure difference in the CH will be minimal, going from 0.7 bar to 1 bar.

 

[Nige F]

The CORGI plumber ...............and he wants nothing to do with it.
Has anyone out there got an opinion on this matter?

Am I right, or is the plumber ( he is not long qualified and I would say not greatly experienced)

Yeah, he`s one of the new "breed" easy ££ and don`t want to get their hands dirty Corgi But a necessary because of safety......here speaks the dinosaur plumber

 

[JohnD]

you might think about adding a Magnaclean.

Even after chemical clean and flush, the one I fitted during the summer is picking up about a teaspoonful of black each week now that the colder weather is here and the rads are on in the evenings.

 

[Perfect1onist]

You are going to have much higher pressure hot water than before with the new boiler(assuming old boiler was a conventional one) and may get small leaks from old/not well done joints and from taps to start with (especially on the domestic hot water supply side). Best thing to do if you are not going to renew old pipe work and old rads is to redo the joints that fail and fix leaking hot taps, assuming not all and only a few fail (small leaks i.e. drips not proper) - should be quite easy. I am an expert at this as i have recently had a new combi boiler and re-did all the pipe work in my maisonette in chrome pipe after using the old boiler to beat Fernox round the system for a month prior to installing the new one. There's loads of lovely chrome pipe on show as the floor is concrete! So new combis is in loft and all pipe work comes through ceiling to rads.

What about the old system?- your "plumber" will need to do some pipe work to install the boiler and run the new cold in feed and domestic hot water supply. Central heating pipe work shouldnot change too much if new boiler is going in same place as old one. Presumably you are going to have to lose the old hot water tank?

Not all Corgi guys are any good at plumbing. For defs!