Will Draining the central heating mean the water heater wont work?

[Madrab]

thats from the manual...

View attachment 122586

That manual isn't for your boiler @james19000 , look at the picture and then you boiler

As you have marked -
DHW outlet is actually the cold water inlet
Return is actually the DHW outlet
Gas is OK

The 2 outside 22mm pipe's (marked flow and DHW inlet) are the 2 to isolate. If you aren't changing the radiator valves though then you don't need to isolate the boiler, just isolate the rad valves, drain it down and replace.

 

[james19000]

that is not your boiler old son. here is a simple trial , turn a hot water tap on and feel which pipe gets hot , that's the dhw outlet. think you will find its the one you marked " return ".

Bang on the money

the one I marked up as flow gets hot...

okay the ones marked up DHW outlet and inlet are my central heating/ rads...

 

[james19000]

That manual isn't for your boiler @james19000 , look at the picture and then you boiler

As you have marked -
DHW outlet is actually the cold water inlet
Return is actually the DHW outlet
Gas is OK

The 2 outside 22mm pipe's (marked flow and DHW inlet) are the 2 to isolate. If you aren't changing the radiator valves though then you don't need to isolate the boiler, just isolate the rad valves, drain it down and replace.

I was actually considering moving a couple of radiators, having removed them, in which case, I thought it would be a good idea to drain the radiator system. and then refill it once the new radiators are in place and installed.

 

[terryplumb]

• Bang on the money
  
  the one I marked up as flow gets hot...
  
  okay the ones marked up DHW outlet and inlet are my central heating/ rads...

  
  No you still haven't got it. the pipe you marked dhw outlet is actually the cold feed !!! as madrab said above ,the far left and right 22mm pipes are the flow and return. as he also said , if you are not taking any rad valves off you don't need to drain the CH anyway.

 

[james19000]

• 
  
  No you still haven't got it. the pipe you marked dhw outlet is actually the cold feed !!! as madrab said above ,the far left and right 22mm pipes are the flow and return. as he also said , if you are not taking any rad valves off you don't need to drain the CH anyway.

ok sorry guy's, I have been a little dim here and I thank you for your patience in trying to teach me something.

And I think I have finally got it and it it makes sense to me now.

I tried what Terryplumb said and I turned on the hot water and worked out what pipes got hot and what didn't

then turned on the heating system and placed my hand on the pipes to work out what got hot first and then second from the remaining pipes...

ok so this is what I think is correct.

Thank you Madrab for correctly pointing out the far left and right pipes... (I think I must be either lazy or dyslexic because it took me a couple of reads to see that he said " and right ", i kept on only seeing the "the far left"... only...

where Madrab says "if you are not taking any rad valves off you don't need to drain the CH anyway."

sorry , yes I will be replacing all the values as well.... and putting newer trv ones on.

thanks once again for helping.

I really appreciate the opportunity to learn, hence the reason I'm trying to get my head around this.