Grant Heatpump Issues

[MartyJ76]

Hi all and great to be able to access the invaluable information shared on this site.

 

Straight to it, I hope someone might point me in the right direction.

 

Grant Aerona3 10KW installed 2 years ago. Now 2 weeks out of installer warranty and has developed problems:

It had been shut down for a couple of months over summer as reroofed parts of the premises. Upon starting up again I noticed the radiators were only getting vaguely warm, everything is kicking in on the Grant controller panel after heat demanded from thermostat. (Only one themostat, in living room). So heating, fan, pump, compressor come on relevant orders. It then cuts out after 5 mins with the heating symbol, and fan symbol going out on screen leaving the pump and lastly the compressor symbols on, the compressor symbol is flashing and is the last to go out. It does this 5 or 6 times an hour (and for over 24hrs if left on) but is not heating the rads.

 

There are no error codes showing on either the controller or on the PCB within the pump. The pump in the heatpump seems to be working fine, as does the pump housed beside the cylinder indoors. The system still delivers piping hot DHW @50degrees on demand every time hence the suggestion the Heat Pump unit itself is in good working order.

 

I contacted Grant technical who were excellent. They agreed the Heat Pump unit, controller and thermostat sounded all fine given delivery of hot water. The suggestion was that the motorised valve on the heating circuit might be the problem. I have jammed it to manual open, and can feel a slight vibration when its operating either on Auto or Manual. It cuts out with a 'whoosh' when it seems the system tells it to stop. I think its working. Since I cant test this 100% without a multimeter any conclusion could not be drawn. But the technician seemed to think it would have should have thrown up error codes if something were faulty.

 

I am still of the mind am missing something. Ive put new batteries in and reset the thermostat, bled radiators, isolated rads in various order, checked system pressure, cleaned Mag filter, cleaned external temperature sensor, and am confident motorised valves are working as well as pumps. Just cant think beyond this. 

For info. The system was installed by approved installers. They omitted the flow regulator within the install, it was just left sitting on the controller in its box? Hence I cant measure flow rates. The system as most Grant funded systems doesnt work as efficiently as it might, I only demand heating for an hour or two a day even through winter as the house is well insulated all round. The system was installed with the additional timer/controller to the Grant one which is set to either Off, On, Auto, or All Day.

 

The Heatpump serves 8 radiators installed as part of the system with no UFH. It has worked well heating each room perfectly well for the last 2 years as set up to give heat when as and only when demanded, hence it has to use large amounts of energy to start up each evening. However this has worked out fine costwise for my purposes.

 

Has anyone experienced anything similar? Is this the system behaviour that is known as 'short cycling'? If so it will remain short cycling on and off 24hrs a day 7 days a week without providing heat unless for the sake of  compressor wear and tear amongst other things....I switch it off. Hope someone might be able to point me in another direction to try to get it whirring again!!

 

 

 

[Beelbeebub]

Is there an isolation valve(s) that was turned off during the building work? Sounds a bit like the heating circuit isn't able to dump enough heat and the HP is shutting down.  

 

If you could get a flow indicator fitted it would be helpful. 

[MartyJ76]

Hi Beelbeebub Thanks for the reply, and also the provision of a diagram (on another post/thread) of a Grant installed heat pump with volumiser etc. This has really helped me as its more or less the system I have installed here (minus the flow regulator which the installer deemed not of any use, worse luck I was working whilst they did the install, needless to say, no customer handover was given or commissioning document filled out, they just upped and offed up the motorway, before I could get home).

 

In response, there are no isolation valves closed on the core system, that is in and around the ASHP itself outdoors, and in the cupboard area of controls and tank. However I have shut down 6 of 8 rads in the vague belief the pump was finding it too hard to push hot water around all rooms, I actually upped the speed of the pump in a naive attempt to alter this) but nothing has varied as a consequence. It warms the 2 of 8 rads left on only slightly for the concurrent cycling of 5 mins on, 20 mins off, despite demand from a fully communicating thermostat. The flame symbol remains continuously on the thermostat even whilst fan, pump, compressor not active in any given order.

 

I just cant work it out? As mentioned before after first checking the thermostat, the Grant technician (dont hesitate to contact them, they are very helpful in my brief experience) seemed to point toward the CH motorised valve needing checking, but couldn't do this without multimeter. However since have moved motorised valve switch to manual and jammed it there, and much the same thing happening? Would anyone suggest that a motorised valve would be the reason to throw the system into this cycling behaviour for any reason if not working properly? I can actually feel the faint buzz of inner workings whilst it is on? Either when on Auto or Manual. As mentioned before there is a distinct 'whoosh' from it when the system cuts out, as has always been when behaving normally and turned off, and i best gauge this is as being a consequence of an issue elsewhere?

 

I just wonder can anyone think of what I might be missing? As mentioned, no error codes, either on controller or main PCBs. Hot water heats perfectly and fan, pump, compressor can be seen to be working in appropriate order to achieve 50 degrees plus in next to no time really, but in terms of CH, it just doesnt want to get off the ground?

