Buffertank, Gas boiler, solar & Backboiler

Zero Tolerance

Hi,

I'm at the stage of my new build where i need to decide on the heating system.

I will have underfloor heating upstairs and down on a 250sqm block built house. High level of insulation (A2 BER standard),airtightness taping and testing, triple glazed windows, MHRV etc.

From reviewing previous posts I am leaning towards a modulating gas or condensing oil boiler feeding a buffertank (combined DHW and UF) with solar and a back boiler also feeding the buffer.

Which is better, oil or gas feeding a buffer tank for underfloor? Is a buffer tank required?

How should the system be configured? i.e stats required, programmable timers etc.

Also, please pm product recommendations for boilers and buffertanks (suitable for a boiler, solar and back boiler feed) so that i can research these.

Any help would be appreciated.
D

heinbloed

600 thermal storage tanks incl. some technical data are listed here:

http://www.sonnewindwaerme.de/sww/content/speicher/

The job you have in mind demands specialist input. It's certainly not a DIY option to calculate the energy demand and decide for the one or other system.
Since you're unsure to decide on the feasability of oil or gas (condensing?) boilers to suport your UFH you haven't figured out the return temperature?

Condensing boilers are only capeable to deliver max. fuel efficiency if they are allowed to operate in the condensing modus.
And this is decided by a. the return temperature and b. the outside (air) temperature.
Oil condensing boilers demand a lower return temperature compared to gas condensing boilers to get the entalphic energy (the condensing effect) into the thermal distribution system.

Zero Tolerance

Hi Heinbloed,

Thanks for your reply, i have sent you a PM regarding the specialist input. This will not be a diy job.

galwaytt

I have 316 sq m, UFH on all floors, and LPG and Solar on 1000L buffer tank.

LPG is particularly good, imho, for the application becuase (as you mention) it's modulating. However, on a buffer arrangement, that's not as critical, as the primary flow/return from the device to the buffer is straightforward. In which case oil is a not unreasonable choice, and it is economically attractive to fit, as well as being widely available/serviceable.

Whilst my buffer has 2 x spare inputs, for future sources, tbh, I haven't used either, and am not sure I ever will. You need to bear in mind that if you have a high performance house, you might rarely, if ever, use your back boiler, so the merit's of connecting aren't as they would be in a colder house, where it might be on more often.

Far too often I see too much heat, too many sources, and too much complication, in modern houses - in many cases, they're simply not needed.