What is Energy Integral

[jamesdiyer]

Regarding the cycling of the vaillant aerotherm plus, has anyone looked into or got information on the power it starts a cycle with? My machine seems to cycle well, however I feel it comes on at a higher rate than needed which pushes temperature up fast, where as if it started at a low compressor speed it wouldn't rap so fast and on cycle would be longer. Maybe it needs the compressor speed to get going and is just how it is. 

[Dreadnaught]

It's a good question and I don't know the answer. 

 

Just to mention there is an Arotherm-Plus setting that could be helpful. A setting which caps compressor speed by an amount and during a time-period set by the user. And I have used this setting to cap the compressor speed during the morning period, when CoP is less favourable.

 

The setting is in the heat-pump controller (not the VRC720): Installer Level > Configuration > "Compr. noise reduct." Range: 40 to 60%; default 40%. The cap is 100% minus the setting value, so, for example, a value of 40% caps the compressor rate at 60%. Once the cap is set, the time period of its application is defined in the VRC720.

 

Obviously the purpose of the setting is limit noise but it can be just as well used to cap the compressor speed for reasons of efficiency.

[JohnMo]

Think most will try to hit target temperature pretty fast and once at target ramp down. Vaillant have quite a few settings than manipulate how it runs.

[jamesdiyer]

10 minutes ago, Dreadnaught said:

It's a good question and I don't know the answer. 

 

Just to mention there is an Arotherm-Plus setting that could be helpful. A setting which caps compressor speed by an amount and during a time-period set by the user. And I have used this setting to cap the compressor speed during the morning period, when CoP is less favourable.

 

The setting is in the heat-pump controller (not the VRC720): Installer Level > Configuration > "Compr. noise reduct." Range: 40 to 60%; default 40%. The cap is 100% minus the setting value, so, for example, a value of 40% caps the compressor rate at 60%. Once the cap is set, the time period of its application is defined in the VRC720.

 

Obviously the purpose of the setting is limit noise but it can be just as well used to cap the compressor speed for reasons of efficiency.

 

Thanks for the quick reply and thoughts. Yes I was reading around this but wasn't sure how helpful it would be in this case. I was trying to set up decent monitoring to be able to have data but struggling with that. 

 

I don't think it's coming on that strong (I haven't bothered to stand by the box and watch it, but having seen on the app we are hitting ~1500W power input, at lowest compressor speed I see around 950W depending on outside temp. Our unit is quite oversized, while we complete renovations, so we cycle down to 4C. Though we will see -7C overnight quite regularly, and heating off as 15C due to solar gain - so our cycle range of temps is shifted lower. I do think it's cycling well, but if I could get it to pace it's on a bit, I think it might run nicer. I can note the off periods when the temp outside is circa 10C and you can feel the lack of heating I to the house. 

 

I guess I could put it in noise reduction mode during the day time and see if it helps. But really I need graphical data first. I would leave it off overnight as we need it to be able to run full to meet potential heat loss at low temps. 

[jamesdiyer]

21 minutes ago, JohnMo said:

Think most will try to hit target temperature pretty fast and once at target ramp down. Vaillant have quite a few settings than manipulate how it runs.

Yes, I feel it's running in that way, and because we have a 15kW beast, at mild temps circa 10C it heats it really quick. 

 

But for example, it's 10C out side right now. But with a huge north wind blowing and snowing 500m above the house. So when it cycles off you can note that it's off. 

 

Perhaps increasing radiator surface area would help dissipate more heat and decide the increase of return temp. 

 

Also I don't think it's a situation of needed to increase weather curve (unless maybe it is) as when it's running and maintaining the flow temp of the curve 0.7, it's maintaining temperature in the house. It's just because it can't modulate low enough and then cycles off. I did wonder about pushing the curve a bit higher so it can keep running, but I think we would then be hot. 

Edited November 8 by jamesdiyer

[JohnMo]

12 minutes ago, jamesdiyer said:

Yes, I feel it's running in that way, and because we have a 15kW beast, at mild temps circa 10C it heats it really quick. 

 

But for example, it's 10C out side right now. But with a huge north wind blowing and snowing 500m above the house. So when it cycles off you can note that it's off. 

 

Perhaps increasing radiator surface area would help dissipate more heat and decide the increase of return temp. 

 

Also I don't think it's a situation of needed to increase weather curve (unless maybe it is) as when it's running and maintaining the flow temp of the curve 0.7, it's maintaining temperature in the house. It's just because it can't modulate low enough and then cycles off. I did wonder about pushing the curve a bit higher so it can keep running, but I think we would then be hot. 

Is it worth trying low noise mode in the day time when it likely to be more mild, than at night time.

[jamesdiyer]

Noise reduction at 60% doesn't help. So clearly the compression isn't ramping on at that higher rate (power input in still the same as it was without noise reduction around 1600W). I guess this means it's doing a good job of not starting too hard, but I feel it could do better if it started lower % of compressor speed max or modulate down faster.