Unvented Cylinder Single coil heat pump vs twin coil solar

[p--man]

Hi, I'm looking to purchase a 300L unvented indirect cylinder to work with a standard heat only boiler.

I may have solar panels in the future, but likely the PV kind rather than the thermal kind, and won't be having heat pump in the future. So the cylinder would be connected to the boiler at least for the short term.

Assuming I only stick to a heat only boiler, I've heard these options would warm the water up quicker:

1. Twin Coil Solar version - Connect in series so x2 coils of around 0.6-0.9m^2 surface area to heat water up quicker
2. Single Coil Heat Pump version - Coil has larger surface area ranging from 2.3-3m^2 which in turn heats water up quicker
3. Combo of option 1 and 2

What option would you recommend to heat up water quicker from the above options, mainly option 1 and 2 as option 3 is double the price of option 1 in most cases.

I'm looking at Joules, Kingspan and Telford brands for their twin/heat pump variations but open to suggestions for any others. It'll be installed in the garage and propety is 4 bedroom, 2 bathrooms and high usage individuals with long showers

Thank you.

 

[ShaunCorbs]

What’s the kw of your boiler ?

 

[p--man]

What’s the kw of your boiler ?

It's 24kW, Baxi. Installed 3 years ago

 

[ShaunCorbs]

A stnd indirect coil normally is 20-25kw so that will do easily if you go for a 25kw one

Eg gledhill pluin300

Normally heat up time is around 30 mins etc

 

[p--man]

A stnd indirect coil normally is 20-25kw so that will do easily if you go for a 25kw one

Eg gledhill pluin300

Normally heat up time is around 30 mins etc

Ok thanks, is having that in twin coil with both coils connected in series theoretically reduce the heat up time when connected to the boiler?

I've heard of these new Mixergy cylinders, whether it's worth having that instead as you can heat up a small amount of water for 1 or 2 people in 10-15 minutes.

I'm essentially ensuring i have a moderate sized cyclinder that has a good heat up time no matter which option I take.

 

[gpbeck]

If your boiler delivers 24KW of heat to coils with a 50kW capacity, the hot water still only receives 24KW of energy and so heats up at the same rate.

 

[ShaunCorbs]

Ok thanks, is having that in twin coil with both coils connected in series theoretically reduce the heat up time when connected to the boiler?

I've heard of these new Mixergy cylinders, whether it's worth having that instead as you can heat up a small amount of water for 1 or 2 people in 10-15 minutes.

I'm essentially ensuring i have a moderate sized cyclinder that has a good heat up time no matter which option I take.

No as above you would need two boilers both at 25kw to get any advantage but then that’s twice as much gas more efficient to let one 24kw boiler and one 25kw coil run longer etc

Do you need that much control eg just heat enough for two people ?

 

[p--man]

If your boiler delivers 24KW of heat to coils with a 50kW capacity, the hot water still only receives 24KW of energy and so heats up at the same rate.

The coils for the cylinders are an output of around 20kW, the input would be much lower at around 3-5kW based on the boiler is my understanding?

 

[Ben-gee]

At last, the solution to the energy crisis.

 

[ShaunCorbs]

The coils for the cylinders are an output of around 20kW, the input would be much lower at around 3-5kW based on the boiler is my understanding?

? Why 3-5kw would give 24kw