The Vaillant controls are excellent IMHO, possibly some of the best.  Why do you think they are too simple?  What do you want to do that you think that they cant do?

Posted by: @jamespa

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The Vaillant controls are excellent IMHO, possibly some of the best.  Why do you think they are too simple?  What do you want to do that you think that they cant do?

Oops, I missed your reply..

And I may have got the wrong impression from posts I read a while back! 

For heating, all we should want it to do is to be able to use wc with an external sensor and work as a programmable thermostat with different temperatures for different times of day and also vary by weekday (not necessarily for 7 days, but some flexibility). 

For the hot water, I am thinking we will need to be able to set the target temperature and times of day we will need it to warm the hot water tank to it. And the legionella cycle of course. And to be wired in, without dependency on the cloud during operation. 

And also have the usual holiday and all day mode..

Ideally it would also provide some state on overall consumption, etc. 

I am wondering if the default controls that come with the heatpump would suit or would we need a specific option..

The vaillant controller and app do all of that (and more) natively.  Forget any external controller it's just not necessary.  Seriously you don't even need (and really shouldn't have) a thermostat (and if you need one the Vaillant wireless controller has a temperature sensor).

The app is cloud dependent but you don't need it for any of the above other than easy access to consumption figures (they are available locally but it's not quite as easy).  

I use do HA to get plots of various things for interest, but not for any control which is done purely by the local Vaillant controller.

Seriously you need nothing other than the valiant controller to control, plus ha if you want fancy graphics to monitor.

Posted by: @jamespa

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The vaillant controller and app do all of that (and more) natively.  Forget any external controller it's just not necessary.  Seriously you don't even need (and really shouldn't have) a thermostat (and if you need one the Vaillant wireless controller has a temperature sensor).

From the quotes I got so far, it seems Vaillant is selling what they call the basic pack in terms of controls for over £3k, almost as much as their pump..

Posted by: @batpred

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Posted by: @jamespa

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The vaillant controller and app do all of that (and more) natively.  Forget any external controller it's just not necessary.  Seriously you don't even need (and really shouldn't have) a thermostat (and if you need one the Vaillant wireless controller has a temperature sensor).

From the quotes I got so far, it seems Vaillant is selling what they call the basic pack in terms of controls for over £3k, almost as much as their pump..

 

What does this include?  3K is well ott.  Check midsummer wholesale for a sense check/Calibration. 

Vaillant are neither the cheapest nor the most expensive, a good mid market choice for a balance of cost and quality.  That doesn't make it the best, just an option seriously worth considering.

Obviously different installers will load things differently which is why shopping around is worthwhile.

The other class of solution I would look at in the 5kW range where you are, is cheapest available homlely compatible unit plus homely.  For this option check you are happy with the subset of homely functionality that is cloud independent imho.  Homely is obviously optional but your posts suggest you want a fairly good UI with a fair few features.

Also don't forget octopus. If posts on here are anything to go buy their vertical integrated, very slightly dumbed down, approach seems to work.  Less opportunity to fiddle though if that matters to you.

@jamespa 

Below is one example. Anyone trying to sell me a £1440 survey is dreaming, but they also list 3k for controls (plus 5k for install)..

Efficiency 391% System design
Flow temperature (°C) 45°C
Cylinder elite cyl HP buff combi 250/60l
Vaillant aroTHERM plus 7kW

Estimate total price £19,138

Vaillant aroTHERM plus 7kW      £4,242
electrical connection                 £540
frost protection                        £632
primary pipework                     £1,640
controls vaillant                       £3,132
elite cyl HP buff combi 250/60l  £2,032
Survey                                    £1,440
electrical labour                       £480
heat pump install                     £5,000
Boiler Upgrade Scheme (BUS) Grant -£7,500

Estimated total                           £11,638

I can see myself complementing my knowledge of an ASHP system in this "estimate evaluation" process... Below is what seems the simplest system (direct) that we could have.

It seems that Vaillant needs to have controls connecting to a HW cylinder. But we could pick the HP HW unit we know will fit the space (and halve the cost in the process) by using the Vaillant VR 10 sensor ...

