Realistically, I'd be concerned from the following points of view:
1. New boiler's secondary heat exchanger has likelihood of bits of dirt from the old heating pipe going into it. Could be warranty issue.
2. Debris may lead to damage to your hot taps and shower mixers (etc.).
3. Unless a check valve has been fitted, there is the possibility of a very minor amount of contamination getting back into the cold water (and hence the public water supply under certain conditions), so you might also damage your cold taps too. Unless the installer is registered with the water board as an approved contractor, YOU are liable for potential non-compliance with the Water Regulations. I'm not sure the dirty pipe is really a breach of the regulations as that dirt is not actually a plumbing material, but the potential for lead solder having being used at joints is a breach. That said, if your plumbing is over 35 years old, it's quite likely all your soldered joints contain lead and these can remain connected under grandfather rights, so ho hum.
4. Re-use of radiator pipe for drinking (potable) water is something you just don't do. In theory, hot water from a combi boiler should be drinkable (potable, (or 'wholesome' as they now like to call it)), and you're going to be bathing or showering in it. Technically, if a plumber were to test any existing solder for lead and to powerflush the old radiator pipe with an acid descaler or similar before re-using it, that might actually get it clean, but sadly the costs involved make this process unlikely.
Point 1 is likely to be the biggest deal, as the pipes will eventually run clean.
1. New boiler's secondary heat exchanger has likelihood of bits of dirt from the old heating pipe going into it. Could be warranty issue.
2. Debris may lead to damage to your hot taps and shower mixers (etc.).
3. Unless a check valve has been fitted, there is the possibility of a very minor amount of contamination getting back into the cold water (and hence the public water supply under certain conditions), so you might also damage your cold taps too. Unless the installer is registered with the water board as an approved contractor, YOU are liable for potential non-compliance with the Water Regulations. I'm not sure the dirty pipe is really a breach of the regulations as that dirt is not actually a plumbing material, but the potential for lead solder having being used at joints is a breach. That said, if your plumbing is over 35 years old, it's quite likely all your soldered joints contain lead and these can remain connected under grandfather rights, so ho hum.
4. Re-use of radiator pipe for drinking (potable) water is something you just don't do. In theory, hot water from a combi boiler should be drinkable (potable, (or 'wholesome' as they now like to call it)), and you're going to be bathing or showering in it. Technically, if a plumber were to test any existing solder for lead and to powerflush the old radiator pipe with an acid descaler or similar before re-using it, that might actually get it clean, but sadly the costs involved make this process unlikely.
Point 1 is likely to be the biggest deal, as the pipes will eventually run clean.
