External refrigerant coils icing up on heat pump?

Hi, my first post here. I have searched the forum but don't seem to be able to find anything the same. I have an issue with a unit which has been working fine since June 2021. Cooling and heating until a couple of weeks go when we dipped in to -3 and and had freezing fog. Now the unit will only run for about 10 minutes before the coils freeze up outside. Any ideas, has the cold weather created a problem with one of the refrigerant lines, i.e. a leak in extended pipework joint? I still get heat from it before it ices up. Or is this a problem with a valve or defrost sensor?
Please see pictures.
Any information as to the possible cause would be brilliant.

Many thanks

IanAttachment 16048Attachment 16049

I assume that the leak has been repaired and the correct refrigerant charge replaced.

That coil looks quite normal to me for the ambient conditions, does the unit defrost correctly?

Thanks for the reply Brian,
Not sure if there is a leak, this is the issue. I live in the middle of nowhere. Trying to get somebody to come and have a look is a nightmare. Although I bought the unit back in November 2020 I didn't get it installed until June 2021 due to some horrible little virus playing havoc with everything!

How would I tell if the unit was defrosting correctly, apart from it defrosting after I turn it off, should it defrost as it's working in heat mode?

I've just been running it at 30c and the air comes out piping hot from the indoor unit, and I can't touch the outbound pipe from the external unit as it's too hot, so does mean it has enough refrigerant if it's getting up to heat?


Again many thanks

Ian

Don't run it at 30c, set it to a comfortable temperature. System will be running flat out to achieve 30c, icing is normal if you're UK based at this time of year, you need to allow unit hit set point and only then if it can't maintain it should you worry, jumping straight to is it leaking is like running a fiat 500 balls out and complaining it can't keep up with a porshe. Is the unit correctly sized, is the room well insulated etc.

Hi,
It is a 12,000 BTU unit recommended 30m3, I'm running it in 28m3, the workshop is SIPs so insulated 100mm walls/floors and 150mm roof. with two small DG windows.

I ran it at 30c just to check the output to make sure it was getting to heat. I'm currently running it as I type at 21c, had it running at 23c for for 10 minutes before that.

When I ran it at 30c it ran for 15 minutes, I watched it do its defrost outside after it got to that point, also heard the reversing valve kick in, so I know that is working ok now. After it had defrosted the fan kicked in again on the outside unit but after 15 minutes the heat and internal blower still hadn't kicked in.
I tried it on AC and it worked, set it to 16c and it kicked in and blew cold air. (actually very cold air :-D) So had the reversing valve not reset? Went for a coffee and something to eat and now it seems okay and has started blowing warm air again.

The issue arose when the unit couldn't maintain 22c the week before last when it dropped to -3 and freezing fog, it never had an issue before, it's programmed to stop the workshop from dropping below 17c by heating to 22c when it gets to 17c, and then turning off at 22c, at -3c with this would happen roughly every 4 hours, but the one night it worked at 3:30am and stopped at 3:45 am (reached 22c) and then kicked in again at 7:50am(17c) but never got to 22c, just sat at 19c with no air flow or heat being distributed in to the workshop.

What I'm really trying to ascertain is, is this an issue with the refrigerant going walkies somewhere, and if so how come it hasn't all just leaked? Or is it a valve issue. Any ideas would be very welcome.

Thanks for your time, much appreciated.

Ian

On heating the indoor fan will usually stay off until coil temp rises, to avoid cold draughts. Without seeing it hard to tell what is going on, it sounds ok for refrigerant, 4 way valve sticking is possible. Are filters clean, is outdoor condenser clean, is outdoor fan running at full speed on heating?

Thanks Al,

Outdoor unit is clean, internal filters are clean, outdoor fan at full pelt when heating.

Yesterday it ran fine, frosted up defrosted, waited a couple of minutes then carried on, this happened a couple of times throughout the day. When I set the temp to 21 from 22, it ran all day fine with just a light to medium frost build up without having to go in to defrost mode.

So I thought it must have been a glitch. Until.....that is....this morning. 5:45am I checked the logs for the automation, the unit kicked in at 5:25am was still going and stuck at 19c.

So I looked at the unit at stupid o'clock this morning, no ice/frost build up, condenser fan running full pelt outside, inside the louvre was in the up pre heat mode with no internal fan running. So it's acting as if it's waiting for the coils to pre heat? But they don't?
I turned the unit off and about 3 minutes later I heard the refrigerant do it's whoosh sound, so I tried again to start the unit, still nothing after 15 minutes...

10:19am
I'm sat here typing and it's running fine at 21c, only difference is the external temperature has now risen from 0c to 2c. Seems to be fine when external temp reaches +c


Many thanks

Ian

What’s the make and model of the unit ?

Hi,

The unit is an ElectricQ eiQ-12WMINV-V3 - I believe these are Panasonics under the hood...

I have noticed that last night the temperature had dropped to -4 as my underfloor heating went in to boost mode.

So could this be an issue with the coil pre heat?

Many thanks

Ian

Have a read of the user manual, especially page 11 where it states that performance in Heating mode will be poor when ambient temperatures are below 5C

https://www.electriq.co.uk/Files/pdf...2020200426.pdf

Also, I find it alarming that the supplier is advertising that the unit does not require installing by an F-Gas registered person.

