Posted by: @toodles

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Well, that’s not an expression one might hear often! Sounds as though thought might be given into how to harness that energy to distribute it elsewhere in the house! Probably no easier than trying to keep cold at bay though😉

The OP has an ashp, he has UFH, start the cooling up, at 14 to 16, let that do most the heat management.

@gary Afternoon, as promised, my weather compensation curve:

Hi

i think you can play with that curve a bit.  It’s set to 25C flow at an outside temp of 35C but then ramps up to 50 at -15.  So for every 2 degree in outside temp drop flow increases 1deg.  

I would try and extend the 25C flow temp down as far as you can.  Until the house can’t keep it upto temp then you can start increasing flow temp on a gradient.  In tne depths of Winter you should be able to work out what the other end needs to be set at.  

I would guess currently the flow temp is going to be too high at autumn temps and it will be cycling on and off with the thermostats where as you need it to just trickle in heat so it never hits the limit of the thermostat but keeps the house warm

My curve is below 32C all the way to 0C ideally it would be lower but mine cycles like crazy below 32C but you should get the idea.  Have yours flat at 25C until house can’t hold your desired temp before you start increasing flow temp

Would suspect some big changes on the WC curve are possible.

Curve should start at the lowest flow temp (normally 25) at about 20 degs.at that setting the heat pump should never get a start permissive from the return temperature, because should be warm enough.

I flicked our cooling off yesterday it's been 15 degs and peeing down and house has stayed at 21 just circulating water no heat added.

Your heat loss looks similar to ours and our max flow temp goes up to 30 at -9. But your mixers will mess this up. They will add about 5 degs.

The attached should give you a start on the cold temp set point. Basically start with UFH pipe centres and the W/m² required output. Draw across to get mean flow temp (min point between flow and return)

@gary Thanks, will adjust curve and go from there, difficult when it's been so warm lately.  Can I ask you for your DHW settings, and if you use timers?  My neostat timers seem to override the main controller.  Also, what should these pumps be set to?

Thanks,

Neil.

@johnmo Afternoon, Thanks for this, I've understood the first few sentences but you've lost me on the UFH pipe centres, even if I could find that out it looks as though it'd be per room for m² my house is 185m²?  Also, you mentioned switching the cooling off?  I wish I did have cooling but not aware of this function on Ecodan.  Do you have a weather compensation curve to post up, would be good to know how your timers are set too, my heatmisers seem to override my main Ecodan controller in that no hot water gets to shower unless timers are on.

Thanks,

Neil

I just use the timer on tne main ecodan controller it’s set for 2 hours overnight and no reheat set to 48C and the tank lasts family of 4. 2 showers, washing up and a full bath without needing to reheat during the day.

Posted by: @ngillam

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Do you have a weather compensation curve to post up,

I don't have a curve I can post as my display is just numbers and letters, no images.

But it starts at 20 degs outside and a flow temperature of 25. It ends at -9 outside at a 29 Deg flow temp.

Timers for heating - I have none, it is set to run 24/7. What happens is the heat pump is always monitoring return flow temperature, it triggers the heat pump compressor to start and it runs a heat cycle. Depending on how quickly the heat pump can replenish the energy back to the floor (how quickly the house looses it's energy) determines the run length.

This system is built-in to every heat pump or boiler, you need low heat losses to exploit it.

Not sure what your heat loss is but as an example let's say 4kW at -3.

So 4000W / 185m² is 21.6W/m².

Assume you have 200mm pipe centres for your UFH. Using the left hand side of the chart I posted drawing a line through 200mm centres and 22 W/m² gives a flow temperature of 28. This is the mean, so add half the difference between flow and return temperature (deltaT of 5), so this becomes 30.5 target flow at -3. You have to add a little to this

Floor covering act as a blanket so you need to add to target flow temp a little.

Mixing valves on the manifold always add some return flow to supply flow so will cool the flow a few degrees.

So set your curve to

starts at 20 degs outside and a flow temperature of 25. It ends at -3 outside at a 34 Deg flow temp. As a starting point.

Move all thermostats to max and remove timers. Let the system run if it gets too warm trim the curve down too cold up a little, 1 Deg makes a big difference when you are close.

Sorry can't help with DHW and timers. I am playing with mine at the moment.

Posted by: @ngillam

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I wish I did have cooling but not aware of this function on Ecodan

Cooling is really easy to set up on the Ecodan.  Turn off the power to the heatpump and the control unit, unscrew the front panel of the main controller that is attached to your hot water cylinder.

Locate dipswitch SW2-4 and move it from off to on position, reattach cover and turn everything back on.

Once your main controller boots back up go to the heating options and cooling will now be visible.

You will need to activate cooling in the Ecodan timing schedule as it has different time schedules for for heating and cooling and you will need to turn up your thermostats to a higher than room temperature than its currently at to open the UFH circuits but then chilled water will circulate.

You can change the water temperature up and down on the main controller I find 14-16C in the summer works well without creating condensation.

If your Ecodan is plumbed as one zone for UFH and rads then your rads will produce condensation so it only really works if you only have UFH or maybe you can isolate the UFH circuit from the rads with your thermostats.

@johnmo Morning. Thanks, that's concise and clear steps to follow, I'll give it a go.  Looking forward to getting this right, quite interesting stuff.

Thanks again, Neil.

@gary Morning. ah, wow, wish I'd known this earlier.  Might be a stupid question but won't this affect the ability to heat hot water?  Can't get my head around how this will work.

Thanks,

Neil.

@ngillam No hot water is unaffected the heat pump just turns back to heating for hot water and back to cooling when its finished.

What you do have to remember is to change it back to the house heating mode on the controller when the outside temp drops again, if the temp drops below the thermostat limit they will call for heat and what you will get is cooling making for a very cold house, I have done this once, heating (cooling) came on overnight it a cheap period and it was 17C downstairs by the morning.