Daikin Altherma ASHP Heat Output Issue

[GHDirect]

Hi all.

 

Are their members that have a Daikin Altherma 7KW Monoblock ASHP installed in a new build and does it work?

Passed days cold spell has generated the following major concern, enough for me to seek other members opinion towards this heating solution.

 

Intro

Past 4 years I have personally been building our 3 bed detached retirement bungalow and currently working on the inside.

Its not passive build but when 100% complete will have above average insulation.

Country location only water and electricity so after much discussion with many suppliers a Daikin ASHP, Hot Water Tank and Underfloor heating solution was designed by an MCS

accredited supplier who were happy to supply all items, for me to install it to their supplied drawings and Daiken manuals with final commissioning through them from a Daikin engineer.

 

As an experienced engineer myself with time on my side I am confident I have installed it all to spec accept setting it's performance up "exactly" is painful as the Daikin installation books are poor although Youtube has some installer controller setup detail.

Although it has yet to be fully commissioned it did/does function but with the following performance issue.

 

Issue

ASHP was turned on late September with outside was around 14deg C, it worked great, I was impressed with its UFH performance heating the floor space to over 24 C quickly.

I worked out how to introduce the Hot Water System, set time clocks to run 8 hr days, room stats around 14 Deg C whilst I worked inside the property.

Then October we had a cold spell and basically it just stalled, ASHP sitting doing its thing gobbling 9 amps but giving very little heat output.

Ran like that day after day. Past few days it been very cold here so same issue.

 

After checking all my installation plus powering on/off etc found nothing obvious, so rang the design company who in conversation suggested that because the outside temp was below 10deg C the Daikin ASHP can go to sleep until its circulating water is above 10deg C. Is this true of a Daikin ASHP there is nothing in any manual that refers to this?

Apparently to kick start it back up, you have to use the immersion system leave the ASHP system circulating water and wait till it all gets warm enough for it to kick in.

 

I await its commissioning in coming weeks but meanwhile need some existing users performance feedback.

 

 

 

[ProDave]

I don't know that particulat heat pump so the following is more general:

 

Question 1, what water temperature are you demanding when the ASHP is heating the UFH? and are you feeding the UFH direct from the HP or through a buffer tank?

 

Question 2:  How are you storing hot water and what temperature is the hot water set for?

 

Now some background:

 

Heat pumps work better at low temperatures.  Generally they should also be set up to heat space heating OR hot water, NEVER both at the same time.  This is usually achieved for example with a diverter valve or two 2 port valves, NEVER a mid position valve.

 

The way mine is set up is the unit mostly heats the under floor heating, but when the hot water tank thermostat calls for heat, it stops heating the UFH and switches over to heating the HW tank.  The crucial thing is when heating UFH my heat pump is delivering water at 37 degrees.  When heating the HW it heats that up to 48 degrees.

 

My heat pump runs fine even sub zero when heating the UFH.

 

When it is heating the hot water, it is working a lot harder and in sub zero outside temperature it can ice up, when that happens the heat pump reverse cycles to defrost, then continues. So in very cold weather it will take longer and use more electricity to heat the HW tank.

 

Let us know the set temperatures and how the thing is plumbed and we can diagnose it a bit further.

 

EDIT:

 

Is it this one? https://www.daikin.co.uk/en_gb/product-group/air-to-water-heat-pump-high-temperature.html

[GHDirect]

Hi ProDave.

 

Thanks for the interest.

Sorry its a bit long but currently its an expensive and frustrating system that doesn't perform

 

1/

The Leaving Water Temp is set at 38 deg C. The Daikin design requires at lease 20 ltrs of water to circulate before any UFH.

In my design this is achieved by an 18 ltr buffer plus a 6 ltr low loss header all positioned before the 2 x UFH pumps.

If I include the 28mm pipework, buffer tank and low loss header tank, I can confirm that there is about 40 ltrs capacity.

 

2/ The Hot Water is a Daikin 300ltr unvented cylinder made to go with this type of ASHP. (Before you ask my tank install has been checked and signed off by a G3 heating engineer).

Currently the system is set to 42 deg C. but this is adjustable upwards.

 

Interesting comment about 3 way valves. This system has a 3 way brass valve casting + an ESBE actuator all supplied by Daiken.

Unlike UK model valves there are no markings on outside of casting and the Daikin Manual is confusing to where to position the actual rotational bit in the valve casing so it correctly closes off the DHW flow when called.

I can say my valve is designed to have either both UFH & DHW or run with DHW off.

As information is poor I have had it out twice to ensure I got it right and confirm it runs the Daiken control panel 3 way valve test.

 

I am very concerned to hear from my supplier that this Daiken can stall at temps lower than 10 deg C.

This suggests it must be left on all time to allow it to cycle even if its not getting a demand for heat.

