Replacement boiler - do radiators need replacing too?

TELLIT01

You don't need to change the radiators if you don't want to.  New radiators the same size as your existing ones will almost certainly be more efficient but it would take years to recoup the outlay.

Jeepers_Creepers

That level of water loss - 0.5 bar every 4 months or so - is not 'drastic' but certainly far from ideal. I mean, you do have an actual 'leak' somewhere! 

Every time you top it up you introduce fresh water which dilutes the inhibitor and also adds dissolved air to your system - a recipe for increased corrosion and system inefficiency. 

Please make sure you tell the installers this so they can hopefully do some tracing. It could be a pipe fitting (any 'green' around the rad valves?) or a seeping safety valve (any drips from the 15mm copper pipe outside you house? (Tape a clear plastic bag over it to catch the evidence!) Are the rad pipes under your floor? If so, is there a void there the plumber could have a gander at? Leaks are usually pretty obvious by a coating of scale or green 'corrosion'. 

Hopefully it's the pressure safety valve, because you are junking that boiler anyway :-)

Soot2006

I have nowhere near as much knowledge as most of the other posters but I have just had a new boiler put in. On a budget, so didn't do radiators which are ancient. Would rather do them all at the same time next summer ... Nonetheless, really pleasantly surprised by how much better the heating system seems to be working - rooms feel warmer and rads heat up much more quickly.

Working_in_pyjamas

Jeepers_Creepers said:

That level of water loss - 0.5 bar every 4 months or so - is not 'drastic' but certainly far from ideal. I mean, you do have an actual 'leak' somewhere! 

Every time you top it up you introduce fresh water which dilutes the inhibitor and also adds dissolved air to your system - a recipe for increased corrosion and system inefficiency. 

Please make sure you tell the installers this so they can hopefully do some tracing. It could be a pipe fitting (any 'green' around the rad valves?) or a seeping safety valve (any drips from the 15mm copper pipe outside you house? (Tape a clear plastic bag over it to catch the evidence!) Are the rad pipes under your floor? If so, is there a void there the plumber could have a gander at? Leaks are usually pretty obvious by a coating of scale or green 'corrosion'. 

Hopefully it's the pressure safety valve, because you are junking that boiler anyway :-)

Why is nothing ever simple eh! There's no obvious leak whatsoever, I did have a 'scare' a few weeks ago (see my last post!) but it turned out to be a once in a blue moon pet accident - glad I didn't have to call a plumber out for that one! The radiator pipes are under the floor so a fair bit of disruption to look at them I'm guessing. I'll be sure to mention it to the plumber, I'm glad I mentioned it on here as I just assumed it was an old and inefficient boiler that needed the occasional top up as standard.

FreeBear

Working_in_pyjamas said:  The radiator pipes are under the floor so a fair bit of disruption to look at them I'm guessing. I'll be sure to mention it to the plumber

Get the plumber to do a pressure test of the pipework. Plumbing that runs under concrete or buried in walls can cause problems... Copper pipe will corrode if in contact with cement (concrete) unless adequately protected. If there are any solder fittings buried in the concrete, these should have been thoroughly cleaned and any flux residue neutralised or the pipes could corrode at those joints.

Old houses can be a pain in the ar...

Jeepers_Creepers

Working_in_pyjamas said:

I'm glad I mentioned it on here as I just assumed it was an old and inefficient boiler that needed the occasional top up as standard.

Annoyingly, it's unlikely that the leak is in the old boiler as the chances are it would be obvious - a drip or a build-up of 'scale'. So I suspect you'll still have the leak with the replacement system.

It is possible for some slight weeps to evaporate away so not leave any actual puddles, but there would still be obvious chemical residue around where it's occurring - usually green or white.

Do you know where your 15mm copper safety discharge pipe comes out of your house? It usually either points down at the ground at near ground level, or else comes out higher up but would then curve back so's the end points against the outside wall. (Basically, if it 'blows', you won't want scalding water squirting at folk...)

Find that pipe and tape a small plastic bag around the end to catch anything that might be coming out. I'm hoping that some water does come out, because then the new boiler will solve it :-)

bris

Working_in_pyjamas said:

theoretica said:

If you decide against changing them it may well be worth getting them cleaned out of gunk.  Do they have individual thermostat valves?

Is that the same as a power flush? I'd read that a power flush is needed when fitting a new boiler so was planning on having that done.

The benchmark requires the system is cleaned, we do that with chemicals rather than a power flush. A proper power flush can cost about £300+ so installers use chemicals and should fit a Magnaclean or similar type filter to the system to keep it clean.

Having the water at the correct PH level is now a warranty issue and a reason to deny warranty claims if it's not right.

Working_in_pyjamas

Jeepers_Creepers said:

Working_in_pyjamas said:

I'm glad I mentioned it on here as I just assumed it was an old and inefficient boiler that needed the occasional top up as standard.

Annoyingly, it's unlikely that the leak is in the old boiler as the chances are it would be obvious - a drip or a build-up of 'scale'. So I suspect you'll still have the leak with the replacement system.

It is possible for some slight weeps to evaporate away so not leave any actual puddles, but there would still be obvious chemical residue around where it's occurring - usually green or white.

Do you know where your 15mm copper safety discharge pipe comes out of your house? It usually either points down at the ground at near ground level, or else comes out higher up but would then curve back so's the end points against the outside wall. (Basically, if it 'blows', you won't want scalding water squirting at folk...)

Find that pipe and tape a small plastic bag around the end to catch anything that might be coming out. I'm hoping that some water does come out, because then the new boiler will solve it :-)

Thanks again for such a detailed reply, really helps those of us who are not DIY/practical minded - the boiler is in the garage and there's all manner of pipes shooting off to various places, there's no pipework on the outside of the house itself so I'm guessing the pipe you mention must be in the garage - I'll take a look tomorrow in daylight.

Jeepers_Creepers

If it helps, take a photo of the pipes as they come out from the boiler.

The discharge pipe will be copper (definitely) and 15mm (usually). Not to be confused with the mains water inlet and the DHW out from the boiler :-) (And even sometimes the gas supply...)

kdotdotdotdot

I've just had a boiler replaced and all five quotes I got from various companies included cleaning out the system first and adding a magnet to where the water comes back into the boiler to 'catch' any remaining sludge.  I got the impression that this was standard, so probably something you'll get quoted for anyway.  

You'll need to tell them how many radiators you'll have and also your plans for adding a shower because they need all that information to calculate what size boiler you need to run the system.  Now's a good time to think of future plans, as you are, to add showers or change over radiators.  Also consider if you want to move the boiler, although that costs more, of course.