DHW CYLINDER CHANGEOVER HELP !!

[mmalone]

Guys, started what I thought was an easy job of changing and moving an old cylinder and its became a nightmare..

think at 1 time this house had coal heating but new system had been put in and old cylinder left.

right now thought it was simple FLOW & RETURN, COLD FEED AND HOT WATER DRAW OFF + VENT.

NOT QUITE THIS OLD CYLINDER HAS 5 PIPES ????

Everything normal but where the cold feed enters it seems to branch through an old chimney breast as well then returns back through into the cylinder above ??? well apears that way anyway..

anyway I though take the old one out cut all the pipes and repipe a standard 4 pipe cylinder, all went well until I filled it and water started coming out the old pipes I had cut from the 5th pipe and where the cold feed branched off.. to me it seems this is connected to the DRAW OFF and its just like an open tap pouring out. For the life of me I cant understand how this is connected, must be somehow on the DHW DRAW OFF so I need to cut the old brick out to get in and cap...

has anyone came accross this type of cylinder and can anyone explain the piping as its nowt ive ever seen ??

 

[joe-90]

Why not cut the old cylinder in half so you can see what goes where?


joe

 

[mmalone]

Why not cut the old cylinder in half so you can see what goes where?


joe

I did mate and im still baffled its a really old cylinder like 2 thin cylinders joined together.

for the life of me I cant understand the 5th pipe and the cold feed branching off its like it loops in a circuit and must be connected to the draw off somewhere. the flow and return are indirect on the other side but Im baffled over the pipework layout and cant track it down.. surely someone with experience of older sysstems has come across this set up ?

 

[chrishutt]

A 5 pipe (boss) cylinder is quite normal. The fifth boss (near top of cylinder, usually in line with cold inlet) is for a hot water return pipe to allow circulation to take place (usually pumped) in the hot water pipes so that hot water is always available near the taps.

Such secondary circulation is not common except in hotels and commercial premises. Be aware that coil connections in hot water cylinder might be on opposite sides, although normally on same side (about 500mm apart), and that old cylinder might have been "direct" - i.e. no coil.

 

[mmalone]

A 5 pipe (boss) cylinder is quite normal. The fifth boss (near top of cylinder, usually in line with cold inlet) is for a hot water return pipe to allow circulation to take place (usually pumped) in the hot water pipes so that hot water is always available near the taps.

Such secondary circulation is not common except in hotels and commercial premises. Be aware that coil connections in hot water cylinder might be on opposite sides, although normally on same side (about 500mm apart), and that old cylinder might have been "direct" - i.e. no coil.

the cylinder was deffo indirect mate flow and retrnd were in 15mm and came in at the top, can clearly see the coil etc..

Im coming round to thinking that this 5th pipe and the tee of at the cold feed may have been to utilise the solid fuel fire when running but strange how the DHW DRAW OFF is tied in also.. hopefully blanking both off with do the trick as every thing else seems to be as normal..

 

[mmalone]

more info..

the extra cold feed and return seemed to be connected to a towel rad in the bathroom, the DHW draw off was connected to the rad also coming back down from the loft. Strange as there was no coil or nothing and the draw off clearly passed through the towel rail...

Ive looped the flow and return just now but if the back boiler coal fire is used then this could cause a problem so I think disconnecting the old towel rail seems the best option...

anyone seen the likes of this and would you think disconnecting would be best ?

 

[Nige F]

2 Thin cylinders joined together Like 2 bottles standing next to each other And you`re far North... I may have heard of summat similar from a m8 who`s bro. lives in Scotland.

 

[cozzmic]

The type of cylinder is called a Dublo (dooblow) it's for fitting into cubpboards that are not that deep while giving the capacity of a 114 litre (25 gal) indirect. If you are not going to use the t/rail cap it off and the tails out of the cylinder to the Back Boiler but Do Not cap the pipes from the back boiler even if you don't ever intend to use it again (someone else might use it) as if you light a fire and it's capped you could end up with a potential bomb in the fireplace. Nowhere for the heated water in the boiler to vent too, builds pressure then flashes to steam.(thats the bomb part) just be very careful.

 

[mmalone]

The type of cylinder is called a Dublo (dooblow) it's for fitting into cubpboards that are not that deep while giving the capacity of a 114 litre (25 gal) indirect. If you are not going to use the t/rail cap it off and the tails out of the cylinder to the Back Boiler but Do Not cap the pipes from the back boiler even if you don't ever intend to use it again (someone else might use it) as if you light a fire and it's capped you could end up with a potential bomb in the fireplace. Nowhere for the heated water in the boiler to vent too, builds pressure then flashes to steam.(thats the bomb part) just be very careful.

what ive done meantime is linked the tails from the back boiler to stop the flow of water constantly dripping and its circulating round the old circuit but my thought were if the old solid fuel boiler was used it would kettle up. although it is linked to the DHW draw off and still has a way of venting .. Is it normal to be linked to the DHW draw off thoug ?? as I found this rather strange..

best to still disconnect I think as it will surely kettle up as soon as the old fire is used and even though it has a way of venting it could probably still cause problems ..

thoughts ??

never done anything with an old solid fuel system and to be honest this has been converted at some time as it has a potterton kinfisher installed and looks like half the job was done and part of the old system still linked and the old cylinder kept

 

[cozzmic]

If your not going to use the boiler drill a 6mm hole in it so if the fire is lit any water left in it will evaporate off through the hole. Remember to make sure it's not connected to anything which can allow water in ie still connected to dhw draw off.
The water in the boiler will be on the direct side so the water in your taps is the same as in the boiler. Your Central heating boiler will be in the coil side which is indirect.

 

[mmalone]

If your not going to use the boiler drill a 6mm hole in it so if the fire is lit any water left in it will evaporate off through the hole. Remember to make sure it's not connected to anything which can allow water in ie still connected to dhw draw off.
The water in the boiler will be on the direct side so the water in your taps is the same as in the boiler. Your Central heating boiler will be in the coil side which is indirect.

cheers mate appreciate the advise.... thank f*** someone knows this set up

need to disconnect the towel rail then just leave the tails open at the boiler as there no need for for the use of the boiler apart from the towel rail and as there is already a radiator in the bathroom it aint doing much .heating this towel rail through the hot water circuit seems a waste anyway.

ps. am i right in thinking half this cyliner is direct and the other indirect ??
is this a standard way for old solid fuel systems etc ??

 

[cozzmic]

Sort of, one tank is slightly taller than the other and the coil heats one side and the pipes that connect the two tanks together allow gravity circulation between them to heat both up.