Considering thermal store and solar

Hello

I currently have a openvented y-plan system with a 140 litre copper cylinder, heating provided by a mexico super 2 cf125 boiler.

I would like to install solar thermal for hot water in the summer and realise that to do so means upgrading the cylinder. I am considering a 200 litre thermal store like a megaflow. As a secondary plan, the new cylinder would be situated downstairs in the boiler room thereby freeing up the space currently occupied by the existing cylinder and cold water storage tank.

I don't really want to upgrade the boiler - can such an old boiler be used to heat water in the likes of a megaflow or is that against the rules?

Another thing i'm not sure about - can the existing Y-plan heating system work with the megaflow, i.e. could i heat the rads from the stored heat and in doing so does the openvented system become a sealed system (it is all copper) ? OR, does the boiler continue to heat the rads as per the existing openvented system and in which case I guess the new storage tank will be heated by the DHW branch of the Y-Plan (as it is currently).

Thanks
Mike

Edit; the incoming water main is the newer blue plastic MDPE (?) type, 25mm, but I realise flow rate needs to be within a certain spec for a megaflow type cylinder.

A Megaflo is not a thermal store, it's an unvented cylinder. There are solar versions of the Megaflo but they only provide hot water.

A thermal store can run CH & HW.

Your boiler doesn't have a manually re-settable overheat stat so shouldn't really be used with a Megaflo but can work with a thermal store. You would need an extra zone valve, on a Megaflo, interlocked with the cylinder's control & limit stats if it's on Y-plan.

Tibbot said:

Your boiler doesn't have a manually re-settable overheat stat so shouldn't really be used with a Megaflo

Click to expand...

Doesn't need to have one.... the cylinder has one.


Megaflow are overpriced tat IMHO.

Plenty of others on the market that are cheaper. Just make sure it is Stainless Steel.


OSO are one of the best, but a little pricey.

Megaflow don't even have the know how to build a thermal store!

That's why I used 'shouldn't really' rather than 'must not'. Some older FS CF's don't have any limit stats at all. Any absent layer of protection is not good practice.