Daiken ASHP

[DOIGAN]

Hello,

 

Hopefully someone may know the answer to the following.

 

My house has a Daiken air to water system that provides hot water and heating. It is a EDLQ07CAV3 unit.

My problem is twofold, the heating side never heats the whole house enough, it can be on for over 12 hours per day and we still regularly need to put on the wood burner as the lounge always feels cold.

Can these systems not produce enough heat to heat a home?

 

The other issue is hot water, from the info from Daiken the system should be able to heat the DHW to 55 degrees, I have since noticed that anything hotter than 40 degrees means that the back up emersion unit kicks in, this obviously is costing me a lot of money. I have been through th manual and installer settings and cannot see anything that states it cannot achieve 55 degrees just by using the unit outside.

 

Any ideas?

 

Thanks

 

 

 

 

 

[SteamyTea]

I think a lot more information is needed.

How many people are in the house.

How large is the house and what is the heat load.

 

Generally, is a system is undersized, it will not work well.  Nothing intrinsically wrong with the technology, unless it is a genuine fault, just that if you need 40 kWh/day to heat your house, and after 12 hours of running the heat pump, it has only delivered 15 kWh, then your house will be cold.

[ProDave]

The heating thing first. What level of insulation in the house?  Heated how, e.g. under foor heating or radiators?

 

Hot water I heat ours to 48 degrees just with the heat pump.  Some heat pumps have default settings to use the immersion for the final heating, but you should be able to change this. I have disabled all use of the immersion heater on mine.

 

We heat a roughly 150 square metre house with an LG 5kW ASHP without problem, and it gets colder here than your island climate.

[Jeremy Harris]

We use an air source heat pump for heating and cooling, but not hot water.  They do need careful setting up, I found that the default settings for our unit were way off what was needed to get it to run economically.  The Daikin unit you have is a low temperature ASHP, in case you don't have it, the manual is here: https://my.daikin.eu/dam/document-library/installation-manuals/heat/air-to-water-heat-pump-low-temperature/EBLQ-CV3_EDLQ-CV3_4PEN403578-1C_Installation manuals_English.pdf

 

The key settings will be the heating curve (page 15) settings and the hot water settings (page 16).  Limiting the hot water temperature to 50° would be a reasonable start, assuming that your water cylinder has enough capacity to allow this to work OK.  Just a 5°C reduction in flow temperature can make a marked improvement to performance.

[DOIGAN]

Hi

 

My house is a 125m/2 bungalow, 4 years old, a Scotframe with low u values. We have under floor heating throughout, no radiators. A pressurised hot water cylinder etc, sure this is standard for these types of systems. We did not build it though.

There is only my wife and I, so nothing extreme.

 

I have been monitoring the energy usage via the control unit. we use about 15kw/h of energy per day. Or bills are around 100 per month, we only have electric.

 

Do you not have the immersion heater on for the 60 degree legionella cycles?

 

I paid to get the company who installed the system out to check it and that Engineer stated that anything over 48 degrees meant that the immersion heater would kick in, seems awfully low temp, you need to boil a kettle to have the water hot enough for dishes

 

I don't know if it is just that I am used to a gas boiler heating system but I am disappointed in how our's is performing, we had looked at self build and I wanted the systems that this house has but cannot see the upside to them.

 

[DOIGAN]

9 minutes ago, Jeremy Harris said:

We use an air source heat pump for heating and cooling, but not hot water.  They do need careful setting up, I found that the default settings for our unit were way off what was needed to get it to run economically.  The Daikin unit you have is a low temperature ASHP, in case you don't have it, the manual is here: https://my.daikin.eu/dam/document-library/installation-manuals/heat/air-to-water-heat-pump-low-temperature/EBLQ-CV3_EDLQ-CV3_4PEN403578-1C_Installation manuals_English.pdf

 

The key settings will be the heating curve (page 15) settings and the hot water settings (page 16).  Limiting the hot water temperature to 50° would be a reasonable start, assuming that your water cylinder has enough capacity to allow this to work OK.  Just a 5°C reduction in flow temperature can make a marked improvement to performance.

Hi Jeremy, thanks I have this, this is what I cannot understand, this document states that the system can achieve 55 degrees for DHW, the only mention of the immersion is for a back up or for the disinfection cycle, mine kicks in at 40 degrees and I cannot figure out why.

