What Is A Thermal Store and How Can It Lower My Bills?
To explain this it's useful to use an analogy. If we change "boilers" to "motor vehicles", we can imagine that an example old Potterton boiler is comparable to an old lorry and a new Alpha boiler is perhaps like a new Honda car.
Let's imagine both vehicles driving on the M25 motorway, with its up hill and down hill sections and extreme tail backs . The MPG achieved by the lorry would be very poor - at the very bottom of the stated efficiency scale for it's urban cycle. The new car would of course do better than the old lorry, but even so it would only achieve it's LOWER stated MPG.
Now imagine that the ups and downs are removed , and the M25 is completely empty of any hold ups and you drive them at their most efficient speed . The MPG achieved would be much higher, way above the urban cycle levels for each vehicle.
When this type of analysis is used with boilers , we see that typically an old boiler is running on a very congested M25 because of the way it turns on, and how long it runs for and it's temperature cycle. This leads to three big problems:
The boiler always has to start from cold [ like driving up hill ],
It always has to heat up a very inefficient cylinder [up hill again ],
It will often be running the hot water cylinder only [ like driving slowly in traffic congestion ],
The only "down hill" stage is when the heating and the hot water are running at the same time, and the water return temperature to the boiler is up to 35c. That is the only time 61% efficiency is achieved by any older boiler.
Now if we adjust your system so that the boiler can run at its best possible output rate , for as long as possible, you'll achieve the highest rated efficiency from that boiler.
That’s what the Thermal Store is for. They are designed to your requirements and will store water at up to 65 Celsius. When your boiler system is turned on, the only "up hill" bit is the first 5 minutes. After that the the water is efficiently heated and stored till you need it, then replenished at higher efficiency as required.
Once the system is up to temperature IT STAYS UP TO TEMPERATURE. Now your boiler is on the motorway - with a clear road ahead!!
Here are some approximate figures for illustration.
With the Thermal Store up to temperature and 1 shower running for 5 minutes [60ltr], the Alpha boiler would start up and run for 3 minutes at 24kw and then turn off. This would use approximately 72kw/min with loss to 60kw/min.
With the old boiler and no thermal store it would start up and run at 70kw for 3 mins and then turn off- using approximately 210kw/min with loss to 120 kw/min.
So the difference between the old boiler with no Thermal Store versus the new boiler WITH a thermal store is a massive 138KW/min of gas you didn't need to burn for that one shower! Your gas bill will be slashed with the new boiler/thermal store!!!
Additional savings can be achieved with optional solar panels . Those would reduce the run time for either the "up hill bit" [from cold ] and the over all run time on boiler use. Over the normal life time of a boiler you where able to add approximately 20% extra life span that would be a great bonus.
Investment in Your Property
The high efficiency boiler/thermal store system will add significant value to your home- conversely a a low "hips" rate can cost up to 12.5% of the property value!
Save Money! 
