What tank to install

[recoveringbuilder]

So after 3 years of battling away with the biomass boiler we will soon be taking it out and replacing with a 35kw grant oil boiler. 
in our previous build we had a grant oil boiler ( which 14 years down the line is still in operation) which heated the ufh and radiators direct and a hot water tank for dhw. What’s the best way to go with this boiler? Should we heat a tank which in turn provides for the ufh, radiators and dhw and if so what sort of tank should we be looking at? The thermal store which is currently part of the biomass system isn’t great, it can lose a few degrees an hour without using anything from it.

[Gone West]

This year I am hoping to replace our oil fired Rayburn with an external Grant oil fired standard boiler. I was going to use a McDonalds thermal store with the TS directly linked to the radiators and a coil for DHW. There will also be a solar thermal coil and a PV powered immersion heating the TS. Something like this:

 

[Roger440]

17 minutes ago, Gone West said:

This year I am hoping to replace our oil fired Rayburn with an external Grant oil fired standard boiler. I was going to use a McDonalds thermal store with the TS directly linked to the radiators and a coil for DHW. There will also be a solar thermal coil and a PV powered immersion heating the TS. Something like this:

 

 

Ive recently started looking at this. But there are things im yet to understand.

 

How does the above cope with the thermal solar circuit overheating?

 

The oil boiler input is half way up the tank. So in the event that solar is producing next to nothing, will the heating circuit get hot enough? It shows rads which would need to be rather higher temp than underfloor. Or is it underfloor?

[Gone West]

12 minutes ago, Roger440 said:

How does the above cope with the thermal solar circuit overheating?

 

The oil boiler input is half way up the tank. So in the event that solar is producing next to nothing, will the heating circuit get hot enough? It shows rads which would need to be rather higher temp than underfloor. Or is it underfloor?

My solar thermal system has a thermostat, which at the moment is set at 60C, but I will increase it to 75C. The solar thermal has apparently been installed for many years and is a low maintenance system.

The boiler stat is near the centre of the tank but it could be set to a higher temperature if required.

I will be using radiators so I would want the temperature in that part of the TS to be around 55C to 60C.