[SteamyTea]

13 minutes ago, DOIGAN said:

15kw/h of energy per day.

That will be 15 kWh/day

 

kW/h is really dividing power by time, energy [kWh] is power multiplied by time.

[Jeremy Harris]

Usually there will be two main modes on an ASHP, heating mode, which will usually be set to deliver a flow temperature of around 35° to 40°C and hot water mode, which will usually be set to deliver a flow temperature of around 50° to 55°C.   It's not clear from the manual whether or not the unit you have actually has a hot water mode.  The manual isn't the easiest thing in the world to decode, either!

 

All I can see on hot water control is this:

 

And that's as clear as mud. . .

 

It looks to me as if this model of ASHP doesn't actually have a hot water mode, and relies on using an immersion heater to boost the hot water up from the low temperature that the ASHP works at.  That seems unusual, but then the unit is described as being a "low temperature monobloc", so it may be that this is a simplified unit that doesn't have an integral hot water capability, but relies on using an immersion heater for boost.

[DOIGAN]

4 minutes ago, Jeremy Harris said:

Usually there will be two main modes on an ASHP, heating mode, which will usually be set to deliver a flow temperature of around 35° to 40°C and hot water mode, which will usually be set to deliver a flow temperature of around 50° to 55°C.   It's not clear from the manual whether or not the unit you have actually has a hot water mode.  The manual isn't the easiest thing in the world to decode, either!

 

All I can see on hot water control is this:

 

And that's as clear as mud. . .

 

It looks to me as if this model of ASHP doesn't actually have a hot water mode, and relies on using an immersion heater to boost the hot water up from the low temperature that the ASHP works at.  That seems unusual, but then the unit is described as being a "low temperature monobloc", so it may be that this is a simplified unit that doesn't have an integral hot water capability, but relies on using an immersion heater for boost.

God, thank you Jeremy, I thought it was just me that could not wrap my head around the manual.  I will try and phone Daiken technical to see if they can shed any light on it, I was hoping for divine inspiration from someone on here to be honest

[ProDave]

On your user control panel, can you independently set the DHW temperature and the heating temperature?  If so what is the heating temperature set to, and try reducing the DHW temperature a bit.

 

I can't see anything about using the immersion heater, so what makes you think it is using that?

 

I am not a fan of weather compensation, I am not convinced there is a need for that, you can disable that and set it instead for a constant output temperature.

[DOIGAN]

5 minutes ago, ProDave said:

On your user control panel, can you independently set the DHW temperature and the heating temperature?  If so what is the heating temperature set to, and try reducing the DHW temperature a bit.

 

I can't see anything about using the immersion heater, so what makes you think it is using that?

 

I am not a fan of weather compensation, I am not convinced there is a need for that, you can disable that and set it instead for a constant output temperature.

Hi Dave, heating is set to 24 degrees, DHW  was set at 52 degrees, I know the immersion kicks in as you can hear the relay clunking on, I have also checked the electrical supply using a test meter, as I stated anything over 40 degrees and the immersion kicks in.

[ProDave]

Is that 24 degrees the room thermostat setting or the "leaving water temperature" setting?

 

If the latter it is probably a bit low which might explain why you are finding the heating performance poor?

[Jeremy Harris]

Looking at the wiring diagram for the indoor control box, there doesn't seem to be provision for getting the ASHP to operate in a hot water mode, just a relay that can turn the immersion on or off.

 

As @ProDave mentioned above, running at a constant temperature seems to work well, it's how I've set ours up.  You could try altering the heating curve settings to set the unit to a fairly high constant flow temperature, say 45°C, as a compromise that might get the hot water tank a bit warmer by using the heat pump.  I'm struggling to see if there's a setting to adjust the temperature at which the immersion relay kicks in, but if there is, then increasing that, along with setting a fixed flow temp that's around 45°C might work OK.  You have the advantage up there of a reasonable climate for an ASHP.  Another member here, @Stones, lives on Orkney, and he has an ASHP that seems to perform well.

[Stones]

@DOIGAN - We live in a circa 170 sq m house with vaulted ceilings, built 3 years ago, using an Mitsubishi Ecodan ASHP to heat UFH and provide our DHW.  Our system works flawlessly, keeping the house to 21C,  24/7 and we have never run out of DHW (300 litre cylinder heated to 50C by the ASHP).  I have ours set on the auto (weather compensation) setting and had no issues, but equally could have used my own custom heating curve or set flow temperature.

