Daikin Altherma EDHQ014BB6V3 Heat Pump runs with Circulation Pump on continuously

[coling2004]

Hi,

as per the title - our heat pump has just recently started to run continuously with the circulation pump, denoted on the controller with the triangle symbol.

This runs even though the heating on the house is turned off (Heatmiser UH1 system and stats) - typically when the heating would be switched off the compressor and pump would both stop.

Just wondering does anyone have any quick fixes or would it be more like something has failed somewhere?

Thanks, Colin

[hyperion]

Colin,

is the Daikin Altherma a new installation or has it been working fine for a period of time?

As you have mentioned that you have a remote thermostat/controls, the heat pump should only run in the heating mode when it gets a demand signal from the external controls.

Is the domestic hot water up to the normal temperature?

So the two possibilities are that one or the other of these circuits are being made unnecessarily, causing the heat pump and circulation pump to run continuously.

Have you tried turning off the DHW system on the controller? Try this. If the heat pump continues to run after about a minute or so, then possibly the problem lies with the central heating controls.

Sorry that this seems a bit vague, but it is easy to check at the machine and not quite so at a remote distance.

Let us know how you get on.

[coling2004]

Its a new install, but has been operating pretty normally for the past month. Only thing that has changed over the weekend (when I think the issue has started) is that i re-wired a couple of the heatmiser stats so that they could be controlled via the central touchpad/netmonitor. One of these stats has a domestic hot water timer, although the control center isn't setup to heat the hot water - the Daikin heat pump tops up the hot water as and when required.

When i turn the domestic hot water off, the water symbol and pump symbol flash - which signifies that the Solar Panels are heating the water solely.

I will try un-wiring the stat which deals with the hot water in an attempt to see if that makes a difference, although when i turn the power off to the Heatmiser system the circulation pump still goes as per normal.

If there is no demand for heat, the compressor doesn't kick in, just the circulation pump, which I would assume isn't good running 24/7, for both electricity consumption as well as life span of the pump.

[hyperion]

Colin,

It would appear that somehow your minor wiring modification is creating a permanent link onto the heating circuit. It could be as you suspect that the Domestic Hot water timer in the Heatmiser is actually switching the heating circuit by mistake.

The Daikin Altherma monoblock unit that you have installed has a simple two wire control circuit going out to your thermostat or control centre. Please ensure that you have turned the power OFF before you make any modifications to the control wiring.

[coling2004]

Well, I've checked out the wiring and disconnected the domestic hot water timer wires on the stat.
However still the same result - circulation pump continuously runs when there is no heating demand, and the compressor etc has stopped running.
Now at 2 points this evening, the pump did stop for a period of time but started again on its own accord, even though there was again no heating demand.

When the heatmiser control system is switched off, typically the heat pump should switch off too, however this isn't the case as the pump continues. I would have thought if there was any configuration or wiring issues on this, that powering it off would rule them out?

[hyperion]

Colin,

Most of the Heatmiser range of controllers have three terminals, one is the Common C, one is the Normally Open NO and one is the Normally Closed NC.

If by accident you happen to have connected the wires into the C and the NC terminals, then the system could still run when no heating demand is being made and potentially if the area of that thermostat became too cold then the contacts could change over causing a break in the circuit and the pump would stop.

If it is not a wiring problem with the thermostats then something else is making the control circuit.

With the control circuit loop, all of the thermostats/control centres should be wired in parallel so that if any one area calls for central heating the pump will start and the Altherma will then be controlled by the water temperature setting. So although you have checked the connections, if any of the thermostats are calling for heating and you happen to have disconnected any one of the other thermostats, then the pump could still potentially run if there is a circuit made.

On the Altherma it may have been set up to run the pump when the ambient temperature drops below 0degC to prevent any possibility of the external water pipework freezing up and causing damage. This feature would normally only run the pump for a limited period of time.

As it is a new installation, it may be best to call back the installers to check the system over and pinpoint where the fault lies.
Before you call them in, just double check that all of your Heatmiser wiring is correct as you do not want to face the possibility of being charged to put right a potential simple wiring error.

[coling2004]

Checked out more wiring of thermostats and the UH1 center and all looks fine. All stats are doing what they should be doing, if they require heating, the compressor and heating led comes on the daikin controller. When they are up to temperature or switched off, the compressor and red light goes off, but 'most' of the time the pump icon remains on and you can hear the pump running on the monobloc outside.

The only wiring that I can see that integrates the UH1 and the Daikin is 2 wires connected into the 'Boiler Enable' part of the UH1. These have never been touched since the install.

Now there was an instance last night where the pump light did go off at the same time as the compressor, yet later on whenever i turned stats off etc, the pump light remained on.

This morning whenever the stats turned off due to the timer - the pump icon also turned off as well, ie all is as it should be, but I'm concerned that it is an intermittant issue.

The installer is due back soon to finish off the integration with the solar panel so i will be running all this past him but i like to know and understand what all is happening myself.

[hyperion]

Morning Colin,

Thanks for the update.

Just a faint possibility that the operating program has been corrupted by a voltage spike or some other external source of interference, if you turn off all of the power supplies to the Daikin Altherma Monoblock unit, and leave them off for a couple of minutes, then turn them back on. This should cause the system to re-initialise and then it will restart. This will not cause the system to loose any stored programming settings or parameters.

It is worth a try as this might clear any potential problems.

Then still mention it to the installation engineer when he returns.