Posted by: @newhouse87

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@derek-m oh man sounds difficult, im presuming the installer had the calculations, is it on the ber cert i posted? When rooms get up to temp, dont the loops just close so they wont overheat. What would you think of leaving all living areas loops open together or would that be costly?

Let me give you an analogy.

You are given the task of making a journey of 100 miles in a 2 hour period, and instructed to arrive on time, no sooner or no later.

You could set off down the motorway at 70 mph, but find that after 1 hour driving you have covered 70 miles, and if you continue at this speed you will arrive much too early. So you have to make the choice, do I stop for a period of time and then travel the remaining 30 miles at 70 mph, or do you slow right down to 30 mph?

Alternatively if you had set off at 50 mph, you would have traveled the 100 miles in the 2 hour period without any problem.

Which do you think would use most fuel?

For best efficiency a heat pump needs to operate in the same manner as driving continuously at 50 mph. Having thermostats switching on and off, is like varying the speed of the car, slowing down then speeding up, which I feel certain will use more fuel.

So, as suggested, turn up the thermostats to get the car running at constant speed, then reduce or increase the speed gradually using WC mode settings, until you get the required temperature in the coldest room. The temperature in the remaining rooms can then be reduced by lowering the water flow rate.

@transparent haha no im a lab technician, the isulation was just helping out one day with the plumber.

@derek-m thanks ill take that as living areas should all be open at once for efficiency, that makes alot of sense now just to actually do it regarding weather settings. so unit settings wise everything is ok i take it now i have changed my dhw temp/schedule and disabled back up heater? I would like to know where i can see flow and return temp to check if its near5 that delta t is set to.Ill leave you alone now as you and transparent have been very good with yere time. Ill update at some stage in near future.

Posted by: @newhouse87

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@derek-m thanks ill take that as living areas should all be open at once for efficiency, that makes alot of sense now just to actually do it regarding weather settings. so unit settings wise everything is ok i take it now i have changed my dhw temp/schedule and disabled back up heater? I would like to know where i can see flow and return temp to check if its near5 that delta t is set to.Ill leave you alone now as you and transparent have been very good with yere time. Ill update at some stage in near future.

Looking at photo ending 1359, the Leaving water at 48.8C is the LWT, and I believe that the Inlet water temp. of 40.1C is the RWT. This would indicate a DeltaT of 8.7C, but will only be relevant if the heat pump and water pump are operating.

You will probably find that the DeltaT will not be exactly 5C, and will vary from time to time. This temperature is not critical.

@derek-m Do them temps not seem v high for ufh or were they taken during dhw cycle or something? Cant access any info while pump in operation unfortunately. Havent a clue of flow raet from unit either.

Posted by: @newhouse87

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@derek-m Do them temps not seem v high for ufh or were they taken during dhw cycle or something? Cant access any info while pump in operation unfortunately. Havent a clue of flow raet from unit either.

I had noticed that the temperatures were high, but had assumed that you had been running DHW heating. I don't have a Daikin heat pump, but cannot understand why you would not be able to obtain data with the unit running.

I would suggest that you read the manual and see if you need to be in installer mode. Conversely maybe one of the Daikin owner's on the forum can give guidance, or there is always YouTube.

@derek-m hopefully thats it, just finished a dhw cycle but didnt know that affeceted lwt temp, i presumed lwt was what it said on main screen the desired temperature. Even on youtube vids the unit seems to be off.

Posted by: @morgan

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that is the absolute opposite of what was suggested to me soon after my system was installed.

Whoever suggested that needs to do "the maths". I would like to know how much heat a couple of meters of 22/28mm pipe emits when carrying water at 35 degC.  As a rough guide, calculate the surface area of the pipes, then find a radiator with equivalent surface area, noting that you don't have the chimney effect on the pipes (which you have with a radiator), so they will emit a bit less than the radiator.  once you have that number, decide if you want to worry about it.  Also consider that this heat is actually going into your house, consider it an extra radiator.

For clarity.

1. Any pipes carrying the high temperature water to the water tank (and back) must be insulated. 
2. Any pipes NOT in the thermal envelope of the building must be insulated
3. Any pipes carrying space heating temperature water running within the thermal envelope of the building, don't need to be insulated, unless they push too much heat into the room or spaces they pass through.

Posted by: @william1066

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I would like to know how much heat a couple of meters of 22/28mm pipe emits when carrying water at 35 degC.

I don't think that provides a fair assessment of the issues being faced by @newhouse87

1: On this site the LWT is currently over 48°C, not 35°C

2: The target Δ is 5°C. It doesn't take much by way of pipe losses to adversely affect this.
We need all of that 5°C to be accounted for in the UFH coils, not lost to the air in the plant-room.

Posted by: @newhouse87

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im a lab technician

OK; so whatever level of educational establishment you work in, it must be embarrassingly obvious that there simply isn't enough knowledge and understanding of energy issues within the general population.

If we're going to stand a chance of reaching Net Zero CO2 emissions in time to prevent runaway climate change, then we can't wait for government public-awareness initiatives to address this.

All of us can help by raising these issues in the staff room at work, and the pub in the evening.
The above insights given by @derek-m on how to set up a domestic heat-pump system need to gain much wider circulation.

This discussion topic will remain here as a reference resource for months to come.
I hope all of us can ensure that we pass the URL to others, and enable them to benefit too.

Posted by: @transparent

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We need all of that 5°C to be accounted for in the UFH coils, not lost to the air in the plant-room.

From what I understand, this is a 260 sqm new build.

@200mm centers this is 1300m of pipe

@150mm centers this is 1735m of pipe

The exposed pipe, is likely a very small % of the overall pipe in the house.

Actual heat loss for un-insulated 28mm copper pipe with 22deg deltaT with ambient is 35watts per meter.  So 10 meters would be 350watts emitted in the plant room, which will find its way to the rest of the house [hopefully].  The plant room may be hotter than the rest of the house.

@william1066 do you think i should leave all lving areas open so? Would it cost much more. Sun/sitting and kitchen all beside each other. Im worried it will just take longer to heat all areas and some rooms might be getting bulk of heat. Bathroom in particular, installer must not have balanced very well as its right beside manifold and piping goes through plant room wall yet has as much flow as any other loop. If more loops open does that mean all the rooms on the loops will be slower to heat up?