Currently as the bungalow is not occupied the time clocks run 8 till 8.

Does your system run 24 hrs?

 

Last night using immersion option I managed to raise it from its sleep so it was cycling.

I shut off the DHW valve (using the Daikin control panel), shut down all room stats except for 3 rooms. At that time each room screed was about 9 deg C.

I  left it all night and all today to see if it could supply heat to each rooms screed.

Results were poor. Control Panel saying "Leaving Water Temp desired temp 38 deg" but the actual output 28mm pipe from ASHP measured 20 Deg C.

This corresponded to the manifold temp and the 3 x floor screed which again measured about 20 deg C.

Tonights measurement is only slightly better at 24 degs.

Unless its been cycling on and off over night that's 24 hrs x continious 7 amps current draw for a mere 3 floors when bungalows got 9 floors in total to heat.

 

The web site you supplied does show the Altherma as it is a current model.

 

Past week I have checked I have put all pumps and flows in right direction, played with the control panel software settings that seem appropriate.

Unless I gain another good idea, I conclude this system not worth leaving on and will wait for the Daikin commissioning engineer next Wednesday to see what he finds.

 

 

 

 

 

 

 

 

 

[ProDave]

14 minutes ago, GHDirect said:

II am very concerned to hear from my supplier that this Daiken can stall at temps lower than 10 deg C.

This suggests it must be left on all time to allow it to cycle even if its not getting a demand for heat.

Currently as the bungalow is not occupied the time clocks run 8 till 8.

Does your system run 24 hrs?

 

Last night using immersion option I managed to raise it from its sleep so it was cycling.

I shut off the DHW valve (using the Daikin control panel), shut down all room stats except for 3 rooms. At that time each room screed was about 9 deg C.

I  left it all night and all today to see if it could supply heat to each rooms screed.

Results were poor. Control Panel saying "Leaving Water Temp desired temp 38 deg" but the actual output 28mm pipe from ASHP measured 20 Deg C.

This corresponded to the manifold temp and the 3 x floor screed which again measured about 20 deg C.

Tonights measurement is only slightly better at 24 degs.

Unless its been cycling on and off over night that's 24 hrs x continious 7 amps current draw for a mere 3 floors when bungalows got 9 floors in total to heat.

 

Turn off the hot water and make sure the 3 port valve is in heating only mode and concentrate first on just getting it to work on heating only.

 

I think what their engineer i saying is BS.  If it is not, I would want it ripped out and replaced with something different.  Ask the question directly to Daiken?

 

Mine is on a programmer so I can have it on when I want it. It will start up fine from cold even when well below zero outside, yours should do the same.

[joe90]

@GHDirect have you seen my thread about my heat pump not working?, similar in that only low water temps were reached. Also we had problems with the “diverter” valve (not three way) In that the valve instructions show DHW when parked and heating when actuated, however my ASHP powers the valve when DHW is required so we had to turn it round. In all this, because of mis information from my room stat supplier I blew the main processor board and had to replace it. Problems setting the programmes followed. I concentrated on heating only at first and found a lot of air in the system so powered the pump directly and left it on full chat for an hour which released a lot of air. I then forced the DHW to be heated and did the same. Mine now works (subject to trimming ) and got nearly 60’ tonight and believe programming and air both contributed to my problems.

[swisscheese]

@joe90- Don't want to jump this thread, but I'm having a similar issue with regards to Air in the system, some loops just will not heat and I'm struggling to release the air:

 

"I concentrated on heating only at first and found a lot of air in the system so powered the pump directly and left it on full chat for an hour which released a lot of air."

 

I'm not exactly clear what you mean by this, could you explain, it seems to have worked for you.

 

[joe90]

3 minutes ago, swisscheese said:

I'm not exactly clear what you mean by this, could you explain, it seems to have worked for you.

 

When you say loops you mean UFH loops?, this is usually done by mains pressure water via a hose connected to the manifold and a drain hose the other end of the manifold. Only open up one loop at a time till no more air bubbles out with the water, when all loops are done leave it pressured at mains pressure. Mine was air in the heating and DHW pipework (not UFH loops) from ASHP to DHW tank and buffer tank for feeding the UFH manifold. For this I directly wired 240 volts with a fly lead and three pin plug to the pump (make sure the other wiring is disconnected so you don’t blow anything.) I then set the pump on full power (6 in my case with a wilo pump) and left it alone, lots of gurgling over the next hour or so. Occasionally I would crack a joint high in the system (where there is not an air bleed valve) and release any air. Hope this helps .

[GHDirect]

Note to Swisscheese & Joe90

 

Whilst I wrestle with my problem ASHP I must advise that if your system is designed like mine it requires a Glycol mix to stop freezing.

