“Anyway, we know that the assumption the heat pump will be running continuously is based on the fact a cylinder is assumed to be always part of the solution. This essentially means unless it is a massive property, the system is never going to be powerful enough to provide direct hot water for showers etc. And don't start me on the electricity capacity, we know these pumps run on a normal socket circuit like normal air cons. “

You seem to need to air your incorrect prejudices. You are very ill informed.

ASHPs NEVER use a normal socket nor circuit and if wired like that it is very unsafe and un-compliant 
ASHPs provide plenty of hot water for showers for any number of occupants and don’t need top up immersion heaters either. It’s a question of the size of cylinder (or phase change heat storage like Mix-energy) and stored water temperature. The heating is off is when the hot water is heated so is often set at night, on the cheapest power rate.

Posted by: @majordennisbloodnok

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Posted by: @batpred

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Yes, but HA allows separation on concerns and also resilience through multiple paths of failure. To be honest, never enough! Dream high and be realistic I'd say.

With batteries doing 8000 cycles I would not loose much sleep. And as others pointed out, the practical limits may be elsewhere.

I am aware these energy systems come with plenty of flexibility and HA is not going to do anything magic. And once it's doing something critical I do not think it is easy to have it delivering consistently anyway.. but it will give you freedom you may not get otherwise. 

In the context of my previous post, I'm not sure what point you're trying to make here.

Having HA concerning itself with what are aspects more likely to change like pricing and having to take into account a growing number of systems seems more future proof. Still, given the way that many HA device facing integration components are tested (and sometimes even "designed"), it is not conducive to high availability. E.g. being able to use different methods to monitor a device on the modbus rather than having one integration flow and assume it will be stable enough may be the only example. That way maybe the "layer" can be relied on.  

Posted by: @majordennisbloodnok

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As for putting batteries through 8000 cycles, I would agree; not much of a problem. However, with Octopus Agile providing half-hourly prices, it wouldn't be difficult to put a battery through hundreds of thousands of cycles in the name of, as you put it before, "pushing the boundaries of optimisation", and yet realise just a few quid more than a dramatically simpler strategy that provides almost as much benefit for almost no effort to implement. It's the 80:20 rule on steroids.

The cycles that manufacturers quote are complete, from nil to full. So charging twice from 20 to 70 is one full cycle. But as others pointed out, there may be electronic components that cannot be reprogrammed more than x,000 times. 

When I mentioned pushing the boundaries of optimisation, I meant moving from having to configure components and install cables to change the way battery or grid are used to using an HA based system.     

Posted by: @grahamf

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You may have been lucky with your analysis.  Still, when a press reporter suggested to the great Gary Player that he had been a lucky golfer, he replied "The more I practise, the luckier I get." 

There is some truth and perhaps even relevance in that!

Posted by: @grahamf

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Our house is a 350m2, so intuitively it feels as though the heat loss should be relatively large.  We have about 70% loft the loft insulated to 300mm and the rest to about 100mm.  We have cavity wall insulation and double glazing installed in 2009.  The floors include concrete, concrete on insulation, suspended wood with foam underneath and suspended wood with a small air gap to concrete.

It sounds like just the sort of house for which the standard fabric calculation could easily be widely out (because of the variable construction - like mine) and for which therefore an independent check based on measured consumption, however obtained or crude, might well be useful if it resolves an important design fork (like 2 fan vs 1 fan, pipe upgrades vs not, 2 unit vs 1 unit or - as in a current live case on the forum, 8kW Daikin vs 9kW Daikin more significant than it looks because the 9kW is actually a 16kW downrated so, for a 5kW house, is way outsized.)

Posted by: @grahamf

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I had problems with one consultant who refused to use a sensible value for ACH.  It makes a massive difference to the total heat loss and seems to be the most common reason for over-estimating it.  People don't seem to use their common sense and think about what 2 air changes per hour actually means.  It is equivalent to opening all the windows and losing all the warm air in the room every half an hour!  A house with decently sealed windows and doors won't come close to that.

Me too, probably the majority TBH.  In the end, once I knew what I wanted, I specified that and included the evidence of loss in the request for quote.  Any who told me that they 'couldn't' take notice simply weren't shortlisted.  

Posted by: @judith

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batpred: 

 

Anyway, we know that the assumption the heat pump will be running continuously is based on the fact a cylinder is assumed to be always part of the solution. This essentially means unless it is a massive property, the system is never going to be powerful enough to provide direct hot water for showers etc. And don't start me on the electricity capacity, we know these pumps run on a normal socket circuit like normal air cons. 

