Thermal Store and ABV

[Ubarrow]

Am looking to have a small biomass system installed and want an Evohome system as control system.
Looking at some of the literature around Thermal Stores I'm puzzled as to why they need bypass valves. If all the TRV's shut at once then surely this doesn't affect the flow from the boiler to the store? Or am I missing something?

 

[Agile]

I think that you are misunderstanding.

There are several different arrangements for thermal stores.

Usually the boiler has a pump to flow to and heat the store.

The store then has another pump to circulate to the rads. Its the rad circuit that needs an ABV to allow flow if all TRVs have closed.

Tony Glazier

 

[Norcon]

If its not a pellet boiler then you don't want complex controls. A pellet boiler operates similar to an oil boiler in that the fuel supply can be controlled automatically.
If its a log boiler then the boiler goes into heat dump mode and the rads accept the heat.
Can be a store fitted or not. Simples.

 

[jason61c]

Am looking to have a small biomass system installed and want an Evohome system as control system.
Looking at some of the literature around Thermal Stores I'm puzzled as to why they need bypass valves. If all the TRV's shut at once then surely this doesn't affect the flow from the boiler to the store? Or am I missing something?

Are you after pellet or logs? Most of the decent range of pellet boilers have very clever controls, which can act as a good saving against bolting anything on.

Your TRV's are after the store so will not affect it. Are you getting confused by a ladomat type valve after the boiler before the store?

What make of boilers are you looking at?

 

[Ubarrow]

It's a pellet boiler which will be installed, along with the thermal store, by a local installer who is used to these systems but not the Evohome system.
I can't see why there needs to be a bypass valve between the store and the radiators. I understand the need, with some boilers, to dump excess heat after the boiler has shut down but can't see why this is necessary on the other side of the store. I.e. The radiator circuit. But I may be missing something here?

 

[Norcon]

The by-pass acts as a differential control after the store for the rad circuit so its connected across the circulator.
So as trv's throttle closed the by pass opens.
See link for further details...
http://heating.danfoss.co.uk/PCMPDF/VD55K902_AVDO_teamcent.pdf