disconnect a back boiler

[ian260281]

hello - I have just bought my first house and wish to drain and disconnect the pipes feeding the backboiler as the chimney breast has recently craked and I need to fit a log burner, therefore digging out the backboiler.

there is a drain tap next to the fire breast.

there is a pipe feeding and returning the HW tank.

if i drain the backboiler next to the fire breast, will the pipes fill back up? I can not find a supply?

would i be right in thinking the system is closed loop, or will it have a fresh water supply which i need to turn off?

I was planning on draining the BB then disconnecting the pipes when i dig the old fire breast out - i will then cap the pipes off. I guess i could do this at the HW tank but there is very little space to get in round the back of the tank.

any advice would be very much appreciated

cheers,

Ian

 

[Mike Jackson]

Sounds like it may be a direct system. The same water will go through the boiler as in the cylinder, fed from the cistern in the loft.

 

[ian260281]

there is a cold water tank directly above the HW tank, this feeds the bottom of the HW tank.

I currently heat the water via immersion.

how do i tell if the BB pipes going into the HW tank are open to feed the boiler or a coil of pipe filled with water only from the BB?

cheers,

ian

 

[Mike Jackson]

If you've only got one tank in the loft it's likely that it will be a direct system. If there is no drain cock on the cylinder it's normally a good indication as well, the drain off will be on the back boiler.

 

[ian260281]

so if i drain it at the BB, it will drain the whole HW tank?

best bet is to drain HW tank, turn off cold supply, cap off the two pipes coming out of the HW tank then fill the HW tank back up?

ian

 

[ian260281]

so i will need some blanking caps to do this? is 21mm the standard for HW?

do these fitting work on a taper to create the seal or do i just tighten them up real good?

 

[Mike Jackson]

so if i drain it at the BB, it will drain the whole HW tank?

best bet is to drain HW tank, turn off cold supply, cap off the two pipes coming out of the HW tank then fill the HW tank back up?

ian

Assuming it is a direct system yes. The pipes coming out of the cylinder will normally be 28mm or 1".

 

[tamz]

The pipes coming out the cylinder will be 22mm or more likely 3/4" as it will have been in a long time

 

[michael c]

Are you planning to use the log burner for your heating?

 

[Whyme]

Are you planning to use the log burner for your heating?

good point.

 

[Sparkgap]

From the sound of it the cylinder is a primatic type where the primary or heating circuit is fed from the cold water tank through a device inside the cylinder which allows water to enter the heating system but maintains the separation between the two. You can get problems with heating and hot water systems mixing if the heating side gets too hot and you get boiling which forces water past the internal air gap.
If you are just capping off the primaries at the cylinder there should be no problem.

 

[lame plumber]

From the sound of it the cylinder is a primatic type where the primary or heating circuit is fed from the cold water tank through a device inside the cylinder which allows water to enter the heating system but maintains the separation between the two. You can get problems with heating and hot water systems mixing if the heating side gets too hot and you get boiling which forces water past the internal air gap.
If you are just capping off the primaries at the cylinder there should be no problem.

sounds much more like a fortic tank Fortic F1 if you ask me

 

[stevetheplumber]

sounds more like an old direct cylinder to me typical set up direct cylinder cold water storage take feeds the cylinder and the f and r to the back boiler probably in galvanised steel pipework start draing and youll see the balvale start to fill then you know its that one that needs to be turned of or tied up