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PWM pump or not?

bontwoody · 2023-04-17T15:56:42Z

Ive just finished installed my new Samsung Gen 6 ASAP and have identified that I made an error. I ordered a Grundfos UPM3 AUTO pump thinking it had PWM, but even though it has the socket for the PWM lead it doesnt. At the moment i have it in radiator mode as a standard pump. My question is, shall I just leave it or get a PWM pump and sell the other on ebay? I will probably lose £50 in doing so but would it be worth it long term? A bit technical I know but I thought I would ask on the off chance someone has the knowledge :-)

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bontwoody

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Topic starter 22/04/2023 4:13 pm

@iancalderbank This pump would do the job wouldnt it Ian? Thanks Mark

https://www.ebay.co.uk/itm/234982440002?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338942597&customid=Cj0KCQjwi46iBhDyARIsAE3nVrax00NlnUcshtoguRnLJTpoB3zshlUaja4e4tRY7fztwnUHfhE5p80aAu-YEALw_wcB&toolid=20006&

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60

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iancalderbank

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22/04/2023 7:13 pm

@bontwoody pretty sure it will yes. This doc is your bible (page 23)

@derek-m I'm actually trying to setup public visibility of my stats via emoncms / heatpumpmonitor.org at the moment, but here's some individual snips of the same time window , hope these are easier to read.

my system performance is not great yet - COP is only ~3 - but I haven't balanced yet, I know I have a shortcut radiator lurking as DT is too low.

My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs

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bontwoody

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Topic starter 22/04/2023 7:19 pm

@iancalderbank Thanks Ian, I was looking at page 12 and was pretty sure but wanted some confirmation 🙂 Ive just managed to get some data for my heatpump out of EmonPi, but the heat meter is underreporting the flow rate so Ive had to put in a correction factor based on the stated flow from the Samsung controller. looking pretty reasonable at the moment

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bontwoody

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Topic starter 02/05/2023 10:27 am

@iancalderbank Fitted the new PWM pump Ian, all working well and it has reduced the power input by 30 W by reducing the flow rate down to 9 lt/min from about 15lt/min. I was a little surprised at that as I thought 15 was supposed to be optimal but i guess it knows what its doing 😀 delta T is still about 3 degrees C though which may or may not be important.

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iancalderbank

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02/05/2023 11:37 am

@bontwoody my experience has been that (in low load situation) it reduces the flow rate to just a smidgen above the min flow rate acceptable to the heat pump - 12l/min in my case with the 16kw unit. this is about a 3.5kw heat output at DT4. to get DT5 it'd have to drop the flow rate below the min that is acceptable to the heat pump which I assume is the reason it doesn't do that.

good to hear it works anyway!

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bontwoody

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Topic starter 02/05/2023 2:06 pm

@iancalderbank That makes perfect sense Ian. Im just having my Mixergy cylinder fitted today so i can hook it up to my Eddi. While that happens Im exploring Home assistant. It was a bit fiddly to get the right version installed but Ive managed that now and an delighted to find that it can connect to both of the above. Ive already got it hooked up to my openenergy monitor system and it looks possible to include Solar Fusion as well!

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bontwoody

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Topic starter 03/05/2023 6:37 am

@iancalderbank Strange thing happened last night, came home about 10pm so no heating on and noticed the pump turned itself on for about 5 mins at high power. Any idea why?

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iancalderbank

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03/05/2023 8:58 am

@bontwoody I think you have other monitoring, temperatures, energy etc - what did those say?

was it below or close to 3C where you live?

there is a "frost protection" in the samsung, if the outside temp is <3C and there's been no pump run for at least an hour, it will run the pump for 5 mins (at full speed by default). if you have DHW it'll open the DHW valve as well. which takes heat from your DHW and uses it to "warm the heat pump up".

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bontwoody

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Topic starter 03/05/2023 9:51 am

@iancalderbank That sounds like exactly what it did but the outside temperature was 14C. I will keep an eye on it. Not a massive issue but curious

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iancalderbank

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21/05/2023 6:27 pm

@bontwoody I've been noticing mine now runs for 5 mins every 24hrs. it has nothing else to cause it to run so I guess this is a "stop the pump sticking" thing.

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bontwoody

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Topic starter 21/05/2023 7:15 pm

@iancalderbank Well its good to know its not unusual behaviour 🙂 Mixergy and Eddi all working now, paying standing charges only now for a week or two. Have appointment from Octopus to cap off my gas too. Im exporting loads in this nice weather so am trying to get and export meter fitted.

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Fazel

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25/05/2023 11:37 am

Posted by: @iancalderbank

↑

@bontwoody I've been noticing mine now runs for 5 mins every 24hrs. it has nothing else to cause it to run so I guess this is a "stop the pump sticking" thing.

Glyn's 5kW Samsung does the same, runs the pump for a few minutes. You would prob be able to check the display on the pcb whilst it's happening