Posted by: @derek-m

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Sorry, I was thinking of another post when I mentioned Ecodan. If you can reduced the required DeltaT setting then this may allow the heat pump to run continuously at a lower output rating.

Is there any reason to believe changing the delta T to 3 when it's milder outside is detrimental? I guess the trade off is possibly a circulation pump having to work a bit more therefore using more electricity but the compressor would cycle less. Which one is the more energetically costly, in your opinion? Of course I will have to test it.

Posted by: @derek-m

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It sounds like the flow regulating valves for the UFH in your colder rooms may need adjusting, or the solenoid valves are not operating. Have you checked the UFH manifolds?

I opened all the valves manually as I wanted to have a fully open circuit not controlled by individual stats, instead of having different zones in the house. I can see on the flowmeter that there is indeed flow. But on an open circuit, the flow at delta T 5 settles to 10-12l/min, and on the individual flowmeters (9 in total) it is very small, like 1l/min. Is the flow rate a constant, meaning that increasing the flow rate in one loop decreases it in all the others? Or the pump will simply have to work harder to maintain the set flow rates in the other loops if I increased it in just one? I'm not saying I am going to do it myself, it's just to udnerstand how it works.

Posted by: @frappzy

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Posted by: @derek-m

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Sorry, I was thinking of another post when I mentioned Ecodan. If you can reduced the required DeltaT setting then this may allow the heat pump to run continuously at a lower output rating.

Is there any reason to believe changing the delta T to 3 when it's milder outside is detrimental? I guess the trade off is possibly a circulation pump having to work a bit more therefore using more electricity but the compressor would cycle less. Which one is the more energetically costly, in your opinion? Of course I will have to test it.

Posted by: @derek-m

↑

It sounds like the flow regulating valves for the UFH in your colder rooms may need adjusting, or the solenoid valves are not operating. Have you checked the UFH manifolds?

I opened all the valves manually as I wanted to have a fully open circuit not controlled by individual stats, instead of having different zones in the house. I can see on the flowmeter that there is indeed flow. But on an open circuit, the flow at delta T 5 settles to 10-12l/min, and on the individual flowmeters (9 in total) it is very small, like 1l/min. Is the flow rate a constant, meaning that increasing the flow rate in one loop decreases it in all the others? Or the pump will simply have to work harder to maintain the set flow rates in the other loops if I increased it in just one? I'm not saying I am going to do it myself, it's just to udnerstand how it works.

The compressor is always going to use much more electrical power than a water pump, and lowering the DeltaT setting should allow the power output to reduce further, until the water pump once more reaches its minimum speed. The limiting factor may then be how low the compressor can go.

When you say that you opened the valves manually, do you mean actual hands-on or via setting to manual on the UFH controller. Can you supply photo's?

I assume that your UFH will have two headers, one containing the flow regulator/indicator valves, and the other with the solenoid operated valves. I would suggest that you check the temperature of each pipe going to your UFH loops to see if any are cooler than the others.

The water flow from the heat pump will be shared around the system dependent upon the position of the flow regulator valves. Obviously opening one valve further, may steal some of the flow from the other loops. The objective is to get the maximum flow through your system, with the flow regulators adjusted to balance the room temperatures, then adjust the weather compensation curve to achieve the desired room temperatures, in that way you do not need thermostats to control the individual room temperatures.

@frappzy

Posted by: @frappzy

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But then I do not understand why I can "force" the system to provide less heat by manually changing the delta T to 3, so that at 10l/min the heat output would be 2.1kW.

I can do the same on my.  Mine is rated at 16kW.  When I was "playing around/fine tuning" the flow temp and delta T I ended up with this [see the squiggly bits below].  Decided this was a really bad thing to do, and quickly changed it, once I spotted it.  Interestingly I got the same when I made the flow rate too low by turning down the pump a bit.

The inverter + scroll compressor + fans ultimately have a minimum output they can achieve, I am still trying to find documentation that details that for my heat pump.  No luck so far.

Posted by: @frappzy

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Clearly I have a LOT to learn about how these systems work

I found additional material for that journey here.  "...Scroll compressors with continuous modulation can adjust from 10 to 100 percent capacity (or vice versa)...Variable speed scroll compressors have up to 7:1 turndown ratio ..." - not sure the type of compressor in my heat pump though.

Posted by: @derek-m

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When you say that you opened the valves manually, do you mean actual hands-on or via setting to manual on the UFH controller. Can you supply photo's?

I assume that your UFH will have two headers, one containing the flow regulator/indicator valves, and the other with the solenoid operated valves. I would suggest that you check the temperature of each pipe going to your UFH loops to see if any are cooler than the others.

I opened the valves on the actuators (white valves in the picture). This was to have an open system for the pump to heat the whole house at once. Originally, it was because I thought the cycling was due to the pump not having enough volume, but it was before I discovered there's a buffer tank (Daikin engineer did not even bother checking and suggested me this was one possibility).

Posted by: @derek-m

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The water flow from the heat pump will be shared around the system dependent upon the position of the flow regulator valves. Obviously opening one valve further, may steal some of the flow from the other loops. The objective is to get the maximum flow through your system, with the flow regulators adjusted to balance the room temperatures, then adjust the weather compensation curve to achieve the desired room temperatures, in that way you do not need thermostats to control the individual room temperatures.

I see. But if the other rooms are fine at the current flow temperatures, having more flow in the currently colder rooms means I will have to further raise the flow temperature as in doing so I will have less flow in the remaining loops?

Posted by: @frappzy

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Is there any reason to believe changing the delta T to 3 when it's milder outside is detrimental?

One of my [many] knowledge gaps.  What is the right delta T?  Should I vary this?  If so, what are the parameters that should drive these changes?  I had more cycling in the evening so opened some internal doors and raised the weather compensation curve by 2 degrees.  I am still not clear on how to prevent cycling at low demand (which is something I need to deal with pretty soon given the clock is ticking).

This is also the first time I have seen the inverter so low - never went below 97% until now.  More questions than answers ... sorry!