View Full Version : Daikin Altherma not reaching flow temp (35C)

Scott MacDonald
02-11-2013, 08:59 AM
Hi all,

Can anyone suggest any reasons to me why my Daikin Altherma LT split does not reach the set flow temperature of 35C. This only seems to happen during the early morning and heats up as the day progresses. Most mornings at around 7am flow will be in the region of 30C or a little less. To simplify things I have set all zone stats to 20C 24/7

My theory is that this is because the return water temperature from the UFH loops is cooler and hence the delta t settings of the altherma unit (set to 5C) only allows the flow temp to be 5C above. Perhaps my take on things is a lot of nonsense but I would like to understand this better.

Thanks for your help and apologies if I am repeating past posts.

02-11-2013, 04:04 PM
Do you have the Altherma set up on a time schedule for the space heating?
What is the model number of the Altherma?
What time schedule do you have set for your DHW regeneration? If these overlap, the DHW will take priority over the space heating. Are you running the space heating in the weather compensated mode, if so have the parameters been set up correctly?
Presumably if this is a new installation you do not have any past years performance to compare the system to. Has the Altherma been correctly selected to match the heat loss requirements?

Scott MacDonald
03-11-2013, 10:30 AM
Its a split ERLQ011CV3 + EHBH16C3V. No time schedule for space heating, its on 24/7. Leaving water temperature is set to an absolute value of 35C, weather compensation mode is off. DHW regeneration is set to daily schedule at 1pm plus reheat, so no practically no overlap because by that time the house has reached the desired temp and space heating is off. It is a new install and has been running since June so no historical data to compare. Overall I am happy but I would like to know why there are times when the leaving water temp does not reach its preset value even when there is a demand for heat. On a simplistic level I would have thought that if it is set to 35C and there was a demand for space heating the system would heat the water to that value but it does not always happen. Perhaps the system is designed to function this way, I don't know.

03-11-2013, 04:48 PM
I would check around the 3 port valve and see if, when it is on heating mode, not DHW, that all of the heat in the flow is going to the house heating system. If you have any heat going to the DHW tank then your valve is not set up correctly.

Also, how hot is the discharge gas pipe going into the indoor unit? Can you hold it comfortably or does it burn your fingers?

Scott MacDonald
03-11-2013, 07:20 PM
3 port valve seems fine, there is a bit of residual heat on the DHW side but I think that is mainly coming from the tank.

The discharge gas pipe is red hot when the flow is around 35C but cooler to the touch when we are at 29 or 30C.

Since I have no experience of any other Alterma unit I cannot be sure what to expect. Leaving water temperatures at times 5 or 6 degrees (28-30C) lower than that expected. Other times running fine at or around the absolute value. I had expected that setting the leaving water temperature at an absolute value would mean that the unit would reach that temperature and run with it provided there is a demand for heating. Perhaps not and my assumptions are mistaken. Would the behaviour I am describing be considered normal, or is it worthy of investigation? Bearing in mind that the cold weather is on its way.

04-11-2013, 08:11 PM
Are you able to measure the temperature of the discharge gas pipe (the big one) at the outdoor unit and also at the indoor unit and post the readings?

install monkey
04-11-2013, 09:29 PM
watch the outdoor to see hoe long it runs and how frequently it going into defrost mode

Scott MacDonald
05-11-2013, 08:39 AM
Frank, would I need an infrared spot thermometer to measure the temps or is there is another way I can do that?

05-11-2013, 10:47 AM
The temperatures can be read from the Daikin controller if you put it into the Installer mode. However, it would not be wise for me to put this information onto an open forum as you could alter some of the operational parameters from this setting and potentially cause more operational problems.

Scott MacDonald
07-11-2013, 12:18 PM
Wasn't aware the information was available on the installers menu, I will check it out and post if necessary. Today the system seems to be performing fine, maintaining a constant 35C flow temp without going off and on/up and down as it did before. Thanks for everyone's input, will let you all know how it goes.

30-12-2013, 09:49 PM
I am having exactly the same problems? Daikin altherma split system. Daikin controller panel set to 35, UFH heating manifold only heats to 29-30?????????? I am in a housing association property, new build. Had loads of probs previously when running heating and DHW together. All fixed now, but now now investigating if both systems have been set up correctly. My housing association are clueless about it! Thermostats only seem to come on at 21 degrees/ help please!!!!!!!!! patchy heat also!