My system requires 30% mix (80 ltrs of particular type of Glycol) and this is very very expensive.

Also difficult to just pump it into a water filled system.

 

Therefore if you purge out the air using mains water and dump the outlet water and your system is already loaded mix of Glycol and water you'll  be throwing real money away.

I have no idea how plumbers do it but I use a portable clean water electric pump (Karcher type about 1.5 bar.) that sits in a big yellow bucket with some mix already in it. 

I connect pump to my system inlet valve, pump in new mix and from the chosen bleed outlet connect a hose back into bucket and look for the air bubbles to cease.

 

Hope this is informative

 

[joe90]

There should be no requirement for antifreeze in the UFH loops as they are within the house. My system uses a buffer tank so the water in the UFH loops and that in the ASHP are separate. My ASHP has an auto anti freeze mode whereby if freezing temps are seen it will kick in so again anti freeze is not required. I have put inhibitor in the ASHP loop because of the different metals therein. Glycol is required for a GSHP and is one of the reasons they are more expensive to fit/maintain.afaik.

Edited November 23, 2018 by joe90

[GHDirect]

Hi Joe90

 

Point taken as your UFH system is different design to mine.

Yours then is much easier to bleed using a mains water flush.

 

I'll get back to my troubled system

[ProDave]

Okay re glycol

 

I used the cheap No Nonsense Inhibitor / antifreeze from Screwfix mixed to 25%

 

As to "getting it in"  I filled the UFH loops with it neat.  Conventional wisdom is to fill the UFH loops one at a time with mains water and a hose.  Well I did use a hose, but the input side was not fed from the mains, but a length of hose fixed to a stand with a funnel on the end into which I poured the neat antifreeze / inhiibitor until it came out of the other end into a bucket to collect it.

 

I had got all the antifreeze in before all the UFH loops were finished so I then used up what was in the bucket before finishing off with plain water.

[Jeremy Harris]

As long as the buffer tank is run indirectly (i.e. with a coil) then the antifreeze volume can be very small.  I used about 5 litres of the stuff to get the right concentration in our ASHP, as the antifreeze inhibitor is only in the ASHP, buffer coil and UFH loops, so not a lot of volume.  To pressurise the system I used a modified garden sprayer, fitted with a new 8mm LDPE pipe (luckily a perfect fit in the pump bottle gland) and terminated that with a 15mm double check valve, using an 8mm to 15mm compression adapter.  This then fits directly to a standard flexible fill loop hose with fill valve:

 

 

This will pump up to a few bar, so can be used for leak testing as well as filling and pressurising.

 

 

[joe90]

So, have I been mis informed and the ASHP needs antifreeze not inhibitor????

 

this from a  screwfix antifreeze/inhibitor product, no mention of ASHP?

 

Effective frost protection, limescale and corrosion control. Suitable for all heating types, including those containing aluminium. Compatible with No Nonsense products. Suitable for use with underfloor systems and ground source heat pumps (GSHP). For use in accordance with BS 7593 code of practice for treatment of water in domestic hot water central heating systems. Dilute at point of use. Addition rate: 25% of system volume.

Edited November 23, 2018 by joe90

[Jeremy Harris]

1 hour ago, joe90 said:

So, have I been mis informed and the ASHP needs antifreeze not inhibitor????

 

this from a  screwfix antifreeze/inhibitor product, no mention of ASHP?

 

Effective frost protection, limescale and corrosion control. Suitable for all heating types, including those containing aluminium. Compatible with No Nonsense products. Suitable for use with underfloor systems and ground source heat pumps (GSHP). For use in accordance with BS 7593 code of practice for treatment of water in domestic hot water central heating systems. Dilute at point of use. Addition rate: 25% of system volume.

 

Yes, the ASHP must be filled with combined antifreeze/inhibitor, to deal with the case when the ASHP is turned off and the outside temperature drops below freezing point, which may risk freezing the water inside the ASHP secondary heat exchanger.

 

It's why I was glad that Newark screwed up and supplied a buffer tank with a coil, as it meant I didn't have to shell out an arm and a leg for around 25 to 30 litres of antifreeze inhibitor, but could get away with just using a bit less than one 5 litre can of the stuff.

[ProDave]

The no nonsesne product contains glycol antifreeze as well as inhibitor.

 

I suspect the inhibitor is less of a necessity than say a conventional boiler and radiators. In my case the only ferrous metal in any of the heating system is the circulating pumps so not a lot to corrode really.

[Jeremy Harris]

FWIW, I used the Screwfix No Nonsense stuff.  Seems fine so far.

[joe90]

Just re read the carrier command units advanced programming and parameter 2 is home antifreeze , if actuated it goes into antifreeze even if the system is off, parameter 3 sets the threshold temp at which it operates. However it still might be worth the cost of the antifreeze in case of power failures etc.