Hi

I can see that the system is setup for weather compensation but no idea what the curve is set to. On the main controller press the menu button then go into heating on the right of the screen will be a magnifying glass, press that and post a picture of the graph, that is your weather compensation curve.

How many other thermostats do you have?  From the picture I’m guessing they are Heatmisers linked to  their wiring centres.  Unless you need to prevent some areas overheating you don’t need zoning but it can be bypassed or just set them all to a high temp that you don’t want to be above. That will give you the largest engaged volume of water to heat in the UFH that will lead to the best efficiencies.

Then it’s just a case of optimising the weather curve to the heat loss of your home.  Lower outside temps need higher flow temps in the ufh and vice versa that is something you can tweak over the heating season

When we built our house we had a thermostat in every room. The first couple of heating months, I nearly fell over we had used so much energy. Reason the thermostats were playing merry hell with cycling even with a big buffer.

Over the rest of the heating season I simplified started to understand what was happening and how-to avoid it. Net results were around 50 to 70% reduction in energy costs (depending on outside temperature. System now consists of a diverter valve, a timer and thermostat for the cylinder, that's pretty much it, no additional pumps, mixers or thermostats. 

First get rid of all the thermostats - (wind them all to max temperature so it forces them open) for best efficiency you need to have WC set and not rely on any third party stuff. You then need to set the WC curve. Start it at 20 outside and min flow temp of the ASHP. (Advantage of this is it becomes self regulating). At design temp you should not need more than 30, possibly lower. However a buffer and mixer will most likely add 5 to 6 degs to that - big efficiency losers.

Simplify - simplify more - then simplify again. I also got rid of glycol, max flow jumped from just over 1m³ HR to 1.3 with no other setting changed.

@gary Thanks for the prompt reply, working away from home until Friday but will post up compensation curve upon my return.  Can you comment on my issue about timers?  Should the shower water come through cold if they're off?  Or should they be set to 24 hrs for weekend and then reduced to a couple of hours morning and evening for the working week?  Struggling to understand efficiencies here.

Thanks,

Neil

@johnmo Thanks for quick response, will open up the thermostats to full but is there still a way to set-back temps for the evenings?  I prefer it to be a little cooler in the bedrooms for sleep and wonder how you'd achieve this with thermostat taken out of the equation?

Each room has a Heatmiser, will open them up and feedback.

Thanks,

Neil.

@ngillam I'm not sure what the timers are doing, you have a Mitsubishi preplumbed cylinder the main ecodan controller has timers for when you want to heat the hot water, so I have no idea why you would need a separate timer, it makes even less sense if you have hot water but it doesn't reach the shower if they aren't on.  Hopefully someone else has some ideas.  Similary for the UFH timer, I guess the installer thought it was simpler for you to use these timers rather than the native one in the ecodan controller.

I would have thought any hot water timing program in the ecodan controller would override the third party timers so I would try setting the third party controllers to permanently on and changing the hot water timing in the main controller.  You said you heat to 48C with a 7C reheat, depending on your usage you may find you don't need a reheat at all.  I heat to 48C for 2 hours at night and its enough to last all day without a reheat, I do this in cheap off peak period overnight, if you don't have a cheap off peak period most efficient time of day to heat water is when its warmest outside.

WRT setbacks overnight you can program setbacks into the heatmiser thermostat schedules but this is going to reduce efficiency as it will close off some circuits overnight and as your house is new its likely to be well insulated and UFH is slow to react so will probably make very little difference to the temperature of the bedroom.  You will just have to keep the thermostats in the bedrooms at a lower temp all the time and see what temp you can get away with.

@gary Morning, yes the timers are an oddity.  From what I can tell, one controls UFH and towel rails, the other water to showers, baths taps etc.  If the timer is off no hot water reaches the taps, it seems the heatmiser timers overide the schedule of the ecodan controller.  The hot water one could be switched to 24hr/7 days a week but the heating timer would mean the towel rails are on 24/7 which doesn't seem efficient.  Confusing..............

Thanks,

Neil.

Posted by: @ngillam

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but is there still a way to set-back temps for the evenings?

Not sure of your screed thickness, we have a 100mm and once up to temp the floor doesn't really cool enough to make set backs meaning full. We did try but we ended up have the whole heating and set sck 12 hrs out of sink. Have found if you run the heating 24/7 the whole house feels warm even though it may only be 20, as the walls floor are no longer sucking the heat from you.

Also setbacks you end up chasing a reheat time that is acceptable, so run elevated flow temperature, you are then reliant on thermostat to keep room temps in check.

We ended up balancing the bedroom flows to get cooler bedrooms all the time. So less loop flow, equals lower heat output. More flow, more heat output. So run the heating for 24 hrs and access room temperature. If any are too hot or too cold tweek the flow for those loops repeat.

When setting up your WC choose a room as the master room, say the lounge, you adjust the WC curve to get that room to correct temp - do not adjust loop flow in that room. You adjust loop flow in all other rooms to get those room correct.

Just looked at the controller photo, is that saying at -1 you flow 42 degs? If so that is bonkers for UFH.

Do you have any drawings of your system you can post up?

The 42C in the photo is the HW tank temperature.  You can’t see flow temp on the front screen only the offset from the curve which is the -1C you can see. It’s not the flow temp at -1C just a 1C decrease in flow temp from the programmed curve 

@johnmo Morning, will be able to post more up on Friday, I'm going to open up all the thermostats in each room and take it from there.  It's the first chance I've had to tackle the heating, we suffer with a lot of solar gain through our south facing windows so its been really quite hot throughout but with autumn coming now's my chance.  I'm interested in how to adjust flow "in certain loops" as you put it.

The 42 degs is my tank temp, the -1 should be a slight set back for my WC which I'll post up on Friday.

Looking forward to getting a good set up and really appreciate the knowledge and help from all the replies.

Thanks,

Neil.

@gary Yep...what Gary said.

@ngillam ‘We suffer with a lot of solar gain’ 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😉. Regards, Toodles.