To replace heating pipework or not when putting in a new boiler and unvented cylinder

[Nathan1976]

Hi
We've just bought a 1970's house with oil fired central heating system with original rads, a new(ish) cylinder at first floor and pipework laid in the floor/screed. Our plumber has recommended renewing the system with an unvented cylinder, new boiler and new rads with TRV's this removing the need for the header tanks if the loft space. He has however suggested re-using the pipework laid in the floors running to the rads.
Clearly not renewing the central heating pipes will be a cheaper option but I am concerned about the risk of using the old pipes.
We've had the old boiler working over the last week or so which suggests the pipework is still watertight.
Is their a significant risk of using the old pipwork with a new system?
Many thanks in anticipation.
Nathan

 

[SimonG]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

Your current system will be vented (open to atmosphere) is your new one going to be vented or sealed?, if your plumber is talking of removing the tanks then I'm guessing sealed. For the money you are spending do you really want to be digging up floors in x amount of time? It also depends on how the pipework was installed in the floors was it wrapped to prevent contact with the cement or just chucked in.

First thing I would be doing is getting a pressure test on the downstairs pipework and then decide from there.

I always have a condition on my estimates that does not guarantee watertightness of existing pipework.

 

[PlumbBobBob]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

i agree you really need to know the state of all the pipes even those buried before subjecting them to pressure. as simon G says get a pressure test done in the first instance, as this will show up any weaknesses.

 

[Best]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

Depends who did the original work & with what materials & how well pipes are protected below the floors etc.
Some work 30 or 40 years old could be as good as new, other work done recently could be poor. Risk of some dirt lying in pipes though. Personally, most work is better renewed, - if you have a plumber capable of doing a perfect job, that is!

 

[happyflyer]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

I would beware of any plumber who is suggesting this in the first place, does he have funny looking eyes that might be x ray, get rid of him
its a poor start with better things to come if you employ him or we will see you on Rouge Traders :75:

 

[Killy Bing]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

Hmm, i avoid pressurising pipework in concrete/screed like the plague, if it leaks you have the hardship of finding where and then getting too it, after that if it leaks the first time then theres a half decent chance to leak elsewhere.

are you planning to do a loft conversion?

 

[Nathan1976]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

Simon
Many thanks for your advice.
We do currently have a vented system with tanks in the loft space which we want to get rid of.
I'll certainly be looking at the pressure test in the first instance and go from there.
As ever, there appears to be conflicting advice from other professionals I've spoken to so I'm really just weighing up the risks and potentional cost implications of not changing the floor encased pipes against biting the bullet and replacing them!
Thanks for your prompt reply again.

 

[happyflyer]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

Simon
Many thanks for your advice.
We do currently have a vented system with tanks in the loft space which we want to get rid of.
I'll certainly be looking at the pressure test in the first instance and go from there.
As ever, there appears to be conflicting advice from other professionals I've spoken to so I'm really just weighing up the risks and potentional cost implications of not changing the floor encased pipes against biting the bullet and replacing them!
Thanks for your prompt reply again.

There always will be a conflict in advice between plumbers, its your level of acceptability, no one in the right mind would put pipe in a slab, unless it was endless and for under floor heating, no one in their right mind would connect a new system to an old system with pipe in the slab, drain it and blank it off and put all new in, you don't have clue of the condition.

 

[Bunker]

Re: To replace heating pipework or not when putting in a new boiler and unvented cyli

Mods, although OP has an oillyboily, this is a thread for a different part of the forum. He may get broader responses from the Central Heating area.