Posted by: @batpred

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It seems that Vaillant needs to have controls connecting to a HW cylinder. But we could pick the HP HW unit we know will fit the space (and halve the cost in the process) by using the Vaillant VR 10 sensor

19k is having a laugh at your expense.  Ignore.

The only connection vaillant need to the dhw tank is a temperature sensor.  Almost all heat pumps need that (and I wouldn't buy one that doesn't), some also need a power control (not needed for vaillant because the legionella cycle is done natively by the heat pump not using any immersion). 

It's s 2 wire connection, more ir any cable will do, bellwire, cat 5, mains cable, whatever is kicking around.  I used a piece of 3 core that I happened to have more of than I will ever need in my life.

Obviously the immersion in the dhw tank will need power if you want it as a back up, otherwise don't bother.  Again true for any heat pump.

I think the diagram you show is what I have.

I note that the cylinder is a buffer/cylinder combi which you don't want.

You can see the retail prices of vaillant controls here, nothing even close to 3K and that's RETAiL

Posted by: @jamespa

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Posted by: @batpred

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It seems that Vaillant needs to have controls connecting to a HW cylinder. But we could pick the HP HW unit we know will fit the space (and halve the cost in the process) by using the Vaillant VR 10 sensor

The only connection vaillant need to the dhw tank is a temperature sensor.  Almost all heat pumps need that (and I wouldn't buy one that doesn't), some also need a power control (not needed for vaillant because the legionella cycle is done natively by the heat pump not using any immersion). 

...

I note that the cylinder is a buffer/cylinder combi which you don't want.

You can see the retail prices of vaillant controls here, nothing even close to 3K and that's RETAiL

So far, no sensible estimates. 

I now make a point to state "no buffer" as you suggested. Often they ignore it and produce something that includes it - as the above. 

Until we start seeing close to sensible estimates, I will not bother drilling down to see whether anything that was included can come off. 

Right now, and even when using a common tool to estimate, installers bundled different things in what appears to be fairly random ways.. 

The main thing we may have to give up is to have it installed on top of our ground floor extension. Sideways would be ideal. Large installers have inflexible policies. Some smaller installers will agree, as it is very accessible and safe.  

Posted by: @batpred

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The main thing we may have to give up is to have it installed on top of our ground floor extension. Sideways would be ideal. Large installers have inflexible policies. Some smaller installers will agree, as it is very accessible and safe.  

On a practical note, what covering do you have for that extension? Replacing it whilst the heat pump is in situ might be awkward and the fact there’s always some condensate needing to drain away means that roof covering will always need to be in good shape.

The extension is 5 or so years old so I would expect the roof to outlive the pump. 

And should the roof need repairs after 10 years, the pump will be out of warranty. I never saw insurance without caveats, so there's always something left for the owner to pick up!

I am also assuming that with the heatpumps being around 120kg, they do not need to be drilled onto the roof.   

We did have a couple of installers that had said they would advise to have it sideways on the flat roof. But I see that BG, Octopus and some larger installers do not empower surveyors to do what is sensible for each case. 

Posted by: @batpred

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The extension is 5 or so years old so I would expect the roof to outlive the pump. 

And should the roof need repairs after 10 years, the pump will be out of warranty. I never saw insurance without caveats, so there's always something left for the owner to pick up!

I am also assuming that with the heatpumps being around 120kg, they do not need to be drilled onto the roof.   

We did have a couple of installers that had said they would advise to have it sideways on the flat roof. But I see that BG, Octopus and some larger installers do not empower surveyors to do what is sensible for each case. 

Given it's not unusual to see air conditioning units installed on flat roofs, your conclusions may well be correct. One alternative, of course, if there is a first floor wall next to your extension's roof, could be to wall mount the heat pump so there's enough room underneath for roofers to make any repairs that might arise.

I can't help but feel, though, that if the details can be sorted out then having the condensate drain onto a roof that's designed to allow liquid to drain away is an eminently practical setup.