 

A couple of addendums to the above install story, if of any use to anyone introducing themselves (as am I) to the world of ASHP installs. As mentioned for the initial 2 years of ownership, it was serving every purpose I needed it for, whilst set up as the rather crude I now understand (oil fired boiler 'on demand') set up that Grant have resorted to to satisfy demand. Nonetheless, I actually liked the thought of my faithful little grey box sat beside the back door. Until now.

 

As mentioned the installers omitted the flow regulator, leaving it in the packaging left behind, this likely in the event that not much could be ascertained of an essentially crude install I might suggest. They really looked like they didnt want to start the job on day 1 of 2 and 1/2 days (3 or 4 engineers/plumbers/electricians/operatives on the job). I was actually impressed with the quality of regular plumbing (rad positions, joints and valves and such included, and tank fitted neatly into the quite small space provided with expansion vessels, mag filters all neatly arranged)

 

As mentioned however, they omitted the now important flow regulator, and have since folded as a company it seems, i wonder why? One strange addition that they did however install were Radbots, on every radiator, i imagine to overcome any zone programming and piping complications (I really would have only needed upstairs and downstairs zones). I have since replaced these with the original TRV's supplied which they kindly left behind. Anyway, if of any interest to anyone thereafter, once 'commissioned', another electrician turned up some weeks later to install timer on immersion to cover off (he programmed once monthly, i thought it was weekly?) Legionella.

 

By this time I had had to tell him system had  gone down 2 or 3 times with a P1 error code (Pump). Hence a further engineer appeared a week or so later and added some flow/return piping? Something like an EGR valve on vehicle engine? Thats as close as I came to understanding it. Apologies for my ignorance. In doing so he completely drained down the system (including the some 15 to 20 litres of glycol that were added originally...) and then refilled it with water only. I have since readded recommended level of glycol at much expense since want to do best for the only heating system I have.

 

As mentioned at the outset of the above, from what I understand my system is as per the diagram referred to provided on another thread. This with a 'volumiser/buffer' outdoors, immedeatly behind the ASHP itself. Is this standard? Outdoors? there are also isolation valves and leak off valves of some kind outdoors just above this box also which I read various opinions upon. I think i'm glad they are there? And that the system includes glycol? Am I? I read others appreciation varies widely...

 

Hoping, really hoping, that someone might have that nugget of info, check or suggestion that might point me in the right direction with the issue that the post was originally intended to overcome? Really want to get things going again. And hoping to learn how to change parameters in future to get it working as it should. I'm not sure if any Weather Compensation has been programmed in. It might be time to invest in the full input of a really well qualified ASHP engineer, but they seem to be very few and far between otherwise overstretched by new installs and commissioning.....I might alter career path after this....!

[dpmiller]

how many pipes go to the buffer/ is there an additional pump associated with it?

[Dillsue]

You mention some modifications since install such as- changing TRVs, shutting off radiators, adding glycol, legionella timer. Has the system worked reliably since any or all of these were done?

You also mention changing parameters but I wouldn't tinker with anything until you get the system working again as installed. By all means tinker and fine tune once it's up and running again, but not until its working for the winter.

[JoeBano]

You mention the heating symbol disappearing after 5 mins on the main grant control with the pump symbol and compressor symbol flashing? If this is the case, I would suggest you’ve got a fault with with your thermostat. 

[sharpener]

The diverter valve may appear to be working externally but if Honeywell they have a tendency to fall apart internally and bits can end up in odd places in the system. Do a search on the Vaillant FB page, lots of threads about this.

I suggest you get some pipe freezer or hire an electrical one and then take it apart to check it thoroughly. If broken replace with another brand e.g. ESBE or Drayton, you might be able to get one on sale or return. Fit the missing flow setter at the same time!

 

Your "whoosh" might be flow through the automatic bypass before the zone valves/diverter are fully open or after they have shut. This happens on my system.

 

8 hours ago, MartyJ76 said:

leak off valves of some kind outdoors

 

These are likely to be antifreeze valves, are they like the this picture? In which case the glycol may be superfluous and so you don't need the pipe freezer.

[Beelbeebub]

When the heating comes on, does the flow pipe out of the HP get warm? 

 

You are saying that when the heating comes on, only 2 of your rads gets warm but then the HP shuts itself down even though there is a call for heat. 

 

That does sound alot like you're not getting the right flow on the heating circuit. 

 

Maybe try this

First I assume you have a single 3 port valve that sends the water to the heating or DHW circuit.

 

Remove the power head from the valve. This is easy, you need to isolate the supply then take the cover off thr case (single screw) once inside carefully undo the two screws on opposite corners thwt hold it down and it pops off.  Replace the cover and leave safely tucked away. 