 

You seem to need to air your incorrect prejudices. You are very ill informed.

ASHPs NEVER use a normal socket nor circuit and if wired like that it is very unsafe and un-compliant 
ASHPs provide plenty of hot water for showers for any number of occupants and don’t need top up immersion heaters either. It’s a question of the size of cylinder (or phase change heat storage like Mix-energy) and stored water temperature. The heating is off is when the hot water is heated so is often set at night, on the cheapest power rate.

Apologies if required Judith, as I had no intention to offend anyone! And no offense taken.  

Of course I am not suggesting a normal socket being used. Anyone would be best advised to use a certified electrician to set them up anyway.

Just stating that, as things stand, most people will have a small heat pump installed that will run from a circuit designed to supply 16A. These type of fixed appliances will of  course be wired in (like gas boilers are meant to, etc) and not plugged on a socket.

But when we say an 8kw heatpump, this is not using 32A. If it has a COP of 4, it draws 2k, so less than 10A.  

Please correct me if I missed anything. 

Posted by: @batpred

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What I mean is that, given it is healthier to have a cooler environment to sleep than when people are active, when the systems are being systematically being setup to maintain constant temperature, when each design is created, arguably it misses a default requirement. I had not even looked at the document you reference. I am not sure if this was done to maximise operating efficiency or the system but it does not facilitate user centered design. 

Sorry but the document I quoted is a requirement for an MCS installation and specifically specifies different design temperatures for bedroom (where people sleep) and living room (where people are active).  Every design I have seen has respected these differences.  This being the case what is the evidence for your statement? 

Posted by: @batpred

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Would there not be cases where a user would like the pump to deliver hotter heating water to avoid resizing circuits, etc? 

Yes there may well be IMHO and some installers will offer this, whereas others insist on designing for maximum efficiency.   The heat geek 'zero disruption' initiative is an example where they specifically offer minimal upgrades as an option.  Others on here have been critical but for my money, provided it is positioned and explained correctly, it is offering choice which is not a bad thing.

Posted by: @batpred

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From what I saw people are being asked to pay for these reports upfront. Is the report then just used by a single installer to create a proposal based on the products they use? Or is it available for the user to provide to other installers so they can make their proposals? 

If the user has paid (and unless there is a contractual clause to the contrary) it is the users property but other installers will, at least in my experience, generally not accept it for obvious liability reasons.  So in reality its installer specific.

Posted by: @batpred

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...

Having HA concerning itself with what are aspects more likely to change like pricing and having to take into account a growing number of systems seems more future proof. Still, given the way that many HA device facing integration components are tested (and sometimes even "designed"), it is not conducive to high availability. E.g. being able to use different methods to monitor a device on the modbus rather than having one integration flow and assume it will be stable enough may be the only example. That way maybe the "layer" can be relied on. 

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That doesn't make much sense. HA can be implemented with as great a degree of redundancy as you might wish, and many different strategies for doing so - ultimately overkill for almost all domestic situations.

Posted by: @batpred

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Posted by: @majordennisbloodnok

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As for putting batteries through 8000 cycles, I would agree; not much of a problem. However, with Octopus Agile providing half-hourly prices, it wouldn't be difficult to put a battery through hundreds of thousands of cycles in the name of, as you put it before, "pushing the boundaries of optimisation", and yet realise just a few quid more than a dramatically simpler strategy that provides almost as much benefit for almost no effort to implement. It's the 80:20 rule on steroids.

The cycles that manufacturers quote are complete, from nil to full. So charging twice from 20 to 70 is one full cycle.

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I'm very well aware. This is not my first rodeo.

Posted by: @batpred

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But as others pointed out, there may be electronic components that cannot be reprogrammed more than x,000 times.

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Once again, I'm very well aware. If you look back, you may find me being one of those doing that pointing out.

Posted by: @batpred

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When I mentioned pushing the boundaries of optimisation, I meant moving from having to configure components and install cables to change the way battery or grid are used to using an HA based system.

With respect, all you're talking about is using HA for the job it was designed to do. Not sure that's pushing boundaries - except, of course, for anyone relatively new to HA, in which case they're pushing their boundaries, not Home Assistant's.

@batpred There will be times when the 8 kW heat pump starts up with a surge much higher than 2 kW and also when adverse weather drags the COP down, there may well be periods where that same pump could draw far more than that 2 kW for an extended period of time. Regards, Toodles.