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Discuss Buffer Tanks - 2 or 4 port connections in the Renewable Energy area at UKPlumbersForums.co.uk.

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  1. missplumb

    missplumb Plumber

    As Worcester said you could use the hot water module on the buffer and pipe the boiler direct to the buffer and come out the other side to your heating. You then add the middle sensor to help monitor the buffer charging status. Difference between the two schematics you've shown is the ETA shows a shunt circuit with mixer valve, the Froling does not.
    We have always used the 4 port buffer system, we set top of buffer to 80 min with 5 deg hysteresis and bottom off at 70 deg. We find that the systems are never short of heat as the buffer is always already 70% charged and boiler only fires using buffer sensors only.
     
  2. Ermintrude

    Ermintrude Plumber GSR

    The buffer works when the boiler isn't even awake.

    Demand established :-

    Buffer satisfies load whilst boiler gets to 55c and flue up to 100c

    Boiler hits :- 55c and flue 100c 3 port and pump wind in ... Buffer still providing load satisfaction

    Boiler hot and 3 port swings in:-

    Buffer almost depleted but boiler coming on line.

    Load side pumps pull from easiest route which is boiler now that the 3 way is playing ball.
     
  3. Nostrum

    Nostrum Plumber GSR

    Won't the boiler and buffer be asking for two separate temperatures though? If the return temperature is coming back in excess of what the boiler is looking for, 20 degrees differential for example, the boiler will modulate to try and match the load?
    so unless the buffer is happy to run at 60 also (which is lower than the desired temp at mixer) I can't see how sufficient flow will enter the buffer to raise the temp?

    Surely in the example I gave above, you could end up with a buffer at 60 providing no additional input to the heating circuit until the heating mixer pump turns off, at that point the buffer could be loaded by the boiler?

    Thats fine for heating, but hot water production is relying on the buffer.

    It's a shame they don't explain the controller in a little more detail, maybe most people aren't interested but I'd prefer to know the capabilities of the product in full detail rather than just pipe it up off a schematic as told. It's my companies reputation at stake at the end of the day.
     
    Last edited: Jul 19, 2015
  4. Nostrum

    Nostrum Plumber GSR

    Yep we've gathered how the set up works on start up, but I'd like to know how the controller can maintain the buffer temp whilst under load.
     
  5. missplumb

    missplumb Plumber

    It doesn't, the buffer is only there for peak load demand, once the boiler is up to temp it takes over the best demand and the buffer sits doing not allot as the least circuit of resistance is not through thousand of litres of water in the buffer. As Ermi said, once the demand has gone and heating mixers are diverting back to the boiler, then the buffer is re charged ready for the next peak demand.
     
  6. missplumb

    missplumb Plumber

    This is why we don't use the 2 port method. Always have heat and boiler only fires on demand from the buffer
     
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  7. Ermintrude

    Ermintrude Plumber GSR

    2 port is a buffer 4 port accumulator which incorporates buffer. I've just fell off a ****ing wall in the dark. Should bay more attention to where I'm walking the dog at 23.17
     
  8. Nostrum

    Nostrum Plumber GSR

    That's how I would have done so prior to this conversation, but if you are being recommended to pipe it in another way to increase efficiency then you've got to look at why?

    For me, efficiency is top of the list, after all, that's what it is being sold on. For you perhaps being non domestic, efficiency is lower on the list because of the non domestic RHI returns.

    The domestic RHI covers the majority of the upfront cost but for it to really stack up financially, it needs to be as efficient as possible for the long term.
     
    Last edited: Jul 20, 2015
  9. missplumb

    missplumb Plumber

    For non domestic rhi, it's more about making the boilers last the 20 years, when we commission and put the fga on, we still have them running at 92-94% efficient, it's what the rest of the system does with that heat.
    Ermi, a 2port would be used as an accumulator and the 4 port would be the buffer as it is inline
     
  10. Nostrum

    Nostrum Plumber GSR

    Just spoken to the technical team at ZCF. Very interesting and the boilers controller is smarter than I first thought.

    The controller can load the buffer and export at the same time. On the P1 and P4 the modulating pump is purely for buffer loading. The boiler uses the internal water ways as Worcester talked about to divert flue gases through various sections of the boiler to achieve the required return temperature, eliminating the need to a return riser. If the buffer temperature drops, the buffer pump will run and the boiler will charge the buffer to the desired set point and provide output for export until it cannot modulate low enough to continue running. When this happens the boiler will switch off, buffer pump goes off and export will come from buffer only by reversing the flow on that section of pipe. So interestingly, the boiler and buffer don't appear to be able to output simultaneously.

    The mixing valve ensures water is only circulated through the export with a minimum temperature as well as a set flow temp. The ESBE controller can also be directly controlled through the boiler controller for weather compensation for blended heating flow but maintain the higher set point for the buffer.
     
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    Last edited: Jul 20, 2015
  11. missplumb

    missplumb Plumber

    Interesting, mind you ive not looked at the Froling pellet boilers as all we do are chip.
     
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  12. Nostrum

    Nostrum Plumber GSR

    Same setup for chip

    image.jpg
     
  13. Nostrum

    Nostrum Plumber GSR

    Even upside down as well!
     
  14. missplumb

    missplumb Plumber

    Yes but that has a mixing valve which allows the boiler to fire and run whilst drawing from the buffer
     
  15. Worcester

    Worcester Plumber

    Yep, we're back to the capabilities of the controllers and boilers. With the changes to the RHI, we're finding that the clients are also looking at the most efficient way to control the heating, and using the built in controllers in both ETA and Froling you'll benefit from weather compensated flows to the heating circuits and hence higher efficiencies from the boilers.

    If you're not using the built in controllers, then the next most efficient is to use the 4 port buffer.

    Next thing is self learning optimised start - we have that built in to our heating circuit controllers that we use with underfloor heating and heat pumps - typically the Heatmiser controls, they offer both comfort levels (i.e different temperatures at different times of day) as well as optimised start. At the moment I'm not aware that either ETA or froling offer optimised start - YET :)
     
    Last edited: Jul 20, 2015
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