Hello. Welcome to Just Answer.

Are you able to turn off the power to the wires in question?

Great. If you can turn off the electricity, and you expect to use those wires for a new boiler, please proceed as follows...

First, turn off power. Disconnect any wires necessary for removal of old boiler. Fold a couple of inches of wire over on the end of each disconnected conductor. Wrap tape around the folded end, so the cut end is completely covered. Leave power off until the electrician is ready to turn it back on.

If possible, please use an electrical tester to verify zero voltage before disconnecting the wires.

You can have all power other than the boiler circuit. If you must turn all power back on, it will be fine if everything is taped up. The electrician will turn it back off when he is ready to reconnect those wires.

Is there a junction box nearby, that those wires go into?

Can you see where they go from the cylinder?

You can take them out up to that point. The electrician will know how to address it from there, if necessary.

My suspicion is that disconnecting wires to facilitate removal of all necessary components is all the electrician will be looking for. It's likely he will remove additional wire, pipe, and other components as needed. Yes, just tape over any exposed ends as described.

Do you mean reconnect circuit wiring to the new boiler, in order to get hot water?

If you are comfortable doing so, and you know which wires to use, and where to connect them, I don't see any issues with it.

Are you able to post photos here?

Your main power wires to the old boiler will likely be the largest of all wires you will disconnect. The new boiler should have terminals on it with markings such as "L1" and "L2". Do you have it onsite now, and if so, do you see those markings?

That would be the input power terminals.

As I'm sure you are aware, wiring practices in the UK vary somewhat from what we do here in the US. Are you able to contact your electrician for verification of the information I am providing?

So far, it's pretty standard, so I think we are fine at this point.

Just those two components? Honestly, I don't know the conversion rates for the dollar vs. the pound. I could estimate a price if the work were being done here, if I knew a little more about what is being provided by you, and what is being provided by the electrician, relative to materials.

So, he will provide any necessary conduit and wire, and perform all labor? Will he be connecting control wiring, in addition to the main power wires? Does he have to bend conduit? US labor rates are about $85 to $95 per hour for an onsite electrician doing commercial work. Residential work is slightly lower.

Would you like me to estimate a full day's labor, and add an estimated material cost, based on US rates?

OK, let's round the labor up to $100 per hour. For 8 hours, that's $800. Good so far?

It's the materials that stymie me somewhat, because I am taking a bit of a wild stab at it, since I can't see it and don't know what all he needs. But it sounds like all components are within close proximity to one another. So I would venture a guess of $200 for materials, since much of what you have will be reused.

That brings the estimated price to $1000 USD.

I was thinking the same thing. Perhaps half a day? If so, that would cut about $400 from the price, if the work were being done here. Roughly that amount, anyway.