Many ways to set up an ASHP

[joe90]

Right (getting cross now). I have changed parameter 100 from 1 (fixed water temp, dry contacts) to 3 (climatic curve no 3 using dry contacts) to see if it will up the temp at all. 

[Gav_P]

Stupid question... are you sure you have it wired up right? 

 

If if it turns on when you crank up the room stat, then this isn’t what you want is it? The room stat should just do the UFH pump and actuators. 

The TS should trigger the ASHP to switch on. 

 

There is the 3rd element to consider... is the command unit acting as a stat without your knowning?

 

 

[Jeremy Harris]

You can set the command unit to report different temperatures; I have mine set to report the flow temperature.  There is very definitely a setting that's awry in the command unit programming - if I was able to access ours I could sort this for you in a few minutes by just reading out the parameters from ours so you can try exactly the same ones in yours. 

 

I'm near-100% certain that this is just a parameter setting that's awry, that's setting the heating flow temp to 25 deg C.  These things have a myriad of interactive settings, and it seems highly likely that one or two of these aren't set correctly for what you want to do.  Sadly the settings aren't well documented, they could do with more descriptive text as to EXACTLY what each parameters does.

[joe90]

1 hour ago, Gav_P said:

are you sure you have it wired up right? 

 

At the mo it’s not wired correctly BUT this is to force the ASHP to heat the buffer to the temp I am trying to achieve.

 

if you prog the command unit to act as a room stat (which is what I wanted originally) you are unable to set the water temp that you want. You can only set the water temp by using dry contacts (means a separate room stat). As above I have tried using a climatic curve to see if I can achieve a better temp. As @JSHarris has said before the command unit is a pig to work out.

 

My plumber neighbour just popped in to see how i was getting on, he reckons I have air in the system (pump sounds noisier than the manifold pump, and it’s the same type!) so going on a bleed everything stint in the morning.

 

 

Edited November 20, 2018 by joe90

[joe90]

Hooray, it’s all working. Got DHW feed up near 60’ and heating near 35. It’s time to play with the parameters and set it up to suit our house. I was beginning to think, like @ProDave I had bought a dud on Ebay. I will report back on how I have now wired it and set it up after a good play tomorrow.

[Gav_P]

Great news!!

[Jeremy Harris]

8 minutes ago, joe90 said:

Hooray, it’s all working. Got DHW feed up near 60’ and heating near 35. It’s time to play with the parameters and set it up to suit our house. I was beginning to think, like @ProDave I had bought a dud on Ebay. I will report back on how I have now wired it and set it up after a good play tomorrow.

 

Saves me having to go and cycle through all the settings on our command unit and write them down, at least for now!  I must get around to doing it sometime, so I have a record of every parameter that's set.

 

Out of interest, what do you think got it working?

 

I have a theory that the command unit only actually sends a programmed parameter to the main board when you enter that parameter in the menu, otherwise it just sits there.  There's a hint on one of the sites somewhere that mentions that a new main board arrives unprogrammed, and needs a command unit to set it up, and I have a suspicion that the command unit doesn't just dump all the default parameters to the main board, it waits until you cycle through and change them, even if changing them to something and then changing them back to what it was before, before the main board actually stores the set parameter.

[joe90]

@JSHarris I think you may well be right, I ended up changing loads of parameters and then changing them back!!! I have wired it differently (again) and converted the Wunda stat back to non dry contacts (using its powered output to drive the manifold pump). I will be changing parameters again tomorrow to try and end up with what we want. P.S. the temp devise you recommended is great and I have ordered a few more to register temps around the system.

[ProDave]

Glad you got it working.  That kind of confirms @JSHarris theory that you need to edit every parameter in turn, even if you then edit it back to what it was previously.

[Onoff]

Can you not suck the parameter sets out of these ASHP units and store them? In case the unit goes down (or someone else wants them). 

 

Just thinking what I do with inverters etc.

[Jeremy Harris]

3 minutes ago, Onoff said:

Can you not suck the parameter sets out of these ASHP units and store them? In case the unit goes down (or someone else wants them). 

 

Just thinking what I do with inverters etc.

 

 

Not as far as I can see.  I looked at the data lines to and from the unit, thinking that I might be able to make a more elegant control system by just sending data directly to the unit, but after hours of trying to reverse engineer the data protocol I gave up.  One thing I did find is that not much data routinely passes from the main board to the command unit, which tallies with the delay there is between something changing and the command unit display reflecting the change.

 

I suspect there is some form of "factory set up" mode that can be enabled to dump every default parameter from the command unit to the main board, but it's not clear how to access that mode.  I do know that you can disconnect the command unit and the unit carries on running perfectly well without it, as once programmed all the settings in the main board are stored in non-volatile memory.

 

If I were designing something like this I'd try to limit the number of writes to the non-volatile memory, as it has a finite write life.  That would explain why the command unit doesn't routinely re-write data to the main board, but only does so when a parameter is actively changed.

[joe90]

Right, apart from trimming, my system is up and running ??. For those that are interested this is how I set mine up. The ASHP via a diverter valve heats either the 90litre buffer tank for the UFH or the DHW tank. There are timers on both in case we use E7 or E10 in the future but for now both permenantly on. The DHW tank has a stat to call for heat when required. The heating is set to a water temp of 40’ (programming in the command unit). The buffer tank also has a stat to call for heat when the tank cools. The room stat controls the UFH manifold pump. During the winter the buffer tank will always be charged and when the heating is required we don’t have to wait for the ASHP to heat the buffer then the slab which could take some time. 

 

P.S. I had to modify the room stat back to its original power output and not dry contacts for this configuration.?

 

all comments welcome.