@mikefl Parameter 41 22 is 30 so presume that's 30 mins which the pump seems to be ignoring.

The other oddity is the outdoor temperature at which the system pump switches off which varies from 5.5C to 7.5C, so it doesn't seem to be following parameters 43 11 & 12 (we've altered those as a test but it makes no difference).

And the sensor still reckons outdoor temp can increase 1.5C in seven minutes which maybe points to it being the issue.

Busy time for installers and engineers so we'll have to wait patiently until someone comes 😐 

Hopes it’s ok to jump onto to this conversation, I have found it really useful but have a further question.

The circulation pump in my system have been on for the past few days due to colder weather…. The issue I have is that it is rather noisy.

Could it be a case of air in the DHW system? The noise stops when the heating kicks in.

If so… any ideas on how to bleed the DHW system?

Thanks in advance.

Posted by: @richw

↑

The circulation pump in my system have been on for the past few days due to colder weather…. The issue I have is that it is rather noisy

Hi @richw, there should be manual bleed valves on your piping or Low Loss Header/Volumiser if fitted. (Items 10 and 11 on diagram) If you don't have a low loss header (item 8) then check what circulation path is open to the pump inside the Grant Aerona when it is running in frost protection. Check it's not pumping against closed 2 or 3 port valves when CH and DHW are and causing the bypass valve to lift & open, Grant pre-plumb cylinders have an automatic bypass valve (Item 6) across the primary flow and return pipe connections, designed to prevent primary flow becoming excessively low, it's noisy when it lifts and operates. It shouldn't normally operate. It's these subtle details such as the internal pump switching on for frost protection that seem to go overlooked by Grant system installers.

@richw Is the frost protection symbol on (on the control panel) when you hear the noise? 

We get the noise but not the frost protection symbol. 

And more bizarre with the control panel as it increased outdoor temp by 5C before our eyes.

Mystery solved. Grant says it can happen where the system pump sticks on and it's not to do with frost protection. Doing reset on the pump stops the issue.

My pump stays on 24/7, as it's the only pump in the system and I don't ever turn my heating off.

@sentinam hi, did resetting really solve the issue. It hasn't for me...The exact same thing is happening to my grant heat pump for the last 2 weeks. The water circulation pump is running for long periods (i.e. no frost protection symbol) when the frost protection turns off and again starts up in the evening several hours prior to the frost protection kicking in? 

Really would be interested to know I you got this issue sorted.

Cheers.

My AERONA 3 circulation pump runs constantly whatever the outside temp, is this right? I am running weather comp, open loop style in that all the room thermostats are set above the temperature the curve will cause them to reach so I assumed the house is constantly calling for water to be sent round the system but when it reaches the desired temp it just keeps circulating. This seemed logical to me as I figured it’s the only way it’d be able to monitor the water temp but having read this thread I’m not so sure. Is there a way it can just check the temp from time to time rather than constantly running the pump

@damonc The only time the circulation pump on my HP runs 24x7 is when it's in "frost protection" mode i.e. OAT goes below 3C, when it stays running until OAT goes above 8C. At other times, it only runs when the house is calling for heat (CH or DHW).  There is a setting on the Grant to 'sniff cycles' rather than "always on" (which is the default I believe, but I think "always on" means "always on when there's a demand for heat"), but I thought that was to reduce HP usage, not increase it, but might be worth checking those values. Parameter '42 00', and following ones.

@mikefl thanks, so to check is your parameter 4200 set to 2? Could you tell me what your parameters 4201, 3202, 4203 and 5111 are set to please?  Also do you have a secondary pump on the other side of the system and does that just keep running to move water round the system in the house even though the water on the heat pump side isn't moving, I guess the buffer separates the two ok?

My parameters are:

42 00 = 0 (so the next three values don't matter, and they are the default values...)

42 01 = 3

42 02 = 5

42 03 = 3

51 11 = 0 (don't use thermal store temperature probe)

I do have the 'standard' Grant install with a LLH, and the secondary pump only operates when there is a CH heat demand (i.e. it's off when the primary pump is just circulating water to prevent freezing).

To sum up:

@mikefl thank you, I've changed 4200 to 2 and now the main pump is starting up every 5 mins for 3 mins to allow the temp to be taken then turning off which seems a good idea to me and better than running all the time.  The secondary pump is running all the time because I'm running full weather comp and therefore the the thermostats are higher than the curve will ever achieve and so always calling for heat.  I thought I had a standard grant install with a 300l litre HW tank with what I thought was a 25l buffer at the bottom of it, do you have something different? Maybe I have a LLH too and didn't know it, not sure what the difference is do you know?