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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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iancalderbank

(@iancalderbank)

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Joined: 4 years ago

Posts: 643

20/04/2023 6:26 pm

@bontwoody

I think they don't like being just a pump distie and want to keep stock to sell with a heat pump as a package. They've been good with the customer service to me - due to a packing error they sent me the wrong pump, when I told them, and said needed a bit that I forgot so they did a free next-day courier for the pump swap and the extra bit.

but I bought mine from them with the heat pump, hence why I got it. I didn't find the UPMM anywhere else. which is peculiar.

which pump were you trying to get from MSW? UPMM or something else? I have a whole list of suppliers I searched my way through before so let me know.

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

(@bontwoody)

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Topic starter 20/04/2023 6:28 pm

I Found this one https://theunderfloorheatingsite.co.uk/shop/water-under-floor-heating/pumps-packs/underfloor-heating-pump-grundfos-upm3-flex-as/

Its listed as having a PWM A Profile not C, does anyone know which profile would be correct for the Samsung Gen 6 HP?

House-3 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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bontwoody

(@bontwoody)

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Topic starter 20/04/2023 6:30 pm

It was this one I ordered, but at the time it didnt have the comment about being sold with a HP

https://midsummerwholesale.co.uk/buy/renewable-heat-accessories/grundfos-upm3

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iancalderbank

(@iancalderbank)

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20/04/2023 6:30 pm

A is what you want for heating. C is for solar. the FLEX AS is available on a number of sites. just make sure you get that one not the AUTO you already have!

a tad cheaper

https://www.handyheat.co.uk/product-page/grundfos-upm3-flex-as

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bontwoody

(@bontwoody)

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Topic starter 20/04/2023 6:34 pm

Thats quite a bit cheaper, thanks Ian. On par with the Midsummer price for the lower spec pump 😀 once you factor in vat and delivery

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iancalderbank

(@iancalderbank)

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Joined: 4 years ago

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20/04/2023 6:43 pm

double double check it is the right version - as the pic is for an AUTO - and includes the PWM cable . Have seen it sold without (even though its a PWM pump). as a spare part they are daft price (only seen one supplier, 20 quid or something). this is all the pain I was having before I found the bundle from MSW (which meant buy the heat pump too, but that was fine!).

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bontwoody

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Topic starter 20/04/2023 6:47 pm

LOL, great minds..... I just sent them an email having noted the image was wrong. Ive got the cable, stoves and solar were pretty good £8 I think although I was trying to find a 2m cable which you can get in Germany.

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Derek M

(@derek-m)

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Posts: 4425

20/04/2023 7:41 pm

Posted by: @bontwoody

↑

Bad news Im afraid, Midsummer Wholesale took my order and confiirmed it and then the day after cancelled it saying they are now only supplying the water pump with a heat pump! It didnt say that when I ordered it (other pumps did). Very poor customer service IMO, they should have honoured the deal that was made. I wont be using them again, but finding another supplier is proving difficult.

So will you get a free heat pump? 😋

In which case you will have a spare water pump and heat pump. 😎

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bontwoody

(@bontwoody)

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Topic starter 20/04/2023 8:38 pm

@derek-m LOL. I dont have room so had to say no to both 🙂

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iancalderbank

(@iancalderbank)

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Posts: 643

21/04/2023 4:25 pm

BTW, here's the effect of PWM. I think we're right at the min output of the ASHP once this reaches steady state at around 14.45. without PWM I suspect it'd be less well behaved.