draining central heating system

[prbrown]

not sure ill get a straight answer but here goes -
single pipe central heating system linked to oil boiler
oil boiler is no more - using immersion heater for hot water as interim untill new boiler installed
need to remove old central heating system / drain down / remove pipes and rads as installing UFH downstairs.
can/how do i drain down system and keep our hot water supply via immersion while removing and installing new UFH pipes and floors ?
cheers in advance
paul

 

[Best]

Your heating system is a different water system to your hot water cylinder water.
You will have a small tank in attic that solely feeds the heating system if it is opened vented heating.
Or you might have a sealed heating system with a manual filling point from mains via a filling loop.
Most likely small f&e tank that needs isolated from mains and heating drained

 

[Best]

Your heating system heats the hot cylinder using a coil pipe inside it (indirectly) so the heating system water does not mix with your hot water.
If it did, your rads and boiler would rust quickly plus your hot water from taps would have corrosion products in it.
You will be able to continue using your immersion if you have a separate large cold water tank supplying the hot cylinder

 

[Riley]

So yes. Two straight answers in fact 😀

 

[prbrown]

thank you - ill double check but i think there is just 1 tank in the loft (I recently re-insulated loft ) - i assume its feeding the hot water tank as its quite large - i'll trace some pipes.......but then not sure what was feeding the central heating - i think it must be a sealed system!

 

[Best]

thank you - ill double check but i think there is just 1 tank in the loft (I recently re-insulated loft ) - i assume its feeding the hot water tank as its quite large - i'll trace some pipes.....but then not sure what was feeding the central heating - i think it must be a sealed system!

The f&e (feed and expansion heating tanks) are quite small - about 45cm x 30cm area and can be hidden. Trace pipes from coil connections at side of cylinder to see if they have a vent and feed pipe teed off rising into loft. If they are just capped, then might be sealed system.
If it is a sealed system then there might be a red expansion vessel somewhere possibly close to oil boiler, or in airing cupboard. Or the boiler might be a system boiler which includes the red vessel within the boiler casing.
There is another type of system that uses an internal vessel inside a special cylinder called Primatic cylinder and that would require the cylinder drained and coil connections plugged at cylinder.

 

[Riley]

Anything on cylinder saying primatic

 

[Rob Foster]

not sure ill get a straight answer but here goes -
single pipe central heating system linked to oil boiler
oil boiler is no more - using immersion heater for hot water as interim untill new boiler installed
need to remove old central heating system / drain down / remove pipes and rads as installing UFH downstairs.
can/how do i drain down system and keep our hot water supply via immersion while removing and installing new UFH pipes and floors ?
cheers in advance
paul

There is no straight answer on UK PF to your enquiry because its unusual ...however there are loads of really experienced people on here whom will help you....Centralheatking esp when you wind in the oil boiler etc ..but yes just go for cylinder with an immersion
UNTIL October when it goes cold