Hi everyone! Advice needed for back boiler

[woody123]

Hi all. Thought i would register so i can get some advice on the correct procedure for draining a potterton 51 combined gas fire and back boiler. I am currently installing a new bathroom and tiling in a customers house and she has the above mentioned back boiler. I have managed to isolate the hot and cold supply no problems and changed over bathroom suite but she is wanting a new towel radiator fitted and i have only ever drained down a combi boiler system before and just want to check i am doing this right.
Ok first i will make sure the boiler and fire is switched off and turn off the pump. Then i will isolate the supply to the feed and expansion tank. The only drain off point i can find is situated on the pipe coming out/going into the chimney breast so im assuming if i attach a hose pipe to this drain valve then start opening the bleed valves on upstairs radiators them move to downstairs this will be fine or is there more to it?
Upon refilling the system after i have adjusted my pipe work then i will close the drain valve and all the bleed valves and then put th water back into feed and expansion tank and bleed radiators from downstairs upwards?
Is this the correct procedure and if not can anyone give any other advice or is there a quicker way i can do this where i only partially drain the system (if that is possible) also plan to add some inhibitor to the f&e tank.
Sorry for the long post!

Cheers Chris

 

[PlumbBobBob]

hi woody123 welcome to the forums

steveb

 

[dontknowitall]

Seems like you're doing the right thing - is the back boiler capable of heating the HTR as well as the other radiators? Would be a pity to fit everything then find it doesn't work as you wanted!

 

[woody123]

Thanks for the reply's guys

I am replacing an old radiator with a HTR in the bathroom. Will this not just be the same output as the radiator that im replacing or do the HTR have higher BTU or something? I am not adding any extra radiator's just replacing.

Should this be ok do you think?

Also have you ever experienced any problems when drainingn down these systems? i have heard you can sometimes get airlock's?

Always grateful for the advice

 

[dontknowitall]

If replacing you should be okay. Air locks are not common. Worry about this if you get one.

 

[woody123]

Good stuff dontknowitall. Thanks for your advice. I had a good idea of how to do it but it's always good to get it confirmed.
Cheers Mate