Nibe VVM320 - Heating Curve

mickey15ie · 08-01-2022 8:51pm #1

Evening All,

I am looking at my heating curve but im a but a bit confused.

The house is 2700 sq ft, A2 Rating, Triple Glazed Windows with solar control on south elevation, there is a lot of glass in the house.

I have slope and offset but i dont know what the offset means.

Currently the house has a day and night meter, for month of December the house is using 23-26kwh on day meter and 13 to 17.5 Kwh on night meter.

Neither of us working from home currently.

Ground Floor living spaces set at 20 degrees, bedrooms set at 19 degrees.

Any advise or propose settings to make house more efficient would be much appreciated.

mickey15ie · 08-01-2022 8:53pm

also have a mechanical ventilation system too.

ec_pc · 09-01-2022 8:39pm

I have a Veissmann heat pump system in a similarly sized house and it has taken a lot of fine tuning to get a balance of heat and efficiency. This is our 2nd Winter in the house and we leave all the stats @ 19 throughout the house unless it is really cold out. Last year I had the stats at 20-21 and obviously this was consuming more power.

This year I focused on the level and slope and I have increased the slope by 0.2 which results in slightly warmer water in the system and the result for me is a house that feels warmer, but definitely much lower electric costs. I know it has been a very mild Winter so far, but I am still monitoring the system closely as I don't think I have hit the sweet spot just yet.

Latro · 10-01-2022 11:00pm

https://www.boards.ie/discussion/2058226729/nibe-vvm320-heating-curve

Offset will change water temperature by offset value for all external temperatures.

For example if you set offset to +2 it will bump produced water temperature across whole curve by 2 degrees.

Let's assume baseline curve: if air +5 then water +30, if air -5 then water +40.

After offset set at +2 the curve would change to: if air +5 then water +32, if air -5 then water +42.

After offset adjusted to -2 the curve would change to: if air +5 then water +28, if air -5 then water +38.

Also in my opinion you should get off night rate. It is not beneficial to you if the usage is as described in your post.

keno-daytrader · 12-01-2022 6:25pm

I wouldnt bother with the heat curve at all, I set mine at the lowest flow temp I can to maintain the downstairs at 21c.

I left the heat curve on when it was first commissioned and it ate electricity! Took a while to get the right flow temp for our house, in the end it paid off nicely. It made a huge difference to our consumption.

We have underfloor heat so the lower you can get the flow temp going around your floors the less energy and higher efficiency the heat pump will generate.

poker--addict · 16-01-2022 2:37am

Keno, so you turn off weather compensation entirely and then aim for a flow temperature that once settled delivers you 21 in the room?

keno-daytrader · 18-01-2022 1:39pm

https://www.boards.ie/discussion/comment/118482955#Comment_118482955

Yes, aim for the lowest flow temp your house can handle without it getting cold, or in our case to hold at least 21c. Took alot of trial and error but finally got it.

I was shocked at how inefficient the heat pump was with stock factory settings.

Mr Q · 18-01-2022 2:16pm

https://www.boards.ie/discussion/comment/118494065#Comment_118494065

That makes sense. I think I reduced the flow temp on my VVM320 by 7 or 8 degrees at least from the original settings with no difference noticed in the house comfort.

Nibe VVM320 - Heating Curve

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