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Does this supply air temperature graph look ok?


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I’ve not had my Brink flair unit connected to the internet for the last 9 months or so, but managed to get it back online about a week ago. I can’t remember exactly what temperature graphs I was getting for the supply temp previously, but I don’t think there was as much variance as this:

 

IMG_6291.thumb.png.25700b2720b524965bb0385fc992cbe4.png

 

Does that look right? There is currently a 1.7 degree delta between outside air temp and supply temp. Is that the only amount of heat I’m recovering? 
 

Not sure how relevant this is, but airflow is set to about 220m3/h

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Question, do the dips coincide with the unit being on boost? If it does the boost flow rates could be slightly out of balance. Or do your filters need to be cleaned or replaced

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38 minutes ago, Adsibob said:

Does that look right? There is currently a 1.7 degree delta between outside air temp and supply temp. Is that the only amount of heat I’m recovering? 

No, something wrong there!  You might expect that in the summer if the unit is clever and does passive cooling based on internal temp being too high, but I don't know if brink does that and I wouldn't expect to see it in the winter either.

 

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Bypass is currently set to auto. Other options are open or closed, which I always found confusing. Presumably “open” means it bypasses the heat exchanger, sobering which shouldn’t be happening in winter, is that right? If so, I could change it to “closed” to see if that stabilises things.

 

The filter was last changed 46 days ago, when I put a brand new G7 filter in. It’s possible I put it in the wrong way around as I remember finding the labelling confusing…

 I’m in a fairly high pollution area (medium to low for London, but that’s still relatively high), so maybe it’s due a clean. 

 

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48 minutes ago, JohnMo said:

Question, do the dips coincide with the unit being on boost?

I don’t think so. Looking at the graph between these two intervals on the x axis, which I assume represents 24hr midnight to midnight, it doesn’t look that way:

 

IMG_6291.jpeg.b0e8083b4a3743a8fb65d986b41ca7cc.jpeg

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Update: I closed the bypass, and now it’s running much more efficiently, adding about 7.3C to the outside air temp of 13C. I think the temp parameters on the “auto” were set incorrectly. What settings do you put on your auto mode?

Edited by Adsibob
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1 hour ago, Adsibob said:

Update: I closed the bypass, and now it’s running much more efficiently, adding about 7.3C to the outside air temp of 13C. I think the temp parameters on the “auto” were set incorrectly. What settings do you put on your auto mode?

I have Zehender so config will be different. 

 

The way I think about efficienty isn't what it adds, but rather that the delta/loss between extract and supply is.  20C extract and 18C degree supply is 90% efficient @ 0C outside.

 

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5 hours ago, Dan F said:

I have Zehender so config will be different. 

 

The way I think about efficienty isn't what it adds, but rather that the delta/loss between extract and supply is.  20C extract and 18C degree supply is 90% efficient @ 0C outside.

 

That’s a good way to think about it. Just checked the figs now and there is almost a 10C difference between the inlet temp of 11.2 and the supply temp of 21.1. Not sure what outside temp is as I’m not home so don’t have all the figures available - the brink online portal just gives you those - but it’s probably about 9C. 

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41 minutes ago, Adsibob said:

I’m losing 1.3C (13C-11.7C) out of 21.4C so at the current outdoor temp of 11.7C it’s 94% efficient?

 

No value for extract air?

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10 hours ago, Adsibob said:

So what is my efficiency based on these numbers:

IMG_6305.thumb.jpeg.ad145376f5d11f4c298afaf8e08b324f.jpeg

 

I’m losing 1.3C (13C-11.7C) out of 21.4C so at the current outdoor temp of 11.7C it’s 94% efficient?

Not sure you are looking at that correctly, the difference to compare is extract temp from the rooms (internal house temp), and that being resupplied to the rooms. You need the room supply air temperature, to be as close to the extraction from room temperature as possible, otherwise you are pumping in cold air - this should be a small dT into the points of degree difference.

 

Supply temp to rooms / extract from the rooms.

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So the supply temp is the same as the inlet temp. On my phone's web portal they call it "supply temp" and on the machine display it's called inlet. Currently that is 21.2C. The extract temp from the rooms will be the weighted average of the temperatures in the parts of the house where we have extraction, which according to Tado is:

kitch 22.3

bath1 21.6

bath2 20.3

bath3 20.6

WC (i'm going to ignore this as it's very small and I'm too lazy to go and take a temp reading - no tado there).

Utility 21.6

 

I get about 21.4C.

 

So that means i'm losing 0.2C against the supply temp of 21.2C. Does that sound right?

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5 hours ago, Conor said:

Why is your inlet fan RPM higher than the exhaust RPM? Is there a part that shows the flow rates? Or pressure drop?

Because we specified a slight positive pressure in the main room of the house, so as to be able to open the wood burning stove without sucking the smoke out of it. But that is quite a large difference, so i'm not sure that is right. Are they usually configured to be equal?

Edited by Adsibob
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30 minutes ago, Adsibob said:
5 hours ago, Conor said:

Why is your inlet fan RPM higher than the exhaust RPM? Is there a part that shows the flow rates? Or pressure drop?

Because we specified a slight positive pressure in the main room of the house, so as to be able to open the wood burning stove without sucking the smoke out of it. But that is quite a large difference, so i'm not sure that is right. Are they usually configured to be equal?

Fan speed is set based on the pressure drop you have to make up, if your extracts are shorter runs, or have less bends generally you will run at a lower speed, for the same flow rates

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32 minutes ago, JohnMo said:

Fan speed is set based on the pressure drop you have to make up, if your extracts are shorter runs, or have less bends generally you will run at a lower speed, for the same flow rates

That makes a lot of sense. Of our 6 rooms with extraction, 4 are adjacent or very close  to the MVHR machine, so pretty short runs. Whereas most of the other rooms of the house which all contain supplies, are further away.

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