31-12-2013, 12:10 PM
Has the system been set up for weather compensation? Is there a cloud symbol visible on the controller? If there is, then with the ambient at around 9-10C today, the weather compensation could be limiting the flow temperature.
Your first point of contact should be the housing association. They should be able to get the original installer back to check that all is working correctly.
The Daikin Altherma is not designed to provide DHW and Space heating both at the same time. It is set to default to regeneration of DHW as a priority over the Space heating.
Normally you would set the DHW to regenerate early in the morning before the UFH is required, thereby making the full output available to the UFH.
If however during the day you have used up all of the stored DHW, then the system will revert to DHW regeneration which could take upwards of 50 minutes, dependent on the size of your DHW tank and the capacity of the system.
The setting point of the room stats is quite important. With UFH it is normal to set the stats at a slightly lower temperature than you would with radiators.
What temperature are you trying to maintain the DHW tank at? Once you set this above 48C and the Altherma has achieved this tank temperature, the booster heater will cut in and the Altherma should then revert to providing Space heating via the UFH.

01-01-2014, 08:16 PM
Has the system been set up for weather compensation? Is there a cloud symbol visible on the controller? If there is, then with the ambient at around 9-10C today, the weather compensation could be limiting the flow temperature.
Hi there, thanks for replying
No I dont have the weather dependant button on.

So am I correct in thinking that the flow temp to the UFH is displayed on the daikin controller? And that the temperature gauges on the heating manifold should show the same temp as the controller? The heating manifold says also that the flow rate is 1.6l/min, but when i turn the heating on, the little spring thing shows a flow rate of 5l/min. Could this be relevant?

I am aware of the systems inability to do DHW and heating at the same time. I have had the priority changed in this respect and it gives priority to the heating .

I have the DHW set to come on during the early hours of the morning.

My room thermostats- these confuse me. The light only comes on on them when i turn it up to 22? That cant be right? my house cant be 22 ALL the time?

I have the DHW set to 42

I will try and get my housing assoc to sort this but I need to know how it should be working before I approach them. Are you aware of any companies which would come and check the efficiency of the system in its entirety. I am not sure that this has been done by anybody.

Hope you'll be able to help!

01-01-2014, 10:05 PM
Thanks for the update on how you have the system set.
It is unusual on new site installations for the weather compensation facility to be not used as this can assist with reducing the overall running costs.
The temperature displayed on the Daikin controller is the required setpoint, but does not actually display the flow temperature being achieved. The actual flow and return temperature could be checked by the service engineer.
On your UFH manifold, how many loops or circuits are controlled? There should be at least one loop for each room that has a wall mounted thermostat. Depending on the size of the room, there may be more than one circuit to provide sufficient water to suit a particular room area.
The flow rate of 1.6l/min is possibly slightly low, however when the heating is turned on, a flow rate of 5l/min is quite high, however this could be a by-product of only having one area calling for heating.
Possibly the room thermostats could be out of calibration, usually there is a means of adjusting these, dependent on the type that has been installed. This could be checked by the service engineer.
You mentioned in your original post that the heating was patchy. Is this in general or when all of the wall thermostats are turned up with the lights on?
Please remember that it will take a little while for the UFH loops to get up to temperature, but after a period of time with all og the thermostats 'ON', you should be able to feel the loop pipework becoming warm to all room areas. The return pipework should also become warm to the touch. Bearing in mind that with the flow temperature set at 35C, the pipes will never feel 'hot' to the touch.
These temperatures can be checked by the service engineer with a surface temperature probe.
The system should have been fully commissioned to the satisfaction of the Housing Association prior to the handover, check with them to see if they can assist you.
Most of these problems can be overcome by careful diagnosis of the setting parameters, flow rates and pipework configurations and once sorted out the system should provide you with trouble free operation. However all of this may take a little time at your house.
Dependent on your location in the UK, there may be a company or individual on here who may be able to offer to assist you. However, unless they happened to be the original installer, there would probably be a charge made, which you might have a difficulty in gaining a refund from the Housing Association.
If your house is part of a new site development, there could be a common incorrect setting that has been carried out on all of the similar properties. This would definitely require further action by the Housing Association. Possibly discuss your thoughts with your neighbours to confirm if others are experiencing similar issues.

02-01-2014, 12:21 AM
Thanks Hyperion. Your info is very helpful!. I'll try to answer your questions !

The weather compnsation function has been enabled on the controller, I just dont use it. It is set to -1 on low ambient temp, 45 High ambient temp, set point at low temp is 20, and 30 set point for high temp. Not sure if these are right. shall i start using this function?

My set point for heating on daikin controller is 35. the temp showing on the UFH manifold is 29. It never seems to reach the 35? EVER.

On UFH manifold I have 7 circuits. I will monitor the flow rates, in various scenarios.

the room thermostats seem to be an issue across the whole development as is patchy heat, lack of DHW etc etc etc!!!

the patchy heat seems to be in general. Today I turned the bathroom floor up to 25 on the thermostat- the light on it never went out at all. Floor got nice and warm, but using this floor as a comparison, other floor areas in the house get no where near as warm?

The UFH loops, both pipes seem to be at the same temp. The flow pipes have a temp gauge on it. this shows 31 max. The return pipe shows 30. This isnt right is it? There should be a diff of 5 or so?

