Size of metal header tank for multifuel stove

[phebas]

I'm planning on replacing a living room back boiler (in a fire place) with a 22kw multifuel stove. The stove will complement an existing oil boiler and feed the radiators serviced by that oil boiler and also occasional heating the living room without turning on the central heating. Back boiler and oil boiler are on opposite sides of a wall dividing the living room from an utility room - pipe runs are about 1M between the two. At the moment the back boiler feeds into the oil boiler flow and return which go to the coil in the hot water tank, i.e. back boiler only heated the hot water tank. The flow and return of the heating system are separate and from the other two oil boiler connections. Planning to route the stove to the heating circuit only (no hot water facilitation). Existing pipe work is in 28mm copper straight up and down to hot water cylinder and existing plastic header tank in roof space.
My question is what is the appropriate size of copper/stainless steel header tank for this combination since there are 7 sizes of header tank (18- 55 litres)? No significant space restrictions in the roof space re choice of header tank size.

 

[SJB060685]

I may be wrong here but what is the combined output of the two units? Looking in my OFTEC book it suggests outputs upto 25KW requires 45 litres and 25-45KW needs 70 litres. I might be wrong though but I’m sure someone else will be along soon.

 

[snowhead]

The size of the the tank is determined by the system volume.

But someone will be on soon mentioning HETAS.

 

[SJB060685]

The size of the the tank is determined by the system volume.

But someone will be on soon mentioning HETAS.

Yes I know the system volume is ultimately what affects the requirement, I was assuming that my OFTEC books took this into consideration, hence why I said I might be wrong lol

 

[SimonG]

What system are you considering to connect the two heat sources?

 

[phebas]

The oil burner is a Nu-Way ST40. The stove under consideration has a 'direct air' feature and integral thermostat which presumably control the air to the stove. I'm hoping to do this without serious expenditure, so no thermal store tank. I was thinking of either a Neutralizer or Heat Hero manifold system to coordinate the outputs from burner and stove. All advice would be welcome.

 

[SimonG]

Neutraliser or h2 panel for me.

 

[SimonG]

But whatever system you use it will be expensive. Normally closed 2 port, anti boil stats etc etc etc.

 

[phebas]

But whatever system you use it will be expensive. Normally closed 2 port, anti boil stats etc etc etc.

A response to the original question would be appreciated, i.e. appropriate size of header tank ?

 

[SimonG]

Ah one of them.

Your hetas engineer will be fully conversant with the size of header tank required.