solid fuel Rayburn, water tanks ?

[richardrich79]

We are going to swap our multi-fuel stove for a multi-fuel Rayburn with a boiler.
We are having a heatas fitter coming down to set it all up and have said we would get everything into position.
At this stage I should say we are pretty skint and the budget is limited, our neighbour has donated the copper cylinder( boiler) which also has an immersion heater (which we won't be connecting). The hot water tap from the rayburn will be into the downstairs shower/bath which will also be serviced by a bath mixer tap from the combi boiler and an electric shower. There will be a towel rail radiator in the boiler system.
My question is what size tank should I have in the loft for 1/ the boiler header? & 2 rhe main cold water.
http://www.screwfix.com/c/heating-p...s/cat830964#category=cat830964&price_to=125.0Looking at Screwfix I'm thinking the 4 gallon for the header and 25 for the cold, is this correct?
Our HEATAS guy is very good but I really would like to have some sort of idea before I see him as he dosn't suffer fools lightly.

 

[Nige F]

As a non HETAS non Gas Safe non OFTEC non FENSA plumber with no PPE but a C+G in plumbers work from 1973 I can only say - leave it to the HETAS bod and ask him about a metal Feed/expansion cistern.

 

[richardrich79]

We've got a galvanized expansion(?) tank that came with the cylinder, the last Rayburn he fited for us had one of those tanks with the cold water tank on top of the boiler, when the water started boiling we used to have to run the hot tap for a while unless a bath was wanted. That installation was in a listed building with no loft space, I was ratheer hoping to have some advice over tank sizes.

 

[Bennachie]

Primary flow and return must be 28mm. 190 litre indirect hot water cylinder, f&e tanks 18 litre min. BS plastic with lid and ply support base extending 150mm all round or galv/grp tank. Metal ball valve and float. Copper overflow at least for the first two metres preferably full length. Ensure low temp stat on Rayburn is connected and that a high limit stat is fitted. Power out heat leak radiator of at least 10% of output (1.5Kw) to be plumbed top to bottom connections from flow/overflow back to return - again preferably in 22mm reducing to 15 for the rad connections. Injector tee must be fitted at junction of primary return and rad return.

What on earth do you mean by 'the hot water tap from the Rayburn?
In addition if your previous installation 'boiled' then there was no heat leak circuit or no high limit stat or both; therefore was not compliant for an unregulated appliance.

 

[richardrich79]

Sorry if I wasn't clear what I was trying to explain is that the hot water supplied by the boiler via the cistern will supply the bath, all the pipeqork will be connected up by a plumber. the last system I refered to was installed by the rayburn supplier (it was purchased new) mind you it was 25 years ago, hot warer used to come out of the overflow.

 

[Bennachie]

Just re read your OP.
You are not intending to use the Rayburn just for hot water only are you?
What model is it?
What 'wet' stove are you taking out?
If connecting to wet rads a neutraliser of some form will be required which won't like a mix of vented and unvented systems...............
Overheat protection was still a requirement.......

 

[richardrich79]

The stove we are taking out does not have a boiler and we do not intend to connect thr rayburn into any other circuit
The Tayburn is an old 'royal' the smaller one, hot water only supplying one rad as per rayburns fitting instructions.

 

[Bennachie]

Ok.
Still needs heat leak radiator of 500 watts and the aforementioned upper and lower stats. Everything as above. Cold water tank for cylinder wants to be the same or bigger than the cylinder volume.
Also requires open vent to the room in which it is situated of about 11 square cms. Not big but a requirement.
Edit. Not the pump and stats as it will be gravity only, makes heat leak vital

 

[richardrich79]

Thanks