With regards to commisioning certs, my household handbook does not have any of them. I am aware that the main contractor has not had them either? Should I insist on seeing them? Not sure that my HA would know if they had been commisioned correctly even if they were available. They dont really understand the system themselves, or how it should be set up for maximum efficiency. I'm sure u can understand my predicament!

I am in discussions with other residents on the development with regards to all the issues, and am keeping tabs on it all! (thats when I'm not in the heating cupboard taking down readings) lol :)

Thankyou for your help!

02-01-2014, 07:26 AM
Morning Cathyr456,

Please do not start adjusting any of the settings until they have been checked and confirmed by the service engineer as he will need to establish how the system is working with the current settings and then, if need be, make changes to achieve a correctly operating system.

Does your controller have a permanent LCD display with a round control button beneath it or does it have a opening plastic door for the bottom half? This will help me to determine which series of Daikin Altherma that you have installed as some of the setting procedures are different on each series.

OK so you have 7 heating loops serving probably six rooms. Are all of the rooms carpeted except the bathroom? If so, it will be harder to appreciate the floor temperature in the carpeted rooms.
You are correct in that there should be 5C difference between the flow and return temperatures when all of the UFH loops are in use, however this would be dependent on the actual flow rate being achieved through the Altherma unit and the flow rate through the UFH loops.

Possibly the loops may not have been correctly balanced. When all of the loops are in use, you would normally expect to see about 2L/min flow rate through all of the loops. Again this would need to be checked and adjusted by the service engineer.

You mentioned in your original post that you had various other problems with the system when you moved in. Presumably you are the first resident in this property? If not, then possibly a previous resident may have made alterations to the settings etc. Again this could be established by the service engineer.

02-01-2014, 10:40 AM

Daikin have been and adjusted some settings so I do have a copy of the field settings. They only came to resolve a 3 port valve issue tho, and didnt check the system for overall efficiency. Incidentally, their report said that the SS1 dip switch had been set to 'no remote' and that this had now been put back to its 'normal' position. I can find no information on what the 'normal' position might be. Any ideas? Also, I have established that SS2 (on the main PCB) that switch no 3 is set to 'Off'. All docs I have got from internet says that this should be 'on' as it is the one which would control the heating via a room thermostat? SS2-2 is on, as this is linked to the DHW tank. Me thinks SS2-2 AND SS2-3 should be on?

My Daikin controller has a plastic flap at the bottom

Yes I have 7 loops serving 6 rooms. When comparing the heat from the floors yesterday I compared my bathroom to my kitchen floor as they both have lino. The bathroom floor was considerably warmer than I have ever felt underfoot in the kitchen. Bedrooms and living room have carpet. Just wondering how I will check that the carpeted areas have uniform heat ???? Hopefully not by pulling the carpet up!

How do I establish the flow rate through the altherma?

I'll check the flow rate of the loops when I put all the thermostats are on and let you know

I am the first resident in this property, but was previously resident in another property on the same development, which also had problems. I also lived there when heating wasnt required so didnt really get to 'know' the system.

Thanks for your help!

02-01-2014, 04:41 PM
Afternoon CathyR456,

Onwards we go.

If you have an SS1 dipswitch, I believe that means that there is a solar hot water input connected to your system, is this correct?

You are correct in that SS2-2 needs to be in the ON position for your DHW tank to work correctly.

With regards to SS2-3, if you have a central control thermostat or remote programmer then the switch 3 would need to be in the ON position as the Altherma would be wired back to one of these devices. However, as you have UFH loops, you will not have a central thermostat, but the Altherma could still be electrically linked to the UFH control centre, which in turn could be linked back to a normal central heating programmer.

The only way that you could establish without a doubt that SS2-3 is in the OFF position, is if you have removed the outer protective metal cover from the Altherma unit and also then you would need to removed the electrical access cover. Hopefully you have not removed any of these covers, PLEASE DO NOT remove them.

You really ought to leave this to the service engineer to check as I am greatly concerned for your SAFETY and well being.

On this Forum I am here to help you with comments, observations and suggestions, but cannot condone or recommend self fixing a system once it involves removing SAFETY covers from the units. PLEASE leave it to the engineer who will be conversant with all of the potential hazards inside this machine.

The flow rate can be established on these series of Altherma units by measuring the water temperature flow and return and then carrying out a small calculation.

It will not be necessary to pull up your carpets to check the temperatures of the loops, this can all be done at the UFH manifold.

16-01-2014, 03:50 PM
Hi Hyperion,

Sorry for delay in replying. I have now managed to get my housing association to arrange a full inspection of the system, so thankyou very much for your help. You have given me lots of info which I can ask them about when they come.

17-01-2014, 10:30 AM
Hi Cathyr456,

Thanks for the update, hopefully everything will get sorted out for you.
Let us know what the engineer finds and corrects, that is if he tells you all that he finds!
All feedback is much appreciated as it might help someone else.