Hi,
Yes, I understand that, but it does also say that it will heat when the ambient temperature is down to -15c, but performance will be will reduce, and it does work really well below 5c. The problem seems to be it doesn't kick in at all now below -1 as if the coil pre heat doesn't function, so it's more than a lack of performance. It had previously kicked in around -5c. It's pre-gassed with R290.

Thanks

Ian

What is the distance between indoor and outdoor?

Was additional refrigerant added at install, these units may only come pre charged for 5m.

It sounds like indoor thermistor is not registering enough heat to start indoor fan.

Causes:

faulty thermistor/board
faulty fan
refrigerant over or under charge
thermistor not properly sensing pipe/coil temperature

Thanks Al,

Distance is using the full 5mtr of pipe with the last bit curled to take up the slack as in the photo. No refrigerant was added as the pre-gas was enough for both 1.5m and 5mtr lengths, allegedly and it was to done by the letter to the instructions.

As this is R290, I guess a leak would be a leak and nothing would stay in the system, so wouldn't work at all then?

Thanks

Ian

Maximum pipe run 12m a couple of that can be seen outside !!

Hi redroge,

Not sure what you mean by that?

Regards

Ian

Are you in the UK? Was this a self install?

Hi Al,

Yes and yes'ish. I installed everything external unit and wall mount but connections made by my wife's cousin who is an F-Gas engineer, who went by the easy install method. Who is away now for a while in hospital, so can't get hold of him...

Thanks

Ian

Hi Al,
I think this is really the last question with this, but if there was a leak, then I an assume there would be no refrigerant left as it is R290?

Many thanks for your time, it's much appreciated.

Ian

Was it pressure tested ,leaks come in all sizes big small and very small.
pipework not particularly neat

Once someone f-gas certed has done it then no bother, to answer the leak question, it depends! You can lose as little as a few grams every week, only in severe weather would you see the issue. I'd bubble test the joints yourself, chances of it being on a welded factory joint/fitting are very slim, either way though i'd suggest you get someone to look at it!

Quote:

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Originally Posted by Ianspeed

I have an issue with a unit which has been working fine since June 2021. Cooling and heating until a couple of weeks go when we dipped in to -3 and and had freezing fog. Now the unit will only run for about 10 minutes before the coils freeze up outside.

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In order for the refrigerant to absorp heat from the outside air, it will have to drop the coil temperature by at least 6K. So, with an ambient temperature of -3C, your coil will be operating around -9C. This will cause any airbourne moisture to condensate onto the coil which is the frost you are seeing.

The frosting pattern looks normal to me.

Quote:

---

Originally Posted by Ianspeed

Hi Al,

Yes and yes'ish. I installed everything external unit and wall mount but connections made by my wife's cousin who is an F-Gas engineer, who went by the easy install method. Who is away now for a while in hospital, so can't get hold of him...

Thanks

Ian

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If that method is what I think it is, I'd be worried.

If this system is a pre-charged self assemble type AC unit which has quick coupling connections
and that is why the manufacturer has claimed it could be installed by non F-gas qualified guys.

Years ago these were referred to a B&Q specials because anyone could buy them off the shelf at B&Q.
All it required was a hole knocked in the wall and then plug the 2 halves together. Power with a 3-pin plug top.

If your unit has developed a leak the refrigerant could leak out quickly in minuets or slowly over days and weeks.
Because the refrigerant charge is pre-set it will leak but work up to the point where it won't anymore and that
is anybodies guess.

It really does need a set of gauges attaching and a proper test carrying out.

.

Rob

.

Thanks Rob,

Everything works wonderfully, except it just won't work at all when ambient temps are -c, just sits waiting for the coils to pre heat.
I have a friend who works on air source heat pumps but is not F-Gas registered, he's more on the fault diagnosis and plumbing side of it. His thoughts were thermistor, as were Al's.

So I've now decided to bite the bullet and get the company to come out and sort it out as nobody is interested locally, installation fault £300 all in fixed, and extended 5 year warranty, else manufacturing fault free of charge.

Thanks to all the people who have given positive input for this, the forum with the knowledge has helped me understand the workings and idiosyncrasies of split source AC/Heat pumps.

I will update the forum with the diagnosis from the engineer.

Again, many thanks to all that helped.

Ian

And the results are in... Turns out the pipe work wasn't pleasing on the eyes! Only kidding.

Once and once only, last Saturday I had a message come up on the Smartlife app which said "External coil temperature sensor failure" So I mentioned this to the support team at Electriq and they said this was a known issue with the V3 R290 units and a firmware upgrade was needed. So the symptoms were not going through the defrosting cycle properly on low ambient temps.

While the engineer was here I asked if he could do a refrigerant check, his reply was they wouldn't connect gauges up without good reason and explained that they way they checked was to run the unit at full heat and check the temperature, as he said mine should reach around 41c, when he checked it was running at 45c with an ambient outside temp of 3.5c

So, all in all it was a known software issue which was sorted under warranty. I live in Mid Wales, the engineer had to come from Reading! Shame they couldn't flash the units before they get sold/installed!

Thanks to all of you who were constructive and helpful!

All the best

Ian

Thanks for the update Ian. It is always nice to hear of a good outcome.

Icing up can be caused by low refrigerant in the system due to a chronic leak. If the system is short on refrigerant charge, part of the coil will run very cold and ice will start to form. The solution here is to have the coil cleaned or replaced by a registered technician.