Advise on connecting a Thermal Store to a Radiator Circuit

I currently have a Navitron TS1400x1800 210 Litre Thermal store http://www.navitron.org.uk/product_detail.php?proID=86&catID=90

It is being heated by 2x 3Kw immersion heaters which is doing a fantastic job providing seemingly endless amounts of hot water. At the moment I am using panel heaters to provide heating for the house however I still have most of the old radiators and associated plumbing installed.

For months I have been toying with the idea of connecting the radiators to use the stored heat using one of the internal coils (Marked 'G - To Space Heating') but don't want to make the investment in buying 2 replacement radiators, expansion vessel etc if:

Will the coil absorb enough heat from the store to drive the radiators?
Will 210 litres have enough stored heat for the radiators?

The radiator sizes and outputs are;

3 x 600x1400 (1.4Kw)
1 x 700x1600 (1.8Kw)
2 x 700x600 (0.7Kw)

Total 7.4Kw

I was told the store I have at the moment would manage such a load due to the already stored heat and by the time the rooms are up to temp the TRVs will shut down reducing the demand on the store therefore allowing the store to recharge.

I understand the common way of using a thermal store for heating is to pump the body of water round the radiator circuit, unfortunately this is not an option on this store.

Your comments are welcome.

You only have about 60-70 /L of stored energy at those port positions on the store.

Regarding the coil you would be better contacting Newark.

Tried it recently with twin solar coils connected in series inside a small custom built cylinder on a heating system and it failed.
Then tried it as a heat dump/hot water supply combination on a solid fuel system and that failed also.

Even when the store was 70c and the mains reduced to a trickle it failed completely.
It managed to raise the flow by a few degrees to just slightly warmish.

Thanks for the reply. I have been searching the web and came across the same sort of answers you gave, I have emailed Newark just on the off chance.

I assumed the coil should be as efficient as possible, earlier this afternoon I flushed cold water though the coil which only came out luke warm.

Just heard back from Navitron who confirm this coil is for space heating however there maybe limits on its capabilities.

Last night I rechecked the coil which did produce hot water and A LOT of gurgling and steam as I funneled the water in.

6 kW of electric heating is not going to fully satisfy 7.4 kW of radiators even if the store started off hot.

Thats ignoring the question of how much energy you can get out of the space heating coil. I would have expected it to have been adequate for a small heating load as thats its purpose.

But it seems you are ignoring simple physics and expecting to get something for nothing!

Tony

Your right there. I accept you cant get more energy out than you put in, I don't know if upgrading a heater to 6kw would be a good workaround, therefore giving a total of 9kw?

Just heard back from Navitron who confirm this coil is for space heating however there maybe limits on its capabilities

Click to expand...

Newarks schematic shows the coil as boiler connection.
I would still contact Newark. Their the manufacturer not navitron.

Its odd that navitron would say that considering the low input. And if the top immersion is above the take off ports then its lower still.

Sorry being a bit of a numpty... The reply was from newark:

On 11 Jan 2011, at 08:30, "andrew" <[email protected]> wrote:

> Hi
> Yes "G" is for space heating but im not sure if the coil would heat six
> radiators
> Andy
>

I have asked if upgrading the bottom immersion to 9Kw be viable.

There are two stores with "G" connections. A direct model and an indirect model.
The direct model using the "G" connections can clearly be used with space heating.

The indirect model can be heated via immersions or the coil for dhw production. Its not an integrated HW/CH thermal store.

I would want a written gurantee from the manufacturer that it will work before proceeding.

Thanks... I believe it is direct as it is heated directly using 2x immersion heaters and not a boiler