Replace Radiators - Can I continue to heat water

[Skid Solo]

I have an old vented heating/hot water system with a boiler in the garage, hot water cylinder in 1st floor airing cupboard and expansion tank, along with cold water tanks in loft.

I am going to replace all radiators in property, before new system boiler and unvented cylinder installed by qualified installer

I estimate replacing the radiators (20 in total) will take me a couple of weekends, so was planning on draining down the system (new radiators will not be connected to existing pipework as all pipework being replaced)

My question is can I continue to use the hot water heating from the gas boiler ? or do I need to use the electric immersion heater for 2 weeks (I would rather use the gas hot water heating)

If I can continue to use the hot water from the boiler, when I drain down the heating system do I have to position the 3 port valve in a particular position and remove the servo head to stop any chance of water being diverted to the heating system which will have unconnected pipes ? Obviously I will turn the heating off from the control unit but assume I will have to ensure that the expansion tank in the loft is full to provide water to the heating part of the hot water circuit

Apologies if I have not used the correct terminology, but I hope the above makes sense, any help appreciated

 

[Rico99]

Skid,

unfortunatley the heating circuit needs to be full and bled. It is this water that runs through your boiler then through your cylinder coil.

You'll have to use your emmersion

Rico

 

[diyangel1]

where will you be getting your radiators from mate?

 

[Skid Solo]

Thanks, not what I had hoped to hear but what I feared.

Already got rads thanks

 

[echoes]

It's possible, but you would need to completely sever your CH-only pipework without leaving any dead legs and then refill & bleed the remaining HW. Sounds far more trouble than using the immersion.

EDIT - just re-read the '3 port valve' - forget it! Immersion it is.