 

Use a pair of pliers or small spanner to old the shaft in the DHW position 

 

Set the system to heat the hot water, the HP should hum away merrily and the flow pipe should get hot and thecpipe to the cylinder.  Once that's ticking along nicely use the spanner to switch the valve to heating. The pipe tonthrntqfiatoranshoukd start to get warm pretty quick.

 

If the system then shuts down, your problem is some sort of flow restriction on the heating circuit. Maybe your rads have been turned down on the balancing vlaves.  If it keeps running an all your rads get plenty hot, then yous system is hydraulicly OK and the issue might be with the controls, a parameter in the settings or an iffy connection. 

 

Alternatively get a local plumber to fit a visual flow indicator so you can see the flow rates. 

[MartyJ76]

@Beelbeebub, @dpmiller, @Dillsue, @JoeBano, @sharpener.

 

Update to update with results, and thanks to all for your input, without it I wouldnt have percevere. I'm hoping Ive solved it!

 

I spent the last two days in various configurations testing everything as everyone suggested:

 

The thermostat is definitely communicating with receiver. The secondary pump is indeed working, i checked this by removing the silver cover and using a flat head screwdriver to see it was turning AOK. Then fired system up and felt the pump for vibration and listened carefully, it was def working. I couldnt get as far as checking flow and return on the Grant Controller, it wouldnt run for long enough to get through the list of parameter settings (glad for the diagram and instructions you attached, this is going to come in extremely useful indeed!).

 

Yesterday by chance, for no fathomable reason than as I'll explain in due course, the system spent the best part of the day (and evening) in and out of Frost Protection Mode? I have no idea why!? And it hasnt done it today. This (fortunatly) however happened to keep the fan going in between periods of me demanding heat and the system cutting out. The temperature outdoors shown on the Grant controller was thereabouts 12degrees until the eve came. I thought I understood that Frost Protection shouldnt kick in until around 4 or 5 degrees on Grant Aerona units? I then came to all sorts of conclusions such as the outdoor temperature probe was giving the unit itself false readings, among many more bewildering theories.

 

Anyway the system came up to a sort of lukewarm heat around all the 8 rads (now set to max temp), was able to discern that heat was passing the motorised valve (2 port). But not confident the valve was operating as it might, I set about taking the head unit off and checking settings lever which following Auto operation doesnt seems to jump out of full Auto position to somewhere in the middle of its line of travel. I tried to cable tie it off to prevent it from moving, but this offered no difference in results> The lever wont stay in manual position at all either, it jumps out of what i assume is its locking position, and no amount of cable tying would keep it there, meaning that the micro switch doesnt stay depressed.

 

I'd like to think I solved things today as a consequence of this, but not 100% sure: I took the head off the valve unit, leaving the valve in what I presumed was the open position in the (very minimal) turn available to it. Thereafter I used a clothes peg to keep the microswitch in the unit depressed. Lo and behold, the system fired up (after I returned power to it....I made sure to isolate power before removing the head of course). It remained in operation mode and for 1/2 an hour I got all radiators up to temp!!

 

I discontinued this experiment thereafter for fear I might damage things with the aforementioned parts out of situ as they were. I am now 95% confident the problem must be a faulty 2 port valve head? Any thoughts, anyone? Ive found a new valve head and valve on ebay. Next step will be to order up and swap the old head unit out. Incidentally, the valve is manufactured by Neomitis (model MTV222a). From what Ive read, these units rarely fail on new installs (mine is 2 years old), but it isnt unheard of? Can anyone shed any light?

 

I cannot think what else could be happening. If , with the head unit in place, I shift the head unit lever to manual and let it settle back to the position it returns to, I can hear a distinct click on and then off in the power supply box. Its not staying on, in either auto or manual lever settings.

 

Re. the aforementioned Frost Protection activity yesterday....I found a loose earth cable of about 5 inches in length coming off a waygo triple connector inside the pump unit. the other two earths were firmly in position on the 30 port bus? connectors on the PCB, cant remember which no's they were. I see the controller is wired in (black and white cables) into ports 1 and 2 of this bus. Ports 3 to 15 as I remember are empty. I think port 3 is labelled up GND, which I assume is Ground? Somewhat naively (some might say stupidly), i took it to mean this loose earth of the Waygo, belonged in port 3 and took to resituating it. Can anyone shed any light if this is (probs unlikely) right?

 

I am hoping, with the advent of a new 2 Port valve head, my woes might be over, and my house warm again. i will have learned much in this process, and importantly that I will have to get an engineer out to put a missing flow regulator in line. Not sure where this should go, but I shant be trying to freeze pipes myself for sure!! Thereafter I shall be reading through as much as possible regarding setting parameters as they should be set, not how Grant advocate setting them, I really like the Grant unit and controller, have confidence in the Pump itself. Such a shame they set it up like an oil boiler (and omit the flow regulator so it cant be questioned or tinkered with).

 

So glad this site exists! Any thoughts on motorised valves anyone?

 

 

[MartyJ76]

Persevered!!