Sorry to hear about the problems, its going to be something fixable for sure.

Posted by: @gutoffowc

↑

Anyone else had a similar problem?

No (I have only one zone) but the obvious questions are

• What is controlling the demand for heat to the heat pump? 
• What is controlling the zone valves?
• What if any schedule have you got on the zones?
• What room influence mode is set, what are the weather compensation settings
• How are the thermostats connected?
• How does the behaviour differ according to whether downstairs is 'on' or not?

And of course 

• Why do you need 2* zones in the first instance, with it's inevitable complexity.  Why not run single zone?

There are a fair number of possible reasons but they almost all come down to the control strategy (including any zone valves), not the heat pump which may be why Vaillant can't immediately help.   Did your installer think through the control strategy properly, or just assume that the more knobs there are to turn the better?

Do you have a controls diagram (and if not Im wondering how your installer knows that the controls design should work)?

*5 zones if the thermostats are still functional!

Posted by: @jamespa

↑

Sorry to hear about the problems, its going to be something fixable for sure.

 

Posted by: @gutoffowc

↑

Anyone else had a similar problem?

No (I have only one zone) but the obvious questions are

 

• What is controlling the demand for heat to the heat pump? 
• What is controlling the zone valves?
• What if any schedule have you got on the zones?
• What room influence mode is set, what are the weather compensation settings
• How are the thermostats connected?
• How does the behaviour differ according to whether downstairs is 'on' or not?

 

And of course 

• Why do you need 2* zones in the first instance, with it's inevitable complexity.  Why not run single zone?

 

There are a fair number of possible reasons but they almost all come down to the control strategy (including any zone valves), not the heat pump which may be why Vaillant can't immediately help.   Did your installer think through the control strategy properly, or just assume that the more knobs there are to turn the better?

Do you have a controls diagram (and if not Im wondering how your installer knows that the controls design should work)?

 

*5 zones if the thermostats are still functional!

I think the mystery is in the first question; 

the sensocomfort is insisting that there is "no heat demand" and the heat pump is therefore not responding; there are in effect 4 zones; and 4 thermostats; the sensocomfort has replaced the upstairs thermostat.
We haven't set time schedules, as it's fairly mild at the moment, I'm assuming weather compensation has been set, as that's what I was told by the installer.

Posted by: @gutoffowc

↑

I'm assuming weather compensation has been set, as that's what I was told by the installer.

Never assume, it makes an ass of u and me!

Posted by: @gutoffowc

↑

the sensocomfort is insisting that there is "no heat demand" and the heat pump is therefore not responding; there are in effect 4 zones; and 4 thermostats; the sensocomfort has replaced the upstairs thermostat.

OK, thats progress.  The sensocomfort is detecting the local temperature as 21C and, because of whatever it has been told (through the configuration that the installer dialed in) has decided that this means that there is no requirement to heat.  Potentially not an unreasonable conclusion, most people want to stop heating at 21.  Don't forget that it only knows what it knows and can only react as it has been told to react.  It doesn't, and cant, know what you intend to happen, only what the installer told it (and the other control elements) to do.

Which brings us back to the central question.  How did the installer intend all the separate control elements to work together?  This then triggers a secondary question - has he put in the right parameters/connected them up so that they do in fact work the way he intended.

This really is your installers' responsibility to draw a diagram and explain how the control elements are supposed to co-exist.  Prima facie you have too many bosses, and thus its predictable that the wrong thing will happen if not carefully configured.  Vaillant cant be expected to support this because its not their (control) system, its the installers control system comprising two sensocomforts and several thermostats connected together in unknown ways.

Its difficult to comment further without more detail of both the house and the control system.  Its also difficult without that information to judge whether your installer knew what he was doing but didn't explain it adequately, or just hadn't got a scooby which unfortunately is not impossible.  He may have installed a control salad not a control system, it happens, can generally be easily sorted out, but is frustrating.

I think you have two options

1. put the responsibility firmly in the lap of your installer and rely on him to sort it out
2. do some simple experiments, a bit of diagnostics and share some information about your system and your house then, with the help of those here, understand your system and fix it up by reprogramming some key components.

Of course someone here may pop up with THE solution, but its unlikely because nobody else has the same control system as you (they may well have the same components, but how do they know that they are connected/configured in the same way)

If this were my house (and because I generally default to prefer option 2) I would start by taking some control elements out of the equation thus simplifying it.  That's (almost certainly) easily done by whacking all the thermostats up to max, so that they are continually calling for heat.  Then its the sensocomforts alone that are 'in charge' and you can take a deeper look at how they are interacting, without being bothered by the extraneous thermostats (which I am presuming are not Vaillant devices but please confirm).  I would then look a bit at how they have been configured in an effort to reverse engineer what the installer has done.  Along the way I would try to understand why I need five zones in the first instance.  My 200sqm house runs just fine on a single zone controlled by the one sensocomfort alone, which is delightfully simple.  Of course yours may be much bigger or you may have more complex needs which, if you care to share them, we might be able to help with.

Please let us know how you wish to proceed, I (and others I am sure) are willing to help but you need to be committed to that route if its to be successful.  It will probably turn out to be very simple once we have understood the control system!

@jamespa We've not had a Vaillant engineer in, who may have sorted out one problem but created another; (he wasn't inspiring confidence in knowing how to sort out the problem, and left us with a timed setting for downstairs, so nothing responded till I spotted this and reset it to manual.

He was here on saturday, last night we noticed the pump serving the upstairs rads loop was working, even though there was no demand for heating. The ASHP wasn't producing heat, but why should a pump still be running?. Stating the bleedin' obvious; it's wasting electricity and adding wear and tear to a pump. if we asked for underfloor heating to come on, it was then circulating the same heated water to upstairs! All we could do was turn off the electric to the heating.

So back to the installer to sort out, we agree on that.

Another sleepless night!

Posted by: @gutoffowc

↑

He was here on saturday, last night we noticed the pump serving the upstairs rads loop was working, even though there was no demand for heating. The ASHP wasn't producing heat, but why should a pump still be running?.

Depends on what controls the pump!  Thats the whole point, a control system needs to be thought through, not just cobbled together from a set of components more or less randomly connected.  Unfortunately, based on what you have told us, there is a fair probability that your installer hasn't got a scooby and will come in, change a few things but wont ultimately sort it (or he will sort this problem but create another)

You may ultimately be best off going back to basics, tracing what connects to what and cutting most of it out.  Assuming you have one heat pump and your house area is less than say 250 sqm what you need is one sensotherm, no thermostats, and the system properly balanced to achieve your desired temperatures (presumably a bit cooler in the bedrooms than the living rooms).

As a matter of interest

a) do you have a buffer tank (a tank of water connected to both flow and return between the heat pump and the emitters)

b) how many water pumps do you have in addition to the one in the Outdoor unit

If the answer to a) is yes or the answer to b is more than zero, then your installer also almost certainly has some plumbing problems to sort out and I wouldn't let him get away until he has.  Have you paid him, if not dont!

The Vaillant heat pump and its controls are excellent pieces of kit.  Unfortunately like any boiler/heat pump poorly thought through controls can make the system as a whole behave weirdly and vastly increase the running cost.