 

Our neighbour lives in slightly newer build, Valutherm kit, Daikin ASHP to UFH and DHW.  House always toasty warm (they heat to 22C).  Initially they had some temperature overshoot and higher than expected running costs which we sorted by changing the flow temperature offsets in the Daikin controller.

 

In terms of your DHW, nothing wrong with topping off water heated by an ASHP using immersion, as heating water above about 40C is not what an ASHP does best, and results in a drop in Co-efficient of Performance.    When I was planning our build I considered this route and costed it out based on using 300 litres of DHW a day.  I found there was virtually no difference in cost using ASHP to 40C then topping off with immersion vs heating water direct to 50C with ASHP.  I decided to keep it simple and just go with the ASHP.  

 

Happy to come and have a look and see if we can tweak the settings etc to get you on track.  Drop me a PM if you want.

 

 

[Stones]

@DOIGAN

 

A few thoughts.

 

Firstly, expectations.  As discussed, the system does not and will not respond in the same way a gas boiler based system would.  It works best running long and slow, and any changes to settings you make will take a couple of days for you to see a difference.  My own view is that you should run it 24/7 - we have certainly found that works very well, or if for reasons of noise disturbance you want it off through the night, the other 16 hours of the day.  It is perfectly possible to charge your UFH slab over a 7 hour period and let it release heat over the rest of the day without significant effect on overall temperature (see @TerryE blog), however in your case my inclination would be to go for the 16 hour option, with the unit being off at night.

 

Cost wise I would ditch E10 at 16p/19p you are paying, get a standard meter fitted and go with the best variable rate which seems to be around the 12.5p per kWh mark - this in itself would represent a significant running cost saving.  Also bear in mind that an ASHP brings down the cost of electric heating to the ballpark of gas based system, but is unlikely to be quite as cheap.

 

I think one of the biggest problems is the location of the master controller / thermostat. Being situated in the cupboard with the DHW cylinder means that it is always going to register a higher air temperature reading than the main body of the house.  This in effect means the ASHP is getting incorrect information and is basing flow temperatures and operating time based on the temperature in the cupboard, not the main house.  Given there is a differntial between the two because of the DHW heat loss, it is I think reducing the amount of heat being delivered to the house, as the unit thinks it has achieved what has been asked of it.  The first thing I would be looking to do therefore, would be to move the controller / master stat outwith the cupboard.  In your case, that's only 600mm or so.  If you were to power down the controller, remove the front plate and unscrew the controller from the wall, you should be able to determine how much slack there is in the control cable/if there is sufficient to relocate the controller without having to splice more wire in.  Simply moving that controller to the outer wall of the cupboard would make a huge difference and allow the unit to work off more accurate and importantly consistent readings of internal household temperature.  The current situation where you have to constantly alter the target temperature to try and force the unit to respond is a consequence of the poorly located controller/master thermostat.

 

Having done that, and given the main issue is the living room not being warm enough, I would proceed as you are (using the room thermostats to keep certain of the UFH loops closed), to concentrate the supply of heat to key rooms.

 

I think I would then be looking to methodically work through the different option settings to see what works best for your house / location.

 

This would involve trying both fixed flow temperature options and the 4 weather dependant heating curve options (we use weather dependant function and it works really well), effectively, that would be trying 6 different settings (assuming you wanted to leave the unit off overnight for noise disturbance reasons) .  In addition there would also be the option of experimenting with the temperature modulation function, although I think I would concentrate on the main functions first, and use the modulation option to tweak things once you have something that does the job the vast bulk of the time. 

 

We'll find the right setting, it'll just take a bit of time.

 

Again as discussed, I think it would be informative if you could contact Daikin to find out how to enable the onboard energy metering so it shows both consumed energy and produced energy (so we can see if there is a problem with CoP)

 

 

[DOIGAN]

Many Thanks for all the responses, a big shout out for Stones who kindly popped in last night to help me with my system. Will get back in touch with Daiken to see if they can provide the info about energy production etc.

It does appear that I am using approximately 28kkw/h over 24 hour period, this seems excessive to me.

[SteamyTea]

29 minutes ago, DOIGAN said:

It does appear that I am using approximately 28kkw/h over 24 hour period, this seems excessive to me.

