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Samsung / Worldheat buffer mixing

nickhorne · 2024-10-19T09:01:01Z

Hello, New to this forum - thanks to all the great discussions and advice I've been reading through. My setup, installed in May this year: Samsung Gen6 14kW, Worldheat integrated cylinder/buffer (250l / 50l). After noticing that rads didn't feel particularly warm compared to the flow temperature out of the heat pump, I've instrumented various points and been measuring temperatures. The graph below shows pump out and return, as well as heating circuit out and return. Once it reached steady state, averages are * output of the heat pump is 41.5C (measured close to outdoor unit) * return to the heat pump is 37C (measured close to outdoor unit) * flow to rads is 35.5C (measured at output of buffer) * return from rads is 29.5C (measured at pipe into buffer) Flow rate from the heat pump primary was 32l/m. No sensor on rad circuit flow rate, but pump is set to maximum. There is a pipe run between outdoor unit, and possible sensor calibration differences, so I think flow to rads is essentially the same as return to heat pump. This all means that I have an average rad temp of 9 degrees below the heat pump output vs an ideal of 2.5-3C (and what all the system design calc assume). I'll need to run at low efficiency as it gets colder to get the output I need from the rads. Info I read online discusses pros and cons of buffers, it seems like my problem is mixing in the buffer, but mine seems extreme as if there is no stratification in the buffer at all and it is completely mixing inside. I'm wondering whether something is set up wrong, or whether the Worldheat buffer had badly designed internals, or is simply too small. I'm wondering whether I should be considering getting it reconfigured as a 2 port series volumiser setup. Other info: weather compensation is set up. Advice gratefully received! thanks, Nick.

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Air Source Heat Pumps (ASHPs)

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Toodles

(@toodles)

Famed Member Contributor

Joined: 4 years ago

Posts: 2711

19/10/2024 4:50 pm

@davidalgarve Do you have fan coil radiators then? Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 3 years ago

Posts: 4718

19/10/2024 5:05 pm

Posted by: @davidalgarve

↑

Oh Crikey! I was hoping I had persuaded my reluctant contractor to change my tank to a volumiser in the return line, as advised by one of the contributors here

Apologies, this was the first time I had heard an argument for putting it in the flow, and the arguments for putting it in the return seem (and I think remain) sound.

However I will readily concede that @heacol s arguments for putting it in the flow are also sound and, since comfort trumps efficiency, arguably stronger.

That said I also agree amputation is also a very good approach.

Don't get too stressed, any of the above should be much better than what you currently have and it's unlikely that the difference between the three options is great.

Every day is a school day!

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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DavidAlgarve

(@davidalgarve)

Reputable Member Member

Joined: 2 years ago

Posts: 240

19/10/2024 5:34 pm

Posted by: @toodles

↑

@davidalgarve Do you have fan coil radiators then? Toodles.

No, Just the usual for here, Roca segmental aluminium type.

That lets me off the hook then?

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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Toodles

(@toodles)

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Joined: 4 years ago

Posts: 2711

19/10/2024 5:56 pm

@davidalgarve From what is written above, ‘amputation’ is probably your best option! Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 3 years ago

Posts: 4718

19/10/2024 5:56 pm

Posted by: @davidalgarve

↑

Posted by: @toodles

↑

@davidalgarve Do you have fan coil radiators then? Toodles.

No, Just the usual for here, Roca segmental aluminium type.

That lets me off the hook then?

How frequently do you get defrost cycles (I ask because if the answer is not very, it really doesn't matter).

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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DavidAlgarve

(@davidalgarve)

Reputable Member Member

Joined: 2 years ago

Posts: 240

19/10/2024 6:14 pm

Posted by: @jamespa

↑

How frequently do you get defrost cycles (I ask because if the answer is not very, it really doesn't matter).

Hardly ever, but started on the weather compensation path last winter and was fiddling with that up to spring this year so ever changing scene. Also added DWH about then and solar PV in August, so fragmented learning curve.

I will stick to the argument I put forward with my contractor

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

ReplyQuote