I shall convert that to 28 kWh/day, which is around 1.16 kW.

If your CoP is around 3, then that is 3.5 kW of thermal energy.

With your floor area, that is ~30W/m²

Now considering you have bungalow (detached I assume), you have a lot of wall and roof area.  I use around 9W/m2 to heat my small terraced house, but if it was just one storey, I suspect that the energy use per square meter would double (I don't have heating upstairs).

And if I was detached, I would be adding an extra 200% of external wall area, so that would probably bring it close to your usage.

Edited February 15, 2020 by SteamyTea

[arg]

On 09/02/2020 at 16:01, Jeremy Harris said:

It looks to me as if this model of ASHP doesn't actually have a hot water mode,

 

I happened to be reading the manuals for this thing recently (it's a candidate for my install when I get to that point later in the year).   I concluded that it DOES have a seperate hot water mode; there's supposed to be a motorised valve to divert the flow water to either the space heating or the water tank coil.  There's separate configuration of the tank target temp(s).

 

There's several documents online, this one "installer reference" seems more detailed than the "installation maual".

 

https://www.daikin.co.uk/content/dam/document-library/Installer-reference-guide/heat/EBLQ05-07CV3-EDLQ04-07CV3_4PEN405544-1D_Installer Reference Guide_English.pdf

 

The exact capabilities of the unit are a bit unclear as it is documenting the whole system including the "optional" backup (resistance) heater, but as I read it the maximum capability of the heatpump alone is 50C (it says you can set it for 55C but won't reach that in low temperature conditions).  You can set the tank target temp up to 80C but that will invoke the resistance heater.

 

The bit you quoted earlier about reheat/scheduled setting is to avoid the DHW demand taking away from the space heating since it can't supply both at once: you can have the DHW heated only on a timer (so deliberately chosen times when you don't anticipate using space heating, eg. overnight), or just on demand (so it will take away from space heating), or a compromise that tries to do it on the timer but will top up at other times if it falls below a threshold.

 

There's a huge lot of settings on this thing and it could easily be set up wrongly such that it's only able to deliver less than its full output.

 

Rated maximum input is 15.7A (=3.6kW) - interestingly the 5kW and 7kW versions are almost the same, suggesting that they share the same compressor and the 7kW unit just has a bigger fan/heat exchanger so there's more opportunity for it to run closer to flat out.

 

Stated typical input powers are 1.55kW (at 35C water temperature) to 2.45kW (at 45C water temperature) given 7C ambient.

 

So if it's taking an average of 1.16kW across the day and it's running continuously day and night, then there's quite a lot more capacity there to be turned up (though will of course cost you more money!).  If it's only running 12 hours a day (and the resistance heater is disabled), then it's effectively flat out and the only way to get more heat out of it is to run it longer - use the scheduling to get the hot water tank heated in those other 12 hours, leaving the daytime hours to keep the lounge warm.  If the 28kWh/day = 1.16kW average included significant amounts of resistance heater usage then there's scope to push the heat pump harder and get more heat for the same money.

 

I think if it was me, I'd start by disabling the resistance heater and see what it's doing by itself.

 

(NB. all the above just based on reading the manuals and analysing the numbers - I don't actually have one of these)

[kla456]

Hello Doigan,

I had a Daiken ASHP installed last August . My unit is Daiken Altherma 3 providing space heating and DHW. I am really satisfied and I also expect to improve efficiency next year after I get to understand the system, and make some adjustments.

 

Given the extent of mis-match between your expectations and the system performance, I'm not sure you should be looking to this forum to solve the issues.

 

I spent months of dialogue with the Daiken-approved installer before committing to the installation, including three meetings and a site visit. The installer provided me with 7-page Daiken Altherma Selection Project Report which included: proposed solution overview, selection criteria, system diagram, 6 graphs including estimated energy consumption and thermal output estimates, and a room-by-room heat loss calculation (it did not agree with my own calculation - based on Jeremy's great spreadsheet - but thats another story for a later post, maybe after first year's heating season).

 

I cant imagine how you could be left with a Daiken system that does not substantially deliver your requirements. I expect you have called back the installer? If he did not respond adequately then I suggest you seek recourse, initially with Daiken, and eventually elsewhere until you get what you ordered and paid for.